Measurement of Electrode Potential Chemistry Notes
Measurement of Electrode Potential :
→ The potential of single half-cell can not be measured. We can measure potential difference of only two half-cells. It gives emf of the cell. The potential of single half-cell can not be measured because half-reduction or half-oxdiation reactions can not be take place singly, These reactions are complementary to each other, So, the potential of a single electrode can be determined on comparsion basis of a reference electrode.
→ The potential of reference electrode is certain We use standard hydrogen electrode (SHE) or normal hydrogen electrode (NHE) as reference electrode because its electrode potential is zero at all temperatures.
For determination of electrode potential, electrode is combined with standard hydrogen electrode to form a cell. The potential of this cell is determined from a suitable method. According to figure 3.16, the potential of Zncell(s) Zn2+(aq)
electrode can be determined as follows. Cell is represented according to figure 3.16.
Today, second type of reference electrodes like calomel electrode, silver-silver chloride etc. can be used in place of hydrogen electrode.