# Nernst Equation - electrochemical half cell

## Description

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## Variables

E_{red} | half-cell reduction potential at the temperature of interest (V) |

Eo_{red} | standard half-cell reduction potential (V) |

R | molar gas constant |

T | temprature (K) |

z | number of electrons transferred in the cell reaction (dimensionless) |

F | Faraday constant |

a_{red} | activity of the reduced form (dimensionless) |

a_{Ox} | activity of the oxidized form (dimensionless) |