# Propanoic acid is a carboxylic acid used as a food preservative. Describe the key properties of carboxylic acids, including their functional group, homologous series membership, and typical chemical behaviour.

> OCR A-Level Chemistry A (H432) — 6.1 Aromatic compounds, carbonyls and acids · Describe · 5 marks

> Propanoic acid (CH₃CH₂COOH) is added to bread and other baked goods to extend their shelf life by inhibiting the growth of mould.

## Mark scheme (5 marks)

1. Carboxylic acids contain the functional group –COOH
2. Carboxylic acids form a homologous series, with members differing by –CH₂– / sharing the same general formula or functional group
3. Names at least two correct members of the homologous series of carboxylic acids (methanoic, ethanoic, propanoic, butanoic)
4. Carboxylic acids have typical acidic properties, e.g. they react with carbonates / metals / alkalis OR they dissolve in water to produce an acidic solution
5. Carboxylic acids can be formed by the oxidation of alcohols

## Key terms

- [carboxylic acids](https://www.gradenine.co.uk/glossary/carboxylic-acids)
- [functional group](https://www.gradenine.co.uk/glossary/functional-group)
- [homologous series](https://www.gradenine.co.uk/glossary/homologous-series)

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/propanoic-acid-is-a-carboxylic-acid-072d6e9e) · Published by Druglandscape Ltd.