Deterioration of metal which happen by the chemical reaction between metal and the substances present in the atmosphere is known as corrosion. Generally corrosion of metal happens by oxidation-reduction reaction.
Role of electrode potential in the prevention of corrosion:
Corrosion is an electrochemical process and corrosion of metal happens by removal of electrode at anode. In an electrochemical cell among two electrodes which one is anode and which one is cathode depends on the electrode potential. Higher the position of electrode in the electrochemical series i.e. greater the value of oxidation potential of an electrode works as an anode and undergoes corrosion. So, to protect any metal from corrosion it must be remembered that it does not work as anode. Apart from this we also know that, chemical reaction in a cell happens spontaneously when value of cell potential is positive. If the summation of oxidation and reduction potential is positive (+) then reaction cell happens spontaneously i.e. corrosion occurs. If the value of potential of both electrodes is same the electron does not flow i.e. no electrochemical reaction can happen. Therefore metal can be prevented from corrosion by making the potential of both electrodes same or by decreasing the value of oxidation potential of anode by passing electricity from external source. In this way electrode potential plays a vital role in the prevention of corrosion.