Relation between Gibb’s free energy and EMF of cell

ΔG^°= -nFE°_cell

n = no. of electrons

F= faraday constant

E°_cell­= Potential difference

ΔG^° = useful work done of system

ΔG° = -nF E°_cell­     

ΔG° = -nF x (2.303 RT/nF)log K_C­

ΔG^° = -2.303 RT log K_C

When conditions are not standard then, ΔG = -nF E_Cell

But at equilibrium, E_Cell = 0 So ΔG = -nF x 0

ΔG = 0