Nernst Equation for Ion Transfer

The basic equation for an ion-transfer reaction is the Nernst equation that results from the equality of the electrochemical potential of a given ion, i, in the two adjacent phases  

P represents the standard partition constant when the interface is not polarized (potential of zero charge). In this way, when one applies a Galvani potential more positive than the standard value, cations will transfer from the aqueous to the organic phase, and the anions from the organic to the aqueous phase. 

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