Answer to Question #287360 in Physical Chemistry for Gunjan

Question

When 50 ml water sample titrated against 0.02 N HCl acid using phenolphthalein

indicator, the titration reading was 24.2 ml. After boiling 100 ml of the same sample using

methyl orange indicator, the titration value was 28.2 ml. Calculate permanent and total hardness.

Answer 1

Hardness $(mg$ of $CaCO_3/L)=\frac{A.N.50000}{ML\>sample}$

Where $A=$ ml of standard acid used to titrate the sample

$N=$ Normality of the standard acid

Temporary hardness $=\frac{24.2×0.02×50000}{50}$

$=484\>ppm$

Permanent Hardness$=\frac{28.2×0.02×50000}{100}$

$=282\>ppm$

Total Hardness $=766\>ppm$