#80
Chemical changes
Paper 1 · Apply
Key steps (method)
- Identify the type of reaction (metal + acid, neutralisation, electrolysis, redox).
- Use correct tests (H₂ squeaky pop; CO₂ turns limewater milky).
- For electrolysis, track ions and what happens at each electrode.
Common mistakes
- Mixing up oxidation/reduction definitions (OIL RIG / electron transfer).
- Wrong electrode products in electrolysis.
- Using state symbols or ionic charges incorrectly.
Exam-style questions (quick)
- Describe how to make a salt from an acid and an insoluble base.
- Explain why aluminium extraction needs electrolysis but iron can be reduced with carbon.
- In electrolysis of molten lead bromide, write half-equations at each electrode.
Revision links
- 9–1 GCSE Chemistry Paper 1 Chemical Reactions playlist: https://www.youtube.com/playlist?list=PL9IouNCPbCxXDlRtCQEG0cGehBvJ7t9Pf
- PMT notes + questions: https://www.physicsandmathstutor.com/chemistry-revision/gcse-aqa/chemical-changes/
- BBC Bitesize: https://www.bbc.co.uk/bitesize/topics/zcdj97h