Question

What do you understand by permanent hardness?

Answer 1

Hint: We have to realise that hardness of water is because of the presence of bicarbonates which are soluble, chlorides and sulfates of magnesium and calcium. We can classify water hardness into two kinds. They are permanent hardness and temporary hardness.

Complete answer:
We can classify water into two types as,
Soft water
Hard water
We can say soft water produces lather with soap. Soft water is water we get from rains. We use soft water for household uses such as laundry and cleaning.
We can say hard water produces no lather with soap whereas they form precipitate. We call it hard water due to the presence of calcium salts and magnesium salts.
We can say temporary hardness and permanent hardness are the two types of hardness of water.
At the point when the soluble salts of magnesium and calcium are available as chlorides and sulfates in water, we call it permanent hardness since this harness can't be eliminated by boiling.
We can eliminate this hardness by treating the water with washing pop. Insoluble carbonates are framed during the reaction of washing soda with the sulfide and chloride salts of magnesium and calcium and along these lines, hard water is changed over to soft water.

Note:
We have to know that permanent hardness is caused by compounds like calcium chloride, magnesium chloride, magnesium sulfate, and calcium sulfate. Some ways by which we can eliminate the permanent hardness of water by treating the water with washing soda, Calgon’s method, synthetic resins method, and ion-exchange method. We have to remember that permanent hardness could not be removed by boiling.