Question

Define electrode potential, oxidation potential and reduction potential. Why is it not possible to calculate the absolute value of electrode potential ?

Accepted Answer

(1) When a piece of metal is immersed in a solution of its own ions, a potential difference is created at the interface of the metal and the solution. The magnitude of the potential difference is a measure of the tendency of electrodes to undergo oxidation or reduction or tendency to lose or gain electrons.The metal and ion represent the half cell and the reaction is half reaction. The immersed metal is an electrode and the potential due to reaction at the interface of the electrode and the solution is called the electrode potential. Thus, electrode potential is the tendency of an electrode to lose or gain electrons.

If the reduction takes place at the electrode, it is termed as reduction potential. If the oxidation takes place at the electrode it is termed as oxidation potential. ${E^{0}}_{(ox)} = Standard Oxidation Potential In general for an electrode, {E^{0}}_{(ox)} = - {E^{0}}_{(red)} {E^{0}}_{(red)} = Standard Reduction Potential$

The equilibrium potential difference between the metal electrode and the solution surrounding it is called the electrode potential. It is also defined as the tendency of an electrode to lose or gain electrons.

When the half cell reaction is carried out at temperature of 298K and the electrode is suspended in a solution of one molar concentration, the electrode potential is termed as the standard electrode potential and is represented by ${E^{o}}_{(red)}$ It enables to assess the thermodynamics activity of various chemical substances. But there are no methods available by which we can measure its absolute value. The electrode potential of an electrode is measured with respect to standard hydrogen electrode.The electrode potential of an electrode depends upon concentration of ions in solution in contact with metal. Simply oxidation potential of an electrode is inversely proportional to the concentration of ions and reduction potential is directly proportional to the concentration of ions.

(2) The absolute value of a single electrode cannot be measured experimentally because a half-cell reaction cannot take place independently. One can measure only the difference between the electrode potentials of any two half-cell reactions.It is due to the fact that neither by itself the oxidation occurs nor the reduction occurs. Experimentally, the absolute value of single electrode can't be determined, because independently half-cell reaction cannot occur.

Define electrode potential, oxidation potential and reduction potential. Why is it not possible to calculate the absolute value of electrode potential ?

Important Questions on Electrochemistry

Learn and Prepare for any exam you want !