Question

4Al+3O2→2Al2O3

What is the theoretical yield of aluminum oxide if 2.40 mol of aluminum metal is exposed to 2.10 mol of oxygen?

Answer 1

find limiting reagent...

4 moles of Al reacts with 3 moles of O2
so 1 mole of Al will react with 3/4 moles of O2
so 2.4 moles of Al will react with 3/4 X 2.4 = 1.8 moles of O2 but no.of moles of O2 given in the question which is more than what is recquired

so O2 is present in excess and ultimately Al is the limiting reagent and amount of products will depend on amount of Al only 4 moles of Al gives 2 moles of Al2O3
so 1 mole of Al will give 2/4 mole of Al2O3
so 2.4 moles of Al will give 2/4 X 2.4 = 1.2 moles of Al2O3