Answer to Question #71411 in General Chemistry for Holly

Question

How many grams of oxygen are necessary to drive a car 250 miles if your fuel mileage is 35.0 miles per gallon and you are using ethanol as your fuel? (Density of ethanol is 0.7893 g/mL)

Answer 1

Volume of the ethanol needed: 250 / 35 = 7.143 gallons
1 gallon = 3.79 L, therefore:
Volume of the ethanol: 7.143 ∙ 3.79 = 27.072 L = 27072 mL
Mass of ethanol: 27072 ∙ 0.7893 = 21367.93 g
Amount of the ethanol: 21367.93 / 46.07 = 463.8 mol
The balanced reaction:
1 C2H5OH + 3 O2 = 2 CO2 + 3 H2O
The ratio (ethanol : oxygen) is (1 : 3), so:
The amount of the oxygen needed: 463.8 ∙ 3 = 1391.4 mol
The mass of the oxygen: 1391.4 ∙ 32 = 44524.8 g
Answer:
44524.8 g