# A Sample of Water Contains Following Impurities : Mg(Hco3)2 =73 Mg/Lit , Mgso4 = 120 Mg/Lit , Cacl2 = 222 Mg/Lit and Ca(No3)2 = 164 Mg/Lit . the Purity of Lime is 74% and Soda is 90% . - Applied Chemistry 1

A sample of water contains following impurities :
Mg(HCO3)2 =73 mg/lit , MgSO4 = 120 mg/lit , CaCl2 = 222 mg/lit and Ca(NO3)2 = 164 mg/lit . The purity of lime is 74% and soda is 90% . Calculate the quantity of lime and soda needed for softening of 50,000 litres of water .

#### Solution

 Impurities(mg/lit) MultiplicationFactor CaCO3 equivalents (mg/lit) Requirement Mg(HCO3)2 100/146 73 x 100/146 =50 2L MgSO4 100/120 120 x 100/120 =100 L + S CaCl2 100/111 222 x 100/111 =200 S Ca(NO3)2 100/164 164 x 100/164 =100 S

Lime Requirement = 74/100 x [CaCO3 equivalent of 2x Mg(HCO3)2 + MgSO4
= 74/100 x [100 + 100 ]
=148 ppm .
Lime Required for 50,000 litres of water with 74% purity
= 148 x 50,000 x 100/74
= 10,000 gm .
Soda Requirement = 106/100 x [CaCO3 equivalent of MgSO4 + CaCl2 + Ca(NO3)2

= 106/100 x [100 + 200 + 100 ]
= 424 ppm .
Soda Requirement for 50,000 litres of water with 90% purity
=424 x 50,000 x 100/90
= 23,556 gm .
The Lime Requirement is 10,000 gm and Soda Requirement is 23,556 gm .

Concept: Softening of water by Hot and Cold lime Soda method and numerical problems
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