Solving Stoichiometry Problems

Question

Determine the mass of oxygen required to completely burn 10.0 g of propane (C₃H₈).

Answer 1

First, you must write a correctly balanced equation for the combustion of propane:

C₃H₈ + 5O₂ ==> 3CO₂ + 4H₂O ... balanced equation

Next, use the molar mass of propane (44.1 g / mol), the molar mass of O₂ (32 g/mol), and the mol ratio of O₂ to propane in the balanced equation to solve the problem.

10.0 g C₃H₈ x 1 mol C₃H₈ / 44.1 g x 5 mol O₂ / mol C₃H₈ x 32 g O₂ / mol O2 = 36.3g O₂ (3 sig.figs.)