Equilibria - AS Chemistry

Currently just finished studying equilibrium, and as revision id like to do some past equilibrium questions, even the most complex ones. So if any one has any questions at all, could you send me the link please thankya

Q. When nitrogen gas and hydrogen gas are allowed to react in a closed container the following equilibrium is established.

N₂ (g) + 3H₂ (g) <==> 2NH₃ (g) .............. ΔH = –92.6 kJ

(a) (i) Outline two characteristics of a reversible reaction in a state of dynamic equilibrium. [2]

(ii) Predict, with a reason, how each of the following changes affects the position of equilibrium. [2]

(iii) Define the term activation energy, Ea. [1]


(b) Ammonia is manufactured by the Haber process in which iron is used as a catalyst.
Explain the effect of a catalyst on the rate of reaction. [2]

(c) Typical conditions used in the Haber process are 500 °C and 200 atm, resulting in approximately 15 % yield of ammonia.
(i) Explain why a temperature lower than 500 °C is not used. [2]

(ii) Outline why a pressure higher than 200 atm is not often used. [1]

(d) (i) Deduce the equilibrium constant expression, Kc, for the reaction shown above. [1]

(ii) When 1.00 mol of nitrogen and 3.00 mol of hydrogen were allowed to reach equilibrium in a 1.00 dm3 container at a temperature of 500 °C and a pressure of 1000 atm, the equilibrium mixture contained 1.46 mol of ammonia. Calculate the value of Kc at 500 °C. [2]

1 mol of N2 and 3 mol of H2 were mixed in a 1 dm3 container at 450 oC and allowed to come to equilibrium.

1 mol of Ar was added to the container.

Predict what effect this would have on the position of the equilibrium.

It is almost a trick question.

You're meant to think that adding Ar will increase the pressure and since there are more gas particles on the left, the equilibrium will shift to the right.

But that doesn't happen. Why not?