Henderson-Hasselbalch Calculator

Select what you want to calculate (pH, pKa, [A⁻], or [HA]), enter the known values, and the calculator will determine the unknown variable. You can also use the common acids dropdown to auto-fill pKa values for standard acids.

The Henderson-Hasselbalch equation is used to calculate the pH of buffer solutions, which resist changes in pH when acids or bases are added. It's widely used in biochemistry, analytical chemistry, and blood gas analysis.

The conjugate base [A⁻] is the deprotonated form of the acid. Its concentration can be calculated using the Henderson-Hasselbalch equation when you know the pH, pKa, and acid concentration [HA].

pKa is the negative logarithm of the acid dissociation constant (Ka). It represents the pH at which exactly half of the acid molecules are dissociated. Lower pKa values indicate stronger acids.

Yes, you can calculate pH using the Henderson-Hasselbalch equation: pH = pKa + log([A⁻]/[HA]). You'll need to know the pKa value of your specific acid to get the exact pH result.

A buffer solution contains a weak acid and its conjugate base (or weak base and its conjugate acid) that resists pH changes. Buffer pH calculation is crucial in biological systems, pharmaceutical formulations, and analytical procedures.

The pKa values provided are standard literature values at 25°C. However, pKa can vary with temperature, ionic strength, and solvent conditions, so adjust accordingly for precise applications.

The equation assumes ideal conditions and works best when the buffer ratio [A⁻]/[HA] is between 0.1 and 10. It may be less accurate at very high or low pH values or high ionic strengths.