10 g of sample of mixture  of Cacl2 and Nacl is treated to precipitate alll the calcium as CaCo3. this CaCo3 is heated to convert all the Ca to Cao and the final mass of CaO is 1.62g. the precent by mass of Cacl2 in the original mixture

CaC0_{3 +} heat = CaO + CO₂ 

x                                1.62

100                             56

x=1.62 x 100/56 = 2.89 g

Cross multiply through the equation and solve for X grams of CaCO₃ we get 2.89 grams of CaCO₃ 

Original reaction CaCl₂ + Na₂CO₃ = CaCO₃ + 2 NaCl 

                                    x                                    2.89
                                   111                                  100

 

 

x = 2.89 x 111/100=3.2 g

Cross multiply again and solve for X grams of CaCl₂, we get 3.2 grams CaCl₂ 

% CaCl₂ in original mixture 3.2 grams CaCl₂ over l0 gms mixture = .32 or 32%