The hardness of a water sample containing $10^{-3}$ M $MgSO_{4}$ expressed as $CaCO_{3}$ equivalents

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 $120.37~g/mol$)

Professor PC Thomas Classes · Answer

$10^{-3} M MgSO_4 \equiv 10^{-3} M CaCO_3$. $10^{-3} 	imes 100 	imes 1000 = 100$ ppm.