what is the excess and limiting reactants?

Question

4Fe + 3O₂  ➡  2Fe₂O₃

 

A sealed container has 4 moles of iron and 4 moles of oxygen inside.

which one is the excess reactant and which one is the limiting reactant?

Answer 1

Compare the moles of rust that are produced: (4 mole Fe) * (2 mole Fe₂O₃ / 4 mole Fe) = 2 moles Fe₂O₃.

(4 mole O₂) * (2 mole Fe₂O₃ / 3 mole O₂) = 2.67 mole Fe₂O₃. So Fe is the limiting reactant and O₂ the excess: there is not enough Fe to make 2.67 moles of product.