Question

About $6\text{g}$ of impure $NaCl$ is dissolved in water and then treated with excess of silver nitrate solution. The weight of silver chloride precipitated was found to be $14\text{g}$. The percentage purity of the $NaCl$ solution would be:

• A. 95%
• B. 85%
• C. 75%
• D. 65%

Answer 1

The correct option is A 95%

The reaction that takes place is:
$NaCl+AgN{O}_2\to AgCl\downarrow +NaN{O}_3$
$\stackrel{..}{.}143.5g$ of $AgCl$ is produced from 58.5 g $NaCl$.
$\stackrel{..}{.}$ 14 g of $AgCl$ is produced from 58.5 g $NaCl$
$\frac{58.5\times 14}{143.5}=5.70$
This is the amount of $NaCl$ in common salt:
$\%$ purity $=\frac{5.70}{6}\times 100=95\%$