a)Hard water
b)Soft water
Water dissolves may substances in it. There are some salts of calcium and magnesium when present causes hardness of water. Hard water does not produce lather with soap easily like soft water. From this we come to know which hard water is. In the boilers, scales are formed which is the deposit of salts of calcium or magnesium. This reduces the life of the boiler.
Hardness of water is due to the presence of salts of calcium and magnesium such as Calcium chloride (CaCl2), Calcium sulphate (CaSO4), Calcium bicarbonate (Ca (HCO3)2), Magnesium chloride (MgCl2), Magnesium sulphate (MgSO4), Magnesium bicarbonate (Mg (HCO3)2). Water which gives lather easily with soap is soft water.
There are two types of hardness of water. They are:
1.Temporary hardness
2.Permanent hardness
Temporary Hardness
Temporary hardness of is due to the presence of bicarbonate salt of calcium and magnesium such as calcium bicarbonate and magnesium bicarbonate.
Permanent Hardness
Permanent hardness is due to the presence of chlorides and sulphates of calcium and magnesium such as calcium chloride, magnesium chloride, calcium sulphate and magnesium sulphate in water.
Hardness of water can be removed by various methods.
