2. Electrochemical systems at equilibrium. Concept of electrode potential

An electrochemical system constituted by a redox system in which all the constituents, including e ^– (of the electrode), are present at the interface between an electrode and an electrolyte, considered in isolation, can give rise to the establishment of an equilibrium, analogous to a chemical equilibrium, which we will represent by writing the redox system with the symbol ⇔. For example:

• for a simple load transfer system :

  Ox + n e ^– ⇔ Red

  (Ox and Red in the electrolyte, e ^– in the electrode);

• or for a metal cation/metal pair :