Great question; very straightforward answer.
You are given a balanced chemical equation:
C3H8(g) + 5O2(g) --> 3CO2(g) + 4H2O(g)
The numbers to the left of each molecule, or the "coefficient" of each term, can allow you to read the equation as follows:
One molecule of C3H8 reacts with five molecules of O2 to form three molecules of CO2 and four molecules of H2O.
Therefore, you need five oxygen (O2) molecules to react with each propane (C3H8) molecule. So, the mole ratio of oxygen molecules to each propane molecule would be 5:1
For the next two questions, the same principle can be applied. We know that for every molecule of propane (C3H8), we get three molecules of carbon dioxide (CO2), as well as four molecules of water (H2O). Therefore, the mole ratio of carbon dioxide product to each propane molecule is 3:1, and the mole ratio of water vapor product to each propane molecule would be 4:1
Best of luck on your exam!
