This exam focus covers Exam Focus within Oxidation & Reduction for GCSE Chemistry. Revise Oxidation & Reduction in Chemical Changes for GCSE Chemistry with 20 exam-style questions and 20 flashcards. This topic appears less often, but it can still be a useful differentiator on mixed-topic papers. It is section 11 of 13 in this topic. Treat this as a marking guide for what examiners are looking for, not just a fact list.
Topic position
Section 11 of 13
Practice
20 questions
Recall
20 flashcards
🎯 Exam Focus
Frequently Examined
Redox is tested across many topics and question types. Key areas examined:
- Identify oxidised/reduced species: Given a reaction, state which species is oxidised and which is reduced (2 marks)
- Define oxidation/reduction: In terms of electron transfer (1 mark each)
- Half equations (HT): Write and balance oxidation and reduction half equations (2-3 marks)
- Identify reducing/oxidising agents: State which substance is the reducing agent (2 marks)
- Redox in context: Explain why rusting, combustion, displacement, or extraction is a redox reaction (2-3 marks)
- Electrolysis link: State whether oxidation or reduction occurs at each electrode (1-2 marks)
Examiner tip: "Which species is oxidised?" always requires you to say which LOSES electrons. "Which is the reducing agent?" always requires you to say which LOSES electrons (the reducing agent is itself oxidised). Two different questions, same substance as the answer.
Quick Check: In the reaction Zn + CuSO₄ → ZnSO₄ + Cu, which species is oxidised and which is reduced?
Zinc (Zn) is oxidised — it loses 2 electrons to become Zn²⁺. Copper ions (Cu²⁺) are reduced — they gain 2 electrons to become copper metal (Cu). Zinc is the reducing agent; copper sulfate is the oxidising agent.
Quick Check: In the extraction of iron, CO reduces Fe₂O₃: Fe₂O₃ + 3CO → 2Fe + 3CO₂. Which substance is the reducing agent?
Carbon monoxide (CO) is the reducing agent. It causes the iron(III) oxide to be reduced (iron gains electrons/loses oxygen, going from Fe³⁺ to Fe). In the process, CO is itself oxidised — it gains oxygen to form CO₂.