Chemical Equilibrium Practice Problems

1. For the rusting of iron initially at equilibrium, predict the shift in the reaction with each perturbation.

3 Fe(s) + 4 H2O (g) <---> Fe3O4 (s) + 4 H2 (g) + heat

a) Increase the amount of water

b) Decrease the volume by half

c) Remove Fe3O4 as it is formed

d) Add hydrogen to the mixture

e) Increase the temperature

2. Hydrogen chloride reacts with oxygen to yield chlorine and water. An equilibrium can be established with this reaction. An experiment was performed in a closed vessel starting with a mixture of 0.50 M HCl and 0.050 M O2. The amount of chlorine was monitored until no change was observed, at 0.048 M chlorine.

a) Which way did the system shift to achieve equilibrium?

b) What is Kc for this reaction, and what are the equilibrium concentrations of all relevant components?

c) What is Kp for this reaction if the final temperature is 25C?

Answers