Question

Find the equilibrium constant, Keq, for the following equilibrium. The initial concentrations of AB and A2D are 0.30 M before they are mixed and when equilibrium is reached, the equilibrium concentration of A2D is 0.20 M. Use an ICE table for your calculation. (Answer: Keq = 0.80)

2 AB (g) + C2D (s) ↔ A2D (g) + 2 CB (s)

Answer 1

The equilibrium constant (Keq) for the reaction is calculated using an ICE table. By tracking the concentration changes from initial to equilibrium, we find that Keq equals 0.80.

Step-by-step explanation:

To determine the equilibrium constant (Keq) for the reaction 2 AB (g) + C2D (s) ↔ A2D (g) + 2 CB (s), we use an ICE table (Initial, Change, Equilibrium) to track the changes in concentration from beginning to equilibrium.

ICE Table Calculation

We start with the initial concentrations:

[AB] = 0.30 M (before mixing)

[A2D] = 0.30 M (before mixing)

At equilibrium, we have:

[A2D] = 0.20 M

Since 2 moles of AB react to form 1 mole of A2D, the change in [AB] should be twice the change in [A2D]. For AB, the change is -0.10 M (because 0.10 M of A2D is formed), leaving us with 0.20 M of AB at equilibrium.

The reaction quotient, Q, is expressed as Q = [A2D] / ([AB]^2) since C2D and CB are solids and do not appear in the expression.

Substituting the equilibrium concentrations into the Q expression gives us Keq:

Keq = [0.20] / ([0.20]^2) = 0.80

Therefore, the equilibrium constant for the reaction is 0.80.