Answer:
5 moles
Explanation:
First, write out the balanced equation:
2Al + Fe₂O₃ → Al₂O₃ + 2Fe
Reaction ratio of Al to Fe₂O₃ is:
2 : 1
This means 2 moles of Al will react with 1 mole of Fe₂O₃
Al: 5 mol
Fe₂O₃: 3 mol
Multiply the reaction to get moles of both reactants you have:
2 : 1 (×⁵/₂) = 5 : ⁵/₂
2 : 1 (×3) = 6 : 3
In other words, 5 moles of Al will react with ⁵/₂ moles of Fe₂O₃;
And 3 moles of Fe₂O₃ will react with 6 moles of Al;
But, we do not have 6 moles of Al, therefore only the 5 moles of Al available will react;
5 moles of Al reacts with ⁵/₂ moles of Fe₂O₃, as we can see from the ratios we calculated above, the remaining ¹/₂ mole of Fe₂O₃ will not react;
We say that Al is the limiting reactant because all the Al will react but all the Fe₂O₃ does not (i.e. it is in excess);
Next and last, the reaction ratio of Al to Fe is:
2 : 2 or, more simply 1 : 1
This means the moles of Al that reacts is the equal to the moles of Fe produced from the reaction;
We've established that 5 moles of Al will react with ⁵/₂ moles of Fe₂O₃, so 5 moles of Fe will also be produced (since the ratio is 1 : 1);
You could also work this out using the moles of Fe₂O₃ that react;
The reaction ratio of Fe₂O₃ to Fe:
1 : 2
So the moles of Fe produced is 2× the moles of Fe₂O₃;
If ⁵/₂ moles of Fe₂O₃ reacts, then simply multiply this by 2 which is 5 moles
