The electrochemical series is the arrangement of various electrode systems in the increasing order of their standard reduction potentials.

Applications of Electrochemical Series

Reactivity of Metals

The reactivity of a metal depends upon its tendency to lose valence electrons which means that how eager a metal is to get oxidized.

Greater the tendency of a metal to get oxidized, greater is it's reactivity.

Since in the electrochemical series, the tendency of the substances to get oxidized decreases from the top to the bottom, the reactivity of the metals decreases in going down the series.

The metal at the top possesses the minimum value of reduction potential. Therefore, it will have the maximum value of oxidation potential and will lose electrons readily. And thus, it will be the most reactive metal.

Feasibility of a Redox Reaction

The electrochemical series is very helpful in predicting the feasibility of a redox reaction.

A redox reaction is feasible when the substance having higher reduction potential gets reduced and the one having lower reduction potential gets oxidized.

If the value of Ecell is positive, the reaction is feasible. 

If the value of Ecell is negative, the reaction is not feasible. 

If the value of Ecell is Zero, the reaction is in equilibrium.

Displacement of metals from salt solutions

In the solution, a metal is present in the form of its ion, The displacement of metals from their respective salt solutions involves the reduction of its oxidized form.

Since the reducing power of the reduced form of a substance decreases when we go down the series, the reduced form of a substance can reduce the oxidized form of any other substance placed below it in the series. Hence, a metal can displace any other metal placed below it in the series from the salt solution of the latter.

Displacement of Hydrogen by metals from dilute acids

On the basis of electrochemical series, it can be predicted whether a metal will displace hydrogen from a dilute acid or not. The displacement of hydrogen from an acid is a reduction process.

The reduction process can be made to take place by a metal whose reducing power is greater than that of hydrogen.

Since the reducing power of the substances decreases in going down the electrochemical series, all the metals placed above hydrogen in the series possess higher reducing powers as compared to that of hydrogen.

Hence, any metal placed above hydrogen in the electrochemical series can displace hydrogen from a dilute acid.

In other words, metals having negative values of standard reduction potentials can displace hydrogen from dilute acids. Thus, metals like Zn, Mg, Ni, Fe etc., can liberate hydrogen from dilute acids like HCl, H2SO4, but metals like Cu, Ag, Au cannot.

Electropositive character of metals and thermal stability of their oxides

The electropositive character of a metal is its tendency to form positive ions by losiing one or more valence electrons. The metal at the top of the electrochemical series possesses the lowest value of reduction potential.

Therefore, its oxidation potential would be the maximum and it will have the greatest tendency to lose electrons.

Consequently, the metal at the top possesses the highest electropositive character. 

As the values of standard reduction potentials increase in going down the series, the electropositive character of metals decreases.

The thermal stability of a metallic oxide depends upon the electropositive character, greater is the stability of its oxide.

Hence, the stability of oxides of metals decreases in going down from the top of the electrochemical series to the bottom of the electrochemical series.

The oxides of Li, Na, K are very stable and do not decompose easily on heating whereas the oxides of metals like Ag, Hg, Au are not stable and decompose on heating.

Calculation of Standard cell potential

The standard cell potential of a galvanic cell is given by