Question

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

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

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.