# Explain what happens in terms of oxygen and electrons during the reaction between copper(II) oxide and hydrogen. Identify which substance is oxidised and which is reduced, and state what type of overall reaction this is.

> AQA A-Level Chemistry (7405) — 3.1.7 Oxidation, reduction and redox equations · Explain · 5 marks

> Copper(II) oxide reacts with hydrogen gas to form copper metal and water: CuO + H₂ → Cu + H₂O

## Mark scheme (5 marks)

1. Hydrogen gains oxygen (to form water), so hydrogen is oxidised
2. Copper(II) oxide loses oxygen (to form copper), so copper(II) oxide / CuO is reduced
3. Copper(II) oxide / Cu²⁺ gains electrons (is reduced) OR hydrogen loses electrons (is oxidised) — in terms of electron transfer
4. Hydrogen / H₂ is the reducing agent
5. The overall reaction is a redox reaction (because oxidation and reduction occur simultaneously)

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