Nernst Equation - electrochemical half cell


In electrochemistry, the Nernst equation is an equation that relates the reduction potential of an electrochemical reaction (half-cell or full cell reaction) to the standard electrode potential, temperature, and activities (often approximated by concentrations) of the chemical species undergoing reduction and oxidation. It is the most important equation in the field of electrochemistry. It was named after Walther Nernst, a German physical chemist who formulated the equation.

The Nernst equation is derived from the standard changes in the Gibbs free energy associated with an electrochemical transformation, which in turn is derived from the ideal gas law.

This is the Nernst equation for an electrochemical half-cell.

Related formulas


Eredhalf-cell reduction potential at the temperature of interest (V)
Eoredstandard half-cell reduction potential (V)
Rmolar gas constant
Ttemprature (K)
znumber of electrons transferred in the cell reaction (dimensionless)
FFaraday constant
aredactivity of the reduced form (dimensionless)
aOxactivity of the oxidized form (dimensionless)