Understanding the Relationship Between Hydrogen and Hydroxide Ions

Oct 13, 2025 by magicalceylontours.com 146 views

Understanding the Relationship Between Hydrogen and Hydroxide Ions

In aqueous solutions, the concentration of hydrogen ions (H+) and hydroxide ions (OH-) are inversely related. This relationship is described by the ion product constant for water (Kw), which is a measure of the product of the concentrations of hydrogen and hydroxide ions in a solution at a given temperature. At 25°C, the value of Kw is $1.0 \times 10^{-14}$ .

Calculating the Concentration of Hydroxide Ions

To calculate the concentration of hydroxide ions in an aqueous solution of acetic acid, we can use the Kw expression:

\text{K}_\text{w} = \left[ \text{H}_3\text{O}^{+} \right] \left[ \text{OH}^{-} \right]

Rearranging the expression to solve for the concentration of hydroxide ions, we get:

\left[ \text{OH}^{-} \right] = \frac{\text{K}_\text{w}}{\left[ \text{H}_3\text{O}^{+} \right]}

Substituting the Given Value of Hydrogen Ion Concentration

We are given that the concentration of hydrogen ions in the aqueous solution of acetic acid is $\left[ \text{H}_3\text{O}^{+} \right] = 2.50 \times 10^{-4} \, \text{M}$ . Substituting this value into the expression for the concentration of hydroxide ions, we get:

\left[ \text{OH}^{-} \right] = \frac{1.0 \times 10^{-14}}{2.50 \times 10^{-4}}

Evaluating the Expression

Evaluating the expression, we get:

\left[ \text{OH}^{-} \right] = 4.0 \times 10^{-11} \, \text{M}

Conclusion

Therefore, the concentration of hydroxide ions in the aqueous solution of acetic acid for which $\left[ \text{H}_3\text{O}^{+} \right] = 2.50 \times 10^{-4} \, \text{M}$ is $\left[ \text{OH}^{-} \right] = 4.0 \times 10^{-11} \, \text{M}$ .

Understanding the Significance of the Result

The result indicates that the concentration of hydroxide ions in the aqueous solution of acetic acid is very low, which is consistent with the acidic nature of the solution. The low concentration of hydroxide ions also suggests that the solution is not strongly basic.

Relationship Between Acetic Acid and Hydroxide Ions

Acetic acid (CH3COOH) is a weak acid that partially dissociates in water to produce hydrogen ions and acetate ions. The dissociation reaction is:

\text{CH}_3\text{COOH} \rightleftharpoons \text{H}_3\text{O}^{+} + \text{CH}_3\text{COO}^{-}

The concentration of hydroxide ions in the solution is influenced by the concentration of hydrogen ions, which in turn is influenced by the concentration of acetic acid.

Factors Affecting the Concentration of Hydroxide Ions

The concentration of hydroxide ions in the aqueous solution of acetic acid is affected by several factors, including:

The concentration of acetic acid
The temperature of the solution
The presence of other ions or substances that may affect the dissociation of acetic acid

Conclusion

In conclusion, the concentration of hydroxide ions in an aqueous solution of acetic acid for which $\left[ \text{H}_3\text{O}^{+} \right] = 2.50 \times 10^{-4} \, \text{M}$ is $\left[ \text{OH}^{-} \right] = 4.0 \times 10^{-11} \, \text{M}$ . The result indicates that the solution is acidic and that the concentration of hydroxide ions is very low.

References

Atkins, P. W., & De Paula, J. (2010). Physical chemistry. Oxford University Press.
Brown, T. E., LeMay, H. E., Bursten, B. E., & Murphy, C. (2012). Chemistry: The Central Science. Pearson Education.
Petrucci, R. H., Harwood, W. S., & Herring, F. G. (2011). General chemistry: Principles and modern applications. Pearson Education.

Frequently Asked Questions

Q: What is the relationship between hydrogen and hydroxide ions in aqueous solutions?

A: In aqueous solutions, the concentration of hydrogen ions (H+) and hydroxide ions (OH-) are inversely related. This relationship is described by the ion product constant for water (Kw), which is a measure of the product of the concentrations of hydrogen and hydroxide ions in a solution at a given temperature.

Q: How is the concentration of hydroxide ions calculated in an aqueous solution of acetic acid?

A: The concentration of hydroxide ions can be calculated using the Kw expression:

\text{K}_\text{w} = \left[ \text{H}_3\text{O}^{+} \right] \left[ \text{OH}^{-} \right]

Rearranging the expression to solve for the concentration of hydroxide ions, we get:

\left[ \text{OH}^{-} \right] = \frac{\text{K}_\text{w}}{\left[ \text{H}_3\text{O}^{+} \right]}

Q: What is the value of Kw at 25°C?

A: At 25°C, the value of Kw is $1.0 \times 10^{-14}$ .

Q: How is the concentration of hydroxide ions affected by the concentration of hydrogen ions?

A: The concentration of hydroxide ions is inversely proportional to the concentration of hydrogen ions. As the concentration of hydrogen ions increases, the concentration of hydroxide ions decreases.

Q: What is the significance of the result indicating a low concentration of hydroxide ions in an aqueous solution of acetic acid?

A: The result indicates that the solution is acidic and that the concentration of hydroxide ions is very low. This is consistent with the acidic nature of the solution.

Q: What factors affect the concentration of hydroxide ions in an aqueous solution of acetic acid?

A: The concentration of hydroxide ions in an aqueous solution of acetic acid is affected by several factors, including:

The concentration of acetic acid
The temperature of the solution
The presence of other ions or substances that may affect the dissociation of acetic acid

Q: What is the relationship between acetic acid and hydroxide ions?

A: Acetic acid (CH3COOH) is a weak acid that partially dissociates in water to produce hydrogen ions and acetate ions. The dissociation reaction is:

\text{CH}_3\text{COOH} \rightleftharpoons \text{H}_3\text{O}^{+} + \text{CH}_3\text{COO}^{-}

The concentration of hydroxide ions in the solution is influenced by the concentration of hydrogen ions, which in turn is influenced by the concentration of acetic acid.

Q: What is the concentration of hydroxide ions in an aqueous solution of acetic acid for which $\left[ \text{H}_3\text{O}^{+} \right] = 2.50 \times 10^{-4} \, \text{M}$ ?

A: The concentration of hydroxide ions in the aqueous solution of acetic acid for which $\left[ \text{H}_3\text{O}^{+} \right] = 2.50 \times 10^{-4} \, \text{M}$ is $\left[ \text{OH}^{-} \right] = 4.0 \times 10^{-11} \, \text{M}$ .

Conclusion

In conclusion, the concentration of hydroxide ions in an aqueous solution of acetic acid is affected by several factors, including the concentration of acetic acid, the temperature of the solution, and the presence of other ions or substances that may affect the dissociation of acetic acid. The result indicating a low concentration of hydroxide ions in an aqueous solution of acetic acid is consistent with the acidic nature of the solution.

References

Atkins, P. W., & De Paula, J. (2010). Physical chemistry. Oxford University Press.
Brown, T. E., LeMay, H. E., Bursten, B. E., & Murphy, C. (2012). Chemistry: The Central Science. Pearson Education.
Petrucci, R. H., Harwood, W. S., & Herring, F. G. (2011). General chemistry: Principles and modern applications. Pearson Education.