Question

Problem 5
A sample of water contains the following dissolved salts
in mgs/lit. Mg(HCO3)2 = 73; CaCl2 = 111; Ca(HCO3)2=81
and MgSO4 = 40. Calculate the temporary and permanent
hardness of the water (At. wts of Ca, Mg, 0, C, CI, S, H
are 40, 24, 16, 12, 35.5, 32 and 1 respectively).​

Answer 1

Explanation:

We can calculate the hardness of given water sample as:

(i) Ca(HCO

3

)

2

CaCO3≡CaCO

3

162ppm≡100ppm

∴81ppm≡50ppm

(ii) Mg(HCO

3

)

2

≡CaCO

3

146 ppm ≡ 100 ppm

∴73ppm≡50ppm

(iii) CaSO

4

≡CaCO

3

136ppm≡100ppm

∴68ppm≡50ppm

(iv) MgSO

4

≡CaCO

3

120ppm≡100ppm

∴60ppm≡50ppm

Total degree of hardness of water =50×4=200ppm