Question

For the reaction shown, find the limiting reactant for each of the following initial amounts of reactants.

4Al(s)+3O2(g)?2Al2O3(s)

In which is Al limiting and which is O2 limiting?

1.) 1 mole Al and 1 mole O2

2.) 4 mole Al and 2.6 mole O2

3.) 11.4 mole Al and 9.5 mole O2

4.)24 mole Al and 19 mole O2

Answer 1

Concepts and reason

Limiting reagent:

A limiting reagent is one of the reactants, which is completely consumed in a chemical reaction. The yield of the product depends on this limiting reagent; it can be determined with the help of a balanced chemical equation for the reaction.

The number of moles of the substance is the simple ratio of the mass to the molar mass of that substance.

Fundamentals

Limiting reactant:

If the reactants do not react according to their stoichiometric ratios, one of the reactants is completely consumed during the completion of the reaction. This is the limiting reactant and the other reactant is in excess.

Mole is a measure of the number of entities like atoms, molecules or ions present in the substance. The mole of a substance always contains the same number of entities, independent of the substance. The number of entities in one mole is known as Avogadro constant.

The given chemical equation is as follows:

The stoichiometric relation for ${\rm{Al}}\,{\rm{:}}\,{{\rm{O}}_{\rm{2}}}$is 4:3.

(1)

(2)

(3)

(4)

Ans: Part 1

${\rm{Al is the limiting reagent}}{\rm{.}}$

Part 2

${{\rm{O}}_{\rm{2}}}{\rm{ is the limiting reagent}}{\rm{.}}$

Part 3

${\rm{Al is the limiting reagent}}{\rm{.}}$

Part 4

${\rm{Al is the limiting reagent}}{\rm{.}}$