## Aqueous acids and bases [ENDORSED]

Mike Vinci 2B
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### Aqueous acids and bases

Are acids and bases always aqueous in order to ionize the presence of water, or can acids and bases exist in any state and still ionize into their component ions?

Chem_Mod
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### Re: Aqueous acids and bases  [ENDORSED]

This is a fascinating question! In the Arrhenius definition of acid/base theory, the reaction must occur in water because an acid is defined as increasing H+ concentration in water and the base is defined as increasing OH- concentration in water. The Bronsted-Lowry and Lewis definitions of acid/base theory are much more general and can occur potentially in any solvent environment. Take for example, pure liquid (anhydrous) ammonia (NH3) which has its own autoionization process. 2NH3 $\rightleftharpoons$ NH4+ + NH2-. It is clear that ammonia can behave in both a Bronsted-Lowry fashion (proton exchange) and Lewis fashion (electron pair exchange).

Other common solvents used to study acid/base chemistry are dimethylsulfoxide (DMSO) and acetonitrile. These can be environments totally free of water molecules!