Question

An organic compound contains 69% carbon and 4.9% hydrogen, the remainder being oxygen. Calculate the masses of carbon dioxide and water produced when 0.20 g of this compound is subjected to complete combustion.

Answer 1

Step I.

Calculation of mass of CO₂ produced

Mass of compound = 0.20 g

Percentage of carbon = 69 g

Percentage of carbon = \(\frac{12}{44}\) = \(\frac{Mass\,of\,carbon\,dioxide\,formed}{Mass\,of\,compound}\) x 100

69 = \(\frac{12}{44}\) = \(\frac{Mass\,of\,carbon\,dioxide\,formed}{(0.20\,g)}\) x 100

Mass of CO₂ formed = \(\frac{69\times44\times(0.20g)}{12\times100}\) = 0.506 g

Step II.

Calculation of mass of H₂O produced

Mass of compound = 0.20 g

Percentage of hydrogen = 4.8%

4.8 = \(\frac{2}{18}\) x \(\frac{Mass\,of\,water\,formed}{Mass\,of\,compound}\) x 100

Mass of H₂O formed = \(\frac{4.8\times18\times(0.20g)}{2\times100}\) = 0.0864 g