# Trimethylamine, (CH₃)₃N, is the compound responsible for the characteristic smell of rotting fish. When trimethylamine dissolves in water, the solution turns litmus paper blue. Explain why trimethylamine produces an alkaline solution when dissolved in water, and describe two other chemical properties you would expect trimethylamine to show.

> WJEC A-Level Chemistry (Wales) — 4.6 Amines · Explain · 5 marks

> Trimethylamine, (CH₃)₃N, is the compound responsible for the characteristic smell of rotting fish. When trimethylamine dissolves in water, the solution turns litmus paper blue.

## Mark scheme (5 marks)

1. Trimethylamine contains a lone pair of electrons on the nitrogen atom
2. The lone pair accepts / accepts a proton (H⁺) from water, producing hydroxide ions (OH⁻), making the solution alkaline
3. Trimethylamine reacts with acids to form a salt
4. Trimethylamine acts as a base / is a base
5. Trimethylamine has a characteristic / pungent / unpleasant smell (fishy odour) and is a volatile compound

## Key terms

- [amine](https://www.gradenine.co.uk/glossary/amine)
- [alkaline](https://www.gradenine.co.uk/glossary/alkaline)

## Related

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

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Source: [GradeNine](https://www.gradenine.co.uk/q/trimethylamine-ch-n-is-the-compound-responsible-aeca8065) · Published by Druglandscape Ltd.