How do you solve this problem?

Question

Consider this balanced chemical equation.

4Al(s)+3O2(g)>2Al2O3(s)

How many moles of Al will remain if 0.60 moles of O2 react with 0.90 moles of Al?

Answer 1

It looks as if you need 4 Al and 3 O2.  Set that up as an equation 4/3 = x/.6

That leaves x = .8 so out of .9 then .1 mole Al would be left.

Answer 2

0.6 mol O2( 4 mole Al/ 3 mole O2) = 0.8 mole  Al needed to react

0.90  mole of Al - 0.80 mol Al= 0.10 mole Al remain