Question

An organic substance ($0.2115$ g) on complete combustion gave $0.4655$ g of carbon dioxide and $0.2533$ g of water. Determine the percentage composition of the compound.

• A. $C=60.03\%,H=13.30\%$ and $O=26.67\%$
• B. $C=50.03\%,H=23.30\%$ and $O=26.67\%$
• C. $C=40.03\%,H=13.30\%$ and $O=46.67\%$
• D. $C=70.03\%,H=13.30\%$ and $O=16.67\%$

Answer 1

The correct option is A $C=60.03\%,H=13.30\%$ and $O=26.67\%$

Mass of $C{O}_2$ formed = $0.4655$ g
Mass pf $H_{2}O$ formed = $0.2533$ g
Mass of the organic substance taken = $0.2115$ g
Percentage pf carbon $=\frac{10}{44}\times \frac{MassofC{O}_2}{Massofcompound}\times 100$ $=\frac{12}{44}\times \frac{0.4655}{0.2115}\times 100=60.03$
Percentage of hydrogen $=\frac{2}{18}\times \frac{Massof{H}_{2}O}{Massofcompound}\times 100$ $=\frac{2}{18}\times \frac{0.2533}{0.2115}\times 100=13.30$
Percentage of oxygen $=100-(60.03+13.30)=26.67$
Composition of the substance: $C=60.03\%;H=13.30\%$ and $O=26.67\%$