# Tollens' reagent and Fehling's solution are both used to distinguish between aldehydes and ketones. Describe what is observed when each type of compound is tested with Tollens' reagent, and explain why ketones do not react with these oxidising agents.

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

## Mark scheme (5 marks)

1. Aldehydes produce a silver mirror (or silver precipitate) with Tollens' reagent
2. Ketones show no change / no reaction with Tollens' reagent
3. Aldehydes are oxidised (by the Tollens' reagent / oxidising agent)
4. Aldehydes are oxidised to carboxylic acids
5. Ketones cannot be oxidised under these conditions because the carbonyl carbon has no hydrogen atom directly attached to it (i.e. it is bonded to two carbon groups)

## Key terms

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

## 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/tollens-reagent-and-fehling-s-solution-are-ac51ef29) · Published by Druglandscape Ltd.