# Ethene reacts with bromine water. Describe what is observed and explain why ethene reacts in this way but ethane does not.

> AQA GCSE Chemistry (8462) — 4.7.2 Reactions of alkenes and alcohols (Chem only) · Describe and Explain · 4 marks

## Mark scheme (4 marks)

1. Bromine water turns from orange to colourless
2. Ethene is unsaturated / has a carbon–carbon double bond
3. The double bond breaks / opens and bromine adds across the double bond (addition reaction)
4. Ethane is saturated / has no double bond, so it does not react with bromine water

## Key terms

- [bromine water](https://www.gradenine.co.uk/glossary/bromine-water)

## Related

- [Revision notes for AQA GCSE Chemistry (8462)](https://www.gradenine.co.uk/learn)
- [How to answer "Describe and Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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