Question

Which by-product of chlor-alkali process is used for manufacturing bleaching powder?

Answer 1

Hint: To solve this question first we have to write the reaction involved in the chlor-alkali process. It is the reaction between common salt and water. After this the byproduct reacts with lime water to form bleaching powder.

Complete step by step answer:
Reactions between common salt and water produce sodium hydroxide along with chlorine gas and hydrogen. This process is known as chlor-alkali process. The chlor-alkali process has a high energy consumption, the products formed in the reaction are in equivalent amounts i.e. two mole of sodium hydroxide for per mole of chlorine so it is necessary to use the products in the same proportion.
The formulae of common salt sodium chloride is NaCl which is used to produce sodium hydroxide i.e. NaOH. The chemical reaction involved in this process is:
\[2NaCl(aq)+2{{H}_{2}}O(l)\to 2NaOH(aq)+C{{l}_{2}}(g)+{{H}_{2}}(g)\]

The byproduct forms sodium hydroxide, chlorine gas and hydrogen. For preparation of bleaching powder, chlorine gas reacts with lime water.
Chemical formula for limewater is $Ca{{(OH)}_{2}}$ i.e. calcium hydroxide.

The chemical reaction involved in the process is:
\[Ca{{(OH)}_{2}}+C{{l}_{2}}\to CaOC{{l}_{2}}+{{H}_{2}}O\]
The product formed after the reaction of chlorine gas with lime water is bleaching powder and water. Bleaching powder is used as a bleaching agent in the chemical industry.
Hence the by-product of the chlor-alkali process which is used for manufacturing of bleaching powder is chlorine gas.

Note: Bleaching powder has many uses, it is used as a disinfectant which means that it disinfects water to make portable water. Bleaching powder is also used as an oxidizer in many industries because it is a strong oxidizing agent.