Question

Explain the relationship between Gibb's standard energy change of the reaction and equilibrium constant.

Answer 1

For the reaction, aA + bB ⇌ cC + dD before approaching equilibrium, the reaction quotient is given by,

Here, the values of concentrations or partial pressures are other than equilibrium values.
At equilibrium, Q = K called equilibrium constant and ΔG = 0, because the reaction mixture
has no tendency to change in either direction.

Therefore, equation ΔG = ΔG° + RT ln Q becomes

0 = ΔG° + RT ln K

∴ ΔG° = - RT ln K

∴ ΔG° = - 2.303 RT log₁₀K

The above equation gives the relationship between standard Gibbs energy change of the reaction and its equilibrium constant.