# Ammonium sulfate, (NH₄)₂SO₄, is used as a fertiliser. State what is meant by the term relative formula mass and use the formula of ammonium sulfate to show how its relative formula mass is determined. (Relative atomic masses: H = 1, N = 14, O = 16, S = 32)

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.4 Relative formula mass · State · 4 marks

> Ammonium sulfate has the formula (NH₄)₂SO₄. It is widely used in agriculture as a nitrogen-containing fertiliser.

## Mark scheme (4 marks)

1. Relative formula mass is the sum of the relative atomic masses of all the atoms in the formula (of the compound)
2. Correct identification of all atoms present: 2N, 8H, 1S, 4O (i.e. correctly expanding the brackets in (NH₄)₂SO₄)
3. Correct substitution of relative atomic masses: (2 × 14) + (8 × 1) + (1 × 32) + (4 × 16) = 28 + 8 + 32 + 64
4. Correct final answer of 132 (no units)

## Key terms

- [relative formula mass](https://www.gradenine.co.uk/glossary/relative-formula-mass)
- [relative atomic mass](https://www.gradenine.co.uk/glossary/relative-atomic-mass)
- [formula](https://www.gradenine.co.uk/glossary/formula)

## Related

- [Revision notes for Pearson Edexcel International GCSE Chemistry (4CH1)](https://www.gradenine.co.uk/learn)
- [How to answer "State" 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/ammonium-sulfate-nh-so-is-used-as-a70fff6b) · Published by Druglandscape Ltd.