What is the use of Clark’s method?

Question

What is the use of Clark&rsquo;s method? (A) Remove temporary hardness of water by adding quick lime or slaked lime. (B) Remove permanent hardness by adding washing soda. (C) Remove permanent hardness by adding permutit. (D) Remove temporary hardness by boiling.

Tardigrade Admin · Accepted Answer

Temporary hardness in water is due to the presence of magnesium and calcium hydrogen carbonates.

Clark’s method: In this method, the calculated amount of lime is added to hard water. It precipitates out calcium carbonate and magnesium hydroxide which can be filtered off.

C a (H C O_{3})_{2} + C a (O H)_{2} \to 2 C a C O_{3} ↓ + 2 H_{2} O

M g (H C O_{3})_{2} + 2 C a (O H)_{2} \to 2 C a C O_{3} ↓ + M g (O H)_{2} ↓

+ 2 H_{2} O

Q. What is the use of Clark’s method?

Remove temporary hardness of water by adding quick lime or slaked lime.

Remove permanent hardness by adding washing soda.

Remove permanent hardness by adding permutit.

Remove temporary hardness by boiling.