Calculate K from Equilibrium

Question

The equilibrium constant, K_c, for the following reaction is 10.5 at 350K.

2CH₂Cl₂(g) CH₄(g) + CCl₄(g)

If an equilibrium mixture of the three gases in a 19.4 L container at 350K contains 0.372 mol of CH₂Cl₂(g) and 0.357 mol of CH₄, the equilibrium concentration of CCl₄ is ______  M.

Answer 1

[CH₂Cl₂] = 0.372 mol / 19.4 L = 0.01918 M

[CH₄] = 0.357 mol / 19.4 L = 0.01840 M

[CCl₄] = ? M

Kc = [CH₄][CCl₄] / [ CH₂Cl₂]²

10.5 = (0.01840)(x) / (0.01918)²

x = [CCl₄] = 0.2099 M = 0.210 M (3 sig. figs.)