Henderson-Hasselbalch equation

== English == === Etymology === Named after Lawrence Joseph Henderson, who devised a related equation in 1908, and Karl Albert Hasselbalch, who re-expressed it in logarithmic terms. === Noun === Henderson-Hasselbalch equation (plural Henderson-Hasselbalch equations) (chemistry) An equation describing the derivation of pH as a measure of acidity (using pKa, the negative log of the acid dissociation constant) in biological and chemical systems.