Question

How many grams of MgCl2 dissolved per litre gives 60 ppm of hardness?

Answer 1

Answer:

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Answer 2

We have to find mass of MgCl2 dissolved per litre gives 60 ppm of hardness.

solution : Hardness of water is generally expressed in term of CaCO3.

molecular weight of MgCl2 = 24 + 35.5 × 2 = 95 g/mol

so equivalent weight = Molecular wt/n - factor = 95/2 = 47.5 g

molecular weight of CaCO3 = 100g

equivalent weight of CaCO3 = 50g

now considering 60 ppm of hardness mentioned in the term of equivalents of CaCO3.

hardness = mass of MgCl2 × equivalent weight of CaCO3/equivalent weight of MgCl2

⇒60 ppm = 60 mg/L = x × 50g/47.5g

⇒60 × 47.5/50 = 57 mg/L

Therefore 57mg of MgCl2 dissolved per litre gives 60 ppm of hardness.