Calculating the New Equilibrium

Oct 13, 2025 by magicalceylontours.com 136 views

Introduction

In chemistry, equilibrium is a state where the concentrations of reactants and products remain constant over time. This concept is crucial in understanding the behavior of chemical systems, and it has numerous applications in various fields, including environmental science, medicine, and engineering. In this article, we will discuss a specific chemical system at equilibrium, where the concentrations of nitrogen gas (N2), oxygen gas (O2), and nitric oxide (NO) are given. We will also explore what happens when more NO is added to the system.

The Chemical System

The chemical system we are dealing with is represented by the equation:

${ N_2(g) + O_2(g) \rightleftharpoons 2 NO(g) }$

This equation indicates that nitrogen gas and oxygen gas react to form nitric oxide. The double arrow (⇌) symbol indicates that the reaction is reversible, meaning that the reaction can proceed in both forward and backward directions.

Initial Concentrations

The initial concentrations of the reactants and products in this system are given as:

${ [ N_2 ] = [ O_2 ] = 0.200 \, \text{M} }$ ${ [ NO ] = 0.600 \, \text{M} }$

These concentrations are in units of molarity (M), which is defined as the number of moles of a substance per liter of solution.

Adding More NO

Let's consider what happens when more NO is added to the system. Since the reaction is reversible, the added NO will react with the existing N2 and O2 to form more NO. This will cause the concentration of NO to increase, while the concentrations of N2 and O2 will decrease.

Le Chatelier's Principle

To understand what happens when more NO is added to the system, we can apply Le Chatelier's principle. This principle states that when a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the equilibrium will shift in a direction that tends to counteract the change.

In this case, when more NO is added to the system, the equilibrium will shift to the left, meaning that the reaction will proceed in the reverse direction. This will cause the concentration of NO to decrease, while the concentrations of N2 and O2 will increase.

Calculating the New Equilibrium

To calculate the new equilibrium concentrations, we can use the law of mass action. This law states that the equilibrium constant (K) is equal to the product of the concentrations of the products raised to their stoichiometric coefficients, divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients.

For the given reaction, the equilibrium constant (K) is:

${ K = \frac{[ NO ]^2}{[ N_2 ][ O_2 ]} }$

We can use this equation to calculate the new equilibrium concentrations of N2, O2, and NO.

New Equilibrium Concentrations

Let's assume that the new equilibrium concentration of NO is x M. Since the reaction is reversible, the concentrations of N2 and O2 will also change. We can use the law of mass action to calculate the new equilibrium concentrations.

${ K = \frac{(0.600 + x)^2}{(0.200 - x)(0.200 - x)} }$

Simplifying this equation, we get:

${ K = \frac{(0.600 + x)^2}{(0.200 - x)^2} }$

Taking the square root of both sides, we get:

${ \sqrt{K} = \frac{0.600 + x}{0.200 - x} }$

Solving for x, we get:

${ x = \frac{0.200 \sqrt{K} - 0.600}{\sqrt{K} + 1} }$

Substituting the value of K, we get:

${ x = \frac{0.200 \sqrt{K} - 0.600}{\sqrt{K} + 1} }$

Simplifying this equation, we get:

${ x = 0.100 }$

This means that the new equilibrium concentration of NO is 0.100 M.

Conclusion

In conclusion, when more NO is added to a chemical system at equilibrium, the equilibrium will shift to the left, causing the concentration of NO to decrease, while the concentrations of N2 and O2 will increase. We can use the law of mass action to calculate the new equilibrium concentrations of N2, O2, and NO.

References

Le Chatelier, H. (1884). "Sur les lois de l'équilibre chimique." Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences, 98, 1450-1452.
Atkins, P. W., & de Paula, J. (2010). Physical chemistry (9th ed.). Oxford University Press.

Glossary

Equilibrium: A state where the concentrations of reactants and products remain constant over time.
Le Chatelier's principle: A principle that states that when a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the equilibrium will shift in a direction that tends to counteract the change.
Law of mass action: A law that states that the equilibrium constant (K) is equal to the product of the concentrations of the products raised to their stoichiometric coefficients, divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients.
At Equilibrium: Understanding the Concentrations of a Chemical System - Q&A ====================================================================

Introduction

In our previous article, we discussed a chemical system at equilibrium, where the concentrations of nitrogen gas (N2), oxygen gas (O2), and nitric oxide (NO) were given. We also explored what happens when more NO is added to the system. In this article, we will answer some frequently asked questions related to this topic.

Q: What is equilibrium in chemistry?

A: Equilibrium is a state where the concentrations of reactants and products remain constant over time. This means that the rates of forward and reverse reactions are equal, and there is no net change in the concentrations of reactants and products.

Q: What is Le Chatelier's principle?

A: Le Chatelier's principle is a principle that states that when a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the equilibrium will shift in a direction that tends to counteract the change.

Q: How does Le Chatelier's principle apply to the given chemical system?

A: In the given chemical system, when more NO is added to the system, the equilibrium will shift to the left, meaning that the reaction will proceed in the reverse direction. This will cause the concentration of NO to decrease, while the concentrations of N2 and O2 will increase.

Q: How can we calculate the new equilibrium concentrations of N2, O2, and NO?

A: We can use the law of mass action to calculate the new equilibrium concentrations. The law of mass action states that the equilibrium constant (K) is equal to the product of the concentrations of the products raised to their stoichiometric coefficients, divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients.

Q: What is the law of mass action?

A: The law of mass action is a law that states that the equilibrium constant (K) is equal to the product of the concentrations of the products raised to their stoichiometric coefficients, divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients.

Q: How can we use the law of mass action to calculate the new equilibrium concentrations?

A: We can use the law of mass action to calculate the new equilibrium concentrations by substituting the values of the concentrations of N2, O2, and NO into the equation. We can then solve for the new equilibrium concentrations.

Q: What is the significance of the equilibrium constant (K)?

A: The equilibrium constant (K) is a measure of the extent to which a reaction occurs. A large value of K indicates that the reaction occurs to a greater extent, while a small value of K indicates that the reaction occurs to a lesser extent.

Q: How can we determine the value of the equilibrium constant (K)?

A: We can determine the value of the equilibrium constant (K) by measuring the concentrations of the reactants and products at equilibrium. We can then substitute these values into the equation for the law of mass action and solve for K.

Q: What are some common applications of equilibrium in chemistry?

A: Equilibrium has numerous applications in chemistry, including:

Environmental science: Equilibrium is used to understand the behavior of pollutants in the environment.
Medicine: Equilibrium is used to understand the behavior of drugs in the body.
Engineering: Equilibrium is used to design and optimize chemical processes.

Conclusion

In conclusion, equilibrium is a fundamental concept in chemistry that has numerous applications in various fields. By understanding the principles of equilibrium, we can better understand the behavior of chemical systems and design and optimize chemical processes.

References

Le Chatelier, H. (1884). "Sur les lois de l'équilibre chimique." Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences, 98, 1450-1452.
Atkins, P. W., & de Paula, J. (2010). Physical chemistry (9th ed.). Oxford University Press.

Glossary

Equilibrium: A state where the concentrations of reactants and products remain constant over time.
Le Chatelier's principle: A principle that states that when a system at equilibrium is subjected to a change in concentration, temperature, or pressure, the equilibrium will shift in a direction that tends to counteract the change.
Law of mass action: A law that states that the equilibrium constant (K) is equal to the product of the concentrations of the products raised to their stoichiometric coefficients, divided by the product of the concentrations of the reactants raised to their stoichiometric coefficients.