Question

(a) What happens when a concentrated solution of sodium chloride (brine) is electrolysed? Write the equation of the reaction involved.
(b) Why is the electrolysis of a concentrated solution of sodium chloride known as the chlor-alkali process?
(c) Name three products of the chlor-alkali process. State two uses of each of these products.

Answer 1

Hint: Electrolysis is a process which takes place in the presence of electricity. In the process of electrolysis electric current is passed through an aqueous solution of a compound. So, this process is carried out in an electrolytic cell. This process is done to convert a non-spontaneous reaction into a spontaneous reaction.

Complete answer:
(a) When a concentrated solution of sodium chloride (brine) is electrolysed, it gets decomposed. This is a decomposition reaction. The products of this reaction are sodium hydroxide, chlorine and hydrogen.
The reaction equation is given as:
$2NaCl(aq) + 2{H_2}O(l) + Electricity \to 2NaOH(aq) + C{l_2}(g) + {H_2}(g)$
(b) The electrolysis of a concentrated solution of sodium chloride is known as chlor-alkali process because the products formed are: Chlor for chlorine and alkali for sodium hydroxide (a base).
(c) The three products formed in the chlor-alkali process are sodium hydroxide, chlorine and hydrogen. Uses of these products are:
Sodium hydroxide
- It is used to manufacture soaps and detergents.
- It used to make paper.
Chlorine
- Chlorine is used to make bleaching powder.
- It is also used to manufacture hydrogen chloride.
Hydrogen
- It is used in the production of hydrogen chloride.
- It can also be used for the hydrogenation of oils.

Note:
The electrolysis process is done in presence of electricity to convert a non-spontaneous process into spontaneous process. It is carried out in an electrolytic cell in which two electrodes are present which are positive electrode known as anode and negative electrode known as cathode. The products can be neutral in nature or any new compound.