Q. Explain laws of Electrolysis?

Ans. A spontaneous reaction takes place by itself. Some redox reactions are not spontaneous.

In a non-spontaneous redox reaction, oxidation (at the anode) and reduction (at the cathode) are forced to occur with the addition of electrical energy.

Electrolysis means decomposition by electricity. Electrolysis is a chemical process in which a redox reaction is forced to take place by passing a direct electric current through an electrolyte.

In the electrolytic cell where the electrolysis reaction occurs, the anode is the positive electrode, and the cathode is the negative electrode. (This is the exact opposite of a voltaic cell where the anode is the negative electrode, and the cathode is the positive electrode.)

During this process of electrolysis, the positive sodium cations are forced to migrate toward the negative electrode (cathode). Likewise, the negative chlorine anions are forced to migrate toward the positive electrode (anode). During this electrolysis process, electrons move from the anode to the cathode through an external wire.

The following half reactions occur in this electrolytic cell:

Oxidation Reaction (at the anode):

2Cl^- -> Cl₂(g) + 2e^-

Reduction Reaction (at the cathode):

2Na⁺ + 2e^- -> 2Na(l)

Notice that the number of electrons that are produced during the oxidation reaction is the same as the number of electrons that is used during the reduction reaction.

In the electrolysis of water, the half-reactions are:

Reduction Reaction (at the cathode):
4H₂O + 4e^- -> 2H₂(g) + 4OH^-

Oxidation Reaction (at the anode):
2H₂O -> O₂(g) + 4H⁺+ 4e^-

And the net reaction for the electrolysis of water is:

6H₂O -> 2H₂(g) + O₂(g) + 4H⁺ + 4OH