Q.

What mass of 95% pure CaCO3 will be required to neutralise 50 mL of 0.5 M HCl solution according to the following reaction  

CaCO3(s)+2HCl(aq)CaCl2(aq)+CO2(g)+2H2O(l)

[Calculate upto second place of decimal point.]                       [2022]

1 1.25 g  
2 1.32 g  
3 3.65 g  
4 9.50 g  

Ans.

(2)

Volume of HCl = 50 mL = 0.05 L

Molarity of HCl = 0.5 M

   Moles of HCl = 0.05×0.5=0.025 moles

CaCO3+2HCl CaCl2+CO2+H2O

For 2 moles of HCl, CaCO3 required = 1 mole

    For 0.025 moles of HCl, CaCO3 required = 0.0252 moles

Mass of CaCO3 required = 100×0.0252=1.25 g

For 95% pure CaCO3, mass of CaCO3 required = 1.2595×100g=1.315g1.32 g