Answer:
2.625
Step-by-step explanation:
The balanced chemical equation is needed to determine the mole-to-mole ratio of Fe to O.
4Fe + 3O2 -> 2Fe2O3
From the equation, 3 moles of O2 react with 4 moles of Fe. Therefore, the mole-to-mole ratio of O2 to Fe is 3:4.
To find how many moles of O2 are needed to react with 3.5 moles of Fe, we can use this ratio:
3.5 moles Fe × (3 moles O2 / 4 moles Fe) = 2.625 moles O2
Therefore, 2.625 moles of O2 are needed to react with 3.5 moles Fe.