Chemistry
posted by Star .
How many liters of air (78 percent N2, 22 percent O2 by volume) at 20 degrees Celsius and 1.00 atm are needed for the complete combustion of 1.0 L of octane, C8H18, a typical gasoline component that has a density of 0.70 g/mL?

(1) Compute the number of moles (n) of octane in 1 liter. The mass of that liter is 700 g, because of the 0.70 g/ml density.
(2) Using the balanced reaction for oxidation, calculate how many moles of O2 are needed to burn n moles of C8H18. That number is 12.5.
C8H18 + 12.5 O2 = 8CO2 + 9H2O
(3) The number of moles of air needed will be 12.5 n/0.22 = 56.8 n
(4) One mole of any gas occupies 24.2 liters at 20 C and 1 atm.
Put the pieces together for the final answer. 
V = 4316 L