# Describe how a pure, dry sample of ammonium sulfate could be prepared in the laboratory starting from ammonia solution and dilute sulfuric acid.

> Cambridge International IGCSE Chemistry (0620) — 7.3 Preparation of salts · Describe · 4 marks

> Ammonium sulfate is a soluble salt used as a fertiliser. It is formed by the reaction between ammonia solution and dilute sulfuric acid.

## Mark scheme (4 marks)

1. Add ammonia solution to dilute sulfuric acid (using an indicator or until acid is neutralised / until no further reaction)
2. Use an indicator (such as litmus) to determine when the solution is neutral, then repeat without indicator / or add exact volumes determined from titration
3. Evaporate (heat) the neutral solution to concentrate it / reduce the volume of water
4. Allow the solution to cool so that ammonium sulfate crystals form, then filter off the crystals and dry them (e.g. between filter papers or in a warm oven)

## 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)
- [Practice this with AI marking (free)](https://www.gradenine.co.uk/start)

---
Source: [GradeNine](https://www.gradenine.co.uk/q/describe-how-a-pure-dry-sample-1fda99fe) · Published by Druglandscape Ltd.