Question

4 Al + 302 → 2Al2O3
If a chemist does the reaction and produces 3.5 moles of aluminum oxide, how many moles of O2 were used in the reaction?

Answer 1

The answer is 5.25 moles
The Stochiometric coefficient between o2 and Al2O3 is 3:2
You have 3.5 moles of aluminum oxide so you have a simple equation you can solve
3.5*3=2x