Question

What is the limiting reactant when 5.6 moles of aluminum react with 6.2 moles of water?

Unbalanced equation: Al + H2O → Al2O3 + H2

Show, or explain, all of your work along with the final answer.

Answer 1

The limiting reactant when 5.6 moles of aluminium react with 6.2 moles of water is

water( H2O)

Explanation

The balanced equation is as below

2 Al +3 H2O → Al2O3 +3 H2

The mole ratio of Al :Al2O3 is 2:1 therefore the moles of Al2O3

= 5.6 x1/2 = 2.8 moles

The mole ratio of H2O: Al2O3 is 3:1 therefore the moles of Al2O3 produced

= 6.2 x1/3= 2.067 moles

since H2O yield less amount of Al2O3 , H2O is the limiting reagent.

Answer 2

Given:

Moles of Al = 5.6 moles

Moles of H2O = 6.2 moles

To determine:

The limiting reagent

Step-by-step explanation:

The chemical reaction is-

2Al + 3H2O → Al2O3 + 3H2

- Based on stoichiometry; 2 moles of Al forms 1 mole of Al2O3

Therefore, 5.6 moles of Al would give: 5.6 Al * 1 Al2O3/2 Al = 2.8 moles Al2O3

-Similarly; 3 moles of H2O forms 1 mole of Al2O2

Therefore, 6.2 moles of H2O would give: 6.2 H2O * 1 Al2O3/3 H2O = 2.07 moles Al2O3

Ans: Since the amount (moles) of Al2O3 formed from H2O is less, water is the limiting reagent.