Question

An organic compound contains 69% carbon and 4.8% hydrogen, the remainder being oxygen. Calculate the masses of carbon dioxide and water produced when 0.20 g of this substance is subjected to complete combustion.

Answer 1

Percentage of carbon in organic compound = 69 %
That is, 100 g of organic compound contains 69 g of carbon.
$\therefore$ 0.2 g of organic compound will contain $=\frac{69\times 0.2}{100}=0.138gofC$
Molecular mass of carbon dioxide, $C{O}_2=44g$
That is, 12 g of carbon is contained in 44 g of $C{O}_2$.
Therefore, 0.138 g of carbon will be contained in $\frac{44\times 0.138}{12}=0.506gofC{O}_2$
Thus, 0.506 g of CO2 will be produced on complete combustion of 0.2 g of organic compound.
Percentage of hydrogen in organic compound is 4.8.
i.e., 100 g of organic compound contains 4.8 g of hydrogen.
Therefore, 0.2 g of organic compound will contain $\frac{4.8\times 0.2}{100}=0.0096$ g of H

It is known that molecular mass of water $\left(H_{2}O\right)$ is 18 g.
Thus, 2 g of hydrogen is contained in 18 g of water.
$\therefore$ 0.0096 g of hydrogen will be contained in $\frac{18\times 0.0096}{2}=0.0864g$ of water
Thus, 0.0864 g of water will be produced on complete combustion of 0.2 g of the organic compound.