How do I calculate liters of CO2 at stp from grams of octane? (3 step stoichiometry conversion)

Question

How do I calculate liters of CO2 at stp from 1,735,513.195g of octane

Answer 1

Before addressing this problem, the grams of octane has 10 significant figures. I will not carry that through the problem. You may, if you wish, but here is my solution with fewer sig.figs.

Octane = C₈H₁₈

Combustion of octane is 2C₈H₁₈ + 25O₂ ==> 16CO₂ + 18H₂O

Step 1: Convert 1,735,513.195 g of octane to moles of octane:

1,735,513.195 g C₈H₁₈ x 1 mole C₈H₁₈ / 114.2 g = 15,197 moles C₈H₁₈

Step 2: Convert moles of octane to moles of CO₂:

15,197 moles C₈H₁₈ x 16 mols CO2 / 2 mols C₈H₁₈ = 121,577 moles CO₂

Step 3: Convert moles of CO₂ to liters of CO₂:

At STP 1 mol of any ideal gas = 22.4 L

121,577 mols CO₂ x 22.4 L / mole CO₂ = 2,723,327 liters of CO₂