# A company manufactures NPK fertilisers using ammonia from the Haber process. Explain why the conditions used in the Haber process are described as a compromise.

> AQA GCSE Chemistry (8462) — 4.10.4 The Haber process and the use of NPK fertilisers (Chem only) · Explain · 4 marks

> The Haber process reacts nitrogen and hydrogen together to produce ammonia. The reaction is reversible. Industrial plants operate at approximately 450 °C and 200 atmospheres pressure, using an iron catalyst.

## Mark scheme (4 marks)

1. Higher pressure increases the yield of ammonia / shifts equilibrium towards ammonia
2. Very high pressure is expensive / dangerous to maintain, so a lower pressure is used
3. Lower temperature increases the yield of ammonia / equilibrium favours ammonia at lower temperature
4. Very low temperature makes the rate of reaction too slow, so a higher temperature is used to give an acceptable rate

## Key terms

- [Haber process](https://www.gradenine.co.uk/glossary/haber-process)
- [compromise](https://www.gradenine.co.uk/glossary/compromise)

## Related

- [Revision notes for AQA GCSE Chemistry (8462)](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-company-manufactures-npk-fertilisers-using-ba6b4acf) · Published by Druglandscape Ltd.