How to Identify What's Oxidised and Reduced
Part of Oxidation & Reduction — GCSE Chemistry
This how it works covers How to Identify What's Oxidised and Reduced 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 6 of 14 in this topic. Use this how it works to connect the idea to the wider topic before moving on to questions and flashcards.
Topic position
Section 6 of 14
Practice
20 questions
Recall
20 flashcards
⚙️ How to Identify What's Oxidised and Reduced
Example: 2Mg + O₂ → 2MgO
- Magnesium: Mg → Mg²⁺ (lost 2 electrons) → OXIDISED
- Oxygen: O₂ → 2O²⁻ (gained electrons) → REDUCED
- Also: Mg gained oxygen (another sign of oxidation)
Example: Fe₂O₃ + 3CO → 2Fe + 3CO₂
- Iron oxide: Fe³⁺ → Fe (gained electrons, lost oxygen) → REDUCED
- Carbon monoxide: CO → CO₂ (gained oxygen) → OXIDISED
- CO is the reducing agent (it causes reduction of iron)
Quick Check: In the reaction Fe₂O₃ + 3CO → 2Fe + 3CO₂, identify the oxidising agent and the reducing agent. Explain your answers.
Fe₂O₃ is the oxidising agent — it gives oxygen to CO and causes CO to be oxidised. It is itself reduced (iron gains electrons, going from Fe³⁺ to Fe). CO is the reducing agent — it removes oxygen from Fe₂O₃ and causes the iron oxide to be reduced. It is itself oxidised, gaining oxygen to become CO₂.