Question

State the factors that influence the preferential discharge of ions at the electrodes.

Answer 1

The following are the factors that influence the preferential discharge of ions at the electrode:
i) Position of the metallic ion in electrochemical series : If all the factors remain the same, an ion placed lower in the electrochemical series gets preferentially discharged at the respective electrode in comparison to all those ios, which are placed above it in the series.

ii) Concentration of ions in the electrolyte : Higher the
concentration of negative ion in the electrolytic solution, greater is its probability of being discharged at the anode.

iii) Nature of the electrode : If the electrode used is inert i,e made of less reactive material such as graphite, platinum etc, the electrode does not play any role in deciding the preferential discharge of an ion at it.

If the electrode used is active i,e made of active material such as Cu, Ag, Ni etc it takes part in the electrode reaction and plays an important role in deciding the ions which will preferentially be discharged. In such a case, anions migrate to the anode but do not get discharged ,Instead the active anode itself loses electrons and form ions.