Teaching and Learning

Accreditation period Units 1 and 2: 2023-2027; Units 3 and 4: 2024-2027

A range of suggested learning activities have been provided for each area of study in Units 1–4. It should be noted that the activities included cover a range of the key knowledge and key science skills for each area of study, but not all of them. Some activities could be completed within one class and others could be completed over an extended period. They include learning activities that involve group work, class discussion, practical application of scientific skills and synthesis of knowledge and skills in written responses. Some of the learning activities have been tagged to provide examples of how the eight scientific investigation methodologies relevant to VCE Chemistry can be applied in each unit. Many of the learning activities could be adapted for use in other areas of study or units, or developed into assessment tasks. All are intended to be examples that teachers may use and/or adapt to suit the needs of their own students.

Included external links are for teacher reference purposes. They do not constitute VCAA endorsement of the views or materials contained on these sites and teachers need to ensure that any information or activities are appropriately adapted to meet the requirements of the VCE Chemistry Study Design Units 1 and 2: 2023–2027; Units 3 and 4: 2024–2027.

View Sample teaching plans.

Unit 1: How can the diversity of materials be explained?

Outcome 1

On completion of this unit the student should be able to explain how elements form carbon compounds, metallic lattices and ionic compounds, experimentally investigate and model the properties of different materials, and use chromatography to separate the components of mixtures.

Examples of learning activities

Key knowledge: Elements and the periodic table

Simulation: Use simulations to investigate atomic structure; for example, Build an Atom to model atomic composition, and consider isotopes and atomic mass to calculate atomic weights.
Literature review: Research a selected isotope and write a media article or produce an infographic on the usefulness of the isotope, from secondary sources such as the IUPAC Periodic Table of the Elements and Isotopes.
Literature review: Investigate the uses of radioactive isotopes and discuss the advantages and risks associated with their use; for example, tracers used in medicine and agriculture, or the use of C-14 by archaeologists and geologists.
Literature review: About 25 different radiopharmaceuticals are routinely used in Australia's nuclear medicine centres, the most common being technetium-99m. Write a short article, intended for a general audience, to explain how a selected radiopharmaceutical works.
Interpret a series of ionisation energies as evidence for electron shells and subshells.
Use the interactive periodic table to explore the arrangement of electrons in shells and subshells, and to visualise patterns, trends and anomalies in the properties of the atoms and elements.
Discuss Herbert Spencer’s quote that ‘Science is organised knowledge’ in terms of the value of placing elements into a periodic table.
Classification and identification: Conduct experiments demonstrating trends within the periodic table based on data related to the physical and chemical properties of a selection of elements and their position in the periodic table. Work in groups to predict the properties of other elements; compare predictions with actual properties.
Classification and identification: Investigate practically the trends in reactivity as you go down a group in the periodic table; for example, the alkaline earth metals or the halogens.
Simulation: Use an interactive digital representation of the periodic table to model how trends such as electronegativity, first ionisation energy and melting / boiling point are exhibited across the elements of the periodic table.
Classification and identification: Investigate alternative representations of the periodic table, such as the periodic table of endangered elements or the periodic table of scarcity, which illustrate the relative amount of each element available for utilisation in society; discuss why multiple formats for the arrangement of elements in a periodic table are useful.
Classification and identification: Compare the chemical properties of main group metals and transition metals; for example, reaction with water and reaction with acid (where safe), including testing for products and formation of colourless and coloured compounds.
Create a periodic table using representations of the electronic structures of elements 1–36; annotate the table to highlight trends in structures and properties.
Case study: Select an endangered element and use the information on individual elements to summarise why it is endangered and what can be done in the future to conserve the element. Work in small groups to argue that your selected element should be prioritised by society in taking action for conservation.
Product, process or system development: Develop an endangered element ‘Top 10’ list equivalent to the ‘Red List’ of endangered animal species, justifying selection of elements.
Literature review: Investigate another ‘trend’ in the periodic table, namely the recyclability of the element. Compare the properties of the 30–35 elements often found in electronic devices, to establish what makes separation and recovery of most elements difficult.

Key knowledge: Covalent substances

Simulation: View computer-generated models of covalent molecular compounds and compare the naming of the molecular and electron geometry of common polyatomic molecules.
Literature review: Research on the internet, using secondary sources, how computer modelling of molecules can be used in medicinal drug design and customisation of polymers for purpose.
Modelling: Individually create ball-and-stick models of simple polyatomic molecules of different shapes; for example H₂, Cl₂, O₂, HCl, H₂O, NH₃, CH₄, CO₂, C₂H₆ and C₂H₄. Sketch them using appropriate chemical conventions to indicate their three-dimensional shape; annotate the models to show polarities and to explain their shapes. Bring together the different molecular models to show the alignments of the molecules and annotate them to show the operation of the intermolecular bonding forces.
Simulation: Use an interactive applet to build simple monoatomic and polyatomic molecules, and associate common molecule names with multiple representations.
Graph the boiling points of alkanes and explain these in terms of intermolecular bonding.
Demonstrate molecular polarity by the deflection of liquids using a static electrical charge; for example, a charged rod will deflect a stream of water from a tap.
Simulation: Simulate how the relative electronegativity of different atoms in a polyatomic molecule affects the molecule’s polarity and predict molecular polarity using bond polarity and molecular shape.
Investigate the polarity of molecules by making bush soap from acacia leaves and compare the capacity of different species of acacia to form a soapy foam. (see Detailed example 1)
Use a predict-observe-explain approach to investigate volume contraction in alcohol-water mixtures. (see Detailed example 2)
Simulation: Build a molecule by utilising the Lewis Dot structures of atoms using ‘Molecule Builder’.
Controlled experiment: Investigate the relationship between the number of hydroxide bonds in a molecule and the strength of the hydrogen bonding by comparing the rate at which a small marble sinks in test tubes containing propan-1-ol, propane-1,2-diol and propane-1,2,3-triol.
Literature review: Investigate some allotropes of carbon and research the technological innovations that apply to these allotropes; present an infographic or information sheet that summarises your findings.
Explain the properties of graphite in ‘lead’ pencils; distinguish between different grades of pencil in terms of the HB graphite scale, including applications; for example, explaining the circumstances in which artists would use a 4B or 2H pencil.
Product, process or system development: Create and annotate models of diamond, graphite, a ‘buckyball’ and a carbon nanotube; compare similarities and differences between their structures; explain their properties in terms of their structures.

Key knowledge: Reactions of metals

Modelling: Participate in group work to model the structure and properties of different metals.
Classification and identification: Compare the physical properties of metals, for example malleability, hardness, electrical conductivity, heat conductivity, and density.
Investigate iron’s position in the reactivity series by heating it with copper and magnesium oxides.
Controlled experiment: Perform simple displacement reactions with pieces of different metals, dilute hydrochloric acid and metal nitrate solutions, to deduce an activity series of metals.
Simulation: Simulate the change to the representation of the metal ions and free-moving electrons when a metal is hit with a hammer.
Classification and identification: Compare the chemical properties of main group metals and transition metals, for example, reaction with water and reaction with acid (where safe), including testing for products and formation of colourless and coloured compounds.
Controlled experiment: React magnesium and calcium with hydrochloric acid to find out which is the most reactive, and generalise the findings to determine the reactivity of group 1 and 2 metals.
Controlled experiment: Measure the relative level of corrosion in different atmospheric conditions, by conducting a controlled experiment varying the corrosion of metals in dry air, moist air and air polluted by acidic sulfur dioxide.
Extract copper from a solution of a copper ore using electrolysis and / or extract copper by heating malachite and carbon.
Illustrate Dalton’s theory that atoms are rearranged in chemical reactions by carrying out a series of experiments whereby a sample of copper metal is reacted to form a series of copper compounds and then extracted as the metal.
Modelling: Model the properties of alloys, for example using plasticine and sand.
Controlled experiment: investigate experimentally the effects of annealing, quenching, and tempering on metals using metal pins or nails; determine which type of heat treatment results in the hardest and / or the strongest metal.
Literature review: Students access secondary sources on the internet to investigate innovative processes for metal recycling from electronic devices, including hard to recover metals such as gold and silver. Students can compare these processes with crude, hazardous chemical processes using strong acids, utilised predominantly in low- and middle-income countries, leading to serious toxic residue build-up.
Case study: Create a presentation or infographic on “metal recycling”; choose one metal of interest; explain why that particular metal needs to be recycled; identify whether the metal can be considered to be endangered; outline a common recycling technique and explain how it contributes to a “circular economy”.
Fieldwork: Visit a community facility that is involved in metal recycling; draw a flowchart of processes involved in the recycling; discuss how any ‘linear economy’ processes can be improved to move towards a ‘circular economy’.

Key knowledge: Reactions of ionic compounds

Modelling: Participate in group work to model the structures and properties of different ionic compounds.
Investigate the physical properties of ionic compounds; for example, malleability, hardness, density, electrical conductivity, and heat conductivity.
Examine mineral crystals using a hand lens and a stereomicroscope; investigate the factors that affect ionic crystal formation over time; for example, temperature, humidity.
Simulation: Build an ionic compound from its component ions by using the ‘Ionic Compounds’ mode (Molecule Builder).
Simulation: Use an interactive applet to investigate both ionic and covalent bonding; interact with as many combinations of atoms as possible to determine the type of bond and the number of atoms needed to form each compound.
Classification and identification: Implement a sequence of small confirmatory tests to identify the presence of anions and cations in salts, and to then identify the ions in different samples of unknown ionic salts.
Participate in the RACI crystal growing competition.
Controlled experiment: Investigate the types of substances that conduct electricity and test the conductivity of covalent and ionic substances in solid and molten states to demonstrate that covalent substances never conduct electricity even as a liquid, whereas ionic compounds conduct when in molten form.

Key knowledge: Separation and identification of the compounds of mixtures

Classification and identification: Create a table to classify given substances according to their polarity (polar or non-polar character) and predict their solubility in a range of solvents.
Controlled experiment: Perform a chromatography experiment to purify a mixture of organic substances.
Explain why different solvents (for example, water and turpentine) are required to clean paint brushes.
Product, process or system development: Make a lava lamp and explain how the concepts of polarity and density are demonstrated by the lava lamp.
Literature review: Research the role of emulsifiers in foods (for example, French dressing compared with mayonnaise) or cosmetics (for example, the use of beeswax in skincare products).
Make soap from acacia leaves or green seed pods (see Making bush soap. Compare the soapiness produced by different species of acacia plants; compare the experimental procedure with the procedure used at Science In First Language – Bush Soap – YouTube.
Controlled experiment: Capillary action, or capillarity, can be demonstrated by the tendency of a liquid to rise in a narrow tube and results from the intermolecular attractions within and between the liquid and solid materials. Investigate capillary action by formulating hypotheses and undertaking experiments for one of the following research questions:
- Is capillary action related to the polarity of the liquid?
- How does the capillary diameter affect capillary action?
- How is capillary action affected by different capillary tube materials; for example glass or plastic?
- Does temperature affect capillary action?
- How does capillary action differ for polar liquids of different densities?
- How does capillary action differ for non-polar liquids of different densities?
Simulation: Use a simulation of the separation of plant pigments (spinach, maple) being separated by paper chromatography to demonstrate how the Rf values of components separated (carotene, xanthophyll, chlorophyll a and b) vary according to the solvent used.
Fieldwork: Collect natural materials from the environment (fallen leaves, petals, peeled bark) and develop a hypothesis related to the coloured components of the materials; for example, that leaves from deciduous trees contain pigments in summer that are not present in winter, or that the yellow colour in different flowers contains the same pigments. Test hypotheses by using chromatography to separate pigments and measuring their Rf values.
Simulation: Compare the movement of more / less polar molecules in a thin layer chromatography simulation, when more / less polar solvents are used.

Detailed example 1

Making bush soap from acacia leaves

Aim

To make soap from acacia leaves as an application of the polarity of a group of chemicals classified as saponins.

Introduction

Aboriginal knowledge systems extend to the use of native plants that can be found across the continent. These plants have not only provided a source of food for Aboriginal people but have also provided medicines and tools. Aboriginal people also discovered that they could use native plants to help maintain cleanliness, which helped to ensure ongoing health and wellbeing. Just like the soaps and detergents we use today, Aboriginal people discovered that leaves from particular trees would foam up into a soapy lather that could be used as a cleaning agent.

The active ingredients in plant materials that produce a soapy lather are known as saponins. These molecules are amphiphilic, having both polar and non-polar ends on their molecules.

Science skills

Teachers should identify and inform students of the relevant key science skills embedded in the task.

Health and safety notes

Students may want to wear gloves in case of skin sensitivity to plant products.

Procedure

Materials needed:

3–5 leaves or green seed pods from an acacia tree
2 x beaker
tap water
drinking straw

Preparation:

This practical investigation can be performed outdoors or within the laboratory. Ideally, an acacia tree will be located on the school grounds. If not, the teacher may need to collect the leaves or seed pods prior to the lesson. If collecting samples prior to the lesson, ensure the leaves are stored in an airtight container until ready for use as this will prevent the degradation of saponins.

Various acacia species can be used for this experiment. However, some species contain more saponin content than others. It may be best for the teacher to first try some samples. Alternatively, different acacia species could be investigated and compared.

If an appropriate acacia species is on the school grounds, this is a good opportunity to explain to students that Aboriginal people learnt their skills from interacting with the natural environment and that science does not only occur in the laboratory.

Students should collect or be given 3–5 leaves or seed pods from an acacia tree. The more the better. However, care should be taken to ensure that not too many leaves are taken from any single tree. If only a single tree is available, make sure leaves or seed pods are collected from different parts of the tree. Ideally, sample collection will be taken from multiple trees.

Method

Part A Making the bush soap

Take leaves or seed pods and scrunch them into your hands before rubbing the leaves between your hands for a couple of seconds.
Apply water to hands by either dipping in a basin of water or pouring water over hands. Not too much water is needed.
Vigorously scrub hands until soap-like foam is formed.
Wash away soap.

Leaves or seed pods can be reused to examine the foaming action.

Part B Foaming action

To demonstrate the foaming action caused by saponins, the saponins can be extracted from the leaves through a simple water extraction.

Add the previously used leaves or seed pods to a beaker of water and let soak for a few minutes.
Taking a drinking straw, blow bubbles into a beaker containing tap water. This will demonstrate how bubbles act in a relatively pure liquid (i.e. bubbles rupture when leaving water surface).
Next, blow bubbles with the straw into the water containing the extracted saponins. A foaming effect should result.
Extension: Students could design and conduct an experiment to quantitatively compare the foaming capacity of different acacia species.

Questions

A series of graded questions could be set for students to answer in their logbook, for example:

Compare: How do the results of different students in the class compare in terms of the foaming capacity of a selected acacia species? Different acacia species?
Generalise: Can the results from the foaming capacity of one acacia species be generalised to other acacia species? Why or why not?
Identify: Suggest factors that may affect the capacity of a species of acacia plant to show foaming capability.
Design: Develop a procedure to quantitatively compare the ability of different species of acacia plants to be used as soaps; for example, a procedure to compare foam heights.
Research: Use the internet to research the terms ‘hydrophilic’, ‘hydrophobic’, ‘micelles’ and ‘saponins’ and prepare an information sheet that illustrates the chemistry of saponins and soaps.

Detailed example 2

Predict-observe-explain: Investigating volume contraction in alcohol-water mixtures

Aim

To investigate and explain volume contraction in terms of relative bonding strengths within and between covalent substances.

Introduction

When ethanol and water are mixed together the final volume is less than the sum of the separate volumes before mixing. This shrinkage is known as ‘volume contraction’ and is due to the strength of hydrogen bonding. Hydrogen bonding is classified as weak bonding but is stronger between water molecules than it is between alcohol molecules. This contraction can have vital consequences in everyday applications; for example, alcohol absorption into the bloodstream where the resultant volume contraction can upset the plasma concentration of various chemicals in the blood and result in a number of medical complications.

Science skills

Teachers should identify and inform students of the relevant key science skills embedded in the task.

Health and safety notes

Safety data sheets should be made available for all chemicals used by students.
Safety warning: alcohol water mixtures can burn even when the amount of alcohol is less than 50%, especially at higher temperatures.

Procedure

Part A

Students:

Measure the volume contractions due to various mixtures of ethanol and water and enter data into a table in the logbook.

Volume of water (mL)	Volume of ethanol (mL)	Final volume of mixture (mL)	% contraction
25.0	75.0
50.0	50.0
75.0	25.0

Use the data to determine the point of maximum contraction (further proportional mixes of water and ethanol will be required – enter data into the table).

