Question

The combustion reaction of propane is described by the reaction. C3H8 + 5O2 → 4H2O + 3CO2. How many moles of O2 are required to generate 3 moles of CO2? A. 2.5 moles B. 3 moles C. 4 moles D. 5 moles

Answer 1

C₃H₈   +   5 O₂   →   4 H₂O   +   3 CO₂

mole ratio based on balance equation of  O₂   :   CO₂ i  s    5  :  3
                      C₃H₈   +   5 O₂   →   4 H₂O   +   3 CO₂

∴ if moles of CO₂  =  3 moles
 
then moles of O₂  = (3 moles ÷ 3) × 5
                             
                             =  5 moles   (OPTION D)