Understanding the Degree of Hydrolysis and Buffer Solutions

Oct 13, 2025 by wbrum.org 99 views

Understanding the Degree of Hydrolysis and Buffer Solutions

Introduction

In chemistry, the degree of hydrolysis is a crucial concept that helps us understand the behavior of salts in aqueous solutions. It refers to the extent to which a salt undergoes hydrolysis, which is the reaction of a salt with water to produce an acid and a base. The degree of hydrolysis is an important factor in determining the pH of a solution. In this article, we will explore the concept of degree of hydrolysis and its relationship with concentration, and we will also discuss the pH of a buffer solution consisting of acetic acid and sodium acetate.

Degree of Hydrolysis

The degree of hydrolysis is a measure of the extent to which a salt undergoes hydrolysis. It is defined as the ratio of the concentration of the hydrolyzed salt to the initial concentration of the salt. The degree of hydrolysis is usually denoted by the symbol "h" and is expressed as a decimal value between 0 and 1.

The degree of hydrolysis is influenced by several factors, including the concentration of the salt, the temperature of the solution, and the nature of the salt itself. In general, the degree of hydrolysis increases with increasing concentration of the salt, as well as with increasing temperature.

Independence of Concentration

The question asks which of the following salts has a degree of hydrolysis that is independent of concentration. To answer this question, we need to consider the nature of each salt and its behavior in aqueous solutions.

CH3COONa (Sodium Acetate): Sodium acetate is a salt of a weak acid (acetic acid) and a strong base (sodium hydroxide). As a result, it undergoes hydrolysis to produce acetic acid and sodium hydroxide. The degree of hydrolysis of sodium acetate is dependent on the concentration of the salt.
KCN (Potassium Cyanide): Potassium cyanide is a salt of a weak acid (hydrocyanic acid) and a strong base (potassium hydroxide). It undergoes hydrolysis to produce hydrocyanic acid and potassium hydroxide. The degree of hydrolysis of potassium cyanide is also dependent on the concentration of the salt.
NH4Cl (Ammonium Chloride): Ammonium chloride is a salt of a weak base (ammonia) and a strong acid (hydrochloric acid). It undergoes hydrolysis to produce ammonia and hydrochloric acid. The degree of hydrolysis of ammonium chloride is dependent on the concentration of the salt.
CH3COONH4 (Ammonium Acetate): Ammonium acetate is a salt of a weak acid (acetic acid) and a weak base (ammonia). It undergoes hydrolysis to produce acetic acid and ammonia. The degree of hydrolysis of ammonium acetate is independent of concentration.

Buffer Solutions

A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. Buffer solutions are used to maintain a stable pH in a solution, even when strong acids or bases are added. The pH of a buffer solution is determined by the ratio of the concentrations of the weak acid and its conjugate base.

The pH of a buffer solution consisting of acetic acid and sodium acetate can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log10([A-]/[HA])

where pKa is the acid dissociation constant of acetic acid, [A-] is the concentration of the conjugate base (sodium acetate), and [HA] is the concentration of the weak acid (acetic acid).

Conclusion

In conclusion, the degree of hydrolysis is an important concept in chemistry that helps us understand the behavior of salts in aqueous solutions. The degree of hydrolysis is influenced by several factors, including concentration, temperature, and the nature of the salt itself. The pH of a buffer solution consisting of acetic acid and sodium acetate can be calculated using the Henderson-Hasselbalch equation.

The correct answer to the question is D) CH3COONH4, as the degree of hydrolysis of ammonium acetate is independent of concentration.

References

Atkins, P. W., & De Paula, J. (2010). Physical chemistry. Oxford University Press.
Brown, T. E., & LeMay, H. E. (2014). Chemistry: The Central Science. Pearson Education.
Chang, R. (2010). Physical chemistry for the life sciences. Cambridge University Press.

Keywords

Degree of hydrolysis
Buffer solutions
pH
Acetic acid
Sodium acetate
Ammonium acetate
Henderson-Hasselbalch equation
Frequently Asked Questions (FAQs) about Degree of Hydrolysis and Buffer Solutions

Q: What is the degree of hydrolysis?

A: The degree of hydrolysis is a measure of the extent to which a salt undergoes hydrolysis. It is defined as the ratio of the concentration of the hydrolyzed salt to the initial concentration of the salt.

Q: What factors influence the degree of hydrolysis?

A: The degree of hydrolysis is influenced by several factors, including concentration, temperature, and the nature of the salt itself.

Q: What is a buffer solution?

A: A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. Buffer solutions are used to maintain a stable pH in a solution, even when strong acids or bases are added.

Q: How is the pH of a buffer solution calculated?

A: The pH of a buffer solution can be calculated using the Henderson-Hasselbalch equation:

pH = pKa + log10([A-]/[HA])

where pKa is the acid dissociation constant of the weak acid, [A-] is the concentration of the conjugate base, and [HA] is the concentration of the weak acid.

Q: What is the Henderson-Hasselbalch equation?

A: The Henderson-Hasselbalch equation is a mathematical formula used to calculate the pH of a buffer solution. It is based on the principle that the pH of a buffer solution is determined by the ratio of the concentrations of the weak acid and its conjugate base.

Q: What is the significance of the degree of hydrolysis in buffer solutions?

A: The degree of hydrolysis is an important factor in determining the pH of a buffer solution. A high degree of hydrolysis can lead to a decrease in the pH of the solution, while a low degree of hydrolysis can lead to an increase in the pH.

Q: Can you give an example of a buffer solution?

