Relation between equilib constant, reaction quotient, Gibbs energy

Relation between equilibrium constant, reaction quotient and Gibbs energy

The value of the equilibrium constant for a reaction does not depend on the rate of reaction.

·         If a change in Gibbs free energy ΔGΔG is negative, then the reaction proceeds in the forward reaction with spontaneity.

·         If a change in Gibbs free energy ΔGΔG is positive, the products of the forward reaction shall be converted to reactants with a non-spontaneous process.

·         If the change in Gibbs free energy is zero, then the reaction is at equilibrium and there is no longer any free energy left to drive the reaction.

 A mathematical expression of this thermodynamic view of equilibrium can be described by the following equation:
ΔG=ΔGo+RTlnQ

Where Q is Reaction Quotient. And Go is standard Gibbs free energy.
At equilibrium, when ΔGo=0 and Qc=Kc
ΔG=ΔGo+RTlnKc=0
ΔGo=−RTlnKc
lnKc=−ΔGo/RT
K=e−ΔGo/RT

from the above equation, from the values of ΔGo , the reaction spontaneity can be interpreted.