Relationship between  ΔG & the Equilibrium Constant

The relationship b/w free energy & equilibrium constant is represented as

ΔG = -2.303 RT log K

Numerical- What is the equilibrium constant K for the following reaction at 400 K.

2 NOCL 2NO + CL₂

ΔH° = 77.2 KJ mol^-1

ΔS° = 122 JK^-1 mol^-1

T = 400 K

ΔG° = ΔH° - TΔS°

77200 – 400 x 122

77200 – 48800

ΔG° = 28400

28400 = -2.303 x 8.314 x 400 log K

(28400/2.303 x 8.314 x 400) = log K

 28400 / -7658.8 = log K

-3.70 = log K

-3 – 0.7 + 1 – 1 = log K

-4.300 = log K

30 x 10^-4 = log K

4.771 x 10^-4 = K

Log K = -5.3

-5.0.3 + 1 – 1

-6.700

70 x 10^-6 = log K

8.451 x 10^-6 = K