Consider The Chemical Equilibrium Of The Reaction:${ NH_4OH(aq) \Leftrightarrow NH_4^{+}(aq) + OH^{-}(aq) }$What Will Happen To The Chemical Equilibrium If ${ NH_4Cl }$ Is Added To This Solution?A. The Chemical Equilibrium Will

Introduction

Chemical equilibrium is a fundamental concept in chemistry that describes the state of a chemical reaction where the rates of forward and reverse reactions are equal, resulting in no net change in the concentrations of reactants and products. In this article, we will explore the chemical equilibrium of the reaction $NH_4OH(aq) \Leftrightarrow NH_4^{+}(aq) + OH^{-}(aq)$ and discuss the effects of adding $NH_4Cl$ to this solution.

Chemical Equilibrium of NH4OH(aq) Reaction

The reaction $NH_4OH(aq) \Leftrightarrow NH_4^{+}(aq) + OH^{-}(aq)$ is a classic example of a weak base dissociation reaction. In this reaction, the ammonium hydroxide ($NH_4OH$) dissociates into ammonium ions ($NH_4^{+}$) and hydroxide ions ($OH^{-}$). The equilibrium constant for this reaction is given by the expression:

$$K_b = \frac{[NH_4^{+}][OH^{-}]}{[NH_4OH]}$$

where $K_b$ is the base dissociation constant, and $[NH_4^{+}]$, $[OH^{-}]$, and $[NH_4OH]$ are the concentrations of ammonium ions, hydroxide ions, and ammonium hydroxide, respectively.

Effect of Adding NH4Cl to the Solution

When $NH_4Cl$ is added to the solution, it dissociates into ammonium ions ($NH_4^{+}$) and chloride ions ($Cl^{-}$). The added $NH_4^{+}$ ions will increase the concentration of ammonium ions in the solution, which will shift the equilibrium to the left. This is because the increased concentration of $NH_4^{+}$ ions will decrease the concentration of $OH^{-}$ ions, which will in turn decrease the concentration of $NH_4OH$.

Le Chatelier's Principle

Le Chatelier's 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, the addition of $NH_4Cl$ increases the concentration of $NH_4^{+}$ ions, which will cause the equilibrium to shift to the left, resulting in an increase in the concentration of $NH_4OH$ and a decrease in the concentration of $OH^{-}$ ions.

Mathematical Treatment

To understand the effect of adding $NH_4Cl$ on the chemical equilibrium, we can use the following mathematical treatment:

Let $x$ be the concentration of $NH_4Cl$ added to the solution. The new concentration of $NH_4^{+}$ ions will be $[NH_4^{+}] + x$. The new equilibrium constant expression will be:

$$K_b' = \frac{([NH_4^{+}] + x)[OH^{-}]}{[NH_4OH]}$$

Since the equilibrium constant $K_b$ is a constant, we can set up the following equation:

$$K_b = \frac{[NH_4^{+}][OH^{-}]}{[NH_4OH]} = \frac{([NH_4^{+}] + x)[OH^{-}]}{[NH_4OH]}$$

Simplifying the equation, we get:

$$[OH^{-}] = \frac{[NH_4^{+}]}{[NH_4^{+}] + x}$$

Substituting this expression into the original equilibrium constant expression, we get:

$$K_b = \frac{[NH_4^{+}][OH^{-}]}{[NH_4OH]} = \frac{[NH_4^{+}][NH_4^{+}]}{([NH_4^{+}] + x)[NH_4OH]}$$

Simplifying the equation, we get:

$$K_b = \frac{[NH_4^{+}]^2}{([NH_4^{+}] + x)[NH_4OH]}$$

This equation shows that the equilibrium constant $K_b$ is a function of the concentration of $NH_4^{+}$ ions and the concentration of $NH_4OH$.

Conclusion

In conclusion, the addition of $NH_4Cl$ to the solution will shift the chemical equilibrium to the left, resulting in an increase in the concentration of $NH_4OH$ and a decrease in the concentration of $OH^{-}$ ions. This is because the increased concentration of $NH_4^{+}$ ions will decrease the concentration of $OH^{-}$ ions, which will in turn decrease the concentration of $NH_4OH$. The mathematical treatment shows that the equilibrium constant $K_b$ is a function of the concentration of $NH_4^{+}$ ions and the concentration of $NH_4OH$.

