CHEM Equilibrium Temp.?

Question

For the following endothermic reaction at equilibrium:

Fe2O3 (s) + 3 H2 (g) 2 Fe(s) + 3 H2O(g)

Decide (YES/NO) if each of the following changes will increase the value of K (T = temperature).


Add Ne(g) (constant T)

Add a catalyst (constant T)

Decrease the volume (constant T)

Add H2 (constant T)

Increase the T

Remove H2 (constant T)

Decrease the T

Answer 1

The only change that will increase the value of K for this reaction is increasing the temperature. Adding heat to an endothermic reaction favors product formation since the value of K increases as the temperature increases. The rest of the changes listed will have no effect on the value of K, except decreasing the temperature, which will decrease the value of K, so it will favor the reactants.

The equilibrium constant of a chemical reaction is constant as long as the temperature is constant.

Answer 2

Kp = P^3(H2O)/P^3(H2)

(Pressure cubed of H2O over pressure cubed of H2) The Fe2O3 and Fe solids are taken as 1.00, because the amount of them does not affect the equilibrium.

Only increasing the T would increase the Kp. This is because in an endothermic reaction, heat appears on the left, so the reaction would shift to the right, increasing P(H2O), and therefore increasing the numerator of Kp.

Decreasing the T would decrease the Kp.