100 mL of a water sample contains 0.81 g of calcium bicrabonate and 0.73 g of magnesium
bicarbonate. The hardness of this water sample expressed in terms of equivalents of CaCO3 is :
(Molar mass of calcium bicarbonate is 162 g mol–1 and magnesium bicarbonate is 146 g mol–1)
Here hardness of water is expressed in terms of CaCO3.
$$ \therefore $$ Equivalent of CaCO3
= Equivalent of Ca(HCO3)2 + Equivalent of Mg(HCO3)2