Editing Acid dissociation constant (section)

== Strong acids and bases ==
An acid is classified as "strong" when the concentration of its undissociated species is too low to be measured.<ref name="Bell" /> Any aqueous acid with a p''K''<sub>a</sub> value of less than 0 is almost completely deprotonated and is considered a ''strong acid''.<ref name=SA5.1c>{{cite book |last = Shriver |first = D.F |author2 = Atkins, P.W. |title = Inorganic Chemistry |edition = 3rd |year = 1999 |publisher = Oxford University Press |isbn = 0-19-850331-8}} Sec. 5.1c Strong and weak acids and bases</ref> All such acids transfer their protons to water and form the solvent cation species (H<sub>3</sub>O<sup>+</sup> in aqueous solution) so that they all have essentially the same acidity, a phenomenon known as [[Leveling effect|solvent leveling]].<ref>{{cite book| title = Inorganic Chemistry| last = Porterfield| first = William W.| year = 1984| publisher = Addison-Wesley| page=260| isbn = 0-201-05660-7}}</ref><ref name=SA5.2>{{cite book |last = Shriver |first = D.F |author2 = Atkins, P.W. |title = Inorganic Chemistry |edition = 3rd |year = 1999 |publisher = Oxford University Press |isbn = 0-19-850331-8}} Sec. 5.2 Solvent leveling</ref> They are said to be ''fully dissociated'' in aqueous solution because the amount of undissociated acid, in equilibrium with the dissociation products, is below the [[detection limit]].<!-- {{efn|1= In dilute solution [[nitric acid]] (p''K''<sub>a</sub> = −1.4<ref>{{Citation |last=Bell |first=R. P. |title=The Proton in Chemistry |edition=2nd |publisher=Cornell University Press |location=Ithaca, NY |year=1973 }}</ref>) behaves as a strong acid. When the ratio of water molecules to acid molecules in a solution of an acid is too small to fully solvate the dissociation products, dissociation is not complete, for example, with extremely concentrated solutions of [[sulfuric acid]] and [[hydrochloric acid]].}}.
 --> Likewise, any aqueous base with an [[Acid dissociation constant#Bases and basicity|association constant]] p''K''<sub>b</sub> less than about 0, corresponding to p''K''<sub>a</sub> greater than about 14, is leveled to OH<sup>−</sup> and is considered a ''strong base''.<ref name=SA5.2/>

[[Nitric acid]], with a p''K'' value of around −1.7, behaves as a strong acid in aqueous solutions with a pH greater than 1.<ref>{{cite journal |title=Dissociation constant of nitric acid|journal=Russian Journal of Physical Chemistry A|volume=91|issue=7|pages=1221–1228|doi=10.1134/S0036024417070196|year=2017|last1=Levanov|first1=A. V.|last2=Isaikina|first2=O. Ya.|last3=Lunin|first3=V. V.|bibcode=2017RJPCA..91.1221L|s2cid=104093297}}</ref> At lower pH values it behaves as a weak acid.

p''K''<sub>a</sub> values for strong acids have been estimated by theoretical means.<ref>{{cite journal |title=Acidity of Strong Acids in Water and Dimethyl Sulfoxide|journal=The Journal of Physical Chemistry A|volume=120|issue=20|pages=3663–3669|doi=10.1021/acs.jpca.6b02253|pmid=27115918|year=2016|last1=Trummal|first1=Aleksander|last2=Lipping|first2=Lauri|last3=Kaljurand|first3=Ivari|last4=Koppel|first4=Ilmar A.|last5=Leito|first5=Ivo|bibcode=2016JPCA..120.3663T|s2cid=29697201 }}</ref> For example, the p''K''<sub>a</sub> value of aqueous [[hydrochloric acid|HCl]] has been estimated as −9.3.