1. What is the Henderson-Hasselbalch Equation?

The Henderson-Hasselbalch equation is used to estimate the pH of buffer solutions. It relates the pH, pKa (acid dissociation constant), and the ratio of the concentrations of the conjugate base and weak acid in the buffer system.

2. How Does the Calculator Work?

The calculator uses the Henderson-Hasselbalch equation:

Where:

• \( pH \) — pH value (dimensionless)
• \( pKa \) — Acid dissociation constant (dimensionless)
• \( [base] \) — Concentration of conjugate base (mol/L)
• \( [acid] \) — Concentration of weak acid (mol/L)

Explanation: The equation shows that the pH of a buffer solution depends on the pKa of the weak acid and the ratio of base to acid concentrations.

3. Importance of pH Calculation in Buffer Solutions

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 and acid concentration in mol/L. All concentration values must be positive numbers greater than zero.

5. Frequently Asked Questions (FAQ)

Q1: What is the valid range for the Henderson-Hasselbalch equation?
A: The equation works best when the ratio [base]/[acid] is between 0.1 and 10, and when the concentrations are within one order of magnitude of each other.

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

Q3: What are typical pKa values for common buffer systems?
A: Common buffers include acetate (pKa=4.76), phosphate (pKa=7.2), and Tris (pKa=8.06). The choice depends on the desired pH range.

Q4: How does temperature affect the calculation?
A: pKa values are temperature-dependent. For precise work, use pKa values measured at the temperature of interest.

Q5: What are the limitations of this equation?
A: The equation assumes ideal behavior and may not be accurate at very high concentrations or when ionic strength effects are significant.