Home
Back
Henderson-Hasselbalch Equation:
| From: | To: |
The Henderson-Hasselbalch equation is used to estimate the pH of a buffer solution. It relates the pH, pKa (acid dissociation constant), and the ratio of the concentrations of the conjugate base [A⁻] and weak acid [HA] in the buffer system.
The calculator uses the Henderson-Hasselbalch equation:
Where:
Explanation: The equation shows that the pH of a buffer solution depends on the pKa of the weak acid and the ratio of the concentrations of its conjugate base to the weak acid.
Details: Accurate pH calculation is crucial for preparing buffer solutions in biochemical experiments, pharmaceutical formulations, and various industrial processes where maintaining a stable pH is essential.
Tips: Enter pKa value, concentration of conjugate base [A⁻] in mol/L, and concentration of weak acid [HA] in mol/L. All concentration values must be positive numbers.
Q1: What is the valid range for the Henderson-Hasselbalch equation?
A: The equation is most accurate when the ratio [A⁻]/[HA] is between 0.1 and 10, and when the concentrations of [A⁻] and [HA] are much larger than the concentration of H⁺ or OH⁻ ions.
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 and is not applicable to strong acids or bases.
Q3: What are common buffer systems that follow this equation?
A: Common buffer systems include acetate (acetic acid/acetate), phosphate (H₂PO₄⁻/HPO₄²⁻), and carbonate (H₂CO₃/HCO₃⁻) buffers.
Q4: How does temperature affect the calculation?
A: Temperature affects the pKa value of the acid. The pKa used in calculations should be appropriate for the temperature at which the buffer will be used.
Q5: What are the limitations of the Henderson-Hasselbalch equation?
A: The equation assumes ideal behavior and may not be accurate at very high ionic strengths or when the concentrations of [A⁻] and [HA] are very low.