0.25 g of an organic compound gave 0.13 g of water after complete combustion. The percentage composition of hydrogen is _____.
Show answer & explanation
Correct answer: A
Explanation
The correct answer is option 1 i.e. 5.78%.
- Given data:
Mass of organic compound = 0.25 g
Mass of water (H₂O) produced = 0.13 g
- Moles of H₂O formed:
Molar mass of H₂O = 18 g/mol
⇒ Moles of H₂O = 0.13 ÷ 18 = 0.00722 mol
- Each mole of H₂O contains 2 moles of H atoms, so:
Moles of H = 0.00722 × 2 = 0.01444 mol
- Mass of hydrogen:
Mass = moles × atomic mass = 0.01444 × 1 = 0.01444 g
- Percentage of hydrogen:
(Mass of hydrogen ÷ Mass of compound) × 100
= (0.01444 ÷ 0.25) × 100 = 5.78%