Chemistry · May / June 2019 · Paper 12 · Question 24

Ammonia is manufactured by the Haber process. N2(g) + 3H2(g) ⇌ 2NH3(g) ΔH = –92 kJ / mol For this reaction, which rows give a true statement together with a correct reason? | | statement | reason | |---|---|---| | 1 | Nitrogen and hydrogen are mixed in the ratio 1 : 3 by volume. | The formula of ammonia is NH3. | | 2 | The pressure used is approximately 200 atmospheres. | A high pressure is needed to produce a good yield of ammonia at equilibrium. | | 3 | The temperature used is approximately 450 °C. | A high temperature is needed to produce a good yield of ammonia at equilibrium. | | 4 | Vanadium(V) oxide is used as a catalyst. | A catalyst speeds up the rate of the reaction. |

1. A1 and 2 only
2. B2 and 3 only
3. C3 and 4 only
4. D1, 2 and 3 only

As printed in the paper