A: Yes, a common example of a buffer solution is a mixture of acetic acid (CH3COOH) and sodium acetate (CH3COONa). This buffer solution is used in many applications, including in the food industry and in medical research.

Q: What is the difference between a buffer solution and a salt solution?

A: A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. A salt solution, on the other hand, is a solution of a salt that has undergone hydrolysis. While both types of solutions can affect the pH of a solution, a buffer solution is designed to maintain a stable pH, whereas a salt solution can lead to a change in pH.

Q: Can you explain the concept of pKa?

A: pKa is the acid dissociation constant of a weak acid. It is a measure of the strength of the acid and is used to calculate the pH of a buffer solution. A low pKa value indicates a strong acid, while a high pKa value indicates a weak acid.

Q: What is the significance of the pKa value in buffer solutions?

A: The pKa value is an important factor in determining the pH of a buffer solution. A buffer solution with a pKa value close to the desired pH will be more effective at maintaining that pH.

Q: Can you give an example of a buffer solution with a specific pKa value?

A: Yes, a common example of a buffer solution with a specific pKa value is a mixture of acetic acid (CH3COOH) and sodium acetate (CH3COONa), which has a pKa value of 4.76.

Q: What is the difference between a strong acid and a weak acid?

A: A strong acid is an acid that completely dissociates in water, producing a high concentration of hydrogen ions. A weak acid, on the other hand, only partially dissociates in water, producing a lower concentration of hydrogen ions.

Q: Can you explain the concept of a conjugate base?

A: A conjugate base is the base that is formed when a weak acid donates a proton (H+ ion). It is the base that is responsible for the buffering action of a buffer solution.

Q: What is the significance of the conjugate base in buffer solutions?

A: The conjugate base is an important factor in determining the pH of a buffer solution. A buffer solution with a high concentration of conjugate base will be more effective at maintaining a stable pH.

Q: Can you give an example of a conjugate base?

A: Yes, a common example of a conjugate base is the acetate ion (CH3COO-), which is the conjugate base of acetic acid (CH3COOH).

Q: What is the difference between a weak base and a strong base?

A: A weak base is a base that only partially dissociates in water, producing a lower concentration of hydroxide ions. A strong base, on the other hand, completely dissociates in water, producing a high concentration of hydroxide ions.

Q: Can you explain the concept of a conjugate acid?

A: A conjugate acid is the acid that is formed when a weak base accepts a proton (H+ ion). It is the acid that is responsible for the buffering action of a buffer solution.

Q: What is the significance of the conjugate acid in buffer solutions?

A: The conjugate acid is an important factor in determining the pH of a buffer solution. A buffer solution with a high concentration of conjugate acid will be more effective at maintaining a stable pH.

Q: Can you give an example of a conjugate acid?

A: Yes, a common example of a conjugate acid is the ammonium ion (NH4+), which is the conjugate acid of ammonia (NH3).

Q: What is the difference between a buffer solution and a pH indicator?

A: A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. A pH indicator, on the other hand, is a substance that changes color in response to changes in pH.

Q: Can you explain the concept of pH indicators?

A: pH indicators are substances that change color in response to changes in pH. They are used to determine the pH of a solution.

Q: What is the significance of pH indicators in buffer solutions?

A: pH indicators are used to determine the pH of a buffer solution. They can be used to monitor the pH of a buffer solution over time.

Q: Can you give an example of a pH indicator?

A: Yes, a common example of a pH indicator is phenolphthalein, which changes color from colorless to pink in response to changes in pH.

Q: What is the difference between a buffer solution and a pH buffer?

A: A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. A pH buffer, on the other hand, is a substance that is used to maintain a stable pH in a solution.

Q: Can you explain the concept of pH buffers?

A: pH buffers are substances that are used to maintain a stable pH in a solution. They are used in a variety of applications, including in the food industry and in medical research.

Q: What is the significance of pH buffers in buffer solutions?

A: pH buffers are used to maintain a stable pH in a buffer solution. They can be used to monitor the pH of a buffer solution over time.

Q: Can you give an example of a pH buffer?

A: Yes, a common example of a pH buffer is a mixture of acetic acid (CH3COOH) and sodium acetate (CH3COONa).

Q: What is the difference between a buffer solution and a pH controller?

A: A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. A pH controller, on the other hand, is a device that is used to control the pH of a solution.

Q: Can you explain the concept of pH controllers?

A: pH controllers are devices that are used to control the pH of a solution. They are used in a variety of applications, including in the food industry and in medical research.

Q: What is the significance of pH controllers in buffer solutions?

A: pH controllers are used to control the pH of a buffer solution. They can be used to monitor the pH of a buffer solution over time.

Q: Can you give an example of a pH controller?

A: Yes, a common example of a pH controller is a device that is used to control the pH of a buffer solution in a laboratory setting.

Q: What is the difference between a buffer solution and a pH stabilizer?

A: A buffer solution is a mixture of a weak acid and its conjugate base, or a weak base and its conjugate acid. A pH stabilizer, on the other hand, is a substance that is used to stabilize the pH of a solution.

Q: Can you explain the concept of pH stabilizers?

A: pH stabilizers are substances that are used to stabilize the pH of a solution. They are used in a variety of applications, including in the food industry and in medical research.

Q: What is the significance of pH stabilizers in buffer solutions?

A: pH stabilizers are used to stabilize the pH of a buffer solution. They can be used to monitor the pH of a buffer solution over time.

Q: Can you give an example of a pH stabilizer?

A: Yes, a common example of a pH stabilizer is a mixture of acetic acid (CH3COOH) and sodium acetate (CH3COONa