Question

On complete combustion, 0.246g of an organic compound gave 0.198 g of carbon dioxide and 0.1014 g of water. Determine the percentage composition of carbon and hydrogen in the compound.

Answer 1

Here, mass of the organic substance taken = 0.246 g
Mass of `CO_(2)` formed = 0.198 g
Mass of `H_(2)O` formed = 0.1014 g
(i) Percentage of Carbon.
One mole of `CO_(2)` contains one gram atom of carbon.
i.e. 44 g of `CO_(2)` contain carbon = 12g
`:.` 0.198 g `CO_(2)` will contain carbon `= (12)/(44) xx 0.198 g`
This is the mass of carbon present in 0.246 g of the compound.
`:.` % age of carbon in the compound `= (12)/(44) xx 0.198 xx (100)/(0.246) = 21.95`
(ii) Percentage of Hydrogen
One mole of `H_(2)O` contains two gram atoms of hydrogen.
i.e. 18g of `H_(2)O` contain hydrogen = 2g `:.` 0.1014 g of `H_(2)O` will contain hydrogen `= (2)/(18) xx 0.1014`
This is the mass of hydrogen present in 0.246g of the compound.
`:.` % age of hydrogen in the compound `= (2)/(18) xx 0.1014 xx (100)/(0.246) = 4.58`