# Explain why carboxylic acids are significantly more acidic than alcohols, despite both functional groups containing an O–H bond.

> IB DP Chemistry Higher Level (2023 syllabus) — S3.2 Functional groups: classification of organic compounds · Explain · 4 marks

## Mark scheme (4 marks)

1. In carboxylic acids, the negative charge on the conjugate base (carboxylate ion) is delocalised / spread over both oxygen atoms via resonance, stabilising the anion.
2. The alkoxide ion formed from an alcohol bears the full negative charge on a single oxygen atom, so it is less stable / higher in energy than the carboxylate ion.
3. A more stable conjugate base shifts the equilibrium further towards dissociation / products, resulting in a higher Ka / lower pKa for carboxylic acids.
4. The inductive / electron-withdrawing effect of the carbonyl C=O also reduces electron density on the O–H bond of the carboxylic acid, further weakening it and facilitating proton release.

## Key terms

- [carboxylic acid](https://www.gradenine.co.uk/glossary/carboxylic-acid)
- [alcohol](https://www.gradenine.co.uk/glossary/alcohol)

## Related

- [Revision notes for IB DP Chemistry Higher Level (2023 syllabus)](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-carboxylic-acids-are-significantly-8df39481) · Published by Druglandscape Ltd.