U3-4-1 - Equilibria
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At equilibrium, the _____ of forward and reverse reactions are equal.
rates
At equilibrium, the _____ of forward and reverse reactions are constant.
concentrations
State the effect a catalyst has on the equilibrium position
None (rates of forward/reverse reactions are increased by the same amount) but equilibrium is reached faster
If pressure is increased, which reaction will be favoured: forward or reverse?
Forward
The forward reaction is favoured if pressure is increased. Why?
Fewer gas moles on product side so favouring forward reaction helps decrease pressure
If pressure is increased, which reaction will be favoured: forward or reverse?
Reverse
Pressure has no effect on this equilibrium. Why?
Same no. of gas moles on both sides
Would you increase or decrease temperature to maximise product yield?
Decrease Reaction is exothermic
Would you increase or decrease temperature to maximise product yield?
Increase Reaction is endothermic
Why does an increase in temperature favour reactants?
Reaction is exothermic (so reverse reaction will be favoured to reduce heat)
State Le Chatelier’s principle
If a system at equilibrium is subjected to any change, the system readjusts itself to counteract the applied change. E.g. increased T = endothermic reaction favoured to lower it again
Why does adding OH− ions increase the rate of the reverse reaction?
Because OH− reacts with H+, and the reverse reaction is favoured to replace the H+ used up
Suggest one way to maximise profit in an industrial process.
Any of: *recycle/sell by-products *use catalysts *run reactions at low temperatures if possible *use cheap feedstocks if possible.