CAIE A Level Chemistry 9701 · Equilibria
A 1.0 dm³ closed vessel contains the following equilibrium at a fixed temperature:
The total pressure in the vessel is increased by forcing more nitrogen gas into the vessel at constant temperature and constant volume. The position of equilibrium does not change. Explain why the position of equilibrium does not change, and state and explain the effect that adding a catalyst would have on the position of equilibrium and on the time taken to reach equilibrium.
7 marks, so the mark scheme is looking for about 7 separate creditworthy points. Making the same point twice in different words earns it once.
Explain means: Give the reasons or the mechanism: why or how something happens. Link each point to the next with because, so or which means. A list of facts with no links usually loses the reasoning marks.
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