Temporary hardness of water can be removed by using calcium hydroxide. How ?

1 Answer
Jun 21, 2018

Ca^(2+)+HCO^(-) -> H^+ +CaCO_3 where Ca^(2+) is removed as precipitate

Explanation:

Hardness is used to describe water containing large amounts of calcium ions or magnesium ions. In some cases it can also contain Cl^-, SO_4^(2-), CO_3^(2-),HCO_3^-

Since it contains these ions, it is difficult to lather and form scum, requiring treatment before the water can be used for things like drinking.

Now there are also 2 types of hardness - temporary and permanent

Temporary hardness refers to when there is dissolved CO_2 which can be removed by boiling

Ca^(2+)+HCO^(-) -> H^+ +CaCO_3 where Ca^(2+) is removed as precipitate