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 buffer pH and is widely used in chemistry and biochemistry.

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 concentrations of the conjugate base to the weak acid in a buffer solution.

3. Importance of pH Calculation

Details: Accurate pH calculation is crucial for preparing buffer solutions in laboratory experiments, pharmaceutical formulations, and biological studies where maintaining specific pH conditions is essential.

4. Using the Calculator

Tips: Enter pKa value, base concentration in M, and acid concentration in M. All values must be valid (concentrations > 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 (where the ratio [A-]/[HA] is between 0.1 and 10).

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 common buffer systems that use this equation?
A: Common examples include acetate buffer (acetic acid/acetate), phosphate buffer, and Tris buffer.

Q4: How does temperature affect the calculation?
A: Temperature can affect the pKa value of the acid. The equation assumes constant temperature and uses the pKa value at that specific temperature.

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