Question

1 g mixture of Caco, and NaCl reacts completely
with 100 ml of HCI. The % of Caco, in the
mixture is
(1) 40%
(2) 60%
(3) 50%
(4) 80%​

Answer 1

Answer:

answer: option (3) 50%

explanation : NaCl is neutral salt so, it can't react with HCl but CaCO3 reacts with HCl and forms CaCl2 compound.

To understand, see chemical reaction ....

CaCO_3+2HCl\rightarrow CaCl_2+H_2O+CO_2CaCO3+2HCl→CaCl2+H2O+CO2

here it is clear that , one mole of CaCO3 reacts with 2 moles of HCl.

given, normality of HCl = 0.1N so, molarity = 0.1M [ as basicity of HCl = 1]

volume of HCl solution = 120ml

so, number of mole of HCl = 0.1M × 100mL = 10 milimole or 0.010 mole

so, for 0.010 mole of HCl 0.005 mole of CaCO3 is require to complete chemical reaction.

hence, mass of CaCO3 = mole of CaCO3 × molar mass of CaCO3

= 0.005 × 100

= 0.5g

so, the mass of NaCl in mixture = 1g - 0.5g = 0.5g

now, % of CaCO3 in mixture = 0.5/(0.5+0.5) × 100 = 50%