Question

Pure iron metal can be produced by the reduction of iron(III) oxide with hydrogen gas.

(a) Write the expression for the equilibrium constant (Kc) for the reversible reaction
Fe₂ O₃(s) + 3H₂(g) ⇌ 2Fe(s) + 3H₂ O(g) ΔH = 98.7 kJ
b) What will happen to the concentration of each reactant and product at equilibrium if more Fe is added?
c) What will happen to the concentration of each reactant and product at equilibrium if H₂O is removed?
(d) What will happen to the concentration of each reactant and product at equilibrium if H₂ is added?
(e) What will happen to the concentration of each reactant and product at equilibrium if the pressure on the system is increased by reducing the volume of the reaction vessel?
(f) What will happen to the concentration of each reactant and product at equilibrium if the temperature of the system is increased?

Answer 1

The equilibrium constant expression for the given reaction is Kc = [Fe]²[H₂O]³ / [Fe₂O₃][H₂]³. Adding more Fe will cause the concentrations of Fe₂O₃ and H₂O to increase, and the concentrations of Fe and H₂ to decrease.

Step-by-step explanation:

Equilibrium Constant expression:

The expression for the equilibrium constant (Kc) for the reversible reaction Fe2O3(s) + 3H2(g) ⇌ 2Fe(s) + 3H2O(g) is:

Kc = [Fe]2[H2O]3 / [Fe2O3][H2]3

Effect of adding more Fe:

If more Fe is added, the concentration of Fe will increase. According to Le Chatelier's principle, the reaction will shift to the left to oppose the increase in Fe. This will cause the concentration of Fe2O3 to increase and the concentrations of H2 and H2O to decrease.

Effect of removing H2O:

If H2O is removed, the concentration of H2O will decrease. According to Le Chatelier's principle, the reaction will shift to the left to compensate for the decrease in H2O. This will cause the concentration of Fe2O3 to decrease and the concentrations of Fe and H2 to increase.

Effect of adding H2:

If H2 is added, the concentration of H2 will increase. According to Le Chatelier's principle, the reaction will shift to the right to consume the excess H2. This will cause the concentrations of Fe2O3 and H2O to decrease and the concentration of Fe to increase.

Effect of decreasing volume:

If the volume of the reaction vessel is decreased, the pressure will increase. According to Le Chatelier's principle, the reaction will shift in the direction that reduces the pressure. In this case, the reaction will shift to the right to consume more H2 and produce more H2O, reducing the number of moles of gas. This will cause the concentrations of Fe2O3 and H2O to decrease and the concentrations of Fe and H2 to increase.

Effect of increasing temperature:

If the temperature of the system is increased, the reaction will shift in the direction that absorbs heat. In this case, the forward reaction is exothermic, so increasing the temperature will shift the equilibrium to the left to consume excess heat. This will cause the concentrations of Fe2O3 and H2O to increase and the concentrations of Fe and H2 to decrease.