Hydrogen And Its Compounds Question 213
Question: 100 mL of tap water containing Ca $ {{(HCO_3)}_2} $ , was titrated with $ N/50HCl $ with methyl orange as indicator. If 30 mL of HCI were requireil. calculate the temporary hardness as part of $ CaCO_3 $ per $ 10^{6} $ parts of water.
Options:
A) 150 ppm
B) 600 ppm
C) 450 ppm
D) 300 ppm
Show Answer
Answer:
Correct Answer: D
Solution:
[d] According to the law of gram equivalence $ mEq.HCl=mEq.Ca{{(HCO_3)}_2}=mEq.(CaCO_3) $
$ 30ml\frac{N}{50}HCl=30ml\frac{N}{50}Ca{{(HCO_3)}_2}=30mlof\frac{N}{50}CaCO_3 $
$ =100 $ ml of tap water.
$ \therefore 30ml\frac{N}{50}HCl=\frac{wt.ofCaCO_3}{eq.wt.ofCaCo_3} $ Eq. wt. of $ CaCO_3=\frac{100}{2}=50 $
$ \therefore \frac{30}{50\times 1000}=\frac{wt.ofCaCO_3}{50} $
$ \therefore wt.ofCaCO_3=\frac{30\times 50}{50\times 1000}=0.03g $ 100 ml of tap water has $ =0.03gofCaCO_3 $ 1 ml of tap water $ =\frac{0.03}{100} $
$ 16^{6} $ parts of tap water $ =\frac{0.03}{100}\times 10^{6} $ Hardness=300 ppm
BETA
