# Butanone and butanal are both carbonyl compounds. Explain why butanone cannot be oxidised by acidified potassium dichromate(VI) solution, whereas butanal can, and describe what would be observed in each case when the reagent is added.

> Edexcel A-Level Chemistry (9CH0) — 17.2 Aldehydes and ketones · Explain · 5 marks

> Butanone has the molecular formula CH₃COCH₂CH₃. Butanal has the molecular formula CH₃CH₂CH₂CHO.

## Mark scheme (5 marks)

1. Butanal is an aldehyde, so it has a hydrogen atom directly bonded to the carbonyl carbon (CHO group)
2. This hydrogen can be removed, allowing the aldehyde to be oxidised to a carboxylic acid
3. Butanone is a ketone, so it has no hydrogen atom on the carbonyl carbon; carbon chains are on both sides of the C=O group
4. With butanal: the orange/orange-brown acidified potassium dichromate(VI) solution turns green
5. With butanone: the acidified potassium dichromate(VI) solution remains orange — no colour change occurs

## Key terms

- [oxidised](https://www.gradenine.co.uk/glossary/oxidised)
- [acidified potassium dichromate(VI)](https://www.gradenine.co.uk/glossary/acidified-potassium-dichromate-vi)

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Source: [GradeNine](https://www.gradenine.co.uk/q/butanone-and-butanal-are-both-carbonyl-27a4f431) · Published by Druglandscape Ltd.