# Ammonia has the formula NH₃. Ammonium sulfate has the formula (NH₄)₂SO₄. Ammonium sulfate is formed when ammonia reacts with sulfuric acid, H₂SO₄. Write the balanced symbol equation for this reaction and state the empirical formula of ammonium sulfate.

> Pearson Edexcel International GCSE Chemistry (4CH1) — 1.5 Chemical formulae, equations and calculations · State · 4 marks

> Ammonium sulfate is widely used as a fertiliser. It is manufactured by reacting ammonia gas with sulfuric acid.

## Mark scheme (4 marks)

1. Correct reactants and products written: NH₃ + H₂SO₄ → (NH₄)₂SO₄
2. Equation correctly balanced with a 2 in front of NH₃: 2NH₃ + H₂SO₄ → (NH₄)₂SO₄
3. Correct identification of atoms in one formula unit of (NH₄)₂SO₄: N₂H₈SO₄ (2 N, 8 H, 1 S, 4 O)
4. Correct empirical formula of ammonium sulfate stated as N₂H₈SO₄ (already the simplest whole number ratio, so empirical formula = N₂H₈SO₄ / equivalent correct simplest ratio accepted)

## Key terms

- [empirical formula](https://www.gradenine.co.uk/glossary/empirical-formula)
- [balanced symbol equation](https://www.gradenine.co.uk/glossary/balanced-symbol-equation)

## Related

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- [How to answer "State" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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