title: The use of approximation formulae in calculations of acid-base equilibria.
abstract: Details of diagrams recently presented for the regions where approximation formulae give the pH of mono- and diprotic acids with an error of less than 0.02 pH unit are discussed.
authors.affiliation: C.I.Q.(U.P.), Chemistry Department, Faculdade de Ciências, 4000 Porto, Portugal.
authors.forename: A A
authors.initials: AA
authors.lastname: Machado