A (g) + B (g) ⇌ 2 C (g) + D (g) initially contains 1.5 M A and 1.0 M B. equilibrium concentration of C is 0.55 M, what is the value of the equilibrium constant (Kc) for the reaction?

Question

Consider the following reaction: A (g) + B (g) ⇌ 2 C (g) + D (g)

A reaction mixture initially contains 1.5 M A and 1.0 M B. If the equilibrium concentration of C is 0.55 M, what is the value of the equilibrium constant (K_c) for the reaction?

Answer 1

A + B <--> 2C + D

1.5...1.0......0........0......Initial

-x....-x......+2x.....+x......Change

1.5-x..1.0-x..2x....x......Equilibrium

@equilibrium [C] = 0.55 which is = 2x, therefore x = 0.275

Summary @ equilibrium:

[A] = 1.5-x = 1.5 - 0.275 = 1.225

[B] = 1.0-x = 1.0 - 0.275 = 0.725

[C] = 0.55

[D] = x = 0.275

K = [C]²[D] / [A][B] = (0.55)²(0.275) / (1.225)(0.725)

K = 0.094