Electrode potential
Electrode potential, E, in chemistry or electrochemistry, according to a IUPAC definition, is the electromotive force of a cell built of two electrodes:
By convention:
From the above, for the cell with the standard hydrogen electrode (potential of 0 by convention), one obtains:
The left-right convention is consistent with the international agreement that redox potentials be given for reactions written in the form of reduction half-reactions.
Electrode potential is measured in volts (V).
Electrode potential appears at the interface between an electrode and electrolyte due to the transfer of charged species across the interface, specific adsorption of ions at the interface, and specific adsorption/orientation of polar molecules, including those of the solvent.
Electrode potential is the electric potential on an electrode component. In a cell, there will be an electrode potential for the cathode, and an electrode potential for the anode. The difference between the two electrode potentials equals the cell potential.
ECell = ECathode − EAnode
The measured electrode potential may be either that at equilibrium on the working electrode ("reversible potential"), or a potential with a non-zero net reaction on the working electrode but zero net current ("corrosion potential", "mixed potential"), or a potential with a non-zero net current on the working electrode (like in galvanic corrosion or voltammetry). Reversible potentials can be sometimes converted to the standard electrode potential for a given electroactive species by extrapolation of the measured values to the standard state.
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