1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation is used to estimate the pH of a buffer solution from the pKa of the acid and the concentrations of the acid and its conjugate base. It provides a simple way to calculate and prepare buffer solutions with desired pH values.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pKa \) — Acid dissociation constant
• \( [A^-] \) — Concentration of conjugate base (M)
• \( [HA] \) — Concentration of weak acid (M)

Explanation: The equation relates pH, pKa, and the ratio of base to acid concentrations in a buffer system.

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for preparing buffer solutions in biochemical experiments, pharmaceutical formulations, and various industrial processes where maintaining stable pH is essential.

4. Using the Calculator

Tips: Enter pKa value, base concentration in M, and acid concentration in M. All values must be valid (pKa ≥ 0, concentrations ≥ 0, acid concentration > 0).

5. Frequently Asked Questions (FAQ)

Q1: What is the valid range for the Henderson-Hasselbalch equation?
A: The equation is most accurate when the pH is within ±1 unit of the pKa value (pH = pKa ± 1).

Q2: Can this equation be used for strong acids or bases?
A: No, the Henderson-Hasselbalch equation is specifically designed for weak acid-base buffer systems.

Q3: What are typical pKa values for common buffers?
A: Acetic acid: 4.76, Phosphoric acid: 2.14, 7.20, 12.67, Tris: 8.06, depending on the buffer system.

Q4: Why is the acid concentration required to be greater than zero?
A: Division by zero is mathematically undefined, and practical buffer solutions require both acid and base components.

Q5: How does temperature affect the calculation?
A: pKa values are temperature-dependent, so for precise work, use pKa values measured at the temperature of interest.