The Nernst Equation allows us to calculate the voltage produced by any electrochemical cell given E^{o} values for its electrodes and the concentrations of reactants and products.

The general Nernst Equation: E = E^{o} -(RT/nF)lnQ
E^{o} = standard electrochemical cell potential (voltage)
R = ideal gas constant T = temperature
n = moles of electrons
F = Faraday constant = 96,485 C mol^{-1} Q = mass-action expression (approximated by the equilibrium expression)

At 25^{o}C the Nernst Equation is simplified to: E = E^{o} -(0.0592/n)logQ
E^{o} = standard electrochemical cell potential (voltage)
n = moles of electrons
Q = mass-action expression (approximated by the equilibrium expression)

For a system at equilibrium at 25^{o}C, E = 0 and the Nernst Equation is simplified to: E^{o} = (0.0592/n)logK
E^{o} = standard electrochemical cell potential (voltage)
n = moles of electrons
K = equilibrium expression