HendersonHasselbalch
The Henderson–Hasselbalch equation is a formula used in chemistry and biochemistry to relate the pH of a buffer solution to the pKa of a weak acid and the ratio of its conjugate base to the acid. For a weak acid HA that partially dissociates to H+ and A−, the equation is pH = pKa + log10([A−]/[HA]). It can also be applied in the form pH = pKa + log10([base]/[acid]) when the species are present in the appropriate conjugate forms. For bases, a related expression for pOH exists: pOH = pKb + log10([BH+]/[B]), and pH can be obtained from pH = 14 − pOH at 25 °C.
Purpose and use: the equation provides a practical way to estimate the pH of buffer solutions and
Assumptions and limitations: the Henderson–Hasselbalch equation assumes a relatively simple, single-buffer system with weak acid/base and
History: named after Lawrence Joseph Henderson, who described the relation in 1908, and Karl Hasselbalch, who