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What Causes Hard Water?

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Kimberly Christensen Profile
Water that contains mineral salts (as calcium and magnesium ions) that limit the formation of lather with soap called hard water. Such water contains metal ions (calcium, magnesium, iron) which, instead of lather form precipitate with soap.

The rain water dissolves sulphates, chlorides and carbonates of calcium and magnesium present in many rocks. These salts cause hardness of water. This water also dissolves carbon di oxide from air which converts the carbonates of calcium and magnesium into bicarbonates. These bicarbonates being soluble in water cause hardness. The hardness of water is of two types. Temporary hardness and permanent hardness. Temporary hardness is due to the presence of bicarbonates of calcium and magnesium in water. These salts are soluble in water and exist in the form of positive and negative ions. The name temporary is given to this type of hardness because these ions are removed merely by boiling. Temporary hardness is removed by boiling water. Due to this calcium and magnesium bicarbonates are converted into insoluble carbonates witch are easily removed.

Permanent hardness is due to the dissolved chlorides or sulphates of calcium and magnesium. These salts can not be decomposed by boiling and hence the name permanent is given to this type of hardness. These salts are soluble in water and produce corresponding ions in solution. Both temporary and permanent hardness can also be removed by ion exchange method which involves the replacement of on ion by another

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