Question

Potassium permanganate is used for purifying drinking water, because?
(A) It is a sterilizing agent
(B) It dissolves the impurities of water
(C) It is a reducing agent
(D) It is an oxidizing agent.

Answer 1

Hint: Potassium permanganate is a purplish-black crystalline solid that dissolves in water to give intensely pink or purple solutions. Potassium permanganate is used for a number of skin conditions. This includes fungal infections of the foot, impetigo etc.

Complete step by step answer:
As we know chemicals like alum, potassium permanganate and bleaching powder are used for water purification. Let us keep in mind that purification of water involves a combination of many different processes designed to remove various types of contaminants.

The reason potassium permanganate is used for purifying drinking water are as follows:
1) As an oxidizing agent it oxidizes dissolved iron, manganese and hydrogen sulfide into solid particles that are filtered out from water.
2) The particles are then filtered with a multimedia filter which can be either manganese-coated aluminum silicate above manganese-treated green sand.
3) If an insufficient amount of iron, manganese, or hydrogen sulfide is oxidized prior to filtration, the manganese coating on the filter media acts as a backup oxidant to treat any remaining contaminants.
4) If too much potassium permanganate is fed into the water prior to filtration, the excess potassium permanganate serves as a regenerant for the filter media.
After the filtration the water should be colorless, this indicates that the water is purified.
Hence, Potassium permanganate is used for purifying drinking water because it is an oxidizing agent. Option D is the required answer.

Note: Potassium permanganate must be diluted since undiluted solution may cause burns. Even with dilution it may irritate the skin, if repeatedly used may still cause burns.