Question

If 4 moles of sulfur reacts with 9.5 moles of oxygen, how many moles of oxygen would remain after the reaction ?

Answer 1

4 Na + O₂ = 2 Na₂O

4* 23 g Na --------> 16 g O₂
9.5 g Na ------------> ?

Mass of O₂ = 9.5 * 16 / 4 * 23

Mass = 152 / 92

Mass = 1.6521 g of O₂

Molar mass O₂ = 16.0 g/mol

1 mole O₂ ------------ 16.0 g
? mole O₂ ------------ 1.6521 g

mole O₂ = 1.6521 * 1 / 16.0

≈ 0.10325 moles of O₂

hope that helped!