# Hydrochloric acid reacts with sodium hydroxide solution to form sodium chloride and water. Explain why this reaction is a chemical change and not a physical change.

> Eduqas GCSE Chemistry — 2.2 Acids, bases and salts · Explain · 4 marks

> Hydrochloric acid reacts with sodium hydroxide solution according to the equation: HCl + NaOH → NaCl + H₂O

## Mark scheme (4 marks)

1. A chemical change involves a chemical reaction
2. The products have a different chemical composition to the reactants
3. A physical change only involves a change in state / the chemical composition remains the same in a physical change
4. This reaction is not a physical change because the chemical composition has changed / different substances are present after the reaction

## Key terms

- [chemical change](https://www.gradenine.co.uk/glossary/chemical-change)
- [physical change](https://www.gradenine.co.uk/glossary/physical-change)

## Related

- [Revision notes for Eduqas GCSE Chemistry](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/hydrochloric-acid-reacts-with-sodium-hydroxide-a1c72e13) · Published by Druglandscape Ltd.