# Explain why a solution of sodium ethanoate (CH₃COONa) has a pH greater than 7 at 25 °C.

> IB DP Chemistry Standard Level (2023 syllabus) — R3.1 Proton transfer reactions · Explain · 4 marks

## Mark scheme (4 marks)

1. Sodium ethanoate fully dissociates / ionises in water to give ethanoate ions (CH₃COO⁻) and sodium ions.
2. The ethanoate ion acts as a Brønsted–Lowry base and accepts a proton from water.
3. This produces ethanoic acid (CH₃COOH) and hydroxide ions (OH⁻), establishing the equilibrium: CH₃COO⁻ + H₂O ⇌ CH₃COOH + OH⁻.
4. The concentration of OH⁻ exceeds that of H⁺ / H₃O⁺, so the solution is basic and pH > 7.

## Key terms

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

## Related

- [Revision notes for IB DP Chemistry Standard Level (2023 syllabus)](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/explain-why-a-solution-of-sodium-1731ad39) · Published by Druglandscape Ltd.