A scientist put 2.00 mol of nitrogen and 3.00 mol of hydrogen into a sealed container with an iron catalyst. The container was kept at a constant temperature and pressure.
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 amount of each gas in the container over time.
| Time / min | Nitrogen / mol | Hydrogen / mol | Ammonia / mol |
|---|---|---|---|
| 0 | 2.00 | 3.00 | 0.00 |
| 5 | 1.80 | 2.40 | 0.40 |
| 10 | 1.70 | 2.10 | 0.60 |
| 15 | 1.65 | 1.95 | 0.70 |
| 20 | 1.65 | 1.95 | 0.70 |
| 25 | 1.65 | 1.95 | 0.70 |
Deduce the earliest time in the table at which the mixture had reached equilibrium. Give a reason for your answer.
Explain why the amounts of the gases stay constant after this time, even though reactions are still taking place.
Determine which reactant is the limiting reactant and the maximum amount of ammonia that could form if the reaction went to completion.
Calculate the amount of ammonia at equilibrium as a percentage of the maximum amount.
In a second experiment the same container, at the same temperature and pressure, was filled with ammonia only. Describe how the amounts of nitrogen, hydrogen and ammonia would change from the start until equilibrium is reached.
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.