A sample of water contains following impurities: Ca(HCO3)2 = 40.5 mg/l, Mg(HCO3)2 = 46.5 mg/l, CaCl2 = 22.45 mg/l, MgSO4 = 27.6 mg/l, CaSO4 = 32.1 mg/l. Calculate the total hardness of water. (Given m.w. for Ca(HCO3)2 = 162, Mg(HCO3)2 = 146, CaCl2 = 111, MgSO4 = 120, CaSO4 = 136.
Answers
Question:
A sample of water contains following impurities: Ca(HCO₃)₂ = 40.5 mg/l, Mg(HCO₃)₂ = 46.5 mg/l, CaCl₂ = 22.45 mg/l, MgSO₄ = 27.6 mg/l, CaSO₄ = 32.1 mg. Calculate the total hardness of water.
Concept:
Water hardness is basically the amount of dissolved minerals in water. Most commonly found water minrals are calcilums and minrals.
Hard water do not produce or form a little foam with contact of saop.
Given:
Ca(HCO₃)₂ = 162, Mg(HCO₃)₂ = 146, CaCl₂ = 111, MgSO₄ = 120, CaSO₄ = 136.
We have find out :
Total hardness of water.
Solution:
Hard salt Weight Molecular weight Weight/Molecular weight
×100(mg/l)
Ca(HCO₃)₂ 40.5 162 40.5/162×100=25
Mg(HCO₃)₂ 46.5 146 46.5/146×100=31.8
CaCl₂ 22.4 111 22.4/111×100=20.1
MgSO₄ 27.6 120 27.6/120×100=23
CaSO₄ 32.1 136 32.1/136×100=23.6
Toatal hardness of water is (25+31.8+20.1+23+23.6)mg/L = 123.5mg/L.
Answer:
The answer is 123.5mg/L.
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Concept
Water hardness is caused by minerals, like magnesium and calcium. Water hardness is essentially the number of dissolved minerals in water.
To find
Total hardness of water.
Explanation
Hard salt Weight relative molecular mass Weight/Molecular weight
Ca(HCO₃)₂ 40.5 162 40.5/162×100=25
Mg(HCO₃)₂ 46.5 146 46.5/146×100=31.8
CaCl₂ 22.4 111 22.4/111×100=20.1
MgSO₄ 27.6 120 27.6/120×100=23
CaSO₄ 32.1 136 32.1/136×100=23.6
Total hardness of water is (25+31.8+20.1+23+23.6)mg/L = 123.5mg/L.
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