A sample of a mixture of $CaCl_{2}$ and $NaCl$ weighing 4.22 g was treated to precipitate all the $Ca$ as $CaCO_{3}$. This $CaCO_{3}$ is then heated and quantitatively converted into 0.959 g of $CaO$. Calculate the percentage of $CaCl_{2}$ in the mixture. (Atomic mass of $Ca = 40,O = 16,C = 12$ and $Cl = 35.5$)

Question

Dr. Abubacker · Accepted Answer

(c)
$CaCl_{2} + CO_{3}^{2 -} \longrightarrow CaCO_{3} + 2Cl^{-}$
111 g 100g
$CaCO_{3} \longrightarrow CaO + CO_{2}$
100 g 56g
$\because$ 56 g $CaO$ is obtained by decomposition of
$CaCO_{3} = 100g$
$	herefore$ 0.959 g $CaO$ will be obtained by the decomposition of
$CaCO_{3} = \frac{100 	imes 0.959}{56}$
$= 1.71$g
Further,
$100\ g\ CaCO_{3} \equiv 111gCaCl_{2}$
$1.71g\ CaCO_{3} = \frac{111 	imes 1.71}{100}$
=1.89 $g\ CaCl_{2}$
% of $CaCl_{2}\$ in the mixture $= \frac{1.89}{4.22} 	imes 100$
$= 44.78$
$= 45\%$

Explanation

Reviewed by Dr. Abubacker

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