Stoichiometry of gases

Question

1. Propane, C3H8, is a gas that is sometimes used as a fuel for cooking and heating. The complete combustion of propane occurs according to the following equation.
C3H8(g) + 5O2(g) → 3CO2(g) + 4H2O(g)
a. What will be the volume, in liters, of oxygen required for the complete combustion of 0.350 L of propane?
b. What will be the volume of carbon dioxide produced in the reaction?
Assume that all volume measurements are made at the same temperature and pressure.

Answer 1

For part A, we need the ratio of moles of propane to moles of oxygen to get the volume of oxygen required. 

 

The equation tells us there are 5 moles of oxygen gas required to combust 1 mole of propane. 

 

So the required volume of oxygen is 5*0.35L = 1.75L

 

The equation also tells us that 3 moles of carbon dioxide are produced from the combustion of one mole of propane. 

 

Therefore the produced volume of carbon dioxide is 3*0.35L = 1.05L

 

 

A side note is that this reaction produces a great deal of heat so the volume produced will be larger than 1.05L in real life until it can cool to the original temperature.