# Carboxylic acids are a homologous series of organic compounds. Explain the typical acidic properties of carboxylic acids and describe how the members of this homologous series differ from one another in terms of their structure.

> OCR GCSE Chemistry A: Gateway Science (J248) — C6.2 Organic chemistry · Explain · 4 marks

> Ethanoic acid is the carboxylic acid found in vinegar. It belongs to a homologous series that includes methanoic acid, propanoic acid and butanoic acid.

## Mark scheme (4 marks)

1. Carboxylic acids react with metals / carbonates / alkalis (accept any one valid acidic reaction)
2. Carboxylic acids have a pH below 7 / turn litmus red / produce hydrogen ions (H⁺) in solution
3. Each successive member of the homologous series has one additional CH₂ group (in the carbon chain)
4. All members share the same functional group –COOH

## Key terms

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

## Related

- [Revision notes for OCR GCSE Chemistry A: Gateway Science (J248)](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/carboxylic-acids-are-a-homologous-series-44a24ddd) · Published by Druglandscape Ltd.