Question 3
HHydrogen can be made by reacting methane with steam.
CH4(g)+H2O(g)⇌CO(g)+3H2(g) \mathrm{CH_{4}(g) + H_{2}O(g) \rightleftharpoons CO(g) + 3H_{2}(g)} CH4(g)+H2O(g)⇌CO(g)+3H2(g)A chemist uses a computer model to find the percentage of methane converted at equilibrium under different conditions. The same mixture of methane and steam is used each time.
The graph shows the results.
a.[3]
Use the data to deduce whether the forward reaction is exothermic or endothermic.
Explain your reasoning.
b.[2]
Explain why the percentage of methane converted is lower at 30 atm than at 1 atm.
c.[3]
The chemist says:
"At 1 atm, hydrogen will be made faster at 900 °C than at 700 °C, because 99% of the methane is converted at 900 °C."
Evaluate the chemist's statement.
d.[2]
Suggest one change, other than changing the temperature or the pressure, that would increase the percentage of methane converted.
Explain your answer.
5.3 Equilibria Questions
47 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.