Understanding Aminoethanol

Oct 13, 2025 by wbrum.org 131 views

Introduction

Aminoethanol, also known as ethanolamine, is a weak base that can accept a proton (H+ ion) to form its conjugate acid. In this article, we will discuss how to calculate the hydroxide ion (OH-) concentration in a solution of aminoethanol. We will use the given concentration of aminoethanol, which is 4.25 × 10^−4 M, and apply the principles of acid-base chemistry to determine the hydroxide ion concentration.

Understanding Aminoethanol

Aminoethanol is a weak base that can accept a proton (H+ ion) to form its conjugate acid. The chemical equation for this reaction is:

CH3CH2NH2 + H2O ⇌ CH3CH2NH3+ + OH-

In this equation, aminoethanol (CH3CH2NH2) reacts with water (H2O) to form its conjugate acid (CH3CH2NH3+) and hydroxide ion (OH-).

Calculating Hydroxide Ion Concentration

To calculate the hydroxide ion concentration, we can use the following equation:

Kb = [CH3CH2NH3+][OH-] / [CH3CH2NH2]

where Kb is the base dissociation constant, [CH3CH2NH3+] is the concentration of the conjugate acid, [OH-] is the concentration of the hydroxide ion, and [CH3CH2NH2] is the concentration of aminoethanol.

We are given the concentration of aminoethanol, which is 4.25 × 10^−4 M. We can assume that the concentration of the conjugate acid is equal to the concentration of aminoethanol, since the reaction is in equilibrium.

Solving for Hydroxide Ion Concentration

We can now substitute the values into the equation and solve for the hydroxide ion concentration:

Kb = [CH3CH2NH3+][OH-] / [CH3CH2NH2] = (4.25 × 10^−4)([OH-]) / (4.25 × 10^−4)

Since the concentration of the conjugate acid is equal to the concentration of aminoethanol, we can simplify the equation:

Kb = [OH-]^2 / (4.25 × 10^−4)

We can now solve for the hydroxide ion concentration by rearranging the equation:

[OH-]^2 = Kb × (4.25 × 10^−4) [OH-] = √(Kb × (4.25 × 10^−4))

Finding the Base Dissociation Constant (Kb)

To find the base dissociation constant (Kb), we need to look up the value in a reference table or use a calculator. The Kb value for aminoethanol is approximately 1.6 × 10^−5.

Substituting the Kb Value

We can now substitute the Kb value into the equation:

[OH-]^2 = (1.6 × 10^−5) × (4.25 × 10^−4) [OH-] = √((1.6 × 10^−5) × (4.25 × 10^−4))

Calculating the Hydroxide Ion Concentration

We can now calculate the hydroxide ion concentration by evaluating the expression:

[OH-] = √((1.6 × 10^−5) × (4.25 × 10^−4)) = √(6.8 × 10^−9) = 2.62 × 10^−4.5 M

Conclusion

In this article, we calculated the hydroxide ion concentration in a 4.25 × 10^−4 M solution of aminoethanol. We used the principles of acid-base chemistry and the base dissociation constant (Kb) to determine the hydroxide ion concentration. The calculated hydroxide ion concentration is 2.62 × 10^−4.5 M.

References

"Aminoethanol" by Wikipedia
"Base Dissociation Constant (Kb)" by Chemistry LibreTexts

Note

Frequently Asked Questions

In this article, we will answer some of the most common questions related to calculating hydroxide ion concentration in aminoethanol solutions.

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

A: The base dissociation constant (Kb) for aminoethanol is approximately 1.6 × 10^−5.

Q: How do I calculate the hydroxide ion concentration in a solution of aminoethanol?

A: To calculate the hydroxide ion concentration, you can use the following equation:

Kb = [CH3CH2NH3+][OH-] / [CH3CH2NH2]

Q: What is the concentration of the conjugate acid in a solution of aminoethanol?

A: The concentration of the conjugate acid is equal to the concentration of aminoethanol, since the reaction is in equilibrium.

Q: How do I find the base dissociation constant (Kb) for aminoethanol?

A: You can find the base dissociation constant (Kb) for aminoethanol in a reference table or use a calculator.

Q: What is the hydroxide ion concentration in a 4.25 × 10^−4 M solution of aminoethanol?

A: The hydroxide ion concentration in a 4.25 × 10^−4 M solution of aminoethanol is approximately 2.62 × 10^−4.5 M.

Q: Why is the hydroxide ion concentration so small in a solution of aminoethanol?

A: The hydroxide ion concentration is typically very small in aqueous solutions, and it is often difficult to measure accurately. This is because aminoethanol is a weak base, and it does not dissociate much in water.

Q: Can I use this method to calculate the hydroxide ion concentration in other solutions?

A: Yes, you can use this method to calculate the hydroxide ion concentration in other solutions, as long as you know the base dissociation constant (Kb) and the concentration of the base.

Q: What are some common applications of calculating hydroxide ion concentration?

A: Calculating hydroxide ion concentration is important in various fields, such as chemistry, biology, and environmental science. It is used to understand the behavior of weak bases in aqueous solutions and to predict their effects on the environment.

Conclusion

In this article, we have answered some of the most common questions related to calculating hydroxide ion concentration in aminoethanol solutions. We hope that this information will be helpful to you in your studies and research.

References

"Aminoethanol" by Wikipedia
"Base Dissociation Constant (Kb)" by Chemistry LibreTexts
"Hydroxide Ion Concentration" by Chemistry LibreTexts