The Effect of Changing Conditions on Equilibrium Flashcards

All 5 cards in this deck

State Le Chatelier's Principle.

If a system at equilibrium is subjected to a change in conditions, the system responds to counteract the change.

What do the relative amounts of reactants and products at equilibrium depend on?

The conditions of the reaction — concentration, temperature and pressure.

What effect does adding a catalyst have on the position of equilibrium?

No effect — it speeds up the forward and reverse reactions equally, so equilibrium is only reached sooner.

What are the steps to predict the effect of a change in conditions on a system at equilibrium?

e.g. increasing the pressure on $\mathrm{N_2(g)} + 3\mathrm{H_2(g)} \rightleftharpoons 2\mathrm{NH_3(g)}$

1. Identify the change: pressure increased.
2. Decide which direction counteracts it: the side with fewer gas molecules (4 → 2), the right.
3. State the shift and its effect: equilibrium shifts right, so the yield of ammonia increases.

What are the steps to deduce from yield data whether a forward reaction is exothermic or endothermic?

e.g. the yield of product falls as temperature increases

1. Read the trend in yield as temperature rises: the yield falls.
2. A lower yield means the equilibrium has shifted to the left on heating.
3. Heating favours the endothermic direction, so the forward reaction is exothermic.