GCSE Chemistry Using Resources Notes
Chemistry provides the materials we depend on. Sustainable use means treating water carefully, assessing product life cycles and recycling metals and polymers.
Key concepts
- Potable water
- Water safe to drink — not chemically pure, but low in dissolved salts and free from microbes.
- Desalination
- Removing salt from seawater by distillation or reverse osmosis; energy-intensive.
- Life cycle assessment (LCA)
- Analysis of the environmental impact of a product across raw materials, manufacture, use and disposal.
- Recycling
- Reprocessing used materials so they can be used again — saves raw materials and energy compared to extraction.
- UK potable water: choose fresh water source → filter → sterilise (chlorine, ozone or UV).
- Sewage treatment: screening → sedimentation → aerobic digestion of effluent, anaerobic digestion of sludge.
- Recycling metals uses much less energy than extracting them from ore.
Worked example
Compare the environmental impact of using a glass bottle and a plastic bottle for drinks.
- 1Raw materials: glass = sand/limestone; plastic = crude oil (finite resource).
- 2Manufacture: glass needs much higher temperatures — more energy.
- 3Use: plastic is lighter — lower transport energy.
- 4Disposal: glass is easier to recycle and does not release microplastics; plastic can persist in the environment.
Answer: Glass has a higher manufacturing energy but is more easily recycled; plastic is lighter but uses finite oil and pollutes on disposal.
Common mistakes
✗ Saying potable water is pure water.
✓ Potable water contains dissolved salts; pure water is only H₂O.
✗ Ignoring transport and disposal in LCA.
✓ A full LCA covers raw materials, manufacture, use AND disposal.
✗ Assuming recycling always saves energy.
✓ Usually yes for metals; but sorting and transport can offset savings for mixed plastics.
Quick check
Try these, then reveal the answers.
Two steps in producing potable water in the UK.Reveal answer
Filtration and sterilisation.
Name a method of desalination.Reveal answer
Distillation or reverse osmosis.
Why is recycling aluminium worthwhile?Reveal answer
It uses far less energy than extracting it from bauxite by electrolysis.
Exam tips
- Give balanced arguments in LCA answers — cover raw materials, energy, transport and disposal.
- Use the word 'potable' rather than 'pure' when talking about drinking water.
- Mention finite vs renewable resources in sustainability answers.
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Frequently asked questions
What is a life cycle assessment?+
A systematic evaluation of the environmental impact of a product from raw materials to disposal, including manufacture, use and transport.
Why is desalination not used more widely?+
It requires large amounts of energy, making it expensive and often unsustainable unless powered by renewables.
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