# Pentan-2-one is a carbonyl compound used as a flavouring agent in the food industry. A student wants to distinguish between pentan-2-one and pentanoic acid using simple chemical tests. Describe the chemical tests the student could carry out, the results expected for each compound, and explain why the two compounds give different results.

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

> Pentan-2-one belongs to the ketone family of carbonyl compounds. Pentanoic acid is a carboxylic acid with five carbon atoms.

## Mark scheme (5 marks)

1. Add sodium carbonate (or sodium hydrogencarbonate) solution to each compound
2. Pentanoic acid produces bubbles / fizzing / effervescence with sodium carbonate; carbon dioxide gas is given off
3. Pentan-2-one shows no reaction / no bubbles with sodium carbonate
4. Pentanoic acid reacts because it is acidic / it donates H⁺ ions / it reacts with the carbonate to form a salt, water and carbon dioxide
5. Pentan-2-one does not react because it is not acidic / it does not contain the carboxyl (–COOH) group / ketones are neutral

## Key terms

- [carbonyl compound](https://www.gradenine.co.uk/glossary/carbonyl-compound)

## Related

- [Revision notes for Eduqas A-Level Chemistry](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/pentan-2-one-is-a-carbonyl-compound-used-0e8525f9) · Published by Druglandscape Ltd.