Conjugate Acid Definition
Conjugate acids and bases are Bronsted-Lowry acid and base pairs, determined by which species gains or loses a proton. When a base dissolves in water, the species that gains a hydrogen (proton) is the base's conjugate acid.
Acid + Base → Conjugate Base + Conjugate Acid
In other words, a conjugate acid is the acid member, HX, of a pair of compounds that differ from each other by gain or loss of a proton. A conjugate acid can release or donate a proton. A conjugate base is the name given to the species that remains after the acid has donated its proton. The conjugate base can accept a proton.
Conjugate Acid Example
When the base ammonia reacts with water, the ammonium cation is the conjugate acid that forms:
NH3(g) + H2O(l) → NH+4(aq) + OH−(aq)
Source
- Zumdahl, Stephen S., Zumdahl, Susan A. (2007). Chemistry. Houghton Mifflin. ISBN 0618713700.