# A student adds bromine water to two test tubes, one containing hexane and one containing ethene. Describe what the student would observe in each test tube and explain why the results are different.

> AQA A-Level Chemistry (7405) — 3.3.14 Organic synthesis (A-Level only) · Describe and Explain · 5 marks

## Mark scheme (5 marks)

1. Bromine water remains orange/unchanged with hexane
2. Bromine water turns colourless with ethene
3. Ethene is unsaturated / contains a carbon-carbon double bond
4. Hexane is an alkane / saturated hydrocarbon, so does not react with bromine water
5. The double bond in ethene makes it more reactive / allows it to react with bromine water (addition reaction / bromine adds across the double bond)

## Key terms

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

## Related

- [Revision notes for AQA A-Level Chemistry (7405)](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)

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Source: [GradeNine](https://www.gradenine.co.uk/q/a-student-adds-bromine-water-to-2b51912f) · Published by Druglandscape Ltd.