Editing Conjugate (acid-base theory) (section)

{{Short description|Chemical compound formed when an acid donates a proton to a base}}
{{use dmy dates |date=April 2021}}
{{Acids and bases}}

A '''conjugate acid''', within the [[Brønsted–Lowry acid–base theory]], is a [[chemical compound]] formed when an acid [[protonation|gives a proton]] ({{chem2|[[Hydron (chemistry)|H+]]}}) to a [[base (chemistry)|base]]—in other words, it is a base with a [[hydrogen  ion]] added to it, as it loses a hydrogen ion in the reverse reaction. On the other hand, a '''conjugate base''' is what remains after an acid has donated a proton during a chemical reaction. Hence, a conjugate base is a substance formed by the [[deprotonation|removal of a proton]] from an acid, as it can gain a hydrogen ion in the reverse reaction. <ref>Zumdahl, Stephen S., & Zumdahl, Susan A. ''Chemistry''. Houghton Mifflin, 2007, {{ISBN|0618713700}}</ref> Because [[Polyprotic acid|some acids]] can give multiple protons, the conjugate base of an acid may itself be acidic.

In summary, this can be represented as the following [[chemical reaction]]:
<math chem display="block">\text{acid} + \text{base} \; \ce{<=>} \; \text{conjugate base} + \text{conjugate acid}</math>

{{multiple image|left|
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 | footer = [[Johannes Nicolaus Brønsted]] (left) and [[Martin Lowry]] (right).
 | image1 = Johannes Brønsted.jpg
 | image2 =Thomas Martin Lowry2.jpg
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[[Johannes Nicolaus Brønsted]] and [[Martin Lowry]] introduced the Brønsted–Lowry theory, which said that any compound that can give a proton to another compound is an acid, and the compound that receives the proton is a base. A proton is a subatomic particle in the nucleus with a unit positive electrical charge. It is represented by the symbol {{chem2|H+}} because it has the [[atomic nucleus|nucleus]] of a hydrogen [[atom]],<ref>{{Cite web|url=https://www.britannica.com/science/Bronsted-Lowry-theory|title=Brønsted–Lowry theory {{!}} chemistry|website=Encyclopedia Britannica|language=en|access-date=2020-02-25}}</ref> that is, a [[hydron (chemistry)|hydrogen cation]].

A [[cation]] can be a conjugate acid, and an [[anion]] can be a conjugate base, depending on which [[chemical substance|substance]] is involved and which [[acid–base reaction|acid–base theory]] is used. The simplest anion which can be a conjugate base is the [[solvated electron|free electron in a solution]] whose conjugate acid is the atomic hydrogen.