A sample of propane (C3H8) gas was burned with excess oxygen gas. If 4.20 L of CO2 were produced from the reaction of at STP, how many liters of propane were used in the reaction?

Question

A sample of propane (C3H8) gas was burned with excess oxygen gas. If 4.20 L of CO2 were produced from the reaction of at STP, how many liters of propane were used in the reaction?

Answer 1

Write the balanced equation for the combustion of propane, C3H8:

C₃H₈ + 5O₂ ==> 3CO₂ + 4H₂O ... BALANCED EQUATION

Use the stoichiometry of the balanced equation to find liters of propane to produce 4.20 L of CO₂:

4.20 L CO₂ x 1 L C₃H₈ / 3 L CO₂ = 1.40 L C₃H₈

NOTE: because the conditions are at STP, we can use L in place of moles in the balanced equation.