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.

∴0.2 g of organic compound will contain= $\frac{69}{100}=0.138\\.g\,of\,C$

Molecular mass of carbon dioxide, CO2 = 44 g

That is, 12 g of carbon is contained in 44 g of CO2 $\frac{44×0.138}{12}$= 0.506 g of CO2

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 $\frac{4.8}{100}=0.0096\,g\,of\\.H$

It is known that molecular mass of water (H2O) is 18 g.

Thus, 2 g of hydrogen is contained in 18 g of water.

∴0.0096 g of hydrogen will be contained in $\frac{1.8×0.0096}{2}=0.0864\,g$ of wate

Thus, 0.0864 g of water will be produced on complete combustion of 0.2 g of the organic compound.