# Propanoic acid is a carboxylic acid used as a food preservative. Describe what is observed and explain what happens when propanoic acid reacts with sodium carbonate powder.

> Eduqas A-Level Chemistry — 3.4 Carbonyls and acids · Describe and Explain · 5 marks

> Propanoic acid is a carboxylic acid with the formula CH₃CH₂COOH. It is a weak acid used to prevent mould growth in bread and other baked goods.

## Mark scheme (5 marks)

1. Effervescence / bubbles / fizzing is observed
2. Carbon dioxide gas is produced / released
3. A salt (sodium propanoate) is formed
4. Water is also produced
5. Carboxylic acids react with carbonates because they are acids / they donate H⁺ ions / the acid neutralises the carbonate

## Key terms

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/propanoic-acid-is-a-carboxylic-acid-a1204382) · Published by Druglandscape Ltd.