Question

In a particular redox reaction, ClO2– is oxidized to ClO4– and Cu2 is reduced to Cu . Complete and balance the equation for this reaction in acidic solution. Phases are optional.

ClO2- + Cu2+ ---> ClO4- + Cu+

Answer 1

Cl in ClO2- has oxidation state of +3

Cl in ClO4- has oxidation state of +7

So, Cl in ClO2- is oxidised to ClO4-

Cu in Cu+2 has oxidation state of +2

Cu in Cu+ has oxidation state of +1

So, Cu in Cu+2 is reduced to Cu+

Reduction half cell:

Cu+2 + 1e- --> Cu+

Oxidation half cell:

ClO2- --> ClO4- + 4e-

Balance number of electrons to be same in both half reactions

Reduction half cell:

4 Cu+2 + 4e- --> 4 Cu+

Oxidation half cell:

ClO2- --> ClO4- + 4e-

Lets combine both the reactions.

4 Cu+2 + 1 ClO2- --> 4 Cu+ + 1 ClO4-

Balance Oxygen by adding water

4 Cu+2 + 1 ClO2- + 2 H2O --> 4 Cu+ + 1 ClO4-

Balance Hydrogen by adding H+

4 Cu+2 + 1 ClO2- + 2 H2O --> 4 Cu+ + 1 ClO4- + 4 H+

This is balanced chemical equation in acidic medium

4 Cu²⁺ + ClO₂^- + 2 H₂O --> 4 Cu⁺ + ClO₄^- + 4 H⁺