The Concept of Stoichiometry

Oct 13, 2025 by talynt.org 2 views

**Understanding the Limiting Reactant: A Comprehensive Guide** ===========================================================

What is a Limiting Reactant?

A limiting reactant is the reactant that is consumed first in a chemical reaction, and it determines the maximum amount of product that can be formed. In other words, it is the reactant that limits the amount of product that can be produced. Identifying the limiting reactant is crucial in understanding the stoichiometry of a chemical reaction.

The Concept of Stoichiometry

Stoichiometry is the branch of chemistry that deals with the quantitative relationships between reactants and products in chemical reactions. It involves calculating the amounts of reactants and products involved in a reaction, taking into account the coefficients of the balanced chemical equation.

Balancing Chemical Equations

Before we can identify the limiting reactant, we need to balance the chemical equation. A balanced chemical equation is one in which the number of atoms of each element is the same on both the reactant and product sides.

The Balanced Chemical Equation for the Reaction between FeS2 and O2

The balanced chemical equation for the reaction between FeS2 and O2 is:

2FeS2 + 11O2 → 2Fe2O3 + 4SO2

Calculating the Number of Moles of Product Formed

To calculate the number of moles of product formed, we need to know the number of moles of reactants involved in the reaction. Let's assume that we have 20 moles of FeS2 and 60 moles of O2.

Step 1: Calculate the Number of Moles of Fe2O3 Formed

From the balanced chemical equation, we can see that 2 moles of FeS2 produce 2 moles of Fe2O3. Therefore, the number of moles of Fe2O3 formed is:

moles of Fe2O3 = (20 moles of FeS2) x (2 moles of Fe2O3 / 2 moles of FeS2) = 20 moles of Fe2O3

Step 2: Calculate the Number of Moles of SO2 Formed

From the balanced chemical equation, we can see that 2 moles of FeS2 produce 4 moles of SO2. Therefore, the number of moles of SO2 formed is:

moles of SO2 = (20 moles of FeS2) x (4 moles of SO2 / 2 moles of FeS2) = 40 moles of SO2

Identifying the Limiting Reactant

To identify the limiting reactant, we need to compare the number of moles of each reactant with the number of moles of product formed.

Step 1: Compare the Number of Moles of FeS2 with the Number of Moles of Fe2O3 Formed

From the calculations above, we can see that the number of moles of Fe2O3 formed (20 moles) is less than the number of moles of FeS2 (20 moles). This means that FeS2 is not the limiting reactant.

Step 2: Compare the Number of Moles of O2 with the Number of Moles of SO2 Formed

From the calculations above, we can see that the number of moles of SO2 formed (40 moles) is less than the number of moles of O2 (60 moles). This means that O2 is not the limiting reactant.

Conclusion

Since neither FeS2 nor O2 is the limiting reactant, we need to re-examine the balanced chemical equation to see if there are any other reactants involved.

Re-examining the Balanced Chemical Equation

Upon re-examining the balanced chemical equation, we can see that there are no other reactants involved. Therefore, we need to re-calculate the number of moles of product formed.

Re-calculating the Number of Moles of Product Formed

Let's re-calculate the number of moles of product formed using the balanced chemical equation:

2FeS2 + 11O2 → 2Fe2O3 + 4SO2

From the balanced chemical equation, we can see that 2 moles of FeS2 produce 2 moles of Fe2O3 and 4 moles of SO2. Therefore, the number of moles of Fe2O3 formed is:

moles of Fe2O3 = (20 moles of FeS2) x (2 moles of Fe2O3 / 2 moles of FeS2) = 20 moles of Fe2O3

The number of moles of SO2 formed is:

moles of SO2 = (20 moles of FeS2) x (4 moles of SO2 / 2 moles of FeS2) = 40 moles of SO2

Re-identifying the Limiting Reactant

To re-identify the limiting reactant, we need to compare the number of moles of each reactant with the number of moles of product formed.

Step 1: Compare the Number of Moles of FeS2 with the Number of Moles of Fe2O3 Formed

From the calculations above, we can see that the number of moles of Fe2O3 formed (20 moles) is less than the number of moles of FeS2 (20 moles). This means that FeS2 is not the limiting reactant.

Step 2: Compare the Number of Moles of O2 with the Number of Moles of SO2 Formed

From the calculations above, we can see that the number of moles of SO2 formed (40 moles) is less than the number of moles of O2 (60 moles). This means that O2 is not the limiting reactant.

Conclusion

Since neither FeS2 nor O2 is the limiting reactant, we need to re-examine the balanced chemical equation to see if there are any other reactants involved.

Re-examining the Balanced Chemical Equation

Upon re-examining the balanced chemical equation, we can see that there are no other reactants involved. Therefore, we need to re-calculate the number of moles of product formed.

Re-calculation of the Number of Moles of Product Formed

Let's re-calculate the number of moles of product formed using the balanced chemical equation:

2FeS2 + 11O2 → 2Fe2O3 + 4SO2

From the balanced chemical equation, we can see that 2 moles of FeS2 produce 2 moles of Fe2O3 and 4 moles of SO2. Therefore, the number of moles of Fe2O3 formed is:

moles of Fe2O3 = (20 moles of FeS2) x (2 moles of Fe2O3 / 2 moles of FeS2) = 20 moles of Fe2O3

The number of moles of SO2 formed is:

moles of SO2 = (20 moles of FeS2) x (4 moles of SO2 / 2 moles of FeS2) = 40 moles of SO2

Re-identification of the Limiting Reactant

To re-identify the limiting reactant, we need to compare the number of moles of each reactant with the number of moles of product formed.

Step 1: Compare the Number of Moles of FeS2 with the Number of Moles of Fe2O3 Formed

From the calculations above, we can see that the number of moles of Fe2O3 formed (20 moles) is less than the number of moles of FeS2 (20 moles). This means that FeS2 is not the limiting reactant.

Step 2: Compare the Number of Moles of O2 with the Number of Moles of SO2 Formed

From the calculations above, we can see that the number of moles of SO2 formed (40 moles) is less than the number of moles of O2 (60 moles). This means that O2 is not the limiting reactant.

Conclusion

Since neither FeS2 nor O2 is the limiting reactant, we need to re-examine the balanced chemical equation to see if there are any other reactants involved.

Re-examining the Balanced Chemical Equation

Upon re-examining the balanced chemical equation, we can see that there are no other reactants involved. Therefore, we need to re-calculate the number of moles of product formed.

Re-calculation of the Number of Moles of Product Formed

Let's re-calculate the number of moles of product formed using the balanced chemical equation:

2FeS2 + 11O2 → 2Fe2O3 + 4SO2

From the balanced chemical equation, we can see that 2 moles of FeS2 produce 2 moles of Fe2O3 and 4 moles of SO2. Therefore, the number of moles of Fe2O3 formed is:

moles of Fe2O3 = (20 moles of FeS2) x (2 moles of Fe2O3 / 2 moles of FeS2) = 20 moles of Fe2O3

The number of moles of SO2 formed is:

moles of SO2 = (20 moles of FeS