An equation relating the limiting molar conductivity Λm0 (see Kohlrausch’s law) to the ionic diffusion coefficients, devised by Walter Nernst and Albert Einstein. The Nernst–Einstein equation is
where F is the Faraday constant, R is the gas constant, T is the thermodynamic temperature, v+ and v– are the number of cations and anions per formula unit of electrolyte, z+ and z– are the valences of the ions, and D+ and D– are the diffusion coefficients of the ions. An application of the Nernst–Einstein equation is to calculate the ionic diffusion coefficients from experimental determinations of conductivity.