Study the chemical reaction.
4Fe + 3O2 → 2Fe2O3
What is the mole ratio between Fe and O2?

Answer: The mole ratio between Fe and [tex]O_2[/tex] is [tex]\frac{4Fe}{3O_2}[/tex]
Explanation:
According to the law of conservation of mass, mass can neither be created nor be destroyed. Thus the mass of products has to be equal to the mass of reactants. The number of atoms of each element has to be same on reactant and product side. Thus chemical equations are balanced.
The given balanced chemical equation is :
[tex]4Fe+3O_2\rightarrow 2Fe_2O_3[/tex]
Thus 4 moles of iron (Fe) reacts with 3 moles of oxygen gas [tex](O_2)[/tex] to give 2 moles of ferric oxide [tex](Fe_2O_3)[/tex]
The mole ratio between Fe and [tex]O_2[/tex] is [tex]\frac{4Fe}{3O_2}[/tex]