→ The standard free energy change of a cell reaction and emf of cell is given by,
△G∘=−nFE∘cell------------1
→ Emf of cell and equilibrium constant K is given by ,
E∘=0.0591nlogK------------2
→ The value of K gives the extent of the cell reaction. If the value of K is large, the reaction proceeds to larger extent.
→ For spontaneous reaction, △G∘ is negative and K>1.