pK

pK

noun \ˈpē-ˈkā\

Definition of PK

: the cologarithm of the dissociation constant K or −log K that serves as a convenient measure of the strength of an acid <K for acetic acid is 0.000018 or l.8 × 10⁻⁵ from which pK is (5 − 0.25) or 4.75>—compare ph