A
conjugate acid, within the
Brønsted–Lowry acid–base theory, is a
species formed by the
reception of a proton (
H+), by a
base—in other words, the base with a
hydrogen ion added to it. On the other hand, a
conjugate base is merely what is left after an acid has donated a proton in a chemical reaction. Hence, a conjugate base is a species formed by the
removal of a proton from an acid. In summary, this can be represented as the following chemical reaction:
- Acid + Base Conjugate Base + Conjugate Acid
Johannes Nicolaus Brønsted and Martin Lowry introduced the Brønsted–Lowry theory, which proposed that any compound that can transfer a proton to any other compound is an acid, and the compound that accepts the proton is a base. A proton is a nuclear particle with a unit positive electrical charge; it is represented by the symbol H
+ because it constitutes the
nucleus of a hydrogen
atom, that is, a
hydrogen cation.