Chemistry Unit 3: How Can Chemical Processes be Designed to Optimise Efficiency?
Students are advised to complete Chemistry Units 1 and 2 before undertaking Chemistry Unit 3. Mathematical Methods is strongly recommended.
The global demand for energy and materials is increasing with world population growth. In this unit, students explore energy options and the chemical production of materials with reference to efficiencies, renewability and the minimisation of their impact on the environment.
Students compare and evaluate different chemical energy resources, including fossil fuels, biofuels, galvanic cells and fuel cells. They investigate the combustion of fuels, including the energy transformations involved, the use of stoichiometry to calculate the amounts of reactants and products involved in the reactions, and calculations of the amounts of energy released and their representations. Students consider the purpose, design and operating principles of galvanic cells, fuel cells and electrolytic cells. In this context they use the electrochemical series to predict and write half and overall redox equations, and apply Faraday’s laws to calculate quantities in electrolytic reactions.
Students analyse manufacturing processes with reference to factors that influence their reaction rates and extent. They investigate and apply the equilibrium law and Le Chatelier’s principle to different reaction systems, including to predict and explain the conditions that improve the efficiency and percentage yield of chemical processes. They use the language and conventions of chemistry including symbols, units, chemical formulas and equations to represent and explain observations and data collected from experiments, and to discuss chemical phenomena.
Areas of Study
What are the options for energy production?
In this area of study students focus on analysing and comparing a range of energy resources and technologies, including fossil fuels, biofuels, galvanic cells and fuel cells, with reference to the energy transformations and chemical reactions involved, energy efficiencies, environmental impacts and potential applications. Students use the specific heat capacity of water and thermochemical equations to determine the enthalpy changes and quantities of reactants and products involved in the combustion reactions of a range of renewable and non-renewable fuels.
Students conduct practical investigations involving redox reactions, including the design, construction and testing of galvanic cells, and account for differences between experimental findings and predictions made by using the electrochemical series. They compare the design features, operating principles and uses of galvanic cells and fuel cells, and summarise cell processes by writing balanced equations for half and overall cell processes.
How can the yield of a chemical product be optimised?
In this area of study students explore the factors that increase the efficiency and percentage yield of a chemical manufacturing process while reducing the energy demand and associated costs.
Students investigate how the rate of a reaction can be controlled so that it occurs at the optimum rate while avoiding unwanted side reactions and by-products. They explain reactions with reference to the collision theory including reference to Maxwell-Boltzmann distribution curves. The progression of exothermic and endothermic reactions, including the use of a catalyst, is represented using energy profile diagrams.
Students explore homogeneous equilibrium systems and apply the equilibrium law to calculate equilibrium constants and concentrations of reactants and products. They investigate Le Chatelier’s principle and the effect of different changes on an equilibrium system and make predictions about the optimum conditions for the production of chemicals, taking into account rate and yield considerations. Students represent the establishment of equilibrium and the effect of changes to an equilibrium system using concentration-time graphs.
Students investigate a range of electrolytic cells with reference to their basic design features and purpose, their operating principles and the energy transformations that occur. They examine the discharging and recharging processes in rechargeable cells, and apply Faraday’s laws to calculate quantities in electrochemistry and to determine cell efficiencies.
Compare fuels quantitatively with reference to combustion products and energy outputs, apply knowledge of the electrochemical series to design, construct and test galvanic cells, and evaluate energy sources based on energy efficiency, renewability and environmental impact.
One task selected from the following:
- Analysis and evaluation of stimulus material.
- A report on a laboratory investigation.
- A comparison of two electricity-generating cells.
- A reflective learning journal.
|Apply rate and equilibrium principles to predict how the rate and extent of reactions can be optimised, and explain how electrolysis is involved in the production of chemicals and in the recharging of batteries.
One task selected from the following:
- Annotations of at least two practical activities.
- A report of a student investigation.
- An evaluation of research.
- Analysis of data including generalisations and conclusions.
- Media analysis/response.
- An analysis of an unfamiliar chemical manufacturing process or electrolytic cell.
- A response to a set of structural questions.
Overall Final Assessment
||Contribution to Study Score (%)
||Unit 3 Coursework
||Unit 4 Coursework
Reproduced by permission of the Victorian Curriculum and Assessment Authority, Victoria, Australia: www.vcaa.vic.edu.au