Question

What mass of lime will bd required to remove the hardness of 1000l of water containing 1.6 gram of calicium bicarbonate?

Answer 1

Mass of calcium bicarbonate = 1000L × 1.62 g = 1620 g

Reaction is given by,

Ca(HCO₃)₂ + CaO ⇒ 2CaCO₃ + H₂O

Here it is clear that,

1 mol of Ca(HCO₃)₂ consumes 1 mole of CaO

∴ (40 + 2 + 120)g/mol = 162g/mol of Ca(HCO₃)₂ is consumed 56g/mol of CaO

∴ 1 g of Ca(HCO₃)₂ is consumed 56/162 g of CaO

∴1620 g of Ca(HCO₃)₂ is consumed 56/162 × 1620 = 560g of CaO

Hence, mass of CaO = 560g = 0.56 kg

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