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Standard IX

Chemistry

Hardness of Water:Causes, Types and Treatments

Number of mol...

Question

Number of moles of $C a O$ required to remove hardness from $1000$ litre water having $324$ ppm of calcium bicarbonate.

8

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4

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3

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2

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Solution

The correct option is D $2$
$C a (H C O_{3})_{2} + C a O \to 2 {C a C O}_{3} ↓ + H_{2} O$ .

Molecular weight of $C a (H C O_{3})_{2}$ $= 162$ gms

Moles of $C a (H C O_{3})_{2} = \frac{324}{162} = 2$

From the reaction, it is clear that 1 mole of $C a O$ is required for one mole of calcium bicarbonate, thus for 2 moles of calcium bicarbonate, we require 2 moles of $C a O$ .

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Number of moles of CaO required to remove hardness from 1000 litre water having 324 ppm of calcium bicarbonate.

The correct option is D 2Ca(HCO3)2+CaO→2CaCO3↓+H2O.Molecular weight of Ca(HCO3)2 =162 gmsMoles of Ca(HCO3)2=324162=2From the reaction, it is clear that 1 mole of CaO is required for one mole of calcium bicarbonate, thus for 2 moles of calcium bicarbonate, we require 2 moles of CaO.

Number of moles of $C a O$ required to remove hardness from $1000$ litre water having $324$ ppm of calcium bicarbonate.