The balanced chemical equation for the combustion of ethane is:
2C₂H₆(g) + 7O₂(g) → 4CO₂(g) + 6H₂O(g)
First, convert the given masses of ethane (5.41 g) and oxygen (27.8 g) to moles using their respective molar masses (C₂H₆ = 30.07 g/mol, O₂ = 32.00 g/mol):
Moles of C₂H₆ = 5.41 g / 30.07 g/mol = 0.180 mol
Moles of O₂ = 27.8 g / 32.00 g/mol = 0.869 mol
Next, divide the moles of each reactant by their respective stoichiometric coefficients:
C₂H₆: 0.180 mol / 2 = 0.0900
O₂: 0.869 mol / 7 = 0.124
Since the value for ethane (0.0900) is smaller, ethane is the limiting reactant.
Using the stoichiometry of the balanced equation, calculate the theoretical yield of CO₂ from the moles of limiting reactant (ethane):
Moles of CO₂ = 0.180 mol C₂H₆ * (4 mol CO₂ / 2 mol C₂H₆) = 0.360 mol CO₂
Convert moles of CO₂ to grams using the molar mass of CO₂ (44.01 g/mol):
Theoretical yield of CO₂ = 0.360 mol * 44.01 g/mol = 15.8 g
Percent yield = (actual yield / theoretical yield) * 100%
Percent yield = (8.24 g / 15.8 g) * 100% = 52.2%