# A student is trying to identify two unknown liquids. One liquid is a haloalkane and the other is an alcohol. The student adds a few drops of each liquid to separate test tubes containing aqueous silver nitrate solution acidified with dilute nitric acid. One test tube produces a cream precipitate, whilst the other shows no change. Explain these observations, identifying which liquid is the haloalkane and which is the alcohol.

> OCR A-Level Chemistry A (H432) — 4.2 Alcohols, haloalkanes and analysis · Explain · 5 marks

> Haloalkanes contain halogen atoms bonded to a carbon chain. Alcohols contain an –OH group bonded to a carbon chain. Both compound types are important in organic chemistry.

## Mark scheme (5 marks)

1. The haloalkane produces the cream precipitate
2. The haloalkane releases / produces halide ions (e.g. bromide ions) in solution
3. Silver ions react with halide ions to form a silver halide precipitate
4. The alcohol does not react / shows no change because it does not contain / release halide ions
5. This test allows the two compounds to be distinguished / identified

## Key terms

- [haloalkane](https://www.gradenine.co.uk/glossary/haloalkane)
- [precipitate](https://www.gradenine.co.uk/glossary/precipitate)
- [alcohol](https://www.gradenine.co.uk/glossary/alcohol)
- [silver nitrate](https://www.gradenine.co.uk/glossary/silver-nitrate)

## Related

- [Revision notes for OCR A-Level Chemistry A (H432)](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/a-student-is-trying-to-identify-ea843fc0) · Published by Druglandscape Ltd.