Part B

Teachers use a predict-observe-explain approach to explore students’ understanding of the bonding within and between molecular substances, including that the strength of dispersion forces becomes more significant as the molecular mass of an alcohol increases.

Students complete the following table by making predictions about different experiments related to volume contraction, investigating and recording observations related to the experiments and explaining their observations in terms of the bonding involved.

Experiment	Prediction	Observations	Explanation in terms of bonding
If volume contraction is due to hydrogen bonding, predict what will happen when water is mixed with methanol
If volume contraction is due to hydrogen bonding, predict what will happen when water is mixed with propan-1-ol
If volume contraction is due to hydrogen bonding, predict what will happen when water is mixed with propan-2-ol
If volume contraction is due to hydrogen bonding, predict what will happen when water is mixed with methyl propan-2-ol
If volume contraction is due to hydrogen bonding, predict what will happen when water is mixed with butan-3-ol
If heat affects the strength of hydrogen bonding, predict the % contraction over a range of temperatures

Questions

A series of graded questions could be set for students to answer in their logbook, for example:

Compare: In what ways is volume contraction similar to, and different from, combining sand and marbles in a jar?
Explain: Use a series of annotated images, including reference to intermolecular bonding, to illustrate how temperature affects volume contraction.
Evaluate: Collate class results for volume contraction and comment on the accuracy, precision and validity of the results.
Generalise: Suggest a relationship between nature of hydrogen bonding and volume contraction.
Reflect: Review your predictions in this activity and comment on Vera Rubin’s quote that: ‘Science progresses best when observations force us to alter our preconceptions’.
Imagine: Under what circumstances could volume expansion occur?

Outcome 2

On completion of this unit the student should be able to calculate mole quantities, use systematic nomenclature to name organic compounds, explain how polymers can be designed for a purpose, and evaluate the consequences for human health and the environment of the production of organic materials and polymers.

Examples of learning activities

Key knowledge: Quantifying atoms and compounds

Simulation: Use an interactive applet to visualise how particles of an atom or molecule sample are separated and visualised as their different relative atomic masses in a mass spectrum.
Perform calculations of relative atomic masses from abundances and relative isotopic masses.
Solve quantitative exercises involving the mole and Avogadro’s constant.
Determine experimentally the percentage, by mass, of magnesium in MgO or copper in CuSO₄.
Determine experimentally the empirical formula of an ionic compound; for example: copper(II) oxide from its reduction by methane; hydrated copper(II) sulfate by comparing the mass before and after heating; and magnesium oxide by heating.
Solve quantitative exercises involving empirical and molecular formulas of organic compounds.
Complete the worksheet, ‘What’s in a meteorite?’ to develop skills in data presentation and interpretation, accessed through the Royal Society of Chemistry (free resources after login).
Create a classroom display of one mole of different substances (students weigh out the different substances after calculating the mass required).
Modelling: Visualise the mole by calculating how deep a ‘blanket’ of a mole of marshmallows over Australia would be, or how high a ‘tower’ made from a mole of dollar coins or sheets of A4 paper would reach, or how long it would take to count a mole of marbles if you counted one every second every day until finished.
Watch the video, ‘A Mole is a Unit!’ to appreciate the mole as an SI base unit of the amount of substance.
Use examples of numerical problems in chemistry to discuss the relationship between the number of significant figures in the answers and the precision and resolution of the initial measurements.

Key knowledge: Families of organic compounds

Fieldwork: As an introduction to organic chemistry, capture an image of a local environment inside or outside the classroom. Print the image and label all physical objects, or parts of objects, as ‘organic’ or ‘inorganic’. Later, re-visit the labelled image and re-label objects as required.
Modelling: Use a MolyMod kit, plasticine with toothpicks or MolView (an online tool) to create models of, and name, a range of alkanes, alkenes and alkynes, including structural isomers, haloalkanes, alcohols, carboxylic acids. Translate each model into a 2D representation drawn in workbook and name according to IUPAC systematic nomenclature; group each model into families.
Use a closed capillary to determine the boiling points of methanol, ethanol and propanol.
Literature review: Research how organic chemicals such as solvents, pharmaceuticals, adhesives, dyes and paints are commonly produced from fossil fuels. Discuss the benefits as well as the impact of these on health and environment; justify why renewable plant-based biomass is a good alternative to fossil fuels.
Fieldwork: Visit an olive leaf distillery or oil refinery; use images and brief descriptions to summarise processes; identify safety precautions involved in processing; note in logbook three points of interest.

Key knowledge: Polymers and society

Literature review: Identify an object that could be made from a polymer and research how a particular set of properties could be achieved in the object through a selection of appropriate monomers or polymer characteristics.
Controlled experiment: Make edible, biodegradable food-safe calcium alginate beads (edible water capsules) and investigate how varying the pH and concentration of acidic beverage juices used impacts the stability and durability of the water capsules formed (see Detailed example).
Controlled experiment: Make absorbable medical sutures from renewable feedstocks, and compare their tensile strength and degradation with commercially available absorbable and non-absorbable sutures.
Modelling: Work in groups to create multiple models of the ethene molecule; join them up to form a segment of a polyethene (PE) molecule; modify the models of ethene molecules to create models of propene molecules and join them to build a model of a segment of a polypropene (PP) molecule. Repeat to build models of vinyl chloride molecules and a segment of a polyvinyl chloride (PVC) molecule; use data about the mean mass or length of PE molecules to calculate how long a model of a complete PE molecule would be on this scale; use the models to compare and explain their properties and uses.
Investigate natural polymers by using the protein casein to make a polymer glue from milk by first separating the casein from milk by coagulation and precipitation; test the glue for strength by sticking together two lolly sticks and attaching weights to them.
Controlled experiment: Collect common biodegradable and non-biodegradable single-use plastics sold in supermarkets and deliberately degrade them (excess light stimulation, UV light, abrasion, soaked in solutions at different pH). Relate their increasing degradation to the structure and behaviour of the monomer of the polymer.
Case study: Evaluate the re-purposing of non-biodegradable plastics (i.e. end-of-use plastics) that we will still need for many applications (polyethylene gas pipes, Perspex windows), and relate these to the structure, properties and behaviour of the monomer and native polymer.
Investigate the motion of water droplets falling on a hydrophobic surface (for example, coated with Teflon or soot).
‘Slime’ is used in hot or cold packs because it is not dangerous if it leaks out, and is formed when polyvinyl alcohol (PVA) has been cross-linked by the addition of borax Na₂B₄O₇.10H₂O (sodium tetraborate). Use a standard recipe for slime and investigate experimentally the effects of: 1) changes in amounts of borax on viscosity of the slime, 2) changes in pH on the properties of slime.
Design and undertake experiments to investigate whether there is a difference in the recyclability of thermosetting and thermoplastic polymers.
Classification and identification: Investigate experimentally the physical properties of thermoplastic and thermosetting polymers. Look at: electrical and heat conductivity, density, hardness, response to immersion in a hot water bath, reaction when a very small sample is exposed to a flame.
Fieldwork: Organise a site tour to a polymer manufacturing or recycling plant; summarise processes, safety aspects and three major points of interest in logbooks.
Product, process or system development: Develop a ‘sustainable city’ concept in the form of an infographic, which must apply the ‘circular economy’ idea of how the city uses biodegradable plastics (bioplastics) and innovative polymer materials which can be broken down using hydrolysis reactions.
Case study: Discuss the process of thermal depolymerisation – published as a lesson plan by the Royal Society of Chemistry (free subscription). Draw a flow chart that explains the process. Explain whether the process is an example of a circular economy. Identify the green chemistry principles that have been utilised in the development of this process. Discuss some of the ethical issues that arise from the process; for example, ‘Should vegetarians use oil made from turkey waste?’, ‘Should oils made from animal products be labelled?’, ‘Does the high energy required to produce useful materials from the waste justify the recycling process?’

Detailed example

Edible water capsules – a biodegradable co-polymer designed to degrade

Introduction

This highly engaging practical activity involves students making a calcium alginate co-polymer in such a manner that forms beads or capsules containing water inside. Being made from food-safe feedstocks, these gel-like beads are effectively liquid capsules that can be easily bitten or torn to release the liquid inside. Innovation globally is focused on marketing these to replace and reduce the production of plastic drinking containers. Notpla is a sustainable packaging company that has demonstrated the application of biodegradable, edible sachets that naturally degrade in 4–6 weeks, compared to over 750 years for traditionally designed sachets.
The co-polymer, calcium alginate is formed by adding together calcium lactate and sodium alginate, which are both safe, renewable, and inexpensive. Sodium alginate is a naturally occurring chemical derived from brown algae (macro algae better known as seaweed). Calcium lactate is prepared from lactic acid, potentially derived from corn, and calcium carbonate. The waste generated producing these beads is environmentally safe. The calcium alginate beads can either be eaten or are readily biodegradable.
A simplified version of the chemistry involved can be explained at a Unit 1 level. Essentially, the sodium ions (Na⁺) in sodium alginate are replaced by calcium ions (Ca²⁺). As a 2+ ion, the calcium ions are able to electrostatically interact with the carboxylate groups (RCOO^-) of two different alginate chains, leading to the weakly cross-linked co-polymer calcium alginate. The chemistry is explored further in the publicly available in an article in Chemistry Teacher International described in the teacher notes below.
If it has not been introduced already during Unit 1, this fun practical activity is a tremendous opportunity to demonstrate to students the application of green chemistry principles. This activity clearly demonstrates designing safer products with benign chemicals, the use of renewable feedstocks, and designing to degrade.
Materials required: Relevant glassware, 0.6% w/v sodium alginate stock solution (0.6 g in 100 mL deionised water), 0.6% w/v calcium lactate stock solution (0.6 g in 100 mL deionised water), food colouring solution (blue, green, red), disposable pipettes with the tip cut off or large measuring spoons for bigger beads, spoons, petri dishes or watch glasses.

Science skills

Teachers should identify and inform students of the relevant science skills embedded in the task.

Health and safety notes

Students should understand that while these beads have been made with food-safe feedstocks, they have been made with chemical laboratory equipment in a school laboratory. Students should therefore be strongly advised to not eat the calcium alginate beads. Alternatively, the experiment could be conducted using plastic containers and measuring spoons in a non-laboratory teaching space.

Method

Add 50 mL of the prepared 0.6% w/v sodium alginate solution into a clean beaker. Add a few drops of coloured food dye and stir with a glass stirring rod to have a consistently coloured solution.
Add 50 mL of the prepared 0.6% w/v calcium lactate solution into a separate clean beaker.
Using a plastic pipette that has had the tip cut off (to make a bigger opening and thus bigger drop), take in some coloured sodium alginate solution and add 3–5 drops slowly to the calcium alginate solution. This video link demonstrates the procedure.

Diagram 1

(For much bigger drops, a measuring spoon (i.e. 1 tbsp) can be used. Tilting the beaker containing the sodium alginate solution, lift out one spoonful of solution. Likewise, tilt the beaker containing calcium alginate and carefully lower the spoon into the calcium alginate solution. After a few seconds, turn the spoon upside down and let the bead fall out of the spoon and into the solution. This technique may need a few goes to get right).

Allow the drops to sit in the calcium lactate solution for 15 minutes. While the beads are forming, record your observations.
After 15 minutes, remove beads from the solution using a plastic spoon, and place on a petri dish or watch glass.
Record physical observations of the beads. Consider the texture, shape and firmness of the bead. Also consider whether it regains its shape when it is gently squeezed. Compare your group’s beads with other students.
Any excess sodium alginate and calcium lactate solutions can be poured together to form solid calcium alginate waste that can be placed in the bin. Any remaining liquids can be poured down the sink.

Discussion questions and report writing in logbook

Students can record their observations taken while the beads were forming in the beaker, and report on the firmness, shape and texture of the beads formed. If time permits, students could leave their beads under exposed light and test their durability a few days or a week later.
Relevant follow-up questions would encourage students to articulate how selected green chemistry principles or aspects of the circular economy are being addressed in this experiment.

Teacher notes

This practical activity has been modified with permission from an experiment designed by the University of Minnesota Centre for Sustainable Polymers (CSP). The CSP have designed a number of high school laboratory activities, including this calcium alginate experiment, an experiment making polymeric medical sutures, and a bioplastic that releases a dye as it degrades, which can be measured using colourimetry. Resources include teacher guides, student worksheets, suggested tables for students to record their observations, technical information about the practical, and worked solutions.
There are numerous ways that this experiment can be modified to extend the student inquiry focus. The original experiment described in the Chemistry Teacher International article describes students investigating the effect of pH on the durability of the beads formed. Reducing the pH increasingly protonates the carboxylate groups (RCOOH), which reduces the amount of cross-linking occurring. The effect of different concentrations of citric acid, or different juices can be investigated. The shape, texture and ability to hold its shape can be measured. The contact angle of the bead formed could also be quantitatively measured with free software program such as ImageJ for a more quantitative experimental analysis.
This practical activity could be undertaken in Unit 2 where pH is explored, in order to link to prior learning from Unit 1. This activity could also be undertaken as an engaging, design-thinking, focused, guided inquiry into biodegradable plastics at the lower and middle secondary level.

Outcome 3

On completion of this unit the student should be able to investigate and explain how chemical knowledge is used to create a more sustainable future in relation to the production or use of a selected material.

Examples of learning activities

General activities and approaches

Investigation topic 1: Endangered elements in the periodic table
Investigation topic 2: Producing and using ‘greener’ polymers
Investigation topic 3: The chemistry of Aboriginal and Torres Strait Islander peoples’ practices
Investigation topic 4: The sustainability of a commercial product or material

This area of study provides opportunities for students to identify, investigate and communicate the importance of considering green chemistry principles, sustainable development and the transition towards a circular economy in the production of chemicals or products for society. Teachers may elect to use a flipped classroom approach to support student agency.

Provide students with the list of the four investigation topics and associated questions in this area of study; organise students who have selected the same option to work in groups to research the key knowledge points in the study design; ask students to compare and summarise research findings; discuss and clarify concepts, discrepant findings and misconceptions that arise from student research.
Use a Socratic seminar to support student agency in exploring contemporary chemistry-related issues in society, for example, Socratic Seminars on the Victorian Department of Education and Training FUSE website (see Detailed example).
Create a short video or animation explaining how chemistry is used to create a more sustainable future for a specific audience, such as students, parents, politicians, business people.
Develop a visual representation, poster or oral presentation that explains how a manufacturing process has become ‘greener’.
Produce an infographic that includes quantitative data related to the advantages in moving from a linear to a circular economy in relation to the manufacture of a chemical or product.
Communicate a chemistry-based response to a socio-scientific issue, for example:
- Letter to a newspaper about the environmental advantage of recycling metals from e-waste metal recycling (Investigation topic 1)
- Opinion piece about banning the use of helium in balloons so that it is available to be used in medicine, scientific research, arc welding, refrigeration, gas for aircraft, coolant for nuclear reactors, cryogenic research and detecting gas leaks (Investigation topic 1)
- Petition to the local supermarket to ban products sold in single-use containers (Investigation topic 2)
- Advertisement promoting the advantages of the use of non-animal leather (Investigation topic 2)
- Poster comparing the properties of bush foods and equivalent non-Indigenous foods (Investigation topic 3)
- Catalogue of the bio-active ingredients in bush medicines (Investigation topic 3)
- Infographic showing quantitative improvements in the development of a product over time (Investigation topic 4)
- Feature article about the development of a new, more sustainable, ’greener’ product (Investigation topic 4).
The teacher selects questions from each of the four topic areas listed in the VCE Chemistry Study Design.

Detailed example

Use of socratic seminars to support student agency in exploring contemporary chemistry-related issues in society

Introduction

Socratic seminars can be used to develop students’ skills in questioning and communicating scientific ideas. These seminars value discussion rather than debate, and inquiry rather than information. They involve students discussing open-ended questions to which there may be a variety of views, listening to the comments of other students, and expressing their own ideas and their responses to the ideas of others. Socratic seminars require that students work cooperatively and question critically and politely. Students may respectfully challenge other students’ interpretations or offer alternative views. In this example, Socratic seminars will be used as a technique to support student agency in responding to a chemistry-related question of interest involving sustainable futures. The teacher uses it after students have selected a research question to investigate and have completed and collated their background research.

Planning before the Socratic seminar

Students self-select into groups to research a question of interest associated with one of four investigation topics listed on pages 26–29 of the VCE Chemistry Study Design, and related to the overall question in the area of study, ‘How can chemical principles be applied to create a more sustainable future?’

Time should be allocated for students to research their questions both inside and outside of class. Students may work in pairs on the same question, but each student must record their own background research and notes in their logbook, and present their own response to their research question.

