Question

Consider a generic redox reaction?

Answer 1

The Nernst equation allows us to predict the cell potential for voltaic cells under conditions other than the standard conditions of 1M, 1 atm, 25°C. The effects of different temperatures and concentrations may be tracked in terms of the Gibbs energy change ΔG. This free energy change depends upon the temperature & concentrations according to   ΔG = ΔG°  +  RTInQ  where ΔG° is the free energy change under conditions and Q is the thermodynamic reaction quotient. The free energy change is related to the cell potential  Ecell by ΔG= nFEcell

so for non-standard conditions
              -nFEcell = -nFE°cell  + RT InQ

or
   
              Ecell  =  E°cell - RT/nF (InQ) 

which is called Nernst equation.