# Copper(II) oxide is a black solid. When excess dilute sulfuric acid is added to copper(II) oxide powder and the mixture is warmed, the black solid disappears and a blue solution forms. Explain what type of reaction is taking place, identifying which species is the acid and which is the base, and describe what happens to the copper(II) oxide in terms of ions formed.

> OCR A-Level Chemistry A (H432) — 2.3 Acid-base and redox reactions · Explain · 5 marks

> Copper(II) oxide is an insoluble black powder. When it reacts with dilute sulfuric acid, the black solid dissolves to produce a blue copper(II) sulfate solution and water.

## Mark scheme (5 marks)

1. The reaction is a neutralisation reaction
2. The sulfuric acid is the acid (donates H⁺ / protons)
3. Copper(II) oxide is the base (accepts H⁺ / protons / neutralises the acid)
4. Copper(II) oxide provides / releases Cu²⁺ ions (into solution)
5. The O²⁻ ions from copper(II) oxide combine with H⁺ ions from the acid to form water

## Key terms

- [acid](https://www.gradenine.co.uk/glossary/acid)
- [base](https://www.gradenine.co.uk/glossary/base)
- [ion](https://www.gradenine.co.uk/glossary/ion)

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

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Source: [GradeNine](https://www.gradenine.co.uk/q/copper-ii-oxide-is-a-black-solid-a6c7d5ce) · Published by Druglandscape Ltd.