EXCHANGE CURRENT DENSITY

"At the equilibrium potential there is no net current flowing through the electrode. However, the equilibrium is a dynamic one, that is, the electrode reaction proceeds at ""equal rates"" both in the forward and in the reverse direction, resulting in a zero ""net"" reaction rate and a zero ""net"" current. The rate of the electrode reaction can be expressed as an equivalent current density and the ""exchange current density"" of a reaction is the current density flowing ""equally"" in both directions in equilibrium. A large exchange current density indicates a fast reaction (see also non-polarizable electrode), while a small exchange current density indicates a slow reaction (see also polarizable electrode) "