A company investigates a batch process for making gaseous Z.
2X(g)+Y(g)⇌Z(g) \mathrm{2X(g) + Y(g) \rightleftharpoons Z(g)} 2X(g)+Y(g)⇌Z(g)The forward reaction is exothermic.
Each batch starts with the same amounts of X and Y. If the reaction went to completion, each batch would make 100 kg of Z. A catalyst is used.
At 40 atm, a new batch is started immediately after the mixture reaches equilibrium.
| Temperature (°C) | Z formed at equilibrium at 10 atm (% of maximum) | Z formed at equilibrium at 40 atm (% of maximum) | Time to reach equilibrium at 40 atm (minutes) |
|---|---|---|---|
| 300 | 74 | 88 | 36 |
| 400 | 58 | 76 | 12 |
| 500 | 41 | 62 | 6 |
Which temperature at 40 atm produces the greatest total mass of Z in 72 minutes? Show your working.
The company decides to operate the process at 500 °C and 40 atm.
Explain the patterns in the table and evaluate the company's choice of 500 °C and 40 atm. Include the effect of removing the catalyst.
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.