Question

How many grams of O2 are reacted when 3.5
mols of P203 are formed?

Answer 1

1.45 moles of P2O3 contains 1.45 moles of O3 which means 4.35 moles of O:

1.45 × 3 = 4.35 moles of O

Then you can calculate moles of O2 by dividing it by 2:

4.35 moles ÷ 2 = 2.175 moles of O2 needed