Henderson-Hasselbach equation

The Henderson-Hasselbalch equation is a fundamental concept in biochemistry used to describe acid-base equilibria in biological systems. Developed by Lawrence Joseph Henderson and later modified by Karl Hasselbalch, it explains how physiological buffers maintain a stable pH in body fluids, even when acids or bases are added.

The equation is typically written as:
[ \text{pH} = \text{p}K_a + \log_{10}\left(\frac{[\text{A}^-]}{[\text{HA}]}\right) ]
where:
* pH is the measure of acidity or alkalinity.
* pKa is the negative logarithm of the acid dissociation constant, indicating the acid's strength.
* [A⁻] is the concentration of the conjugate base.
* [HA] is the concentration of the weak acid.

This equation is crucial for understanding how systems like the carbonic acid-bicarbonate buffer in blood maintain a neutral pH, essential for life.1