Understanding the Concept of Limiting Reactant

Oct 13, 2025 by pynkocean.com 110 views

Understanding the Concept of Limiting Reactant

In a chemical reaction, the limiting reactant is the reactant that is consumed first and determines the amount of product that can be formed. It is the reactant that is present in the smallest amount relative to the stoichiometric ratio of the reaction. In this article, we will determine the limiting reactant when 11 moles of $O_2$ reacts with 1.1 mole of $C_{10}H_8$ .

The Balanced Chemical Equation

The balanced chemical equation for the combustion of $C_{10}H_8$ is:

C_{10}H_8 + 12O_2 \rightarrow 10CO_2 + 4H_2O

Determining the Limiting Reactant

To determine the limiting reactant, we need to compare the mole ratio of the reactants to the stoichiometric ratio of the reaction. The stoichiometric ratio is the ratio of the coefficients of the reactants in the balanced chemical equation.

In this case, the stoichiometric ratio is 1 mole of $C_{10}H_8$ to 12 moles of $O_2$ . We are given 1.1 mole of $C_{10}H_8$ and 11 moles of $O_2$ .

Calculating the Mole Ratio

To calculate the mole ratio, we can divide the number of moles of each reactant by the number of moles of the other reactant.

For $C_{10}H_8$ :

\frac{1.1 \text{ mole}}{11 \text{ mole}} = 0.1

For $O_2$ :

\frac{11 \text{ mole}}{1.1 \text{ mole}} = 10

Comparing the Mole Ratio to the Stoichiometric Ratio

The stoichiometric ratio is 1 mole of $C_{10}H_8$ to 12 moles of $O_2$ . We can compare this to the calculated mole ratio:

For $C_{10}H_8$ : 0.1 (calculated) vs. 1 (stoichiometric)
For $O_2$ : 10 (calculated) vs. 12 (stoichiometric)

Determining the Limiting Reactant

Based on the comparison, we can see that $C_{10}H_8$ is the limiting reactant. This is because it is present in the smallest amount relative to the stoichiometric ratio of the reaction.

Conclusion

In conclusion, when 11 moles of $O_2$ reacts with 1.1 mole of $C_{10}H_8$ , the limiting reactant is $C_{10}H_8$ . This is because it is present in the smallest amount relative to the stoichiometric ratio of the reaction.

Answer

The correct answer is:

A. $C_{10}H_8$

Additional Information

The limiting reactant determines the amount of product that can be formed.
The stoichiometric ratio is the ratio of the coefficients of the reactants in the balanced chemical equation.
The mole ratio can be calculated by dividing the number of moles of each reactant by the number of moles of the other reactant.
Frequently Asked Questions (FAQs) about Limiting Reactants =============================================================

Q: What is a limiting reactant?

A: A limiting reactant is the reactant that is consumed first and determines the amount of product that can be formed in a chemical reaction.

Q: How do I determine the limiting reactant in a chemical reaction?

A: To determine the limiting reactant, you need to compare the mole ratio of the reactants to the stoichiometric ratio of the reaction. The stoichiometric ratio is the ratio of the coefficients of the reactants in the balanced chemical equation.

Q: What is the stoichiometric ratio?

A: The stoichiometric ratio is the ratio of the coefficients of the reactants in the balanced chemical equation. For example, in the balanced chemical equation:

C_{10}H_8 + 12O_2 \rightarrow 10CO_2 + 4H_2O

The stoichiometric ratio is 1 mole of $C_{10}H_8$ to 12 moles of $O_2$ .

Q: How do I calculate the mole ratio?

A: To calculate the mole ratio, you can divide the number of moles of each reactant by the number of moles of the other reactant.

Q: What is the difference between a limiting reactant and an excess reactant?

A: A limiting reactant is the reactant that is consumed first and determines the amount of product that can be formed. An excess reactant is the reactant that is present in excess of the stoichiometric ratio and is not consumed.

Q: Can a reactant be both a limiting reactant and an excess reactant?

A: No, a reactant cannot be both a limiting reactant and an excess reactant. If a reactant is a limiting reactant, it means that it is consumed first and determines the amount of product that can be formed. If a reactant is an excess reactant, it means that it is present in excess of the stoichiometric ratio and is not consumed.

Q: Why is it important to determine the limiting reactant in a chemical reaction?

A: It is important to determine the limiting reactant in a chemical reaction because it determines the amount of product that can be formed. Knowing the limiting reactant also helps to predict the yield of the reaction and to optimize the reaction conditions.

Q: Can I use the limiting reactant to predict the yield of a reaction?

A: Yes, you can use the limiting reactant to predict the yield of a reaction. The yield of a reaction is the amount of product that is actually formed, compared to the maximum amount of product that could be formed if all of the reactants were consumed.

Q: How do I calculate the yield of a reaction?

A: To calculate the yield of a reaction, you need to know the amount of limiting reactant that is consumed and the stoichiometric ratio of the reaction. You can then use the following formula to calculate the yield:

Yield = (Amount of limiting reactant consumed / Stoichiometric ratio) x 100%

Q: What is the significance of the limiting reactant in real-world applications?

A: The limiting reactant is significant in real-world applications because it determines the amount of product that can be formed in a chemical reaction. This is important in industries such as pharmaceuticals, where the yield of a reaction can affect the cost and availability of a product.

Q: Can I use the limiting reactant to optimize the reaction conditions?

A: Yes, you can use the limiting reactant to optimize the reaction conditions. By knowing the limiting reactant, you can adjust the reaction conditions, such as temperature, pressure, and concentration, to maximize the yield of the reaction.

Q: How do I optimize the reaction conditions?

A: To optimize the reaction conditions, you need to know the limiting reactant and the stoichiometric ratio of the reaction. You can then use the following steps to optimize the reaction conditions:

Determine the limiting reactant.
Adjust the reaction conditions, such as temperature, pressure, and concentration, to maximize the yield of the reaction.
Monitor the reaction and adjust the conditions as needed to achieve the desired yield.

Q: What are some common mistakes to avoid when determining the limiting reactant?

A: Some common mistakes to avoid when determining the limiting reactant include:

Not balancing the chemical equation.
Not calculating the mole ratio correctly.
Not considering the stoichiometric ratio of the reaction.
Not adjusting the reaction conditions to maximize the yield of the reaction.

Q: How do I avoid these mistakes?

A: To avoid these mistakes, you need to:

Balance the chemical equation correctly.
Calculate the mole ratio correctly.
Consider the stoichiometric ratio of the reaction.
Adjust the reaction conditions to maximize the yield of the reaction.

By following these steps, you can avoid common mistakes and determine the limiting reactant correctly.