https://doi.org/10.1351/goldbook.A00080
The @E02177@ \(K_{\text{a}n}\) for splitting off the nth @P04906@ from a charged or uncharged acid, to be defined. One may write \(K_{\text{a}}\) for \(K_{\text{a}1}\).
Source:
Orange Book, 2nd ed., p. 13 [Terms] [Book]