Question

Write the causes of temporary and permanent hardness of water

Answer 1

Hard water contains dissolved mg and ca ions .

Temporary hardness - It is caused by dissolved
calcium hydrogen carbonate
Temporary hardness can be removed by the process of boiling.

Permanent hardness - It is caused by dissolved
sulphate of mg and ca .
this can't be removed by boiling , so the the water is softened by washing soda or ion-exchange resin .

Answer 2

Temporary hardness of water is due to the presence of soluble salts of magnesium and calcium in the form of hydrogen carbonates (MHCO3, where M = Mg, Ca) in water.

Permanent hardness of water is because of the presence of soluble salts of calcium and magnesium in the form of chlorides in water.