Question

An impure sample of silver $(1.5g)$ is heated with S to form $0.124$ g of $Ag_{2}S$. What was the per cent yield of $Ag_{2}S$?

• A. $21.6\%$
• B. $7.2\%$
• C. $1.7\%$
• D. $24.8\%$

Answer 1

Answer: (B)

$7.2\%$

Answer 2

(2) : $\underset{2 \times 108 = 216g}{2Ag} + s \rightarrow \underset{248g}{Ag_{2}S}$

216 g of Ag forms 248 g of $Ag_{2}S$

$1.5g$Ag forms $\frac{248}{216} \times 1.5 = 1.722g$of $Ag_{2}S$

% yield of $Ag_{2}S$

$= \frac{0.124}{1.722} \times 100 = 7.2\%$