Equilibrium Constant

Question

Consider the reaction:

SO2Cl2(g) ↔ SO2(g) + Cl2(g)

A reaction mixture is made containing an initial [SO2Cl2] of 0.020M. At equilibrium, [Cl2] = 1.2x10-2M.

Calculate the value of the equilibrium constant (K).

Answer 1

SO₂Cl₂(g) <==> SO₂(g) + Cl₂(g)

0.020....................0..............0...........Initial

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

0.20-x....................x..............x...........Equilibrium

At equilbirum [Cl₂] = 1.2x10^-2 M = x. Use this to fill in rest of the ICE table at equilbrium

Summary @ equilbrium:

[SO₂Cl₂] = 0.200 - 2x = 0.200 - 2.4x10^-2 = 0.176 M

[SO₂] = x = 1.2x10^-2 M

[Cl₂] = x = 1.2x10^-2 M

The equilibrium constant expression is Keq = [SO₂][Cl₂] / [SO₂Cl₂]

Keq = (1.2x10^-2)(1.2x10^-2) / 0.176

Keq = 8.18x10^-4