# Chlorine water is added to a solution of potassium bromide. Describe what is observed and explain why this reaction occurs, referring to the reactivity of the halogens.

> Edexcel GCSE Chemistry (1CH0) — 6.2 Group 7 · Describe and Explain · 4 marks

> Chlorine is a halogen in Group 7. When chlorine water is added to a solution containing bromide ions, a chemical reaction takes place.

## Mark scheme (4 marks)

1. The solution turns orange/brown
2. Chlorine displaces bromide ions / chlorine displaces bromine from potassium bromide
3. Chlorine is more reactive than bromine
4. Halogens become less reactive going down Group 7, so chlorine (higher up the group) is more reactive and can displace bromine

## Key terms

- [halogens](https://www.gradenine.co.uk/glossary/halogens)
- [reactivity](https://www.gradenine.co.uk/glossary/reactivity)

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](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/chlorine-water-is-added-to-a-fcaf0593) · Published by Druglandscape Ltd.