Question
Propane reacts with oxygen in a combustion reaction. What volume of carbon dioxide gas is formed when 20 L of propane are reacted with 55.7 L of oxygen?
Answers
DrBob222
C3H8 + 5O2 ==> 3CO2 + 4H2O
When gases are involved, we can omit the conversion to mols stage and use only volumes.
Convert 20L C3H8 to L CO2. 20 x (3 mol CO2/1 mol C3H8) = 60 L C3H8.
Convert 55.7 L O2 to CO2. 20 x (3 mols CO2/5 mols O2) = 33.4 L CO2.
One of these answers must be wrong; the correct value in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting reagent. Therefore, 33.4 L CO2 will be produced. There is some unreacted propane left over.
When gases are involved, we can omit the conversion to mols stage and use only volumes.
Convert 20L C3H8 to L CO2. 20 x (3 mol CO2/1 mol C3H8) = 60 L C3H8.
Convert 55.7 L O2 to CO2. 20 x (3 mols CO2/5 mols O2) = 33.4 L CO2.
One of these answers must be wrong; the correct value in limiting reagent problems is ALWAYS the smaller value and the reagent producing that value is the limiting reagent. Therefore, 33.4 L CO2 will be produced. There is some unreacted propane left over.