# The Haber process is used to manufacture ammonia. The reaction is a reversible reaction that reaches dynamic equilibrium. Explain what happens to the rate of the forward reaction and the rate of the backward reaction as the system moves towards dynamic equilibrium, and state what this means for the concentrations of ammonia, nitrogen and hydrogen once dynamic equilibrium is reached.

> Edexcel GCSE Chemistry (1CH0) — 5.3 Dynamic equilibria, calculations involving volumes of gases (Chem only) · Explain · 4 marks

> In the Haber process, nitrogen and hydrogen react together to form ammonia. The reaction is reversible and is carried out at 450°C and 200 atm using an iron catalyst.

## Mark scheme (4 marks)

1. As the reaction proceeds, the rate of the forward reaction decreases (as reactants are used up)
2. The rate of the backward reaction increases (as products build up)
3. At dynamic equilibrium the rate of the forward reaction equals the rate of the backward reaction
4. The concentrations of nitrogen, hydrogen and ammonia remain constant at dynamic equilibrium

## Key terms

- [dynamic equilibrium](https://www.gradenine.co.uk/glossary/dynamic-equilibrium)
- [forward reaction](https://www.gradenine.co.uk/glossary/forward-reaction)
- [backward reaction](https://www.gradenine.co.uk/glossary/backward-reaction)
- [concentration](https://www.gradenine.co.uk/glossary/concentration)
- [reversible reaction](https://www.gradenine.co.uk/glossary/reversible-reaction)

## Related

- [Revision notes for Edexcel GCSE Chemistry (1CH0)](https://www.gradenine.co.uk/learn)
- [How to answer "Explain" questions](https://www.gradenine.co.uk/tools/command-word-cheatsheet)
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