Establish conduct protocols for the Socratic seminars with the class. Guidelines may include:

one person speaking at a time
everyone has a turn in speaking and asking questions
understanding that different people will have different points of view about controversial topics
ensuring that discussions focus on the arguments and views presented by each student without criticism of the person.

Either before the Socratic seminar, or at the initial stage, an open-ended question for each of the four investigation topics should be developed; for example, ‘How can endangered elements in the periodic table be saved?’, ‘How can ‘greener’ polymers be produced?’, ‘How can chemistry be used to explain some Aboriginal and Torres Strait Islander practices involving the use of natural substances?’ and ‘How can commercial products or materials be manufactured more sustainably?’

Implementation of the Socratic seminar

Step 1

Organise students into two equal groups for each investigation topic to form an inner circle and an outer circle.

Students in the inner circle should respond to the open-ended question relevant to their topic. They should not speak to the teacher; instead, they should speak to the other students in the inner circle. They should listen to each others’ ideas about the question and ask their own further questions to facilitate deeper understanding.
Students sitting in the outer circle should not speak during the seminar. They should observe and actively listen. They may record questions that could be presented to students in the inner circle at the end of the inner circle discussions, or they could present clarifying questions and / or comments to students in the inner circle at the end of the seminar, or they could be asked to summarise the main points in the discussions between students in the inner circle.
If teachers have organised more than one set of inner and outer circle seminars, then one student in the outer circle should be appointed to ensure that student discussions in the inner circle are on-topic.

Step 2

Swap the students in the inner and outer circles so that the students previously in the outer circle have the opportunity to discuss their ideas, and students previously in the inner circle listen to the second seminar and make notes, as in Step 4.

Step 3

Pair students – one from the inner circle and one from the outer circle – to undertake a think-pair-share reflection about the Socratic seminars. Students may share what they found interesting about the seminars, what points require further clarification, and / or how the discussions relate to the overarching area of study question as well as to their own research question.

Step 4

Conduct a debriefing session to evaluate the strategies that enabled a better understanding of the overarching area of study question and the individual research questions, and to discuss the feedback offered through the seminars.

Extension

Socratic seminars may also be used at the end of Unit 1 Area of Study 3 to provide students with an overview of various contemporary chemistry applications in society and how chemistry contributes to a sustainable future.
Students seated in the outer circle may be required to summarise the main points of the chemistry questions investigated by the class and presented in the inner circle of a Socratic seminar.

Unit 2: How do chemical reactions shape the natural world?

Outcome 1

On completion of this unit the student should be able to explain the properties of water in terms of structure and bonding, and experimentally investigate and analyse applications of acid-base and redox reactions in society.

Examples of learning activities

Key knowledge: Water as a unique chemical

Literature review: Summarise data from world maps showing freshwater distribution and proportion of available drinking water; interpret the data and discuss the trend of freshwater availability over time.
Case study: In groups, discuss how Australia manages its freshwater and whether our freshwater is scarce. Debate: Should we recycle our freshwater? Expand the discussion to a water catchment issue: the case of the Murray-Darling basin, using information here and here (select relevant extracts from these online documents).
Controlled experiment: Design and perform an experiment to determine the effect of temperature on the density of water.
Modelling: Produce an animation to illustrate why ice is less dense than liquid water.
Compare the specific heat capacities of water and cooking oil.
Create an imaginative response to the question, ‘What would Earth and its life forms be like if water followed the same trends in melting point and boiling point that are displayed by the other Group 16 hydrides?’
Use a Bunsen burner, paper cup, and balloon to investigate the thermal properties of water.

Key knowledge: Acid-base (proton transfer) reactions

Classification and identification: Perform experiments to differentiate between strong and weak acids on the basis of conductivity, pH and rate of reaction with magnesium.
In groups, discuss the relationship between the strength and concentration of acids and bases with the safety procedures for their use.
Classification and identification: Discuss and distinguish between the terms ‘accuracy’, ‘precision’ and ‘validity’ of collated class measurements of the pH of a variety of everyday solutions; for example, tap water, bottled mineral water, distilled water, saline solution, drain cleaner (sodium hydroxide), vinegar (acetic acid), dishwashing powder (sodium carbonate), cloudy ammonia, baking soda, battery acid (sulfuric acid), concrete cleaner (hydrochloric acid), albumin and yolk of an egg.
Investigate indicator colours at different pH values.
Product, process or system development: Work in groups to create a pH indicator chart using natural indicators (for example, red cabbage, turmeric, beetroot, onion skins, cherries, grape juice, curry powder, tomato).
Simulation: Use a pH Indicator Learning Tool to visualise the change in colour of a pH indicator as carbon dioxide gas is bubbled through an aqueous solution.
Case study: Discuss the development of litmus paper as an indicator by preparing a case study. Discuss the advantages and disadvantages of its use compared with pH meters. Debate whether the manufacture of litmus paper should continue in the future given that some varieties of the lichens that are used to produce it are becoming extinct.
Controlled experiment: Using dyes made from natural feedstocks (carrot tops, onion skins, black rice, dried flowers from tea bags), investigate how the colour formed when dyeing wool is influenced by the pH of the dye solution. (see Detailed example)
Controlled experiment: Use red cabbage pH indicator to test sample solutions and compare the results with litmus paper or other indicators. Collate class results and discuss the terms ‘accuracy’, ‘precision’, ‘repeatability’, ‘reproducibility’ and ‘resolution’ in terms of the data.
Modelling: Create a logarithmic scale that is compared with an arithmetic scale to show the relative positions of solutions with [H₃O⁺] of 1.0 M, 0.1 M, 0.01 M and 0.001 M.
Classification and identification: Identify possible components in antacids and summarise their advantages and disadvantages. Examine the labels of different antacids (both liquid and tablet forms) and compare the list of ingredients and possible side effects. Suggest a procedure to compare the effectiveness of different antacids.
Case study: Use a problem-based learning approach to investigate the applications of acid-base reactions in society; for example, source and effects of acid rain on living and non-living things, source and effects of ocean acidification on living things and the environment, effect of metal corrosion on marine and acidic environments, effect of the production of vast quantities of sulfuric acid as a result of extracting metals from sulfide ores.
Controlled experiment: Design an investigation to test the effects of solutions of different pH on the mass of calcium carbonate dissolved; relate findings to shell growth in marine invertebrates.
Reposition ‘test yourself’ questions relating to pH scale to engage students with the context of ocean acidification to explain why ocean acidification is an urgent issue to address for a sustainable future.
Simulation: Using data from National Oceanic Atmospheric Administration (NOAA) in the USA, explore relationships between carbon dioxide, ocean pH and aragonite saturation state. By examining these parameters using graphs and models, predict whether ocean conditions support the growth and survival of shell-building marine life, both now and in the future.

Key knowledge: Redox (electron transfer) reactions

Perform simple redox reactions; for example, combustion of magnesium and metal displacement reactions. Write balanced redox reactions including states; annotate equations to identify the direction of electron flow, oxidising agents, reducing agents, and conjugate redox pairs.
Perform experiments to determine the order of metals in a reactivity series; compare predictions with results (the experiment can be performed on a microscale). Discuss the advantages and disadvantages of performing experiments on a microscale.
Controlled experiment: Fold a 4 cm x 4 cm sheet of copper foil into the shape of an envelope (wearing eye protection) and light a Bunsen burner. Hold the copper envelope in tongs and heat strongly in the flame for 5 minutes. Place the copper envelope on a heatproof mat to cool. Open the envelope and compare the inside to the outside and record observations in your logbook. Explain results in terms of oxidation; devise an experiment to show that the effects on the outside of the envelope were not due to carbon formation.
Controlled experiment: Test the rate of corrosion of iron nails that are uncoated and coated with different materials, including different metal foils, and embedded in agar gel containing phenolphthalein. Record observations over a period of several days.
Controlled experiments: Illustrate iron’s position in the reactivity series by heating it with copper and magnesium oxide; investigate the effects of the pH level of a solution on the corrosion of iron and copper; investigate the effect of different atmospheric conditions on iron corrosion; explore different methods of corrosion prevention.
Literature review: Research current alloy technology that prevents corrosion.

Detailed example

The effect of pH on the colour formed from naturally dyed wool

Introduction

A common practical activity to introduce the concept of acid and base is to have students inquire into making pH indicator solutions from natural products (cabbage) and demonstrating their colour at different pH levels. While engaging in this inquiry, students are quickly moved on to other indicators (such as phenolphthalein and bromothymol blue) traditionally used in chemistry.
The practical activity below extends this ‘natural indicator’ concept further and applies it to a real-world context – the dyeing of wool fibres. The chemistry of wool yarn is complex, but at its simplest it can be described as an amphoteric material, as it contains both cationic (positively charged due to the presence of -NH₃⁺) and anionic (negatively charged due to the presence of -COO^-) reactive sites. Having both sites means a change in pH in either direction impacts the relative ratio of -NH₃⁺ and -COO^-, which in turn varies how the dye interacts with the wool.
This activity has two parts. First, dye solutions are made from natural products. Second, the pH of the solutions is changed in a systematic manner, and strands of wool are heated gently in the dye solution while students observe the new colour of the wool. Part 1 involves 30 minutes of heating and to save time, these solutions could be pre-made for the students. Alternatively, this step could be undertaken in a previous lesson with the dye solutions stored until use. Possible extension activities are outlined in the teacher notes below.
Materials required: Relevant glassware (small beakers, glass stirring rod), apparatus to heat solutions (a hot plate, or a tripod and gauze mat over a Bunsen burner), pieces of wool yarn cut to consistent length, acetic acid or vinegar, 1 M ammonia solution, a pen to label beakers, paper towel, natural products for dye solutions (green tops from carrots, yellow onion skins), kitchen equipment if needed (knife, chopping board), sandwich bags to store the dyed wool, pH strips or a pH meter.

Science skills

Teachers should identify and inform students of the relevant science skills embedded in the task.

Health and safety notes

Students should wear appropriate personal protective equipment because ammonia and its vapours can damage the eyes.
Students should be advised to not wear contact lenses during this experiment because gaseous vapours may condense on the contact lens and damage the eye. Dilute ammonia solution is used here, however it would still be prudent to use ammonia only in a well-ventilated area.

Method

Part 1: Prepare the dye solutions

Cut the carrot tops into pieces, with enough to fill approximately 100–150 mL of a 250 mL beaker. Fill to 250 mL with distilled water and place the beaker on the heating apparatus.
Likewise, take the onion skins and fill approximately 100–150 mL of a 250 mL beaker, cover with distilled water and place the beaker on the heating apparatus.
Raise the temperature of both solutions and let simmer (hot but not boiling) for 30 minutes.
Carefully decant the liquid from each solution into two clean, dry 250 mL beakers. Either use immediately, or label and store to conduct Part 2 in another lesson.

Part 2: Dying wool at different pH

With six small beakers (100–150 mL), separate both the carrot top solution and the onion skin solution into three equal amounts.
For one beaker of each solution, use a pH meter or pH strips to check and record the pH of the beakers. Label these beakers appropriately (control, or neutral pH).
For one beaker of each solution, add dropwise acetic acid (or vinegar) and stir until the pH is approximately 3–4 (requires 2–3 mL depending on how much dye solution is used). Use a pH meter or pH strips to check and record the pH of the beakers. Label these beakers appropriately.
For one beaker of each solution, add dropwise 1 M ammonia solution and stir until the pH is approximately 9–10 (requires 2–3 mL depending on how much dye solution is used). Use a pH meter or pH strips to check and record the pH of the beakers. Label these beakers appropriately.
Take one strand of wool yarn (cut to a consistent length, ~10cm) and add to each beaker.
Over a heating apparatus, heat gently (hot but not boiling) each beaker for 15–20 minutes.
Fill a large 500 mL beaker with warm tap water.
Using a glass stirring rod, lift the wool strand out of the beaker and dunk into the warm water. Swirl the wool strand around to rinse it thoroughly. Lift the thread out and place on a paper towel to dry.
For storage, the dyed wool can be kept in Ziploc or sandwich bags (the dyes will leach over time so it is not advised to keep the dyed wool in pockets!).

Discussion questions and report writing in logbook

Students should record their results in a table showing the dye solution used in each instance, the pH of the dyed solution, and the resultant colour of the wool yarn.
Students can be tasked to describe the ratio of -NH₃⁺ and -COO^- reactive sites on the wool strand at each pH.
Referring to pH, students could be asked to predict what would happen if each strand was washed with soapy water, which is basic.
Teacher notes
This practical activity example has been modified from a Natural Dyes Lab practical activity from Beyond Benign. The resource contains a teacher description of the two parts of the activity, along with a third part which involves students experimenting in a controlled manner to discover how the colour changes by the addition of a mordant (metal ions from CuSO₄, Al₂(SO₄)₃ or FeSO₄, that form coordination complexes with the dyes, improving the fastness of the bond between the dye and the natural fibre). The resource contains student sheets for the three activities along with worked solutions.
Another extension activity would be to test the fastness of the dye. The wool strands could be tested in a controlled manner to see how durable the colour formed becomes. The coloured wool strands could be rubbed on a rough surface systematically; they could be washed in a soap solution, or they could be left exposed to UV light for a set amount of time. It is likely the colour will disappear easily without the addition of a mordant (copper or alum) – see the third activity suggested by Beyond Benign).
In this activity, the green tops of carrot and yellow onion skins were used to form the natural dye solutions, but other natural products could be trialled. Recent studies have shown black rice, containing anthocyanin, to be an excellent natural dye. However, it is advisable to heat the black rice for a longer time, so this step should be pre-prepared for the students. Tea bags with dried flowers (dandelion, elderberry, camomile) will also work well.
In the dye industry, dyes are themselves often classed as basic (‘cationic’) or acidic (‘anionic’) dyes. While the chemistry of how dyes interact with reactive sites on fibres such as wool is complex, students could be encouraged to draw out the chemical structure of common acid and base dyes they find on the internet or in textbooks, and label the parts of the chemical structure that take part in acid / base reactions.
With a curriculum connection to Unit 1, students could investigate artificial fibres, and how dyes interact with these co-polymer-based fabrics. Students investigating fabrics will also discover that twice as much polyethylene terephthalate (PET) is used for fabrics than for PET bottles. Antimony, a heavy metal that is toxic to both humans and the environment, is used as a catalyst in the PET process, which poses a health and environmental concern when antimony is leached from the fabric. Green chemistry-relevant innovation is focused on making antimony-free artificial fibres for different applications.
Using natural dyes as opposed to artificial dyes will be an obvious sustainable development context for teachers and students to explore here. Another will be to consider the environmental impact of industrial effluent (waste solutions), and how these are being re-purposed in a circular economy.

Outcome 2

On completion of this unit the student should be able to calculate solution concentrations and predict solubilities, use volumetric analysis and instrumental techniques to analyse for acids, bases and salts, and apply stoichiometry to calculate chemical quantities.

Examples of learning activities

Key knowledge: Measuring solubility and concentration

Refer to the infographic, A Traveller's Guide to Tap Water and discuss the factors that make water ‘safe’ to drink; who determines what makes water ‘safe’ to drink?
Determine qualitatively the solubility of a variety of solid, liquid and gaseous solutes in water; write equations for substances dissolving in water.
Controlled experiment: In groups each with one of the research questions below, formulate hypotheses, design and perform experiments and reports on your chosen research question:
- Can a saturated solution of sodium chloride dissolve any Epsom salts?
- Can a saturated solution of sugar dissolve any Epsom salts?
- Can a saturated solution of Epsom salts dissolve any sodium chloride?
- Can a saturated solution of Epsom salts dissolve any sugar?
- Can a saturated solution of sodium chloride dissolve any sugar?
- Can a saturated solution of sugar dissolve any sodium chloride?
- How does solubility vary with temperature?
- How does solubility vary with the atomic mass of the solute?
- How does solubility vary with the polarity of the solute?
Prepare ionic substances by precipitation; for example, copper(II) hydroxide, copper(II) hydroxide, barium sulfate, silver chloride.
Prepare precipitates representing football club colours.
Use solubility rules to predict the outcomes of precipitation reactions and experimentally test the predictions; write ‘full’ and ionic equations for precipitation reactions that occur.
Design a procedure to identify an unknown salt dissolved in a water sample.
Examine the ingredients list of chemicals and foods for which solution quantities are provided. Convert between given units and alternate units of concentration; for example %(m/m), %(m/v), %(v/v), ppm and ppb, g L^-1 and mg L^-1.
Product, process or system development: Adapt a scale such as Mohs Scale of Hardness to develop a solubility scale.
Classification and identification: Collect, individually, an empty package of processed food that contains salt or sugar; calculate total amount of salt or sugar for the product contained in the package; produce a class display to show increasing salt or sugar content for the food products.
Use a multimeter to compare the total amount of electrolytes in various drinks; for example, tap water, mineral water, fruit juices, soft drinks, and sports drinks. Research and provide a brief report on the function of electrolytes in the human body.
Controlled experiment: Design and perform an investigation to determine the types of contaminants that alum can coagulate in water, whether there are optimal concentrations of alum that should be added to coagulate contaminants in a water sample, or how effectively alum can inactivate microbes in a contaminated water sample.
Fieldwork: Visit a water treatment plant; summarise the physical processes and chemical reactions involved in purifying the water.

