Henderson-Hasselbalch

The Henderson-Hasselbalch calculator determines the pH of buffer solutions using the equation pH = pKa + log([A⁻]/[HA]). This formula connects the concentration of an acid (HA) and its conjugate base (A⁻) to the pH, based on the acid's dissociation constant (pKa). It's essential in analytical chemistry for predicting ionic equilibrium in buffered solutions.

The equation assumes chemical equilibrium and that hydrogen ion concentration is dominated by the acid and conjugate base. To apply it, you need the pKa of the acid and molar concentrations of HA and A⁻. The logarithm of the [A⁻]/[HA] ratio adjusts the pH relative to the pKa, showing whether the solution is acidic, basic, or neutral.

It's suitable for predicting the pH of buffer solutions in lab experiments, such as chromatography or culture medium preparation. It also helps determine the optimal acid/base ratio for a desired buffer solution. However, avoid using it for strong acids or bases, where dissociation is complete.

Note: the equation ignores ionic activity and high-concentration effects. Results may be inaccurate for very dilute solutions or strong electrolytes. Always validate data with experimental measurements when the application is critical.