Method of corrosion
A metal in contact with an aqueous solution functions as an electrode. The potential of this electrode is a measure of the tendency of the metal to act as an anode and become oxidized when coupled with some other material or with localized portions of the same metal which can act as cathodes. The anodic or corrosive half reaction can be represented as
Where, M1 is metal corroded. The e.m.f. of the galvanic corrosion cell formed is given by
Ecell = -Eanode + Ecathode
This gives a driving force behind the process under equilibrium conditions. The values of e in the above expression for both anode and cathode are considered as reduction potentials which explain the negative sign for anode.
