Briefly discuss Le Chatelier's Principle. Ammonia is made in the Haber Process (3H2(g) + N2(g)<-> 2NH3(g)). Using Le Chetelier's Principal, what happens to the equilibrium yield of ammonia when...: A) Temp increases, B) Press increases C) Catalyst changes

Le Chetelier's Principal gives us a guide to work out what will happen when we change the conditons of a reaction in dynamic equilibrium. It states that if the dynamic equilibiurm is disturbed, the equilibrium position will change in order to counteract the change that has occured. 

A) When we increase the temperature of the system, the reaction with the greatest surface area, or the one which produces the most moles of gas, is more favourable. Hence the equilibrium position will shift towards the reverse reaction in the Haber process and the equilibrium yield of ammonia will decrease. 

B) Increasing the pressure has an opposite effect to an increase in the temperature in that it favours the reaction which produces the least moles of gas. Since the forward reaction produces 2 moles from 4 moles, the number of moles of gas is decreasing hence the forward reaction is favoured when the pressure increases. The equilibrium yield of ammonia will therefore increase. 

C) A catalyst is a compound, usually a metal such as Fe or Pd, that provides the reaction with an alternative reaction pathway with a lower activation energy. Hence it increases the rate of the reaction. A catalyst has NO EFFECT on the equilibrium position hence the equilibrium yield of ammonia does not change (though the rate at which the reaction reaches equilibrium might).