Question

The process used for the removal of hardness of water is:
A.Baeyer
B.Calgon
C.Hoope
D.Serpeck

Answer 1

Hard water is described as the water does not readily give a good lather with soap and so wastes soap as well as causing a ‘scum’. The hard water contains a high mineral content mainly Ca and Mg. It is a high mineral content water.

Complete step by step answer:
Hard water classified into two varieties:
Temporary hardness: It is caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). It can be softened by boiling the water.
Permanent hardness: It is caused by very soluble magnesium sulfate and slightly soluble calcium sulfate. It can’t be softened by boiling. To soften the permanent hard water, we must remove calcium ions and magnesium ions.
Hard water is spread over Calgon (sodium hexametaphosphate $N{a_6}{P_6}{O_{18}}$). Calgon reacts with Mg or Ca ions present in hard water and inactive complex ions are formed that do not form a precipitate with soap. Hence, option B is correct.
Calgon process: It is a trade name of a complex salt of sodium hexametaphosphate ${\left( {NaP{O_3}} \right)_6}$. It is used for softening the permanent hard water. It ionizes to give a complex anion:
${\left( {NaP{O_3}} \right)_6} \to 2N{a^ + } + N{a_4}{P_6}O_{18}^{2 - }$
Calgon is added to hard water which causes the magnesium and calcium ions of hard water to replace or displace sodium ions from the anion of calgon.
$C{a^{2 + }} + N{a_4}{P_6}O_{18}^{2 - } \to 2N{a^ + } + CaN{a_2}{P_6}O_{18}^{2 - }$

Note:
We can also use some other methods-
Adding washing Soda (calcium and magnesium ions react with sodium carbonate to form insoluble carbonates).
Using Ion Exchange Resins (big organic molecules have acidic or basic groups are called Ion exchange resins. Acid resins exchange their $H^+$ and basic resins exchange their $OH^-$).