Question

1g sample of chalk is completely neutralized by 100 ml of 0.04 HCl solution .Find the (wt/wt) °/• of caco3 sample.

Answer 1

Explanation:

First of all write balanced chemical equation which is

CaCO3 + 2 HCl >> CaCl2 + H2O +CO2 (since chalk is chemically CaCO3)

One can learn from above equation

HCl = 1/2 CaCO3

Or 1000 mL 1N HCl = 50g of CaCO3 ( = 1/2 Ca+C+ 3O =1/2( 40+12+4)

1000 mL 1N HCl = 50 g

100 mL 0.04 N HCl

= 50 × 0.04 × 100/1000

= 0.2 g

so it is clear that 1 g sample actually contains 0.2 g of CaCO3 i.e. 20% .