# Vinegar contains ethanoic acid, a member of the carboxylic acids homologous series. Describe the key features of carboxylic acids, including their functional group, typical chemical properties, and name the other three members of the homologous series to which ethanoic acid belongs.

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

> Vinegar is a dilute solution of ethanoic acid, widely used in food preservation. Ethanoic acid is formed when ethanol is oxidised. It belongs to a homologous series of organic compounds that share a common functional group and display typical acidic behaviour.

## Mark scheme (5 marks)

1. Carboxylic acids contain the functional group –COOH
2. Carboxylic acids have typical acidic properties (e.g. react with bases/carbonates/metals, or produce H⁺ ions in solution)
3. Methanoic acid is the first member of the homologous series
4. Propanoic acid is the third member of the homologous series
5. Butanoic acid is the fourth member of the homologous series

## 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)
- [ethanoic acid](https://www.gradenine.co.uk/glossary/ethanoic-acid)

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](https://www.gradenine.co.uk/learn)
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