Question

0.25g of an organic compound containing carbon, hydrogen and oxygen was analysed by the combustion method. The increase in mass of calcium chloride tube and the potash bulbs at the end of the operation was found to be 0.15 g and 0.1837g respectively. Calculate the percentage composition of the compound.

Answer 1

Mass of the compound taken = 0.25 g.

Mass of water produced (increased in the mass of calcium chloride tube) = 0.15 g.

Mass of carbon dioxide produced (increase in the mass of potash bulbs) = 0.1837 g.

Percentage of Hydrogen = $\quad \frac { 2 }{ 18 } \times \quad 0.15\quad \times \quad \frac { 100 }{ 0.25 } \quad =6.66$

Percentage of Carbon = $\quad \frac { 12 }{ 44 } \times \quad 0.1837\quad \times \quad \frac { 100 }{ 0.25 } \quad =\quad 20.04$

Percentage of Oxygen (Difference) = $\quad 100\quad -\quad (6.66\quad +\quad 20.04)\quad =\quad 73.30$