Editing Conjugate (acid-base theory) (section)

==Identifying conjugate acid–base pairs==
To identify the conjugate acid, look for the pair of compounds that are related. The [[acid–base reaction]] can be viewed in a before and after sense. The before is the reactant side of the equation, the after is the product side of the equation. The conjugate acid in the after side of an equation gains a hydrogen ion, so in the before side of the equation the compound that has one less hydrogen ion of the conjugate acid is the base. The conjugate base in the after side of the equation lost a hydrogen ion, so in the before side of the equation, the compound that has one more hydrogen ion of the conjugate base is the acid.

Consider the following acid–base reaction:

{{block indent | em = 1.5 | text = {{chem|HNO|3}} + {{chem|H|2|O}} → {{chem|H|3|O|+}} + {{chem|NO|3|-}}}}

[[Nitric acid]] ({{chem|HNO|3}}) is an ''acid'' because it donates a proton to the water molecule and its ''conjugate base'' is [[nitrate]] ({{chem|NO|3|-}}). The water molecule acts as a base because it receives the hydrogen cation (proton) and its conjugate acid is the [[hydronium]] ion ({{chem|H|3|O|+}}).

{| class="wikitable" style="text-align:center"
|-
! Equation !! Acid !! Base !! Conjugate base !! Conjugate acid
|-
| {{chem|HClO|2}} + {{chem|H|2|O}} → {{chem|ClO|2|-}} + {{chem|H|3|O|+}} || [[chlorous acid|{{chem|HClO|2}}]] || [[Properties of water|{{chem|H|2|O}}]] || [[chlorite|{{chem|ClO|2|-}}]] || [[hydronium|{{chem|H|3|O|+}}]]
|-
| {{chem|ClO|-}} + {{chem|H|2|O}} → {{chem|HClO}} + {{chem|OH|-}} || {{chem|H|2|O}} || [[hypochlorite|{{chem|ClO|-}}]] || [[hydroxide|{{chem|OH|-}}]] || [[Hypochlorous acid|{{chem|HClO}}]]
|-
| {{chem|HCl}} + {{chem|H|2|PO|4|-}} → {{chem|Cl|-}} + {{chem|H|3|PO|4}} || [[hydrochloric acid|{{chem|HCl}}]] || [[phosphate#Chemical properties|{{chem|H|2|PO|4|-}}]] || [[chloride|{{chem|Cl|-}}]] || [[phosphoric acid|{{chem|H|3|PO|4}}]]
|}