Help with this chemistry problem please?

[Tyler]

Can someone just show me how to do this problem? I don't need to know the answer, just to know how.

What volume of oxygen, at STP, is required to completely react with 12.0 moles of aluminum?
4Al(s)+3O2(g) -> 2Al2O3

 

[Jeff]

12mol Al x 3mol O2/4mol Al x 22.4L O2/1mol O2 = 201.6 L O2

 

[Izzy S]

1- coefficients are the ratio of moles in this type of problem so for every 4 moles of Al there are three moles of o2 so if there are 12 moles o2 there are __ moles O2
2- convert moles to grams. the average atomic mass=the number of grams per mole of that element. multiply the atomic mass by the mole count but DO NOT FORGET that you have two molecules of oxygen so the answer will be 2(atomic mass of O)(number of moles)
GOOD LUCK!