Determining Limiting and Excess Reactants and Calculating Product Formation in the Reaction of Iron(III) Chloride with Oxygen

In the context of chemical reactions, understanding the concepts of limiting and excess reactants is crucial for predicting the extent of the reaction and the amount of product formed. This article will delve into the process and calculations associated with determining the limiting reactant and the excess reactant when iron(III) chloride (FeCl3) reacts with oxygen (O2), specifically focusing on the formation of chlorine gas (Cl2). The reaction of interest is:

4FeCl3 3O2 → 2Fe2O3 6Cl2

Understanding the Reaction

The balanced chemical equation for the reaction between iron(III) chloride and oxygen is:

4FeCl3 3O2 → 2Fe2O3 6Cl2

This equation indicates that 4 moles of FeCl3 will react with 3 moles of O2 to produce 2 moles of Fe2O3 and 6 moles of Cl2. This stoichiometric relationship forms the basis of the calculation.

Determining the Limiting Reactant and Excess Reactant

When 4 moles of FeCl3 react with 4 moles of O2, the determination of the limiting and excess reactants is required. The stoichiometric ratio from the balanced equation is 4:3, meaning 4 moles of FeCl3 should theoretically react with 3 moles of O2.

Step 1: Determining the Theoretical Amount of O2

Using the stoichiometric ratio:

FeCl3 : O2 4:3

Theoretical moles of O2 required (3/4) x 4 3 moles

Step 2: Comparing Theoretical to Actual Amount of Reactants

Given that we have 4 moles of O2, and the theoretical requirement is 3 moles, 1 mole of O2 remains unreacted. This indicates that O2 is in excess.

Step 3: Identifying the Limiting Reactant

Since the ratio of FeCl3 to O2 is 4:3 and we have the exact ratio required to react completely, FeCl3 is the limiting reactant.

Calculating the Amount of Cl2 Produced

Given that FeCl3 is the limiting reactant, we can now calculate the amount of Cl2 that will be produced.

Using the stoichiometric ratio from the balanced equation:

FeCl3 : Cl2 4:6

Moles of Cl2 produced (6/4) x 4 6 moles

Conclusion

In the reaction of FeCl3 with O2, FeCl3 is the limiting reactant, and O2 is the excess reactant. The amount of Cl2 produced is 6 moles.

By understanding the concepts of limiting and excess reactants and their impact on the amount of product formed, chemists and researchers can predict and control the outcomes of chemical reactions with precision. This knowledge is applicable in various fields, including environmental science, material science, and industrial chemistry.