Life cycle assessment — AQA GCSE Chemistry
Test yourself on Life cycle assessment with AQA GCSE practice questions.
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Life cycle assessment explained
A life cycle assessment (LCA) tracks a product through raw material extraction, manufacture, use and disposal.
Read the full explanation
Some inputs and outputs are measurable: a factory's water meter records litres used, electricity bills give kilowatt-hours, and a balance gives the mass of material consumed. Waste masses sent to landfill or recycling can be weighed. For example, making 1000 paper bags might use 2500 dm³ of water and 400 MJ of energy, while 1000 plastic bags might use 500 dm³ of water and 700 MJ of energy. These quantities are objective because instruments give numbers in defined units. However, quantification is only 'fairly easy' for measurable flows; it does not tell us which impact matters more.
Your focus
- List measurable inputs and outputs at each stage of an LCA.
- Interpret given data on water, energy, resources and waste for two products.
- Explain why measured quantities are more objective than opinions.
Life cycle assessment exam tips
Marking Points
- Identify the four stages of an LCA: extracting raw materials, manufacture, use and disposal.
- State that water use, resource use, energy use and waste production can be measured in defined units such as dm³, kg, MJ and kWh.
- Explain that measured quantities are objective because they come from instruments, meters or mass balances rather than opinion.
- Use a comparative example, such as water and energy totals for paper and plastic bags, to show how data are collected.
- Recognise that quantification is limited to measurable flows and does not by itself rank environmental harm.
Examiner Tips
- 💡Name the unit whenever you quote a quantity, for example 400 MJ or 2500 dm³.
- 💡Link each measurable item to its LCA stage so the answer is structured.
- 💡Use a short comparison of two products to show the data are quantitative.
Common Mistakes
- Treating an LCA as only the disposal stage; correct by including extraction, manufacture, use and disposal.
- Confusing energy with power; correct by using joules or kilowatt-hours for energy and watts for power.
- Assuming all impacts can be measured equally easily; correct by noting that some pollutant effects need value judgements.