Key knowledge: Analysis for acids and bases

Product, process or system development: Make sherbet to investigate an acid-base reaction. This involves thinking proportionally by scaling quantities.
Explain why acids should be added to water, rather than adding water to acids, when diluting acids or when undertaking acid-base experiments.
Perform dilutions of different solutions and calculate quantities at each dilution stage.
Prepare a standard solution of anhydrous sodium carbonate and use it to standardise a solution of hydrochloric acid.
Controlled experiment: Perform an acid-base titration and use volume–volume stoichiometry to calculate the concentration of an acid or base in a water sample.
Investigate the action of antacids by comparing the effectiveness of different antacids in the market. In groups, each allocated a different antacid, summarise the active ingredients and side effects of your allocated antacid. Each group performs an acid-base titration (for example, using methyl orange indicator and 0.5 M HCl) to calculate the average volume of acid neutralised per gram (or per mL) of antacid.
Product, process or system development: Formulate an effective antacid to neutralise a given volume of acid, trialling different proportions of common active ingredients found in commercial antacids (i.e. aluminium hydroxide, calcium carbonate, sodium bicarbonate, magnesium carbonate and magnesium hydroxide). Discuss other factors that need to be considered in antacid formulations apart from effectiveness in neutralising acids.
Simulation: Run a titration screen experiment on a computer or tablet. Carry out a strong acid versus strong base titration (or any combination of strong and weak acid-base titrations). On this site it is also possible to run a redox titration experiment (although this relates more directly to content in Unit 4 Area of Study 2) for further practise in understanding and skills, in order to become more confident and familiar with the procedures in the laboratory.
Participate in the RACI Victorian State Titration Competition.
Analyse and evaluate data from titrations in terms of accuracy and precision.
Investigate the acid content in different soft drinks by using a titration procedure.
Controlled experiment: Investigate the effect of acid rain on the growth of seedlings or leaves by simulating acid rain (mix water with vinegar or lemon juice) and using a spray bottle to spray 10 fast-growing seedlings (for example, radish, soybeans, marigold) with the solution daily for a week and comparing the growth of the seedlings with 10 other seedlings of the same type that are sprayed with distilled or tap water. Monitor the state of the seedlings, recording both qualitative and quantitative effects in logbooks. Extend the experiment to compare effects on metals and chalk or eggshells; discuss how experimental variables were controlled in the investigations.
Literature review: Research the issue of acid sulfate soils.

Key knowledge: Measuring gases

Modelling: Design a flow chart or other representations to show unit conversions for, and relationships between, pressure, volume and temperature of gases.
Use the Keeling Curve to explore changes in carbon dioxide levels in Earth’s atmosphere over time.
Use statistics from the Bureau of Meteorology to plot trends on global concentration of carbon dioxide, air temperature or sea surface temperature; comment on the observed trends in graphs.
Simulation: Use an interactive applet to investigate how the global warming potential (GWP) of greenhouse gases is related to the infrared portion of the electromagnetic spectrum, because different greenhouse gases absorb in different parts of the infrared spectrum. An activity on modelling GWP of greenhouse gases can be found in Part 2 of this Climate change chemistry lessons resource from Beyond Benign (US).
Literature review: Compare the Global Warming Potentials for greenhouse gases CO₂, CH₄, and H₂O; explain why the differences occur.
Use a gas syringe to collect and measure the gas evolved in a chemical reaction; plot your results as a volume-time graph.
Determine the relationship between p and V when the pressure on a gas sealed in a syringe is increased.
Complete stoichiometric exercises requiring the calculation of a combination of an amount of solids, liquids, gases, solution concentrations or volumes, and the volume, temperature and pressure of gases (including consideration of quantities in excess in chemical reactions).
Case study: Investigate the basic chemical principles of recent innovative techniques being trialled to directly remove CO₂ from the atmosphere, using Direct Air Capture.
Literature review: Investigate why the solubility of oxygen in water is limited, but its presence in the hydrosphere is important for living species.

Key knowledge: Analysis for salts

Discuss the rationale for why what is considered ‘safe’ drinking water varies for different chemical pollutants (or more specifically, what the different concentration limits are, and why).
Classification and identification: Use local examples of the management of chemical contaminants in each of the categories of salts, organic compounds and acids or bases.
Describe two sampling protocols and identify how they would contribute to accuracy, precision, repeatability, reproducibility and / or validity of water analysis results.
Classification and identification: Perform an experiment to determine the water of a hydrated salt to distinguish between the terms, ‘hydrates’, ‘water of hydration’, ‘efflorescence’, ‘deliquescence’ and ‘hygroscopic’.
Undertake a water quality analysis for samples of water; for example, combine laboratory ‘wet’ and instrumental techniques with online calculators such as that at the Water Research Centre in Dallas, Texas, USA, which calculates water quality based on nine indicators (in order of decreasing significance: dissolved oxygen, fecal coliform, pH, biochemical oxygen demand, temperature change, total phosphate, nitrates, turbidity, total solids).
Discuss the principles of colorimetry including the relationship between concentration and absorption; use secondary colorimetry data to construct a calibration curve and determine the concentration of an ingredient in a consumer product.
Perform an instrumental analysis of a coloured species in solution; for example, compare the phosphate content of various fertilisers or washing powders; investigate why phosphates pose problems in waterways and how these problems are resolved.
Literature review: Bottled water is sometimes fortified with various vitamins and nutrients. Investigate and produce a short report to explain the purpose of the additives and how the amounts that are added are determined.
Case study: Refer to the Australian Government Initiative, Water Quality Australia, and discuss why salinity is an issue for the quality of water or soil. Also refer to the Murray-Darling Basin issue. Summarise strategies for managing salinity.
Classification and identification: Investigate the applicability of Benford’s Law, also called the first-digit law (in lists of numbers from many everyday sources of large datasets, the leading digit is distributed in a specific, predictable way: 1 = 30.1%, 2 = 17.6%, 3 = 12.5%, 4 = 9.7%, 5 = 7.9%, 6 = 6.7%, 7 = 5.8%, 8 = 5.1%, 9 = 4.6%), to chemical data. For example, refer to global water quality data such as those at GEMStat or data obtained from state or local water authorities.
Respond to a chemistry-based issue in society; for example ‘Would you drink recycled water? (see Detailed example)

Detailed example

Responding to a chemistry-based issue in society: would you drink recycled water?

Aim

To communicate a justified response to a social issue involving chemistry concepts through participation in a Question & Answer panel discussion.

Introduction

Teacher poses the question, ‘Would you drink recycled water?’ as a summative learning task following learning activities related to measurements of solubility and concentrations, chemical analysis or a class excursion to a water treatment plant. The focus of this activity is on students being able to consider the nature of evidence, distinguish between facts and opinion, and synthesise arguments to communicate a response to a chemistry-related social issue.

Teachers could organise the class so that students work in groups to form a number of different Q&A panels where each student takes on the role of a different stakeholder, or use a jigsaw approach to create one class Q&A panel with each panelist having a team of ‘researchers’ to assist in the development of panel arguments.

Students role-play a Q&A panel discussion to examine the arguments for and against using recycled water as a source of drinking water. Each student will assume the role of one stakeholder, or become part of the stakeholder’s research team, and become part of the panel discussion. Following the panel discussion each student provides an individual response to the question ‘Would you drink recycled water?’ by producing a public communication in an agreed format; for example, newspaper article, infographic or TV advertisement. The communication must include referenced qualitative and quantitative data, distinction between identified facts and opinions presented in the Q&A panel discussion, and a justified personal stance on the question.

Science skills

Teachers should identify and inform students of the relevant key science skills embedded in the task.

Preparation

Prior learning experiences related to water sampling techniques, measurement of solubility and concentration, and analytical techniques used to analyse for salts, organic compounds, and acids and bases.
Prior consideration of validity, facts and opinions; for example, students have discussed sources of reliable information related to the following chemistry-based information:
1. Drinking water, also known as potable water or improved drinking water, is defined as water that is safe enough for drinking and food preparation.
2. Globally, in 2020, 74% of people used safely managed water services (improved source accessible on premises, available when needed and free of contamination) compared with 70% in 2015.
Students should have discussed examples of ‘effective’ and ‘ineffective’ oral and written communication techniques and practices.
Students become panel members who represent stakeholder interests (students select the names of stakeholders at random ‘from a hat’); for example, local resident with young family, mayor, local water authority representative, analytical chemist, site worker from company contracted to carry out water treatment, medical professional, local producer of carbonated water, meteorologist, and environmental activist.
Students should have access to ‘fact sheets’ or authoritative sites related to water treatment and drinking water specifications; for example, excerpts from the Australian Drinking Water Guidelines, the World Health Organization’s guidelines for drinking water quality, and comparisons of drinking water standards around the world, such as those provided by the Safe Drinking Water Foundation (SDWF).

Health, safety and ethical notes

Students should be respectful of others and their opinions at all times.
Students should be reminded that this activity is simply a role-play and the comments made do not necessary reflect the attitudes of the individual speakers.

Procedure

Lessons 1 and 2: In these lessons students consider general information about the process of treating water to make it potable, including statutory requirements for water to be classified as ‘drinkable’; put themselves in the role of one stakeholder and present their position; construct a question they would like addressed by a discussion panel; and prepare possible responses to these questions from their perspective as one stakeholder. Some time out of class may also be required for students to complete background research. Students:

Read through the ‘fact sheets’ or websites relating to water treatment and water quality.
Note in the logbook major points of interest.
Select at random the name of a stakeholder relevant to the issue.
Spend 10 minutes brainstorming the likely perspective of the stakeholder towards the issue. Students may discuss their ideas with peers and the teacher. Students need to consider the biases (feelings, opinions, prejudices) that their stakeholder may have for this issue and write these into the logbook.
Present a 20-second oral summary of the stakeholder to the class, for example: ‘My name is X and I am the mayor of this town where it is proposed that we supplement our drinking water supplies with treated water, since we often need to apply water restrictions due to low water reserves in our dam. The majority of my constituents are against the proposal since there are concerns that the treated water will still contain microbes or chemicals that may threaten human health and that treated water could never exactly replicate the quality of rain water or the water in our dams.’
On a slip of paper, construct one question that they would like addressed by someone relating to this case study. Students may suggest which stakeholder they would like to primarily respond to their question. The question should be well thought out so as to give maximum insight into different perspectives in considering the issue. Students may use the following list of question terms to assist them:

List 1: Who / What / Where / When / Why / How…?
List 2: …would / could / should / is / are / might / will / was / were…?
Submit the question to the teacher, who will collate (perhaps by photocopying all slips onto a single sheet of paper) and distribute them to the relevant discussion panel.

Now working with the other members of the panel, discuss the questions that have been submitted and write notes in the logbook detailing the response to these questions from the perspective of a stakeholder. Include as much scientific data as possible in the responses. Students may need to conduct additional Internet research to develop responses.

Lesson 3: In this lesson students role-play the perspective of one stakeholder as part of a panel discussion. They may use any notes already written in the logbook and may also make additional notes in the logbook during the class.

Lesson 4: In this lesson students provide an individual response to the question ‘Would you drink recycled water?’ by producing a public communication in an agreed format; for example, newspaper article, infographic or TV advertisement. At the end of the lesson they submit a draft of their response. They may use any notes from the logbook.

The communication must include referenced qualitative and quantitative data, distinction between identified facts and opinions presented in the Q&A panel discussion, and a justified personal stance on the question.

The media communication should identify / highlight:

a likely target audience
specific scientific concept(s) being communicated
distinction between fact and opinion
scientific data used to justify position of the stakeholder.

Students will be assessed with respect to:

accuracy of scientific information
clarity of explanations
appropriateness for purpose and audience.

Outcome 3

On completion of this unit the student should be able to draw an evidence-based conclusion from primary data generated from a student-adapted or student-designed scientific investigation related to the production of gases, acid-base or redox reactions or the analysis of substances in water.

Examples of learning activities

Key knowledge: Investigation design

Discuss the importance of developing investigable questions for scientific investigation considering Albert Einstein’s quote that: ‘The important thing is not to stop questioning’, Robert Half’s quote that ‘Asking the right questions takes as much skill as giving the right answers’ and Nancy Willard’s quote that ‘Sometimes questions are more important than the answers’.
Work in groups to prepare instructions to new chemistry students on:
- how to prepare a standard solution
- how to convert between different concentration units; for example, mol L^-1 → g L^-1
- how to convert between different gas measurement units; for example, kPa → atm
- how to perform a titration
- how to balance redox equations
- how to set up a calibration curve in colorimetry.

Key knowledge: Scientific evidence

Research why the Brønsted-Lowry theory of acids and bases is considered more useful than the Arrhenius theory of acids and bases.
Crumple a sheet of paper in your hand to form a ‘clot’ approximating a sphere and measure its diameter; collate class data to plot a histogram of clot diameters and account for the shape of the histogram; identify and distinguish between sources of error and uncertainty; use the results to discuss the difference between accuracy, precision, repeatability and reproducibility; calculate the mean; discuss how the mean would be similar / different if the activity is undertaken by a different class; explain why accurate measurements are important in chemistry.

Key knowledge: Science communication

Select examples of scientific posters and post them around the room at stations. Use post-it notes or similar to provide feedback on the samples, identifying two strengths and two weaknesses for each. Conduct a class walkthrough of all the posters, summarising and discussing the strengths and weaknesses; develop a whole-of-class summary of do’s and don’ts for a high-quality scientific poster.

Examples of research topics

The following topics are a sample of practical investigations that may be considered. Students may use different scientific methodologies to generate primary data. In particular, controlled experiments, fieldwork, modelling, and product, process or system development are the most appropriate methodologies for this area of study. Simulations may be used in situations where students do not have access to appropriate laboratory equipment and where students are able to manipulate variables to generate a unique data set, but teachers must subsequently determine how students’ ability to design an investigation will be assessed for this outcome. Teachers must determine the appropriateness of proposed student investigations in terms of resources and safety; modifications or alternative investigations may be suggested in cases where proposed investigations are unsafe, impractical and / or cannot be resourced by the school.

Is solubility related to biodegradability?
Investigate the temperature range over which chocolate can exist in both molten and solid states and its dependence on relevant parameters. Note: chocolate appears to be a solid material at room temperature but melts when heated to around body temperature, and then when cooled down again it often stays melted even at room temperature. Explain these phenomena in terms of what may be happening from a molecular structure perspective.
Design and perform experiments to investigate the properties of vitamins, for example:
- Are water-soluble vitamins more prone to destruction by cooking than non-water-soluble vitamins?
- Which cooking methods preserve the most Vitamin C in carrots?
- Do water-soluble vitamins react differently to UV light than non-water-soluble vitamins?
- When is the Vitamin C content of fruit at its peak?
Investigate experimentally the sensitivity of Vitamin C to light, oxygen or pH.
Investigate experimentally the claims that:
- citric acid can be considered as an antioxidant mainly due to its low pH and that other fruit acids could also act as antioxidants if their pH was low enough
- a 0.01% solution of EDTA (ethylene diamine tetraacetic acid) protects apple juice from oxidation
- a 0.9% solution of sodium chloride may act to counter the oxidation of ascorbic acid
- some fruit juices contain substances that help destroy Vitamin C; for example, apple juice held at 37 °C with a pH of 3.5 for 60 days will lose about 99% of its ascorbic acid, while pineapple juice under the same conditions will lose about 70%.
Use the Briggs-Rauscher reaction to determine which fruits or teas contain the most antioxidants.
Investigate the chemistry underpinning the claim that the following is a ‘chemical-free and easy way to clean fruit’: fill a sink with water, add 1 cup of vinegar and stir; add all fruit and soak for 10 minutes (water will be dirty and fruit will sparkle with no wax or dirty film). This is great for berries as it keeps them from moulding; do this with strawberries and they last for two weeks.
How does water quality differ at various points along a waterway or around a body of water? (see Detailed example)
How do commercial brands of water differ from each other?
How does bottled water differ from tap water?
How does bottled water differ from filtered tap water?
How is bottled water sanitised for human consumption?
What are some practical ways to recycle plastic bottles?
How does the solubility of a solute vary in fresh water as compared to sea water?
How are different types of shells / polymers / metals affected by different pH conditions?
How effective are different sampling methods in the accurate analysis of the quantity of a substance that is dissolved in water?
How are the specific heat capacities of different liquids affected by the addition of salts, acids, bases, oxidants or reductants?
How are the conductivities of different liquids affected by the addition of salts, acids, bases, oxidants or reductants?
Which ions are more important in determining the ‘hardness’ of water?
How do different types of detergents perform in water of varying ‘hardness’?
Is the pH of sea water affected in the same way as the pH of fresh water when acidic or basic substances are added to them?
How does the rate of corrosion of different metals compare in salt and fresh water?