References

• Atkins, P. W., & De Paula, J. (2010). Physical chemistry. Oxford University Press.
• Chang, R. (2010). Chemistry. McGraw-Hill.
• Levine, I. N. (2014). Physical chemistry. McGraw-Hill.

Keywords

• Chemical equilibrium
• NH4OH(aq) reaction
• NH4Cl
• Le Chatelier's principle
• Equilibrium constant
• Base dissociation constant
  Q&A: Understanding Chemical Equilibrium of NH4OH(aq) Reaction ===========================================================

Introduction

In our previous article, we discussed the chemical equilibrium of the reaction $NH_4OH(aq) \Leftrightarrow NH_4^{+}(aq) + OH^{-}(aq)$ and the effects of adding $NH_4Cl$ to this solution. In this article, we will answer some frequently asked questions related to this topic.

Q: What is chemical equilibrium?

A: Chemical equilibrium is a state of a chemical reaction where the rates of forward and reverse reactions are equal, resulting in no net change in the concentrations of reactants and products.

Q: What is the base dissociation constant (Kb)?

A: The base dissociation constant (Kb) is a measure of the strength of a base. It is defined as the ratio of the concentrations of the products to the concentration of the reactant at equilibrium.

Q: What is Le Chatelier's principle?

A: Le Chatelier's 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.

Q: What happens to the chemical equilibrium when NH4Cl is added to the solution?

A: When $NH_4Cl$ is added to the solution, it dissociates into ammonium ions ($NH_4^{+}$) and chloride ions ($Cl^{-}$). The added $NH_4^{+}$ ions will increase the concentration of ammonium ions in the solution, which will shift the equilibrium to the left.

Q: How does the addition of NH4Cl affect the concentration of OH- ions?

A: The addition of $NH_4Cl$ will decrease the concentration of $OH^{-}$ ions. This is because the increased concentration of $NH_4^{+}$ ions will decrease the concentration of $OH^{-}$ ions, which will in turn decrease the concentration of $NH_4OH$.

Q: What is the mathematical treatment of the effect of adding NH4Cl on the chemical equilibrium?

A: The mathematical treatment of the effect of adding $NH_4Cl$ on the chemical equilibrium is given by the equation:

$$K_b' = \frac{([NH_4^{+}] + x)[OH^{-}]}{[NH_4OH]}$$

where $K_b'$ is the new equilibrium constant, $[NH_4^{+}]$ is the concentration of ammonium ions, $x$ is the concentration of $NH_4Cl$ added to the solution, and $[OH^{-}]$ and $[NH_4OH]$ are the concentrations of hydroxide ions and ammonium hydroxide, respectively.

Q: What is the significance of the equilibrium constant (Kb) in this reaction?

A: The equilibrium constant (Kb) is a measure of the strength of the base. It is used to predict the direction of the reaction and the concentrations of the reactants and products at equilibrium.

Q: Can the chemical equilibrium be shifted by changing the concentration of NH4Cl?

A: Yes, the chemical equilibrium can be shifted by changing the concentration of $NH_4Cl$. By increasing or decreasing the concentration of $NH_4Cl$, the equilibrium can be shifted to the left or right, respectively.

Conclusion

In conclusion, the chemical equilibrium of the reaction $NH_4OH(aq) \Leftrightarrow NH_4^{+}(aq) + OH^{-}(aq)$ is affected by the addition of $NH_4Cl$. The addition of $NH_4Cl$ will shift the equilibrium to the left, resulting in an increase in the concentration of $NH_4OH$ and a decrease in the concentration of $OH^{-}$ ions. The mathematical treatment of the effect of adding $NH_4Cl$ on the chemical equilibrium is given by the equation:

$$K_b' = \frac{([NH_4^{+}] + x)[OH^{-}]}{[NH_4OH]}$$

References

• Atkins, P. W., & De Paula, J. (2010). Physical chemistry. Oxford University Press.
• Chang, R. (2010). Chemistry. McGraw-Hill.
• Levine, I. N. (2014). Physical chemistry. McGraw-Hill.

Keywords

• Chemical equilibrium
• NH4OH(aq) reaction
• NH4Cl
• Le Chatelier's principle
• Equilibrium constant
• Base dissociation constant