Selective Discharge
The preferential reaction of one ion over others at an electrode during electrolysis.
Unit
V
In depth
Which ion discharges depends on its position in the electrochemical series, its concentration, and the overpotential at the particular electrode material. Concentration can override the series, which is why concentrated brine gives chlorine at the anode while dilute brine gives oxygen.
Examples in the real world
Hydrogen rather than sodium being released at the cathode during the electrolysis of aqueous NaCl.