Detailed example

How does water quality differ at various points along a river?

Introduction

This practical investigation builds on knowledge and skills developed in Unit 2 Area of Study 1 and / or Unit 2 Area of Study 2. Teachers must consider the management logistics of the investigation, taking into account number of students, available resources and student interest. The following questions require consideration:

What input will students have into the selection of the investigation question?
Will different groups of students in the class be able to undertake different investigations?
To what extent will all students consider the same investigation question, or complete different parts to the same question so that class data can be collated?
What input will students have into the design of the experiment?
Will off-school site work be involved?

Teachers could provide students with a template that structures the investigation into a series of timed phases. The template may subsequently be adapted by students as a personal work plan in their logbooks.

Topic selection phase

In Unit 2 Area of Study 2, the teacher made use of the local river that ran through the town to explore concepts related to identifying and measuring different substances in water. In this detailed example, a general class investigation question was generated following student interest in exploring factors that affected the river’s water quality.

In a class discussion following Unit 2 Area of Study 2 activities where students measured the pH and total dissolved solids of river water samples, students wondered whether their results would have been different if they had performed the experiments at different times of the day or in different seasons of the year. They discussed the different environment conditions at various points in the river, such as shaded or exposed sites, and treed versus cleared areas. One environmentally conscious student noted that a public picnic ground abutted the river and that paper, plastic and food scraps often ended up in the river. Another student referred to sections of the river allocated to swimming and boating activities and wondered whether factors such as body oils and turbulence affected water quality. From this discussion students formulated a number of research questions for investigation, based on a general question: How does water quality differ at various points along a river?

Sample student-generated research questions include:

What chemical categories of rubbish are dumped into the river and how is water quality affected?
How do recreational activities such as swimming and fishing affect water quality?
Does exposure to sunlight affect the pH of water?
Does exposure to sunlight affect the solubility of salts in water?
Do overhanging trees change the chemical composition of the water?
Is the proportion of chemicals in faster-running parts of the river different from the proportion of chemicals in slower-running parts of the river?
Is the proportion of chemicals in deeper parts of the river different from the proportion of chemicals in shallower parts of the river?

Planning phase

Students may need guidance in:

formulating a testable hypothesis
fitting the investigation into the time available, and developing a work plan
identifying the technical skills involved in the investigation
ensuring that resources are available that meet the requirements of the investigation.

Teachers should work with students to:

determine to what extent students will work independently or in groups in undertaking the experiment (for example, different students or groups may investigate different aspects of river quality; all students may investigate a selected question and work at different sites along the river to collect and collate data; a limited number of questions may be self-selected for investigation by students)
discuss the independent, dependent and controlled variables in proposed experiments
determine the types of quantitative experiments that will be performed; for example titrations, solubility tests, instrumental analysis
identify safety aspects associated with undertaking experiments in the field and in the laboratory, and in working with chemicals and apparatus
establish the use of physical units of measurement and standard notation
determine the nature of the communication: Who would be interested in the results of students' investigations? What would be the most effective way to communicate results to an interested audience?

Investigation phase

Student-designed methodologies must be approved by the teacher prior to students undertaking practical investigations. A possible schedule for management of the multiple investigations in the class is as follows:

each student undertakes internet research to find background information related to the general topic for investigation
students work individually or in groups to confirm a research question, formulate a hypothesis and propose a research methodology, including management of relevant safety and health issues
teacher approval for the methodology is granted prior to students undertaking the investigation
time is allocated for water sample collection in the field
if required, time is allocated to access equipment / instrumentation out-of-school
students perform investigations, record and analyse results and prepare final presentation of their findings using an agreed report format.

Reporting phase

Students consider the data collected, report on any errors or problems encountered, and use evidence to explain and answer the investigation question. Other avenues for further investigation may be developed following evaluation of their experimental design and quality of data.

Students may work individually or in groups.

The above phases could be recorded in the student logbook. The report of the investigation can take various forms including a written report, a scientific poster or a multimedia or oral presentation of the investigation.

Unit 3: How can design and innovation help to optimise chemical processes?

Outcome 1

On completion of this unit the student should be able to compare fuels quantitatively with reference to combustion products and energy outputs, apply knowledge of the electrochemical series to design, construct and test primary cells and fuel cells, and evaluate the sustainability of electrochemical cells in producing energy for society.

Examples of learning activities

Key knowledge: Carbon-based fuels

Literature review: View real or virtual displays of fuel samples; for example, coal, crude oil, kerosene, paraffin oil, candles, peanut oil, biodiesel, bioethanol, wood. Predict melting points and boiling points based on the physical states of each sample; compare predictions with experimentally determined or accepted values from chemical databases.
Conduct a combustion analysis experiment of an unknown CxHyOz sample using, for example, a glass tube apparatus, to identify the formula by measuring CO₂ and H₂O trapped in the tubes.
Literature review: Use the internet and other sources to investigate and compare the use, renewability and environmental impact of the sourcing and combustion of a selected fossil fuel and a selected biofuel energy source. Compare class findings to discuss whether there is a clear case for the use of a biofuel in preference to a fossil fuel.
Experiment / Demonstration: Conduct a series of short hands-on activities to visualise photosynthesis, for example: adding sodium bicarbonate (this increases the carbon dioxide in the water) to a test tube with Elodea canadensis under water and comparing the number of bubbles formed relative to a control; fitting a balloon over flasks containing Elodea canadensis in water and subjecting them to different amounts of light to compare the amount of oxygen formed.
Discuss the viability of the use of biofuels (using information at Biofuels International) as a replacement for fossil fuels, and consider the arguments presented.
Case study: Analyse and evaluate the development of a biofuel demonstration facility in the Hunter Valley in NSW. Construct a flow chart to show how plant biomass can be converted to ethanol through the process of fermentation. Explain how this innovation impacts on the ‘food versus fuel’ debate in relation to ethanol production. Discuss how the project’s aims of supporting the reduction of greenhouse gas emissions in the transport industry can be met. Suggest why a demonstration facility has been built prior to building a commercial-scale plant.
Literature review: Use information from secondary sources to summarise the processes involved in the industrial production of ethanol from sugar cane. Debate whether sugar cane is better used primarily for producing a region’s food or fuel supply.
Case study: Use information from secondary sources to summarise the social and scientific issues involved in the utilisation of seaweed (macroalgae) as a biofuel. Debate whether seaweed can be sustainably and ethically sourced from aquatic environments.
Case study: Access online information about companies developing more sustainable energy alternatives and products; for example, the Indigenous-owned company South Coast Seaweed uses traditional methods of harvesting and collecting sea kelp to produce consumer products using seaweed. Investigate the claim that about 70% of the world’s oxygen comes from seaweeds and algae, and that seaweed is one of the biggest carbon sequesters on our planet so that its cultivation needs to be part of a global solution to climate change. Compare the renewability of seaweed with the renewability of fossil fuels; discuss whether seaweed could be considered as a ‘biofuel’.
Modelling: Design a flow chart or other representation to show unit conversions for and relationships between pressure, volume and temperature of gases.
Classification and identification: Investigate the products of the complete and incomplete combustion of a fuel.
Determine the enthalpy of a solution (for example, sodium thiosulfate or ammonium chloride).
Use enthalpy calculations to discuss the use of an appropriate number of significant figures in calculations, including the use of calculators and ‘rounding off’.
Literature review: Explain why ammonium nitrate was used in first-aid cold packs but has now been replaced by chemicals such as calcium ammonium nitrate, ammonium chloride and urea.
Demonstrate the concept of a limiting reagent; for example, by testing how much copper carbonate will react with a given quantity of acid. Use stoichiometry to confirm recorded observations.
Modelling: View a video on limiting reagents to see how picture models can be used to illustrate limiting reagent situations. Work in pairs to each create a picture model, or use different shapes of pasta to represent a stoichiometric problem involving limiting reactants, then swap models with your partner and solve the stoichiometric problem.

Key knowledge: Measuring changes in chemical reactions

Investigate the heat of combustion of ethanol, including determination of the energy efficiency of its combustion using data from a data table, and identification of sources of energy loss through energy transformation and energy transfer.
Apply the principle of mass–mass, mass–volume and volume–volume stoichiometry to determine the heat energy and amounts of major greenhouse gases (CO₂, CH₄ and H₂O) released from the combustion of fuels.
Literature review: Investigate the amount of CO₂ released in a year in Australia based on fuel usage per industry; predict the usage of fuels by applying the principles of stoichiometry.
Undertake quantitative exercises related to solution calorimetry.
Determine the calibration factor of a calorimeter. Determine the enthalpy change of chemical reactions; analyse temperature-time graphs obtained from solution calorimetry.
Experimentally investigate the extraction of essential oils (for instance from lemons) and compare the energy requirements using traditional techniques, steam distillation and using novel approaches such as pressurised liquid CO₂.
Modelling: Access Sankey diagrams and other representations of the energy transformation occurring in a combustion reaction to show why the combustion of fuels cannot be 100 per cent efficient; comment on the use of Sankey diagrams versus pie charts as representations of energy efficiency.
Controlled experiment: Compare the heats of combustion of various fuels, such as the amount of heat energy produced by the combustion of different alcohols, or the combustion of ethanol; compare experimentally determined values with published values for heat of combustion; suggest improvements to the experimental methodology and / or method.

Key knowledge: Primary galvanic cells and fuel cells as sources of energy

Observe metal displacement reactions under stereomicroscopes; identify the products, oxidising and reducing agents, and conjugate pairs; write balanced chemical equations, including states, for observed reactions.
Determine the relative strengths of reducing agents and oxidising agents using metal displacement reactions; construct and test simple galvanic cells based on the findings.
Controlled experiment: Predict how the temperature will change over time in the bulk of the liquid in a metal displacement reaction; for example in the reaction between zinc and copper(II) chloride. Use a temperature sensor to monitor the temperature change in the reaction over time and explain any differences between predicted and experimental results.
Construct simple galvanic cells and explain in general principles their operation in terms of reactions occurring at the electrodes and the movement of electrons and ions (the focus is on the application of general principles rather than details for specific cells).
Controlled experiment: Investigate whether there is a relationship between the temperature rise in direct metal displacement reactions and the voltage of the galvanic cells driven by those reactions. (see Detailed example)
Product, process or system development: Use the electrochemical series to design, set up and test a galvanic cell that can deliver a particular cell voltage; compare predicted with experimentally determined cell voltages; draw an annotated diagram of the cell and identify its key features; write and annotate equations for the relevant half-cell and overall cell reactions.
Capture photos or images of the progress of a galvanic cell; use the images and add text to produce a photo essay of the progress of the reaction, identifying products formed and writing half and overall equations for the redox reactions involved.
Product, process or system development: Apply problem-solving and design-thinking to improve the voltage of a poorly constructed galvanic cell (provided by the teacher) which does not produce a useful voltage.
Product, process or system development: Work in small groups to produce an instructive multimodal clip to show the step-by-step construction and operation of a simple laboratory galvanic cell, including the use of a galvanometer to determine direction of electron flow.
Use the electrochemical series to predict the outcome of competing electrode reactions in galvanic cells; design and perform experiments to test predictions; identify the limitations of the use of the electrochemical series in predicting electrode reactions.
Design a flow chart or other representation to compare the energy transformations occurring in a metal displacement reaction when the reactants are in direct contact and when they are separated in a galvanic cell.
Literature review: Research and prepare a short report on the operation of a contemporary galvanic cell that has been designed for a specific purpose.
Analyse secondary data on the use of hydrogen as a fuel.
Design a poster showing the operation of a fuel cell.
Construct a simple fuel cell and measure its voltage output; draw an annotated diagram of the cell, identifying its key features and annotate equations for the cell processes.
Modelling: Create an animation of the cell processes in a typical galvanic cell and / or a typical fuel cell, including at the particle level.
Design a flow chart or other representation to compare the operation of fuel cells, the operation of galvanic cells and the combustion of fuels.
Literature review: Investigate developments and applications of fuel cell technology; compare the advantages and disadvantageous of fuel cells with other energy sources.
Literature review: investigate the comparison between battery electric vehicles and fuel-cell electric vehicles including the type of electrochemical reaction, energy produced, safety issues and cost-effectiveness.
Product, process or system development: Build a dye-sensitised solar cell (DSSC), a third-generation development in solar cells, designed to be a method to capture energy from the sun for conversion into electricity, for example, follow the procedure at How to Build and Use a Dye-Sensitized Solar Cell. Undertake a water-based extraction of a fruit dye molecule that allows the transfer of light energy into electrochemical energy (known as the dye sensitiser). The dye is applied to a conductive glass slide that has been treated with a substrate (titanium dioxide) that allows the dye to stick to it. Compare the effectiveness of different berries grown on country.
Case study: Use the internet to find secondary data that demonstrates how the chemical and physical properties of hydrogen relate to its tremendous potential to act as an energy carrier in fuel cells in transport applications (cars, trucks, buses, planes, boats – a good source is the Australian Hydrogen Council).

Detailed example

Is there a relationship between the temperature rise in direct metal displacement reactions and the voltage of the galvanic cells driven by those reactions?

Introduction

A systematic investigation of direct metal displacement reactions can be used to establish or to confirm an electrochemical series. Exothermic metal displacement reactions can be used to drive galvanic cells, in which the energy released in the reaction is in the form of electrical energy instead of heat energy.
Students should record a justified prediction of the metal displacement reactions in their logbooks prior to undertaking the experimental investigation.
The temperature rise that occurs in metal displacement reactions, which is directly proportional to the heat energy released, is determined by using a temperature probe. The voltage across the galvanic cells driven by those reactions is measured using a voltmeter connected in parallel with each cell. The voltage is directly proportional to the electrical energy delivered by the cell per second by the relationship.
Required: relevant glassware, equipment and materials including a voltmeter; a globe; electrical wiring; a temperature probe; strips of zinc, copper, iron and tin; strips of filter paper and solutions of 1.0 M ZnCl₂, 1.0 M CuCl₂, 1.0 M FeCl₂, 1.0 M SnCl₂ and 0.1 M NaCl (for salt bridges).

Science skills

Teachers should identify and inform students of the relevant science skills embedded in the task.

Health and safety notes

Students must:

dispose of metal strips and metal solutions in properly labelled waste containers and not down sinks
wash their hands after handling the chemicals.

Method

Students place a metal strip in a test tube with a temperature probe, add 20 mL of a 1.0 M solution of one of the test metals, and measure and record the temperature rise that occurs over 5 minutes. They also record their observations of any reaction that they observe over that time. This is repeated for a range of combinations of metals and metal solutions and the results compared with their predictions using the electrochemical series.
Students set up galvanic cells, each using one of the metal displacement reactions that are identified as exothermic, and place the same globe across the two electrodes. They measure and record the voltage across each cell.

Discussion questions and report writing in logbook

Students complete a results table showing the temperature rise and voltage for each metal combination. They then draw a scatterplot graph of voltage against temperature rise from all the data points to test if there is a relationship between the temperature rise and the voltage.
Questions should focus on identification of the dependent and independent variables, controlled variables, sources of error and the validity of this experimental method and how it could be improved.

Teacher notes

This is a systematic procedure producing quantitative and qualitative data.
Students should be aware that the experiment is not being conducted at standard conditions, as the temperature is not being held constant at 25 ^oC, and the metal strips are not made from the pure metal.
Extensions to this activity may involve students testing other metals, or processing the class results, to create more data points for the scatterplot graph.

Outcome 2

On completion of this unit the student should be able to experimentally analyse chemical systems to predict how the rate and extent of chemical reactions can be optimised, explain how electrolysis is involved in the production of chemicals, and evaluate the sustainability of electrolytic processes in producing useful materials for society.

