# Describe how bromine water can be used to distinguish between an alkane and an alkene, and explain why the two substances give different results.

> Cambridge International IGCSE Chemistry (0620) — 11.5 Alkenes · Describe · 4 marks

## Mark scheme (4 marks)

1. Bromine water remains orange/brown with the alkane
2. Bromine water is decolourised / turns colourless with the alkene
3. The alkene contains a carbon–carbon double bond (C=C) which reacts with bromine
4. The alkane 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)
- [alkane](https://www.gradenine.co.uk/glossary/alkane)
- [alkene](https://www.gradenine.co.uk/glossary/alkene)

## Related

- [Revision notes for Cambridge International IGCSE Chemistry (0620)](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/describe-how-bromine-water-can-be-990fb297) · Published by Druglandscape Ltd.