o The relation between Δ_rG and Δ_rG^Θ (standard Gibb's free energy of reaction) of a reaction is as follows:

Δ_rG = Δ_rG^Θ + RT and, where, K is the equilibrium constant.

At equilibrium , Δ_rG becomes 0

And Δ_rG^Θ = - RT lnK .

o Δ_rG^Θ can only be 0 when the value of K is =1. So, for all the other K values Δ_rG^Θ cannot be zero.