# Propanal and propanone are both carbonyl compounds with the molecular formula C₃H₆O. Explain how the structural difference between propanal and propanone accounts for their different reactions with Fehling's solution, and describe what you would observe in each case.

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

> Propanal is an aldehyde and propanone is a ketone. Both compounds contain a carbonyl group (C=O).

## Mark scheme (5 marks)

1. Propanal is an aldehyde because its carbonyl group is at the end of the carbon chain (bonded to at least one hydrogen)
2. Propanone is a ketone because its carbonyl group is in the middle of the carbon chain (bonded to two carbon atoms on either side)
3. Propanal (aldehyde) is oxidised / acts as a reducing agent and reduces the Cu²⁺ ions in Fehling's solution
4. Propanal gives a brick-red/orange-red precipitate with Fehling's solution (copper(I) oxide formed)
5. Propanone (ketone) cannot be oxidised and therefore does not react with Fehling's solution, so the solution remains blue

## Key terms

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

## Related

- [Revision notes for Edexcel A-Level Chemistry (9CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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Source: [GradeNine](https://www.gradenine.co.uk/q/propanal-and-propanone-are-both-carbonyl-bdd954e3) · Published by Druglandscape Ltd.