Types

• A half-cell reaction involves the cathode or anode either oxidizing or reducing its respective electrolyte. Reduction always occurs at the cathode, and oxidation always occurs at the anode.
  
  

Features

• A half-cell reaction is solely composed of the reduction or oxidation of the ions present in the electrolyte solution of either the cathode or anode. The cathode and anode themselves do not react; they merely cause the ions either to gain electrons, as in the case of reduction, or lose them, as in oxidation.
  
  

Considerations

• By merging the two half-cell reactions of an electrochemical cell together, the overall cell reaction may be obtained. However, the half-cell reactions by themselves do not actually represent what is occurring inside the electrochemical cell, as they do not occur independently of each other. Half-cell reactions are thus only a convenient way to obtain the overall reaction, and nothing more.