# Butanal and butanone are both carbonyl compounds. A chemist wants to identify which of two unlabelled bottles contains butanal and which contains butanone. Describe how the chemist could use Fehling's solution to distinguish between the two compounds, and explain the results that would be observed.

> WJEC A-Level Chemistry (Wales) — 4.4 Aldehydes and ketones · Describe · 5 marks

> Butanal has the molecular formula C₄H₈O and belongs to the aldehyde family. Butanone has the molecular formula C₄H₈O and belongs to the ketone family.

## Mark scheme (5 marks)

1. Add Fehling's solution to a sample of each compound and heat / warm the mixture
2. Butanal (the aldehyde) produces a brick-red / orange-red precipitate
3. Butanone (the ketone) produces no change / Fehling's solution remains blue
4. Aldehydes are oxidised / butanal is oxidised (by Fehling's solution)
5. Ketones cannot be oxidised (under these conditions) / ketones do not react with Fehling's solution

## Key terms

- [Fehling's solution](https://www.gradenine.co.uk/glossary/fehling-s-solution)

## Related

- [Revision notes for WJEC A-Level Chemistry (Wales)](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/butanal-and-butanone-are-both-carbonyl-e49c2c29) · Published by Druglandscape Ltd.