# Explain what happens when hydrochloric acid is added to a solution of sodium hydroxide, in terms of the ions present and the formation of a salt.

> AQA A-Level Chemistry (7405) — 3.1.12 Acids and bases (A-Level only) · Explain · 5 marks

> Hydrochloric acid and sodium hydroxide solution are mixed together in equal volumes with equal concentrations.

## Mark scheme (5 marks)

1. Hydrochloric acid dissociates/ionises to produce hydrogen ions (H⁺) and chloride ions (Cl⁻)
2. Sodium hydroxide dissociates/ionises to produce hydroxide ions (OH⁻) and sodium ions (Na⁺)
3. The hydrogen ions and hydroxide ions react together to form water (H⁺ + OH⁻ → H₂O) — this is the neutralisation reaction
4. The sodium ions (Na⁺) and chloride ions (Cl⁻) remain in solution and form the salt sodium chloride (NaCl)
5. Because equal concentrations and equal volumes are used, the resulting solution is neutral (pH 7)

## Key terms

- [salt](https://www.gradenine.co.uk/glossary/salt)

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](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/explain-what-happens-when-hydrochloric-acid-bd1c9a57) · Published by Druglandscape Ltd.