In an ammonia plant, nitrogen and hydrogen pass through a reactor containing an iron catalyst at 450 °C.
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 the percentage of ammonia in the equilibrium mixture at 450 °C at different pressures.
| Pressure / atm | Percentage of ammonia at equilibrium / % |
|---|---|
| 50 | 9 |
| 100 | 16 |
| 200 | 27 |
| 300 | 35 |
| 400 | 42 |
A student says that the percentage of ammonia at equilibrium is directly proportional to the pressure. Evaluate this statement using the data.
The gases leave the reactor before equilibrium is reached. Only 15% of the nitrogen entering the reactor is converted into ammonia each time the gases pass through. Calculate the mass, in tonnes, of ammonia formed when 5.6 tonnes of nitrogen pass through the reactor once. Relative formula masses: N2=28,NH3=17\mathrm{N_{2}} = 28, \mathrm{NH_{3}} = 17N2=28,NH3=17
The gas mixture leaving the reactor is cooled. Explain how cooling allows the ammonia to be separated and the unreacted gases to be used again.
Suggest why the plant removes the gases from the reactor before equilibrium is reached rather than waiting for equilibrium.
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.