# Explain why a solution of ethanoic acid has a higher pH than a solution of hydrochloric acid of the same concentration.

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

> Ethanoic acid and hydrochloric acid are both acids, but they behave differently in aqueous solution.

## Mark scheme (5 marks)

1. Hydrochloric acid is a strong acid and fully/completely dissociates (ionises) in aqueous solution
2. Ethanoic acid is a weak acid and only partially/incompletely dissociates (ionises) in aqueous solution
3. At the same concentration, ethanoic acid produces fewer hydrogen ions (H⁺ / H₃O⁺) in solution than hydrochloric acid
4. A lower concentration of H⁺ ions means a higher pH
5. Therefore, at the same concentration, ethanoic acid has a higher pH than hydrochloric acid because its H⁺ ion concentration is lower

## Key terms

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

## 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-why-a-solution-of-ethanoic-1c14732e) · Published by Druglandscape Ltd.