Chlorination is a process used for water purification. The disinfecting action of chlorine is mainly due to:
- The formation of hydrochloric acid when chlorine is added to water
- The formation of hypochlorous acid when chlorine is added to water
- The formation of nascent oxygen when chlorine is added to water
- The formation of hydrogen when chlorine is added to water
Explanation
Option (b) is correct
- When chlorine is added to water, it reacts with water molecules to form hypochlorous acid and hydrochloric acid. Hypochlorous acid is a weak acid but a very strong oxidising agent. It penetrates the cell walls of microorganisms and disrupts vital cellular functions by oxidising enzymes and structural proteins. According to World Health Organisation guidelines on drinking water quality, hypochlorous acid is the principal disinfecting agent responsible for killing bacteria, viruses and protozoa. The germicidal effectiveness of chlorine is directly related to the concentration of hypochlorous acid present in water, which is influenced by pH. The disinfecting action is not due to hydrochloric acid, nascent oxygen or hydrogen formation.
