How many molecules of co2, h2o, c3h8, and o2 will be present if the reaction goes to completion?

The reaction that we could come up with the given compounds is combustion reaction. We burn C3H8 (propane) in the presence of oxygen (O2) in order to produce carbon dioxide (CO2) and water (H2O). The combustion reaction is written below.

C3H8 + O2 - - > CO2 + H2O

To balance the equation, we simply have to match the number of atoms in the left hand side of the reaction to that of the right hand side. This will give us an answer of,

C3H8 + 5O2 - - > 3CO2 + 4H2O

Thus, the number of moles are:

propane (C3H8) = 0 (totally consumed)

oxygen (O2) = 0 (totally consumed)

carbon dioxide (CO2) = 3 moles

water (H2O) = 4 moles