Hasselbalch

Definition

Hasselbalch refers to the Henderson-Hasselbalch equation, which relates the pH of a solution to the pKa and the ratio of the concentrations of its conjugate acid-base pair. It is used to estimate the pH in buffer solutions.

5 Must Know Facts For Your Next Test

1. The Henderson-Hasselbalch equation is written as $\text{pH} = \text{pKa} + \log \left( \frac{[A^-]}{[HA]} \right)$.
2. It helps in calculating the pH of buffer solutions by providing a relationship between pH, pKa, and the concentrations of acid and conjugate base.
3. The equation assumes that the activity coefficients are equal, which is a good approximation for dilute solutions.
4. It can be used to determine the required ratio of conjugate base to acid for a desired pH.
5. This equation is crucial in designing buffers with specific pH values necessary for various chemical and biological processes.

Review Questions

• How does the Henderson-Hasselbalch equation relate pH, pKa, and concentrations of acid and base?
• What assumptions are made when using the Henderson-Hasselbalch equation?
• Why is the Henderson-Hasselbalch equation important in preparing buffer solutions?

Related terms

Buffer Solution: A solution that resists changes in its pH upon addition of small amounts of an acid or base.

Conjugate Acid-Base Pair: Consists of two species that transform into each other by gain or loss of a proton (H+).

pKa: The negative logarithm of the acid dissociation constant (Ka) and indicates the strength of an acid.