# Calcium chloride is an ionic compound. When calcium chloride dissolves in water, it forms an aqueous solution. Explain why solid calcium chloride does not conduct electricity, but an aqueous solution of calcium chloride does conduct electricity.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.6 Ionic compounds · Explain · 4 marks

> Calcium chloride, CaCl₂, is an ionic compound used to de-ice roads in winter. It dissolves readily in water.

## Mark scheme (4 marks)

1. In solid calcium chloride, the ions are held in a fixed lattice / the ions cannot move
2. Because the ions cannot move, charge cannot be carried / electrical current cannot flow in the solid
3. When dissolved in water, the ionic lattice breaks down / the ions separate and become free to move
4. The free ions in solution carry electrical charge / allow current to flow, so the solution conducts electricity

## Key terms

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

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](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/calcium-chloride-is-an-ionic-compound-36a9621d) · Published by Druglandscape Ltd.