The
Brønsted acidBH+
formed on protonation of a base
B
is called the conjugate acid of
B, and
B is the conjugate base of
BH+. (The conjugate acid always carries one unit of positive charge more than the base,
but the absolute charges of the species are immaterial to the definition.) For example:
the
Brønsted acidHCl
and its conjugate base
Cl−
constitute a conjugate acid–base pair.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1099