How many grams of oxygen are needed to burn a gallon of gas?

Question

So for all you chemisty majors out there, I really need help on how you would do this. If you could also try and write the formula out too that would be awesome. Also, one pound of gas is 454 grams.

Thanks!

C8H18 + O2 --> CO2 + H2O might help to start you off idk though

Answer 1

There is about 20% oxygen in the air which is more than enough.

Although a pound is 454 grams. you asked about gallons. Gasoline is about 6 pounds per gallon.

Most gasoline is burned in internal combustion engines which do not burn it completely.It forms carbon monoxide.

Gasoline is not pure octane, C8H18

2C8H18 + 25O2 ---> 16CO2 + 18H2O

Now you can work out the rest, 2 moles of octane to 25 moles of O2. Use themolecular weight per mole of each.Figure out how many moles of octane yoy have.

Answer 2

There is such a variety of mixtures called gasoline as to render your question unanswerable. You can run out the numbers for octane, but this is merely an exercise, as octane represents only a small portion of gasoline. In point of fact gasoline octane ratings are based on their performance versus isooctane, (CH3)3CCH2CH(CH3)2¹.
I see that someone else has set up the necessary conditions for a solution for octane, so I won't bother. Incidentally, 1 lb of almost anything is 453 grams.
The s.g of octane is 0.703 while the s.g. of isooctane is 0.69.¹