Question

A sample of water contains 120 mg MgSO4 per litre.Calculate hardness in terms of CaCO3 equivalents

Answer 1

Answer:

Given that the water sample contains 0.001 mole of MgSO4 per litre of water.

Therefore, the hardness of water sample is 1000.

0.001×100×106=100ppm

Answer 2

Answer: Hardness =100ppm

Explanation:

The hardness of water is mostly calculated in terms of equivalents of CaCO₃ (in mg/litre or ppm)

$1kg\ of\ water\ has\ 120mg\ MgSO_{4}\\10^{6}g\ of\ water\ has\ 120 g\ of\ MgSO_{4}\\1 mole\ of\ MgSO_{4}\Rightarrow 1mole\ of\ CaCO_{3}\\120g\ of\ MgSO_{4}\Rightarrow 100g\ of\ CaCO_{3}$

$10^{6}g\ of\ water\ has\ 100 g \of\ CaCO_{3}\\Hardness\ of\ water=100ppm$

Degree of hardness of water is 100 ppm.