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Nomenclature of Acids and Bases

Before continuing on to more problems, it is useful to consider some general rules for the nomenclature of species common to acid-base systems.

The names of species with a positive charge (cations) almost always end with an “ium” ending.

NH3 was ammonia.  Its protonated ion (\(\ce{NH4+}\)) is called the ammonium ion.

Earlier the species methyl amine (CH3NH2) was mentioned.  The protonated form of this (\(\ce{CH3NH3+}\)) would be the methyl ammonium ion. 

When you name the protonated form of a base, the scheme is to remove the last vowel (which is usually an“e”) and replace it with “ium”. 

The protonated form of aniline, a base, would be anilinium.

The elements sodium and calcium are found in nature as the Na+ and Ca2+ ion respectively.

We can therefore state that the protonated form of “wenzel” would be “wenzelium”.

The names of most species with a negative charge (anions) end with an “ate” ending.

H2SO4 is sulfuric acid, whereas \(\ce{SO4^2-}\) is the sulfate ion.

Butyric acid (CH3CH2CH2COOH) has the smell of dirty socks.  CH3CH2CH2COOis the butyrate ion.

The general rule is to drop the “ic” ending of the name of the acid and replace it with “ate”.

When in doubt, if you need the name of the anion, add an “ate” ending.  The anion of “wenzel” is therefore “wenzelate”.

There are other endings in the nomenclature for anions besides the “ate” ending.  For example, we are quite familiar with the “ide” ending that occurs with the halides (e.g., fluoride, chloride, bromide, and iodide).  There are other anions that are named using an “ite” ending (e.g., nitrite, sulfite).