An ammonia plant uses the Haber process at 200 atm with an iron catalyst.
N2(g)+3H2(g)⇌2NH3(g)\mathrm{N_{2}(g)} + 3\mathrm{H_{2}(g)} \rightleftharpoons 2\mathrm{NH_{3}(g)}N2(g)+3H2(g)⇌2NH3(g)
The table shows how the temperature affects the percentage of ammonia at equilibrium and how quickly equilibrium is reached, at 200 atm.
| Temperature / °C | Percentage of ammonia at equilibrium / % | Rate of attaining equilibrium |
|---|---|---|
| 350 | 49 | slow |
| 450 | 27 | moderate |
| 550 | 12 | fast |
Explain why equilibrium is reached more quickly at a higher temperature.
Explain why the plant operates at 450 °C rather than at 350 °C or 550 °C.
The plant uses an iron catalyst.
State the effect of the catalyst on the percentage of ammonia at equilibrium.
Explain the effect of the catalyst on the time taken to reach equilibrium.
Give one reason why the plant does not use a pressure much higher than 200 atm.
43 exam-style questions on Edexcel GCSE Chemistry 6.3 Dynamic equilibria, covering 6.3.1 The Haber process as a reversible reaction, 6.3.2 Conditions and rate in industrial equilibria, and 6.3.3 Fertilisers and the preparation of ammonium sulfate. Each one has a worked solution and a mark scheme showing where the marks go.