Question

The hardness of a water sample containing $10^{-3}$ M $MgSO_4$ expressed as $CaCO_3$ equivalents (in ppm) is__________.
(molar mass of $MgSO_4$ is 120.37 g/mol)
Given --

Answer 1

$10^{-3}$ molar $MgSO _{4}=10^{-3}$ moles of $MgSO _{4}$ present in 1 Litre.
$n _{ CaCO _{3}}= n _{ MgSO _{4}}$
$PPM \left(\right.$ in term of $\left.CaCO _{3}\right)=\frac{10^{-3} \times 100}{1000} \times 10^{6}$
$=100 ppm$