# Copper sulfate (CuSO₄) is an ionic compound. Explain how the bonding and structure of copper sulfate account for the following observations: copper sulfate does not conduct electricity when solid, but does conduct electricity when dissolved in water.

> Edexcel A-Level Chemistry (9CH0) — Topic 1 Foundations in chemistry · Explain · 5 marks

> Copper sulfate is a blue crystalline solid that is widely used in agriculture and industry. When dissolved in water it forms a blue solution.

## Mark scheme (5 marks)

1. Copper sulfate is made up of positive and negative ions (Cu²⁺ and SO₄²⁻) held in a giant ionic lattice / regular arrangement
2. In the solid state the ions are fixed / cannot move
3. Because the ions cannot move (in the solid), charge cannot be carried / electricity cannot flow
4. When dissolved in water, the ionic lattice breaks down / the ions separate and become free to move through the solution
5. The free-moving ions in solution carry the electrical charge, allowing the solution to conduct electricity

## Key terms

- [ionic compound](https://www.gradenine.co.uk/glossary/ionic-compound)
- [ions](https://www.gradenine.co.uk/glossary/ions)

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/copper-sulfate-cuso-is-an-ionic-334bf519) · Published by Druglandscape Ltd.