Examples of learning activities

Key knowledge: Rates of chemical reactions

Modelling: Create a model or develop an analogy of the concept that chemical reactions involve the breaking and making of bonds.
Modelling: Create an animation or develop an analogy to illustrate collision theory.
Demonstrate that the rate of reaction depends on frequency of collisions using reaction between lead(II) nitrate and potassium iodide, in the solid and aqueous states.
Classification and identification: Distinguish between the terms ‘exothermic’ and ‘endothermic’; identify useful endothermic and exothermic reactions in everyday life.
Controlled experiment: Compare the rate of reaction between zinc granules and sulfuric acid, with and without copper as a catalyst, by measuring the rate of production of hydrogen gas bubbles.
Controlled experiment: Compare the use of a data logger and a thermometer to measure and record temperature changes over time for an exothermic and an endothermic chemical reaction. Compare and discuss how accuracy, precision, repeatability, reproducibility, resolution and validity are affected when a data logger, rather than a thermometer, is used. Identify situations where a data logger is more appropriate to use than a thermometer; identify situations where a thermometer is more appropriate to use than a data logger.
Controlled experiment: Determine the ideal temperature and concentration conditions to demonstrate that Vitamin C can be used as catalyst to speed up the decomposition of hydrogen peroxide.
Controlled experiment: Use primary data to explain the effect of changing pressure on the rate of a gaseous reaction.
Classification and identification: Identify examples from everyday situations where fast and slow reactions are desirable; compare between combustion reaction and rusting of iron.
Controlled experiment: Conduct a laboratory investigation on the effect of temperature, solution concentration and surface area on the rate of reaction; predict outcomes of investigations based on kinetic molecular theory; calculate reaction rates by determining the gradient of a graph of an amount of product produced versus time graph (or mass loss over time graph) and plot a graph of reaction rate versus time; explain observations in terms of the distribution of kinetic energies at different temperatures.
Controlled experiment: Investigate quantitatively the effect of a catalyst on the rate of a chemical reaction.
Classification and identification: Illustrate the concept of activation energy using energy profile diagrams for catalysed and uncatalysed endothermic and exothermic reactions.

Key knowledge: Extent of chemical reactions

Conduct a laboratory investigation related to the reversible nature of reactions; for example, the hydration and dehydration of copper(II) sulfate; an equilibrium reaction involving copper(II) ions; or the equilibrium involving carbon dioxide in aqueous solution.
Classification and identification: Interpret evidence for the dynamic nature of equilibrium in a chemical reaction and identify how it is different from the rate of reaction.
Classification and identification: Explain why some chemical reactions are reversible and others are not; provide examples of reversible and irreversible reactions, including appropriate chemical equations and ‘product arrow’ notation.
Modelling: Draw a cartoon strip or create an animation to show what happens in a closed equilibrium system at the particle level; include concentration-time graph representations of both reactants and products as they reach equilibrium.
View and discuss the high-speed video of the effect of pressure change on the NO₂ / N₂O₄ equilibrium system.
View and discuss the Science Photo Library high-speed video of the effect of concentration changes on the equilibrium between Co²⁺ complexes in solution.
Controlled experiment: Conduct a laboratory investigation of the effect of changing temperature, changing concentration, and adding chemical species (AgNO₃) to the homogenous equilibrium Co(H₂O)₆²⁺ + 4Cl^- → CoCl₄^2- + 6H₂O.
Capture photographs or images of the progression of an equilibrium reaction subject to temperature or concentration changes, and adding chemical species that are detectable by a colour change. Use the images and add text to produce a photo essay or infographic of the phenomenon, including identification of the direction of the equilibrium shift.
Literature review: Investigate how the amount of dissolved CO₂ in aquatic environments, increasing due to ocean acidification, is a measure of the health of marine ecosystems.
Case study: Aragonite, a type of calcium carbonate formed by multiple marine organisms, is a control variable for Earth system processes and a measure within the planetary boundaries framework. Investigate how this control variable, and other variables in the planetary boundary framework, have varied over previous decades with this interactive applet.
Case study: Investigate examples of chemical innovations that are seeking to rebalance the depleted carbonate ion state of oceans due to increased ocean acidity.
Product, process or system development: Explore the relationship between reaction rate and reagent concentration by investigating a ‘green’ version of a clock reaction using starch solution, Vitamin C in solution, 3% hydrogen peroxide, tincture of iodine and water. Compare the effectiveness, safety and waste considerations of this version with the ‘Old Nassau’ clock reaction, which includes mercury(II) chloride, metabisulfite and iodate ions which are all moderately to highly toxic.
Simulation: Use a spreadsheet to manipulate data to illustrate the constancy of K_c at constant temperature; perform calculations based on the equilibrium law, reaction concentrations and K_c.
Classification and identification: In a variety of equilibrium reactions, use Le Chatelier’s principle to make predictions about changes (concentration, temperature, pressure) made to a system at equilibrium. (see Detailed example)
Case study: Use the ‘ammonia from hydrogen and nitrogen’ example to discuss the conflict between optimal rate and temperature considerations in producing equilibrium reaction product, considering the green chemistry aspects of catalysis and designing for energy efficiency.
Case study: Use a systems perspective to inquire into the actual feedstock of ammonia-based fertilisers, namely methane from fossil fuels (CH₄ is used to produce H₂ by steam methane reforming (SMR), with CO₂ as a by-product). Investigate the potential for electrolysis to replace SMR as the main process to produce the necessary H₂ feedstock for fertiliser production.
Literature review: Investigate the use of nanoparticles to develop new catalysts to improve the efficiency of chemical processes. Explain how the green chemistry principles of catalysis and designing for energy efficiency apply to these innovations.

Key knowledge: Production of chemicals using electrolysis

Modelling: Create an animation of the processes occurring in a typical electrolytic cell, including at the particle level.
Predict and test the products of electrolysis of aqueous solutions; use image capture to illustrate and annotate a cell diagram; write balanced chemical equations for the reactions, including states.
Construct a simple electrolytic cell to identify factors that determine the products of electrolysis.
Modelling: View an animation of the processes occurring in a smelter where a metal is extracted from its ore by electrolysis and explain what is occurring at the particle level, including use of the terms ‘oxidation’, ‘reduction’, ‘oxidising agent’, ‘reducing agent’, ‘cathode’, ‘anode’ and ‘electron transfer’.
Observe what happens during the electrolysis of brine (sodium chloride solution), using universal indicator to help follow the reaction that takes place.
Literature review: Research Humphrey Davy’s discovery of many Group 1 and Group 2 metals by electrolysis of their molten salts and explain how this led to development of processes for extraction of aluminium and other highly reactive metals from their molten ores
Literature review / Case study: Use secondary sources to investigate the scale of emissions in Victoria and Australia from the production of aluminium and extend this investigation to inquire about ongoing efforts to ‘green’ this production process.
Analyse data showing the relationship between the amount of metal deposited in an electrolytic cell and the charge flowing through the cell.
Use the electrochemical series to predict the products of the electrolysis of potassium iodide solution. Determine experimentally the products and account for any differences between predictions and results.
Calculate the value of the Faraday constant from the quantitative electrolysis of copper(II) sulfate solution.
Use Faraday’s laws in quantitative calculations related to electrolysis.
Design a flow chart or other representation to compare the operation of electrolytic cells with that of galvanic cells.
Explain why some batteries are rechargeable while others are not; annotate a cross-section of a non-rechargeable battery to identify design features that could be changed to make the battery rechargeable.
Modelling: Draw simplified diagrams to explain how a rechargeable battery works, including half and overall cell reactions; for example, nickel-cadmium, nickel-metal hydride, lead acid, lithium ion, or lithium polymer.
Construct a simple lead-acid accumulator and suggest how to test for factors that affect the operation of the battery.
Simulation: Use an interactive simulation of the role of the KOH electrolyte in an electrolysis.
Simulation: Use a simulation of a proton exchange membrane (PEM) fuel cell to investigate the design and system development of novel electrolysers for the hydrogen economy.
Literature review: Research and investigate the general principles behind the operation of a contemporary rechargeable cell.
Case study: Research and investigate the role of innovative design of cells to produce ‘green’ hydrogen (including equations in acidic conditions) using (a) electrolytic method powered by solar or wind energy, and (b) artificial photosynthesis using water oxidation and proton reduction catalysts. Research the economical and efficiency comparisons of the two methods; research and explain why water splitting into oxygen and hydrogen using light energy is thermodynamically preferable. .

Detailed example

Can Le Chatelier’s principle be demonstrated while being green?

Introduction

In schools, a systematic investigation of how changes in temperature, concentration and pressure leads to a change in an equilibrium mixture involves students conducting a series of short laboratory activities where they can clearly visualise the change (for instance, a colour change, a change in pH). While the hands-on activities are engaging and motivating for students, they involve handling toxic and hazardous chemicals (cobalt in solution, dichromate ions, thiocyanate ions) that need to be disposed in a specific manner. In the following practical activities, students can still visualise a colour change from an equilibrium shift but do so with non-toxic materials.
In Part 1, students observe the equilibrium shifts that occur to a starch-iodine complex when the solution is heated or cooled. Heating causes a shift to the left (more colourless), whereas cooling causes a shift to the right (more blue-black).

Iodine_(aq) + Starch_(aq) ⇋ Starch-Iodine complex_(aq) colourless blue-black

In Part 2, students observe the effect of pH on equilibrium on a solution of brewed tea (in this case, a blue solution of butterfly pea tea). Reducing the pH by adding vinegar or lemon juice causes a shift to the left (lighter blue), whereas the addition of baking soda or vinegar causes a shift to the right (darker purple). The relevant molecules in tea are theaflavins, a group of polyphenols. The addition of H⁺ ions causes the alcohol functional groups of theaflavin to become protonated, resulting in a highly soluble theanaphthoquinone compound (more information is provided in the link below).

Tea_(aq) + H⁺_(aq) ⇋ TeaH⁺_(aq) blue purple

Materials required: relevant glassware, a hot plate or kettle, test tube rack, thermometer, ice, tincture of iodine, soluble starch, vinegar (or lemon juice), baking soda (or dilute ammonia solution), and brewed tea (the original instructions use butterfly pea tea).

Science skills

Teachers should identify and inform students of the relevant science skills embedded in the task.

Health and safety notes

Students should wear appropriate personal protective equipment, as iodine is a minor eye irritant and vinegar and ammonia can cause skin irritation. Individuals with sensitive skin should wear gloves.

Method

Part 1 (starch-iodine complex):

Students separate an amount of a starch solution into three labelled test tubes, then add a drop of tincture of iodine to all three and stir.
One test tube is safely placed in a large beaker containing ice and water. One test tube is safely placed into a large beaker containing hot water (~80 ^oC). The third remains as the control colour.
Students observe the colour change and relate this colour change to the equilibrium shift that occurred.

Part 2 (tea):

Students separate an amount of a room temperature butterfly pea tea solution into three labelled test tubes.
To one test tube, add 10–15 drops of vinegar, stir and observe the colour change.
To another test tube, add ~1g of baking soda (or 10–15 drops of dilute ammonia solution), stir and observe the colour change.
Students observe the colour change and relate this colour change to the equilibrium shift that occurred.

Discussion questions and report writing in logbook

Students complete a results table showing the change in temperature or pH that they instigated in each instance, and the resultant colour change. Students can then relate this to the direction in shift (to the left, the right, or no change).
For temperature, students can be asked which direction is exothermic and which direction is endothermic. For pH, students can be asked which direction the equilibrium shifted when pH was lowered and which direction the equilibrium shifted when pH was raised.
For a link to green chemistry principles, supplementary questions can be given that provide the equation for other equilibrium mixtures (albeit toxic mixtures) and students have to relate their answers in this practical activity to determine what they would observe if they were to conduct the experiment practically. For example:

Cr₂O₇^2-_(aq) + H₂O_(l) ⇄ 2CrO₄^2-_(aq) + 2H⁺_(aq)
orange yellow

Students can be asked to predict what colour changes, and thus equilibrium shift, they would observe from the addition of H⁺, as they did in this practical activity. A follow-up question could ask students to investigate why they didn’t use dichromate ions (because they are hazardous, because they produce unnecessary waste etc.).

Teacher notes

This practical activity example has been modified from an Equilbrium/Le Chatelier’s Principle practical activity from Beyond Benign. The resource contains a teacher description of the two activities, further information on theaflavins (a group of polyphenols found in tea), a student pre-lab exercise and student practical activity worksheets along with worked solutions
Students can undertake this activity as an initial practical inquiry into Le Chatelier’s principle, or as part of a guided inquiry. Students could be challenged to investigate what other reagents can be used (for instance, experimenting with different types of tea) to get a change in colour.

Unit 4: How are carbon-based compounds designed for purpose?

Outcome 1

On completion of this unit the student should be able to analyse the general structures and reactions of the major organic families of compounds, design reaction pathways for organic synthesis, and evaluate the sustainability of the manufacture of organic compounds used in society.

Examples of learning activities

Key knowledge: Structure, nomenclature and properties of organic compounds

Create a poster, a mind map, or an infographic that shows why the carbon atom differs from other elements in terms of its contribution to the diversity of organic compounds; include several unique characteristics such as valence electrons, bond strength, stability, and structural isomerism.
Modelling: Construct models or other representations of the structures of hydrocarbons, haloalkanes, alcohols, carboxylic acids and primary amines, primary amides, aldehydes and ketones, non-branched esters. Use models such as the MolyMod kit or MolView online tool to construct 3D representations of structures. Create and compare isomeric structures using these tools, then draw and translate into 2D representations in a logbook.
Classification and identification: Classify a range of primary, secondary and tertiary alcohols by testing with acidified potassium dichromate solution.
Classification and identification: Distinguish between aldehydes and ketones using acidified dichromate solution and Tollens reagent.
Case study: Discuss the role of creative thinking in chemistry when reviewing August Kekulé’s work in suggesting a structure for benzene.
Classification and identification: Prepare a summary sheet or flow chart outlining the rules for naming organic compounds.
Classification and identification: Undertake a think-pair-share exercise where each member of the pair creates and names a series of isomers of an organic molecule based on hexane (first member of the student pair) or heptane (second member of the pair) with the addition of no more than two functional groups; critique each other’s structures and nomenclature.
Determine experimentally the boiling point of isopropyl alcohol and the melting point of powdered acetamide; conduct a safety audit prior to undertaking the investigations.
Determine experimentally the trend in boiling points of a series of organic compounds; conduct a safety audit prior to undertaking the investigation.
Controlled experiment: Compare the viscosity of different liquids by inverting sealed tubes with different liquids and measuring time taken for an air bubble to reach the surface; design and conduct a different experiment to test the viscosity of liquids.
Case study: Research the production and use of haloalkanes and how they contribute to having negative effects on the environment. Focus on the relationship between haloalkane stability and their toxicity / photolability. Discuss the case of ozone depletion by CFCs; consider how green chemistry principles can be applied to develop safer alternatives that reduce harmful environmental effects.

Key knowledge: Reactions of organic compounds

Relate the oxidation of ethanol → ethanoic acid to the smell of vinegar in wines that have been exposed to air.
Classification and identification: Design and annotate flow charts to represent reaction pathways for: the synthesis of primary haloalkanes and primary alcohols by substitution; addition reactions of alkenes; esterification; ester hydrolysis; the synthesis of primary amines and carboxylic acids; transesterification to produce biodiesel; hydrolysis of proteins, carbohydrates and fats; and condensation polymerisation reactions to produce biomolecules.
Controlled experiment: Design and perform test-tube scale ester synthesis from a variety of alcohols and carboxylic acids. Compare the experimental results using acid and base catalysts, write balanced chemical equations, and compare the mechanism of acid-catalysed and base-catalysed reactions.
Measure the change in pH as the enzyme urease (sourced from ground whole soya beans) hydrolyses urea (carbonyl diamide) in solution (see a useful resource from the Royal Society of Chemistry), analogous to how large biologically important molecules are broken down. Add HCl to lower the pH and observe the rate of the subsequent increase in pH as ammonia is produced from the reaction. Relate this experiment to how urea and fertilisers are used for food production. (see Detailed example)
Discuss the following examples of the uses and properties of organic compounds:
- iodine dissolves in ethanol but is not easily dissolved in water
- small organic compounds may be used as solvents for non-polar molecules; for example, propanone (acetone) in industry
- ethanol is used in some cosmetics and topical skin applications because it evaporates quickly when applied to the skin
- fruits smell the way they do because they contain esters; for example, pineapple contains the ester ethyl butanoate
- esters are used in the food industry as fragrances and flavouring agents because of their sweet smells
- the volatility of small esters make them useful in perfumes
- the volatility of many organic solvents, such as some ketones and esters, makes them hazardous
- many short-chain carboxylic acids, such as butyric acid, have unpleasant odours (for example, the compounds found in parmesan cheese, vomit, sweaty socks)
- cooking in triglycerides retains water-soluble nutrients that would be removed from the food if cooked in water.
Prepare a sample of nylon in the laboratory and extract a protein from food (for example, casein from milk); compare the structure of nylon with that of a protein.
Identify the functional groups present in monosaccharides; write equations to show how monosaccharides condense to form disaccharides and polysaccharides.
Model the ring structures of two D-glucose molecules, the condensation reaction between them and the glycosidic bond that is subsequently formed.
Edible oils and fats are distinguished on the basis of their melting points: explain the relationship between the structure of an oil or a fat and its melting point.
Product, process or system development: Make small-scale biodiesel using available materials such as cooking oils (can be compared with used ones), grease and animal fats, by reacting them with a mixture of methanol and sodium hydroxide. Construct a hypothesis and prediction, conduct investigation, observe quality and quantity of produced biodiesel, and make a comparison of base- and acid-catalysed transesterification.
Case study: Research a selected industrial process or product synthesis and summarise the operating conditions, including temperature and pressure conditions and the use of catalysts; for example, selected processes and products from Essential Chemical Industry. Calculate atom economies of products; investigate the use of green and safer reagents; for example, the use of acidified potassium dichromate for oxidation of alcohols can be replaced by Fenton’s reagent.
Controlled experiment: Determine the ideal temperature and concentration conditions to demonstrate that Vitamin C can be used as catalyst to speed up the decomposition of hydrogen peroxide.

