# Butanone and butanal are both carbonyl compounds with the molecular formula C₄H₈O. A chemist wants to identify which compound is which using Tollens' reagent. Describe what the chemist would observe with each compound and explain why the two compounds give different results.

> Eduqas A-Level Chemistry — 4.4 Aldehydes and ketones · Describe and Explain · 5 marks

## Mark scheme (5 marks)

1. Butanal produces a silver mirror (or silver precipitate) with Tollens' reagent
2. Butanone produces no change / no reaction with Tollens' reagent
3. Butanal is an aldehyde and can be oxidised (acts as a reducing agent)
4. The silver ions in Tollens' reagent are reduced to silver metal by butanal
5. Butanone is a ketone and cannot be oxidised under these conditions, so it does not reduce Tollens' reagent

## Key terms

- [Tollens' reagent](https://www.gradenine.co.uk/glossary/tollens-reagent)

## Related

- [Revision notes for Eduqas A-Level Chemistry](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/butanone-and-butanal-are-both-carbonyl-93bbe6c4) · Published by Druglandscape Ltd.