Question

What is the limiting reactant when 4.5 moles of aluminum react with 6.7 moles of oxygen gas? Unbalanced equation: Al + O2 → Al2O3 Show, or explain, all of your work along with the final answer.

Answer 1

4Al + 3O₂ -----> 2Al₂O₃
4 mol 3 mol

4 moles of aluminium react with 3 moles of oxygen
4,5 moles of aluminium need........???

4 mol Al -------- 3 mol O₂
4,5 mol Al ----- X
X = 3,375 mol

--- 4,5 moles of aluminium need 3,375 moles of oxygen.
We used 6,7 moles of oxygen, it's too much. So, oxygen is excess reactant and aluminium is limiting reactant.

:•)

Answer 2

Answer : The limiting reagent is, Aluminum (Al)

Explanation : Given,

Given moles of Al = 4.5 moles

Given moles of
`O_2` = 6.7 moles

First we have to calculate the limiting and excess reagent.

The balanced chemical reaction is,

`4Al+3O_2\rightarrow 2Al_2O_3`

From the given balanced reaction, we conclude that

As, 4 moles of
`Al` react with 2 moles of
`O_2`

So, 4.5 moles of
`Al` react with
`(2)/(4)* 4.5=3.375` moles of
`O_2`

From this we conclude that,
`O_2` is an excess reagent because the given moles are greater than the required moles and
`Al` is a limiting reagent because it limits the formation of product.

Hence the limiting reagent is, Aluminum (Al)