Chemistry In Everyday Life

To understand the method used to remove temporary hardness of water, let's first identify what temporary hardness is and the processes involved in its removal.

Temporary Hardness:
Temporary hardness of water is caused by the presence of dissolved bicarbonate minerals (calcium bicarbonate and magnesium bicarbonate). It can be removed by boiling the water, which precipitates calcium carbonate, or by using chemical methods.

Methods to Remove Temporary Hardness:

1. Calgon's Method: This method is primarily used for removing permanent hardness by using sodium hexametaphosphate to sequester calcium and magnesium ions.
2. Clark's Method: This involves adding lime (calcium hydroxide) to the water. The chemical reaction precipitates calcium carbonate and thus removes calcium bicarbonate and magnesium bicarbonate responsible for temporary hardness. This is the correct method for removing temporary hardness.
3. Ion-Exchange Method: This is mostly used for removing both temporary and permanent hardness by exchanging calcium and magnesium ions with sodium ions.
4. Synthetic Resins Method: Similar to ion-exchange, synthetic resins are used to remove permanent hardness by exchanging calcium and magnesium ions with hydrogen or sodium ions.

Conclusion:
The method specifically used to remove temporary hardness of water is Clark's method. This method effectively reduces calcium and magnesium bicarbonate ions through chemical precipitation.