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# Nernst equation

In electrochemistry, the Nernst equation (named after German physical chemist Walther Nernst) gives the reversal potential[?] of an electrode E, relative to the standard electrochemical potential, E0, of the electrode couple or, equivalently, of the half cells of a battery

$E = E^0 - \frac{RT}{zF} \ln\frac{a_{red}}{a_{ox}}$

where R is the universal gas constant, T the temperature in Kelvin, z the charge number or valence of the electrode reaction, and a the chemical activities on the reduced and oxidized side, respectively. F is the Faraday constant, equal to 96,494 J volts-1 mol-1.