Question

Complete combustion of $1.80g$ of an oxygen-containing compound $\left(C_x{H}_y{O}_z\right)$ gave $2.64g$ of $C{O}_2$ and $1.08g$ of $H_{2}O.$ The percentage of oxygen in the organic compound is:

• A. $63.53\%$
• B. $51.63\%$
• C. $53.33\%$
• D. $50.33\%$

Answer 1

The correct option is C $53.33\%$

$n_{C{O}_2}=\frac{2.64}{44}=0.06$

$\therefore n_C=0.06$

$\text{Weight of carbon}=0.06\times 12=0.72g$

$n_{H_{2}O}=\frac{1.08}{18}=0.06$

$\therefore n_H=0.06\times 2=0.12$

$\text{Weight of hydrogen}=0.12g$

$\text{Weight of oxygen in}{C}_x{H}_y{O}_z=1.8–(0.72+0.12)=0.96g$

$\%\text{weight of oxygen in}{C}_x{H}_y{O}_z=\frac{0.96}{1.8}\times 100=53.33\%$