A series in which elements or ions are arranged in the decreasing order of their standard reduction potential values is called electrochemical series (ECS).
The merits and characteristics of the electrochemical series are given in the following:
i. Metals above hydrogen in ECS undergo oxidation in the comparison cell i.e they act as anode. A metal placed below hydrogen undergoes reduction i.e. it is cathode.
ii. lf the sign of electrode potential is positive then the reaction is spontaneous, and the electrode act as canoed. It the sign is -ve the reverse reaction will occur and the electrode will act as cathode.
iii. The reducing strength decrease s from top to bottom in ECS. It means the tendency to lose electrons decrease from top to bottom in ECS.
iv. The metals are placed in the order of their reactivity and show the displacement order. Metals displace metals lying below them.