Question

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

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

Answer 1

The correct option is B $7.2\%$

Reaction involved:

$2Ag+S\to A{g}_{2}S$

216 g pure Ag react with 32 g S to give 248 g $A{g}_{2}S$.

To obtain 0.124 g $A{g}_{2}S$ amount of Ag reacts with S is calculated as:

$=\frac{216}{248}\times 0.124=0.108$ g

Thus out of 1.5 g sample only 0.108 g (i.e.pure silver) will react to form $A{g}_{2}S$

% yield of $A{g}_{2}S=\frac{0.108}{1.5}\times 100=7.2$%