Question

An organic compound on combustion gives 0.22 g of CO₂ and 0.126 g of H₂O. If the percentage of C in given organic compound is 40%, the percentage of H will be?

Answer 1

In complete combustion, the organic compound reacts with oxygen to produce CO₂ and H₂O. From the masses of CO₂ and H₂O produced, we can calculate the masses of carbon and hydrogen in the compound.

Step 1: Calculate the mass of carbon

From the mass of CO₂, we can find the mass of carbon in the compound. The molar mass of CO₂ is 44 g/mol, and the molar mass of carbon (C) is 12 g/mol. The mass of carbon in CO₂ is proportional to the molar masses: \[ \text{Mass of C} = \left( \frac{12}{44} \right) \times 0.220 = 0.060 \, \text{g}. \] We are given that the percentage of carbon in the compound is 24%. Hence, the total mass of the organic compound can be found by: \[ \frac{0.060}{\text{Total mass of compound}} = 0.24 \quad \Rightarrow \quad \text{Total mass of compound} = \frac{0.060}{0.24} = 0.250 \, \text{g}. \]

Step 2: Calculate the mass of hydrogen

Next, we calculate the mass of hydrogen in the compound. The molar mass of H₂O is 18 g/mol, and the molar mass of hydrogen (H) is 1 g/mol. The mass of hydrogen in H₂O is proportional to the molar masses: \[ \text{Mass of H} = \left( \frac{2}{18} \right) \times 0.126 = 0.014 \, \text{g}. \]

Step 3: Calculate the percentage of hydrogen

The percentage of hydrogen in the compound is: \[ \% \, \text{of H} = \left( \frac{0.014}{0.250} \right) \times 100 = 5.6\%. \] Thus, the percentage of hydrogen in the compound is 5.6%