Define oxidation. Identify and name the substance oxidised in the following reaction :
CuO + H₂ → Cu + H₂O
Generated by claude-sonnet-4-6 · 2026-06-14 10:29 · grounding rag
Model Answer
Oxidation: If a substance gains oxygen (or loses hydrogen) during a reaction, it is said to be oxidised.
In the reaction CuO + H₂ → Cu + H₂O, hydrogen (H₂) is oxidised because it gains oxygen to form water (H₂O).
Source: Chapter 1, Section 1.2.5 – Oxidation and Reduction
---
Explanation
- 1 mark for the definition: must mention gain of oxygen (or loss of hydrogen).
- 1 mark for correctly identifying and naming hydrogen (H₂) as the substance oxidised, with a brief reason (it gains oxygen).
- Do NOT say CuO is oxidised — CuO loses oxygen, so it is reduced.
- Always state why the substance is oxidised (gain of oxygen) to secure full marks.