Conjugate Acid Definition in Chemistry

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.