What is the value of the equilibrium constant, Kc ?

Question

X(g) + Y(g) ⇄ 2Z(g)

When 6.00 mol each of X(g) and Y(g) are placed in a 1.00 L vessel and allowed to react at constant temperature according to the equation above, 8.00 mol of Z(g) is produced. What is the value of the equilibrium constant, Kc ?

Answer 1

x(g) + y(g) <==> 2Z(g)

6.0....6.0...........0.......Initial

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

6-x...6-x..........2x.......Equilibrium

2x = 8.00 mol

x = 4.00 mol

At equilibrium...

[x]=6-4 = 2.0 M

[y] = 6-4 = 2.0 M

[z] = 8.0 M

Kc = [z]2 / [x][y] = 64 / 4

Kc = 16