Nomenclature of Acids

The nomenclature of acids was described in Table 6.6 and in Sections 6.2B3 and 6.2C1. That material is summarized here in Table 12.3.

An acid containing only hydrogen and a nonmetal is named hydro-ic acid; for example, HCl is hydrochloric acid, and H₂S is hydrosulfuric acid.

Among the acids containing different numbers of oxygen atoms with the same nonmetal, the names of the most common include the root of the element and the ending ic. Thus, H₂SO₄ is sulfuric acid; HNO₃ is nitric acid. These names and formulas must be memorized.

The acid containing one fewer oxygen than the most common is named with the root of the element and the ending ous. Thus, H₂SO₃ is sulfurous acid; HNO₂ is nitrous acid.

Occasionally one encounters an acid containing two fewer oxygen atoms than the most common. These are named hypo-ous acids. Thus, HClO is hypochlorous acid.

Acids containing carbon are named by a wholly different system. The system need not be learned, but the formulas and names of a few of these acids should be memorized: HC₂H₃O₂ is acetic acid, H₂CO₃ is carbonic acid, and HCOOH is formic acid.

**TABLE 12.3** Some common acids
Acid	Molecular formula	Anion formed in solution	Anion name
hydrochloric acid	HCl	Cl^-	chloride
sulfuric acid	H₂SO₄	HSO₄^-	hydrogen sulfate (bisulfate)
	HSO₄^-	SO₄^2-	sulfate
sulfurous acid	H₂SO₃	HSO₃^-	hydrogen sulfite (bisulfite)
	HSO₃^-	SO₃^2-	sulfite
nitric acid	HNO₃	NO₃^-	nitrate
nitrous acid	HNO₂	NO₂^-	nitrite
carbonic acid	H₂CO₃	HCO₃^-	hydrogen carbonate (bicarbonate)
	HCO₃^-	CO₃^2-	carbonate
phosphoric acid	H₃PO₄	H₂PO₄^-	dihydrogen phosphate
	H₂PO₄^-	HPO₄^2-	hydrogen phosphate
	HPO₄^2-	PO₄^3-	phosphate
Organic acids
acetic	HC₂H₃O₂	C₂H₃O₂^-	acetate
formic	HCOOH	HCOO^-	formate

Example:

Give the formula and name of the acids that have the following anions. Name the anions.

NO₂^-, F^-, HCOO^-

Solution

NO₂^- is the anion of HNO₂. This formula contains one less oxygen than nitric acid. HNO₂ is named nitrous acid and the anion is nitrite. F^- is the anion of HF, an acid containing no oxygen atoms. The acid is named hydrofluoric acid and the annion is fluoride. HCOO- is the anion of HCOOH, formic acid, and the anion is formate.

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