Ammonium carbamate decomposes reversibly when heated.
NH2COONH4(s)⇌2NH3(g)+CO2(g) \mathrm{NH_{2}COONH_{4}(s) \rightleftharpoons 2NH_{3}(g) + CO_{2}(g)} NH2COONH4(s)⇌2NH3(g)+CO2(g)A student heats ammonium carbamate in a sealed container at a constant temperature. The table shows how the amounts of the substances change.
| Time in minutes | Amount of NH2COONH4\mathrm{NH_{2}COONH_{4}}NH2COONH4 in mol | Amount of NH3\mathrm{NH_{3}}NH3 in mol | Amount of CO2\mathrm{CO_{2}}CO2 in mol |
|---|---|---|---|
| 0.0 | 0.050 | 0.000 | 0.000 |
| 1.0 | 0.044 | 0.012 | 0.006 |
| 2.0 | 0.041 | 0.018 | 0.009 |
| 3.0 | 0.040 | 0.020 | 0.010 |
| 4.0 | 0.040 | 0.020 | 0.010 |
| 5.0 | 0.040 | 0.020 | 0.010 |
Explain what is happening in the reaction mixture from 3.0 minutes to 5.0 minutes.
After 5.0 minutes, the container is opened. The ammonia and carbon dioxide can escape, but the ammonium carbamate remains in the container.
Predict what happens to the amount of ammonium carbamate if the container is kept open and heating continues. Explain your answer.
124 exam-style questions on OCR GCSE Chemistry 5.3 Equilibria, covering 5.3.1 Reversible reactions and dynamic equilibrium and 5.3.2 Changing the position of equilibrium. Each one has a worked solution and a mark scheme showing where the marks go.