Explain Hard and Soft water

1.	Explain Hard and Soft water
Answer» Solution :Rain water is ALMOST pure, Being a good solvent, when it flows on the surface of the earth, it dissolves many salts. Presence of calcium and magnesium salts in the form of hydrogencarbonate, chloride andsulphate in water makes water .hard.. Hard water does not give LATHER with soap. Water free from soluble salts of calcium and magnesium is CALLED Soft water. It gives latherwith soap easily. Hard water forms scum/precipitate with soap. Soap containing sodium stearate `(C_17 H_35 COONa)`. Reacts with hard water to precipitate out Ca/Mg stearate. `2C_17H_35COONa_((AQ)) + M_((aq))^(2+) to (C_17H_35COO)_2M darr + 2Na_((aq))^(+)`, M is Ca/Mg It is, therefore, unsuitable for laundry. It is harmful for boilers as well, because of deposition of salts in the form of scale. This reduces the EFFICIENCY of the boiler. The hardness of water is of two types: (i) temporary hardness, and (ii) permanent hardness.

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