Question

on complete combustion 0.246g of an organic compound gave 0.198g of CO2 and 0.1014g of H2O. What is the ratio of carbon and hydrogen atoms in the compound?

Answer 1

Solution:

The molar mass of CO₂ is 44.01 g/mol

Therefore,

Moles of CO₂ = (0.198 g CO₂) × (1 mol CO₂ / 44.01 g CO₂) = 0.00450 mol CO₂

The molar mass of H₂O is 18.0153 g/mol

Therefore,

Moles of H₂O = (0.1014 g H₂O) × (1 mol H₂O / 18.0153 g H₂O) = 0.00563 mol H₂O

Schematic equation:

CO₂ → C

According to the shematic equation above:

Moles of C = Moles of CO₂ = 0.00450 mol

Moles of C = 0.00450 mol

Schematic equation:

H₂O → 2H

According to the shematic equation above

Moles of H = 2 × Moles of H₂O

Moles of H = 2 × 0.00563 mol = 0.01126 mol

Moles of H = 0.01126 mol

Thus, the ratio of carbon and hydrogen atoms in the compound is:

Moles of C : Moles of H = 0.00450 mol : 0.01126 mol = 1 : 2.5

Moles of C : Moles of H = 1 : 2.5

Answer: The ratio between the carbon and hydrogen atoms is 1 : 2.5