Detailed example

Hydrolysis of urea – a cross-cutting real-world context for high school organic chemistry

Introduction

Curriculum concepts of organic chemistry are spread across Units 1–4, which should come as no surprise to educators of chemistry who will be aware of the prominence of studying organic chemistry in science and engineering in post-secondary courses (chemistry, medicine, pharmacy, microbiology, chemical engineering). However, many of the types of reactions studied in Unit 4 Area of Study 1 are difficult to undertake practically in a high school setting, either because they take too long, are messy and difficult to manage with a large class of students; involve solvents or catalysts not normally seen in high schools; or have observations that students find difficult to connect to their learning. As such, large biologically important molecules tend to stay as three-dimensional representations in textbooks and in internet sources.
Urea is a biologically important molecule, but it is not large. However, it can be used in a laboratory setting to provide students with observations for (a) the synthesis of primary amines, and (b) the hydrolytic reaction of an amide linkage (through the addition of the enzyme urease acting as a catalyst), breaking down the slightly larger molecule into smaller molecules (CO₂ and NH₃) for important biological and chemical purposes.

Diagram 2

Urease
NH₂CONH_2(s) + H₂O_(l) → 2NH_3(aq) + CO_2(aq)

Area of Study 1 includes calculating atom economy, which is easy for students to carry out with this single step hydrolysis reaction (CO₂ as the by-product). Also included in this area of study is using the IUPAC systematic naming of organic compounds. Students can investigate why urea’s accepted systematic name is carbonyl diamide, but that it could also be called carbonyldiamine, diaminomethanal and diaminomethanone.
Urea has a vital link to the narrative of sustainable development, with its main application being as a fertiliser (SDG2: Zero hunger). Added as a solid fertiliser, it is dissolved and then hydrolysed by urease in the soil, eventually into ammonium (NH₄⁺) and nitrate (NO₃^-) ions taken up by plants. However, the highly soluble nitrate ions leach into groundwater, leading to acute toxicity, oxygen-depletion and eutrophication in aquatic environments (SDG14: Life below water).
When approaching VCE examinations, students will benefit from an activity that also links to previous curriculum across Units 3 and 4. This is essentially an activity about the rate of reaction of the enzyme catalyst, and other variables affecting reaction rate.
Despite all of these possible curriculum contexts, the practical activity itself is fairly simple and can easily be conducted in a single period. Instead of a pure source of urease, the catalyst can be a food source high in urease, such as whole soya beans that you can buy from health food shops. They are extremely hard so you will have to use an electric coffee grinder or similar device to reduce them to powder.
Materials required: relevant glassware, a pH meter, whole soya beans, cotton wool and Buchner funnel (for solid filtration), dilute (0.66 M) urea solution, dilute (0.1 M) HCl solution, dilute (0.1 M) sodium hydroxide solution), a means to deliver a measurable volume of solution (burette, graduated pipette, drop pipette of known volume), a glass stirring rod or magnetic stirrer, a grinder to produce a powder from the soya beans.

Science skills

Teachers should identify and inform students of the relevant science skills embedded in the task.

Health and safety notes

Students should wear appropriate personal protective equipment, including eyewear, as dilute (0.1 M) sodium hydroxide solution and dilute (0.1 M) hydrochloric acid are eye irritants.

Method

Shake 2 g of the urease powder (pre-ground from the whole soya beans) with about 20 mL of deionised water in a 100 mL conical flask for about a minute.
Filter the mixture by passing through damp cotton wool in a Buchner funnel or by passing through damp cotton wool in a 50 mL (or smaller) plastic syringe. The resulting liquid may be cloudy. Use a measuring cylinder to put 10 mL of the filtrate into a 100 mL beaker.
Place the beaker on a magnetic stirrer and clamp a pH meter so that it dips into the solution without interfering with the stirrer bar (alternatively, stir the beaker solution consistently with a glass stirring rod). Add deionised water so the probe of the pH meter is covered. Adjust the pH of the solution to 6.5 by adding drops of 0.1 M hydrochloric acid or drops of 0.1 M sodium hydroxide solution. Record the pH at the start of the experiment.
Use a 2 mL graduated pipette to add 2.0 mL of 0.66 M urea solution to the beaker and start a stop clock. Stir the solution consistently (with a magnetic stirrer or by hand with a glass stirring rod).
After a set amount of time, add enough 0.1 M hydrochloric acid solution dropwise to bring the pH back to 6.5. Record accurately the amount of 0.1 M hydrochloric acid solution added (a burette containing HCl solution could be fixed above the beaker, or a graduated pipette could be used, or even a drop pipette with a known volume).
Monitor the pH. After a similar set of time, once more add a measured volume of 0.1 M HCl solution to return the pH to 6.5. Record this amount.
Repeat the HCl addition step at least a third time, so that you have measurements for the volume of HCl needed to return the pH to 6.5 after each fixed interval of time.
All waste material and solutions can be safely poured down the sink.

Discussion questions and report writing in logbook

Students complete a results table showing the amount of HCl added in a fixed amount of time (determined by the students) to reduce the pH back to the starting pH of 6.5. Accompanying questions should lead students to conclude that the raising of the pH was due to the formation of the weak base ammonia.
While students don’t need to calculate in the rate coefficient in VCE Chemistry, they could be expected to demonstrate that the rate of reaction of the catalyst slows as the concentration of the reactant in solution (urea) reduces.
As an experiment involving several variables known to impact reaction rate (temperature, concentration, surface area of solids, use of a catalyst), students can be tasked to describe how these have been controlled through the design of their experiment.
Logical questions to engage students with the real-world context of urea would be to ask them to explain:

why urea is such an important fertiliser (It has high N content and is readily hydrolysed into ammonia for plant life.)
why farmers would wet the soil (As demonstrated in this practical activity, urea is first converted into ammonia. Wet soil will dissolve more ammonia in solution, reducing nitrogen loss from the soil before it can be utilised by the plants.)
why farmers add urease inhibitors in conjunction with urea (To slow the reaction down, giving more time for nitrogen take-up by plants, and leading to less nitrate run-off into groundwater.)
advantages and disadvantages of organic fertilisers such as urea, compared to inorganic fertilisers.

Teacher notes

This practical activity has been modified from a Royal Society of Chemistry (RSC) practical activity Rate of hydrolysis of urea. The resource contains student worksheets and teacher notes, along with worked solutions. It should be noted that the activity was designed to have students practically demonstrate that the reaction rate is first order and to determine the rate equation for the hydrolysis of urea. This aspect of chemical kinetics is not in the VCE chemistry curriculum.
This activity was part of a RSC set of practical activities Challenging plants, which had a central focus on understanding chemical changes involved in making fertilisers, which are often designed to meet specific requirements such as particular nutrient deficiencies and methods of application (including rate of release). The RSC also have collated a number of practical and non-practical activity resources as part of a Feed the World package, to engage students with chemistry’s importance in addressing global food security and SDG 2.
Another sustainable development extension activity would be to have students undertake a case study into how urea is industrially produced. The Bosch-Meiser process, now 100 years old but still the main industrial production process, utilises CO₂ and NH₃. Both of these reactants are traditionally sourced from fossil fuel production (NH₃ requiring H₂ via the Haber-Bosch process – itself sourced from fossil fuels). Therefore, for urea to be considered a ‘green’ fertiliser, we must first have ‘green’ ammonia produced from ‘green’ hydrogen.

Outcome 2

On completion of this unit the student should be able to apply qualitative and quantitative tests to analyse organic compounds and their structural characteristics, deduce structures of organic compounds using instrumental analysis data, explain how some medicines function, and experimentally analyse how some natural medicines can be extracted and purified.

Examples of learning activities

Key knowledge: Laboratory analysis of organic compounds

Perform qualitative tests for carbon–carbon double bonds, hydroxyl and carboxyl functional groups.
Discuss the role of chemical analysis in determining the quality of consumer products.
Case study: Analyse and evaluate a case study of the analysis of an unknown compound; for example, food poisoning, drug detection, metal contamination.
Classification and identification: Discuss the relationship between the properties of a chemical under investigation and different analytical techniques.
Determine the concentration of an organic compound in an aqueous solution.
Perform a titration to determine degree of saturation of fats and oils; for example, at the Royal Society of Chemistry website.
Perform redox titrations to determine quantities of specific organic substances in consumer products; for example, alcohol in white wine or Vitamin C in fruits.
Billy goat plum / Kakadu plum (Terminalia ferdinandiana) is a native fruit found in the woodlands of the Northern Territory and Western Australia and is said to be the world’s richest source of Vitamin C. One claim is that the plum has 50 times the Vitamin C content of oranges. Design and perform a redox titration to investigate the validity of the claim.

Key knowledge: Instrumental analysis of organic compounds

Literature review: Research and discuss the principles of mass spectrometry; interpret mass spectrographs of atoms and molecules.
Literature review: Research and discuss the principles and application of infrared spectroscopy; interpret simple IR spectrographs.
Literature review: Research and discuss the principles and application of proton and carbon-13 NMR; interpret some simple proton and carbon-13 NMR spectrographs in determining the composition and structure of an unknown compound.
Determine the identity of an unknown organic compound from microanalysis, mass spectrometry, IR spectroscopy, carbon-13 and proton NMR spectroscopy results (using the free app Chemical Detectives, available on Apple App Store and Google Play, investigate unknown organic compounds with a particular functional group, or for only molecules relevant to VCE Chemistry).
Predict the spectra of given organic compounds. (see Detailed example)
Use this interactive applet to demonstrate that the behaviour of CFCs is dependent on both the wavelength of radiation as well as position of the molecule in the atmosphere. In this applet the user can investigate the various interaction modes of a CFC molecule with electromagnetic radiation across the entire spectrum.
Using a free app on a smartphone as a light meter, some fruit juice and a torch, measure changes in concentrations across different juice drinks with smartphone spectroscopy (this video 'Chemistry in your cupboard' from the Royal Society of Chemistry demonstrates how to collect spectroscopy data). Project 2 of this collection of resources, Phone-y science, has PowerPoint slides and student booklets.
Compare class measurements of the length of a specified object and use the results to discuss the difference between the terms ‘accuracy’ and ‘precision’. Determine the maximum resolution of length measurement with a steel ruler compared with a wooden ruler. Discuss the importance of accuracy and precision in analytical chemistry.
Discuss the general principles and selected applications of chromatography.
Describe qualitatively and quantitatively what happens when a drop of coloured liquid is placed on a piece of absorbent paper; compare this phenomenon with the principles of HPLC.
Modelling: Create an animation or other visual representation to illustrate how an HPLC column works at the particle level.
Use data from a number of analytical techniques to determine the identity of an unknown compound.
Complete exercises involving the identification of an appropriate analytical technique for a specified purpose.
Create a flow chart describing the steps to obtaining a pure organic compound of an organic synthetic reaction, which includes the purification step using chromatographic techniques and the analysis of the purity of the final product using mass spectrometry, IR and NMR spectroscopies.
Fieldwork: Arrange a site tour of an analytical laboratory to observe chemical instrumentation at work; process sample data.
Product, process or system development: Build a do-it-yourself spectrometer from cardboard or thick paper and a smartphone, and collect spectra for further analysis. You can also upload the spectra to public databases such as Spectral Workbench.
Use an interactive applet to investigate how the global warming potential (GWP) of greenhouse gases is related to the infrared portion of the electromagnetic spectrum, because different greenhouse gases absorb in different parts of the infrared spectrum. (Part 2 of this Climate change chemistry lessons resource from Beyond Benign (US) has an activity on modelling GWP of greenhouse gases).
Many of the plants used in traditional medicines and bush medicines contain anti-bacterial and anti-inflammatory compounds that are known to western medicine. Discuss how instrumentation could be used to identify and compare the active ingredients in these medicines.
Compare the spectra from instrumental analysis of different brands of commercial tea tree oils to identify common functional groups or spectral regions.

Key knowledge: Medicinal chemistry

Classification and identification: Using a range of examples of medicinal compounds, identify structure and functional groups, including isomers and chiral centres which may be attributed to the bioactivity of the compounds.
Suggest ways that the active ingredients of known bush medicines can be extracted and purified.
Access the set of PowerPoint slides at ‘Investigating the chemistry of the Uncha plant' and explain the processes for extraction and purification of the natural components in Uncha leaves as possible active ingredients for medicines. Discuss how collaboration between Aboriginal researchers and Western researchers contributes to developing improved understanding of medicinal chemistry.
Suggest why the plants used by Aboriginal and Torres Strait Islander peoples to treat illnesses were applied differently in terms of the physical and chemical properties of their active ingredients; for example, goat’s foot (Ipomoea pes-caprae or Oxalis pes-caprae) was crushed, heated and applied to the skin; other plants were boiled, inhaled or drunk undiluted; some saps were directly smeared on the skin; and barks were smoked or burned to inhale the fumes. Discuss how the physical and chemical properties of substances affects the techniques selected to separate the active ingredients from the rest of the plant.
Alkaloids, for example strychnine, morphine, cocaine and nicotine, are found in a number of plants and have a potent effect on the human central nervous system. Discuss whether the difficulty of determining safe doses can explain that few native plants containing alkaloids are used in traditional medicines.
Literature review: Develop a presentation about the production, chemical structure and use of a selected natural product or synthetic medicine; for example, citridiol insect repellent from lemon eucalyptus tree, a range of antibiotics, and cisplatin for cancer treatment.
Case study: Review the timeline from the discovery of penicillin in 1928 to its commercial production to treat bacterial infections in 1944, beginning with the discovery of the antibacterial properties in a mould growing on a bacterial culture plate by Alexander Fleming in 1928, followed by the isolation of penicillin from the mould and a study of its properties by Ernst Chain and Howard Florey in 1938, leading to commercial production in large quantities in 1944. Discuss the importance of careful observation and creative thinking in chemistry by considering Alexander Fleming’s work; explain the collaborative nature of the development of scientific knowledge; suggest why there are generally lengthy periods of time between the discovery of a possible bioactive substance and its commercial production.
Controlled experiment: Design and perform an experiment to extract bioactive compounds from pomegranate fruit using solvent mixtures with increasing / decreasing polarity. Compare the yield of the extract; discuss the relationship of the yield with types of solvents used; perform qualitative tests for phenolic compounds of the extract.
Controlled experiment: Undertake the extraction of essential oils (for instance from lemons) using steam distillation.
Modelling: Model the ‘lock-and-key’ mechanism of enzyme action; discuss its significance in the functioning of enzymes in biochemical reactions.
Use a data table of amino acids to model the molecular structures of 2-amino acids, their condensation reactions and peptide links.
Controlled experiment: Design an experiment to investigate the effect of changing the temperature or pH on the rate of an enzyme-catalysed reaction. Distinguish between the terms ‘catalyst’ and ‘enzyme’.
Create an animation of the action of an enzyme in a biochemical reaction at the molecular level.
Controlled experiment: Investigate the effect of temperature, pH and catalyst concentration on reactions catalysed by enzymes. For example:
- the effect of changing temperature on the time taken for lipase to break down the fats in milk to form fatty acids and glycerol
- the time taken for amylase to completely break down a sample of starch under different pH conditions
- the effect of varying concentrations of trypsin on the time taken to digest the gelatine coating on photographic film.
For each experiment, calculate reaction rates; produce a reaction rate versus time graph; discuss how temperature, pH and enzyme concentrations affect the rate of reactions.
Design and conduct an experiment to compare the rates of enzyme activity in different brands of lactase oils that are used by lactose-intolerant individuals to break down the lactose in milk (useful worksheets can be found here).
Investigate the effect of competitive and non-competitive inhibitors on the enzyme β-galactosidase (teachers can login to the free resources).
Controlled experiment: Investigate the degree of denaturation (caused by the copper ions breaking down the tertiary structure of the albumin in egg white) of egg white by adding varying concentrations (for example, 0.002 M to 0.01 M) of copper(II) sulfate solution. Centrifuge the solutions after denaturation to quantify the degree of denaturation. Explain why copper bowls are often used in stabilising egg foams.
Case study: Discuss the action of penicillin as a competitive enzyme inhibitor: penicillin functions by interfering with the synthesis of cell walls of reproducing bacteria → penicillin inhibits an enzyme (transpeptidase) that catalyses the last step in the biosynthesis bacterial cell walls → the resulting defective cell walls then cause bacterial cells to burst (human cells are not affected because they have cell membranes, not cell walls).

