Question

Consider the gas-phase reaction, Cl2(g) + Br2(g) <=> 2 BrCl(g), for which Kp = 32 at 500 K. If the mixture is analyzed and found to contain 0.19 bar of Cl2, 0.29 bar of Br2 and 1.4 bar of BrCl, describe the situation:a) Q > K and more reactants will be made to reach equilibrium.b) Q > K and more products will be made to reach equilibrium.c) Within 1 decimal place, Q = K and the reaction is at equilibriumd) Q < K and more products will be made to reach equilibrium.e) Q < K and more reactants will be made to reach equilibrium.

Answer 1

Answer:

• a) Q > K and more reactants will be made to reach equilibrium

Explanation:

The reaction quotient, Q, is the actual ratio of concentrations or pressure of products to reactants.

When Q is equal to the equilibrium constant, the reaction is at equilibrium.

When Q > K, the concentrations, or pressures, of the products will have to decrease to reach the equilibrium, thus more reactants will be made.

When Q < K the concentrations, or pressures, of the reactants will have to decrease to reach the equilibrium, thus more products will be made.

Calculate Q:

• Reaction equation: Cl₂(g) + Br₂(g) ⇄ 2 BrCl(g),

         $P_{Cl_2}}=0.19bar\\\\P_{Br_2}}=0.29bar\\\\P_{BrCl}=1.4bar$

        $Q=\dfrac{(P_{BrCl})^2}{(P_{Br_2}).(P_{Cl_2})}$

        $Q=\dfrac{(1.4bar)^2}{(0.19bar).(0.29bar)}$

        $Q\approx 36$

Therefore, since Q > K, the pressure of the products should decrease to reach the equilibrium, meaning that more reactants will be made, i.e. option a).