Answer
5.87 mol $O_{2}$
Work Step by Step
Balanced chemical reaction:
4 Fe (s) + 3 $O_{2}$ (g) ${\longrightarrow}$ 2 $Fe_{2}O_{3}$ (g)
3 moles oxygen produce 2 moles $Fe_{2}O_{3}$ . To find out how many moles oxygen produce 3.91 mol $Fe_{2}O_{3}$, the conversion factor should be: $\frac{3_{mole (O_{2})}}{2_{mol (Fe_{2}O_{3})}}$.
So the number of moles of oxygen needed to produce 3.91 moles $Fe_{2}O_{3}$ is:
3.91 mol $Fe_{2}O_{3}$ x $\frac{3_{mole (O_{2})}}{2_{mol (Fe_{2}O_{3})}}$ = 5.865 mol $O_{2}$ or 5.87 mol $O_{2}$
