Useful Identities
- (for constant temperature)
- (see Chemical equilibrium)
and rearranging gives
which relates the electrical potential of a reaction to the equilibrium coefficient for that reaction (Nernst equation).
where
ΔG = change in Gibbs free energy, ΔH = change in enthalpy, T = absolute temperature, ΔS = change in entropy, R = gas constant, ln = natural logarithm, ΔrG = change of reaction in Gibbs free energy, ΔrG° = standard change of reaction in Gibbs free energy, K = equilibrium constant, Qr = reaction quotient, n = number of electrons per mole product, F = Faraday constant (coulombs per mole), and E = electrode potential of the reaction. Moreover, we also have:
which relates the equilibrium constant with Gibbs free energy.
Read more about this topic: Gibbs Free Energy