Question 32

# 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.

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 69x.02 / 100 = 0.138g of C

Molecular mass of carbon dioxide, CO2 = 44 g

That is, 12 g of carbon is contained in 44 g of CO2.

Therefore, 0.138 g of carbon will be contained in 44x0.138/12 = 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 4.8x0.2/100 = 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 18x0.0096/2 = 0.0864g of water

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