Detailed example

Predicting the spectra of given organic compounds

Introduction

Mass spectrometry, infra-red (IR) spectroscopy and proton and carbon-13 nuclear magnetic resonance (NMR) spectroscopy each provide unique information about the structure of an organic compound, enabling that structure to be deduced. Conversely, if the structural formula of an organic compound is already known, then the m/z value of its molecular ion peak on its mass spectrum, key features of its NMR spectra, as well as some key absorption bands on its IR spectrum, can be predicted, using the same principles

Aim and method

Students work individually or in pairs on this task. They use a data book to assist in this task. Students may be:

given the semi-structural formulas of butanal, CH₃CH₂CH₂CHO, and butan-2-one, CH₃COCH₂CH₃, and asked to draw their structural formulas
asked to determine the m/z value of the molecular ion peak for each compound; teachers should establish that the two compounds are structural isomers through questioning / class discussion
asked to identify the key bonds present in each molecule that would be detected in their infrared spectra and at what wave numbers the corresponding key bands would be located in their spectra
provided with two pairs of axes to predict and sketch the high resolution proton NMR spectrum for each compound; the relative peak heights as well as the number of peaks and their location should be shown; students may then be asked whether this is sufficient to distinguish between the two compounds
asked to predict the number of peaks that would be observed in the carbon-13 NMR spectrum of each compound
given copies of the MS, IR and proton and carbon-13 NMR spectra to evaluate their predictions and to analyse the reasons for any errors they made.

Discussion questions and recording in logbook

A series of questions may be set as a pre-activity for students to answer in their logbook, for example:

Understanding: Why does an organic molecule produce a range of peaks when it is analysed by a mass spectrometer? What determines their m/z value?
Predicting: If an organic molecule is an ester, what are two bonds present in the molecule that will produce a characteristic absorption band on its IR spectrum and at what wave numbers should those bands be located?
Applying: For the molecule CH₃CH₂CH(OH)CH₃, how many different hydrogen environments and how many different carbon environments are present? Hence, how many peaks will be present on the low-resolution proton NMR spectrum and carbon-13 NMR spectrum of this compound? What will be the resulting splitting pattern on the high-resolution proton NMR spectrum?

Teacher notes

Teachers may access the free site Spectral Database for Organic Compounds (SDBS) to obtain the actual spectra for butanal and butan-2-one.

Outcome 3

On completion of this unit the student should be able to design and conduct a scientific investigation related to the production of energy and / or chemicals and / or the analysis or synthesis of organic compounds, and present an aim, methodology and method, results, discussion and conclusion in a scientific poster.

Examples of learning activities

Key knowledge: Investigation design

Compare class observations of a single chemical phenomenon or process and discuss why careful observation is important in scientific investigations. Comment on the quote from Johann Wolfgang von Goethe (1749–1832) German poet, dramatist: ‘We see only what we know.’
Discuss the significance of precision in measurements in chemistry.
Discuss the following quote by Edward Teller: ‘A fact is a simple statement that everyone believes. It is innocent, unless found guilty. A hypothesis is a novel suggestion that no one wants to believe. It is guilty, until found effective.’ (Teller, E, Teller, W & Talley, W (1991) Conversations on the Dark Secrets of Physics, Basic Books, New York).

Key knowledge: Scientific evidence

Comment, in terms of the nature of science, on Bill Gaede’s quote that ‘Science is not about making predictions or performing experiments. Science is about explaining.’
Discuss whether there is a role for ‘guessing’ in chemistry experimentation and research.

Key knowledge: Science communication

Comment, in terms of the importance of scientific communication, on Anthony Hewish’s quote that: ‘I believe scientists have a duty to share the excitement and pleasure of their work with the general public, and I enjoy the challenge of presenting difficult ideas in an understandable way.’
Debate the topic: ‘It is more important, in presentations, to impress rather than to inform’.
Download and print prepared scientific posters (for example, from the University of Texas website) and work in groups using a provided set of criteria to evaluate investigation aims, methodologies, data presentation, conclusions and effectiveness of scientific communication for each poster.
Organise small group discussions in class to identify the strengths, weaknesses and areas for improvement of a range of scientific posters; for example, those found at University of Texas website. Collate and reflect on class results and provided online evaluations to develop a set of ‘do’s’ and ‘don’ts’ for constructing a scientific poster.

Examples of research topics

The following topics are a sample of student-designed practical investigations that may be considered. Students may use different scientific methodologies to generate primary data. In particular, controlled experiments, modelling, and product, process or system development are the most appropriate methodologies for this area of study. Simulations may be used in situations where students do not have access to appropriate laboratory equipment and where students are able to manipulate variables to generate a unique data set, but teachers must subsequently determine how students’ ability to design an investigation will be assessed for this outcome. Teachers must check all students’ proposed investigations for safety, practicability and resource availability.

Compare combustion and properties of biodiesel made from different oils.
Design and perform experiments to determine whether the resultant heat of combustion of a mixture of fuels is related to the proportion of fuels in the mixture and their ∆H values (for example, if Fuel A has a ∆H of 1200 kJ mol^-1 and Fuel B has a ∆H of 1800 kJ mol^-1 then will a 50:50 mixture of the fuel have a ∆H of 1500 kJ mol^-1?).
Controlled experiment: Formulate a hypothesis and then design and perform an experiment to investigate how the molecular shape of a fuel molecule affects its heat of combustion, for example:
- Do the heats of combustion of the three isomers of C₄H₉OH (butan-1-ol, butan-2-ol and 2-methyl-propan-2-ol) have similar ∆H values?
- Does the presence of oxygen in a molecule make a molecule more combustible (for example, compare hexane and hexanol)?
Product, process or system development: Design and construct a torsion viscometer; use it to compare the viscosities of different fuels or hydrocarbons; use it to investigate and explain the differences in the ‘viscous’ properties of hens’ eggs that have been boiled for different lengths of time; suggest modifications to the design to improve precision of readings.
Product, process or system development: Design and perform an experiment to determine the optimal conditions for producing algal oil; develop criteria to enable evaluation of its usefulness as a fuel source.
Investigate the effectiveness of cathodic protection in inhibiting metal corrosion.
Controlled experiment: Investigate experimentally how changing temperatures may affect the rate or the extent of a reaction in an electrochemical or electrolytic cell.
Use Faraday’s Laws to determine the percentage purity of a copper sample.
Product, process or system development: Design, construct, test and modify a polarimeter to study chirality in glucose molecules.
Investigate the electrical conductivity as a function of temperature, as a hot solution of gelatine (derived from the protein collagen) cools to form a gel; explain the results in terms of protein structure and the formation of zwitterions.
Product, process or system development: Design and construct an optical device for measuring the concentration of a non-soluble material in aqueous colloid systems; use your device to measure the fat content of different types of milk.
Compare the effectiveness of using direct titration against using a thermometric titration (where the temperature change is measured each time a portion of acid is added, with the highest temperature indicating the endpoint of the reaction) to determine the endpoint of a titration using sodium hydroxide solution and hydrochloric acid.
Use a back titration to calculate an unknown amount of an organic compound in a consumer product; discuss why a direct titration was an inappropriate analytical technique for the purpose.
Modelling: Devise and test a model of the relationship between the structures of different triglycerides and their melting points.
Investigate the change in viscosity when a mixture of starch (for example, cornflour or cornstarch) is mixed with water and stirred.
Controlled experiment: Design and perform an experiment to determine whether the sugar content (for example, glucose:fructose proportions) of a fruit is related to its degree of ripeness.
Design and perform an experiment to compare the fermentation rates of sucrose, glucose and fructose: individually, using different combinations, and using different percentage compositions; justify experimental design by taking into account that grape juice is made up of approximately equal proportions of glucose and fructose.
Investigate the ripening of bananas after they have been picked (their average starch content just before ripening reaches 25 per cent and drops over a few days of ripening to less than 1 per cent, with the drop in starch content to an increase first in sucrose followed by glucose and fructose); measure the amount of glucose during the ripening process by using either glucose test strips or a glucometer, or perform titrations using either Benedict’s solution or iodine / thiosulfate.
Compare the precision of using a DCPIP titration versus an iodine titration to determine the Vitamin C content of fruit juices.
Determine whether colorimetry is an accurate measure of Vitamin C loss from fruit juice, based on the observation that fruit juices get darker as Vitamin C breaks down.
Controlled experiment: Design and conduct an experiment to compare the rates of enzyme activity in different brands of lactase pills that are used by lactose-intolerant individuals to break down the lactose in milk.
Controlled experiment: Determine the peroxidase activity per gram of fruit or vegetable; for example potatoes, carrots, tomatoes, kiwifruit, cauliflower, green beans, horseradish, turnips, zucchinis.
Product, process or system development: Investigate how the calorimetric technique for the measurement of the heat content of foods and fuels in a school laboratory can be improved. (See see Detailed example)

Detailed example

How can the calorimetric technique for the measurement of the heat content of foods and fuels in a school laboratory be improved?

This practical investigation builds on knowledge and skills developed in Unit 3 Area of Study 1 and particularly in Unit 4 Area of Study 2. Teachers are reminded that the students must initially select their own topics within the scope of the school’s resources, frame their own research questions and design their own investigations.

Background

Following work on the heat of combustion of fuels, calorimetry and the heat content of foods, a student has expressed interest in the problem of the loss of heat energy when measuring the heat energy that is released when a fuel or food is burned in a school laboratory. The student has performed a simple experiment in class in which the molar heat of combustion of ethanol was determined by measuring the temperature rise of water contained in a can above the flame. The student has compared this with the published value, noted the large discrepancy with the experimental value and identified some key sources of error that led to this discrepancy. The student has read widely about the design of bomb calorimeters and processed second-hand-data from them and has seen in media reports that in addition to it being used as a material for wall insulation in homes, people suffering from hypothermia or from severe burns are wrapped in aluminium foil to help prevent loss of body heat. The student has expressed an interest in designing an experimental set-up and procedure that will lead to a more accurate result, and poses a question for investigation. The student has proposed an investigation question: ‘How can the calorimetric technique for the measurement of the heat content of foods and fuels in a school laboratory be improved?’

Planning the investigation

The student:

plans to design and trial different experimental set-ups and procedures to identify which one leads to results that are closest to the published molar heat of combustion of ethanol and the published heat content of a biscuit; in each case the student will use the specific heat capacity of water and the temperature rise of water to determine the heats of combustion of the samples
makes a written and photographic record of the experimental set-up used in each trial, as well as records all measurements taken (the student’s prior learning includes understanding that each piece of equipment used will have its own specific heat capacity, and that heat energy loss to the surroundings is the major source of error)
should seek the assistance of the teacher in identifying the risk factors involved should the investigation include using a source of oxygen to make the combustion more efficient, as is used in a bomb calorimeter. The student consults with the laboratory technician about the equipment, the materials required and the health and safety protocols to be implemented when burning materials.

Method

The student identifies three major areas in which the experimental design might be improved: the container in which the water is heated, the use of insulation around the apparatus, and the flow of oxygen to the flame. The student tests each area in turn, keeping all other variables controlled, and then tests the combination of conditions that has led to the most accurate results.

The student is supplied with ethanol, an unopened new packet of biscuits, a spirit burner, a crucible, a wide roll aluminium foil, a large polystyrene foam box, and other relevant equipment and materials.

The water container
Six different water containers are set up using different shapes and materials. Three are made from copper and the other three from tin-plated steel. For each material, one is a tall cylindrical shape like a drink can, with an open end at the top, one has the same shape and size but has a wooden lid placed over it with two holes for the stirrer and thermometer, and the third is the same as the second with the addition of aluminium foil wrapped tightly around its curved surface.

Insulation around the apparatus
Three different arrangements are set up. In the first, no insulating material is used. In the second, the entire apparatus is encased in an envelope of aluminium foil with an entry and an exit hole for air-flow on opposite sides. In the third, the polystyrene box is up-ended over the apparatus and two holes are drilled into it at opposite ends for air-flow.

Flow of oxygen to the flame
Three different arrangements are trialled. In the first, the natural flow of air is used. In the second, a small hair drier is used on a cold setting to slightly increase the speed of air flowing to the flame. In the third, oxygen gas produced by the addition of manganese dioxide catalyst to hydrogen peroxide solution is directed to the flame via a plastic tube.

Results

The student photographs each set-up that is trialled, and measures and records the mass of the fuel and biscuit burned, and the temperature rise in the same mass of water for both the ethanol and the biscuit for each set of conditions tested. The molar enthalpy of ethanol and the heat content of the biscuits are calculated from these results. The results are presented in two tables, one for ethanol and one for the biscuit. The photographs are printed and appropriately labelled to show the conditions used for each trial.

Discussion

The student analyses the results, and considers the limitations of the investigation and how the investigation could be improved. The student considers the need to account for why the set of conditions that led to the most accurate results for the combustion of the ethanol and of the biscuit worked best.

Conclusion

The student uses the data generated to respond to the investigation question asked.

Sample teaching plans

VCE units are designed based on a minimum of 50 hours of class time; these sample teaching plans are based on 3 hours per week over 19 weeks for each unit and include activities covering the eight scientific methodologies. Teachers are advised to consider their own contexts in developing learning activities: Which local issues lend themselves to debate and investigation? Which experiments can students complete within the resource limitations of their learning environments? Which local fieldwork sites and chemistry-based facilities would support learning in the topic area? Which chemical industries would be appropriate for site visits?

Teaching and Learning

Unit 1: How can the diversity of materials be explained?

Unit 1 – Area of Study 1: How do the chemical structures of materials explain their properties and reactions?

Outcome 1

Examples of learning activities

Detailed example 1

Making bush soap from acacia leaves

Aim

Introduction

Science skills

Health and safety notes

Procedure

Method

Questions

Detailed example 2

Predict-observe-explain: Investigating volume contraction in alcohol-water mixtures

Aim

Introduction

Science skills

Health and safety notes

Procedure

Questions

Unit 1 – Area of Study 2: How are materials quantified and classified?

Outcome 2

Examples of learning activities

Detailed example

Edible water capsules – a biodegradable co-polymer designed to degrade

Introduction

Science skills

Health and safety notes

Discussion questions and report writing in logbook

Teacher notes

Unit 1 – Area of Study 3: How can chemical principles be applied to create a more sustainable future?

Outcome 3

Examples of learning activities

Detailed example

Use of socratic seminars to support student agency in exploring contemporary chemistry-related issues in society

Introduction

Planning before the Socratic seminar

Implementation of the Socratic seminar

Extension

Unit 2: How do chemical reactions shape the natural world?

Unit 2 – Area of Study 1: How do chemicals interact with water?

Outcome 1

Examples of learning activities

Detailed example

The effect of pH on the colour formed from naturally dyed wool

Introduction

Science skills

Health and safety notes

Method

Discussion questions and report writing in logbook

Unit 2 – Area of Study 2: How are chemicals measured and analysed?

Outcome 2

Examples of learning activities

Detailed example

Responding to a chemistry-based issue in society: would you drink recycled water?

Aim

Introduction

Science skills

Preparation

Health, safety and ethical notes

Procedure

Unit 2 – Area of Study 3: How do quantitative scientific investigations develop our understanding of chemical reactions?

Outcome 3

Examples of learning activities

Detailed example

How does water quality differ at various points along a river?

Introduction

Topic selection phase

Planning phase

Investigation phase

Reporting phase

Unit 3: How can design and innovation help to optimise chemical processes?

Unit 3 – Area of Study 1: What are the current and future options for supplying energy?

Outcome 1

Examples of learning activities

Detailed example

Is there a relationship between the temperature rise in direct metal displacement reactions and the voltage of the galvanic cells driven by those reactions?

Introduction