Question
Download Solution PDFWhat is the temporary hardness of water if water contains 7.3 mg/L Mg(HCO3)2 16.2 mg/L Ca(HCO3),. 9.5 mg/L MgCl2 and 13.6 mg/L CaSO4?
Answer (Detailed Solution Below)
Detailed Solution
Download Solution PDFCONCEPT:
Temporary Hardness of Water
- Temporary hardness is caused by the presence of bicarbonates of calcium and magnesium.
- It is removed by boiling and is expressed as equivalent amount of CaCO₃ in mg/L.
- Formula:
Hardness (as CaCO₃) = (Mass of salt × 100) / Molar mass of salt
EXPLANATION:
- Only Mg(HCO₃)₂ and Ca(HCO₃)₂ contribute to temporary hardness.
- Mg(HCO₃)₂ → (7.3 × 100) / 146.3 ≈ 4.99 mg/L
- Ca(HCO₃)₂ → (16.2 × 100) / 162.1 ≈ 9.99 mg/L
- Total temporary hardness = 4.99 + 9.99 ≈ 15 mg/L
Correct Answer: Option 4
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