Organic and Inorganic Acids
Acids, like all chemical compounds, are classified as either organic or inorganic. Organic acids occur in, or can be produced from, animal and vegetable matter. In addition to hydrogen, organic acids always contain carbon and at least one other element.
Nucleic acids and amino acids are organic. Other common organic acids are acetic acid, found in vinegar and cider; citric acid, found in citrus fruits, gooseberries, and currants; tannic acid (tannin), found in oak galls; formic acid, which occurs in insects and plants; lactic acid, a constituent of sour milk; oleic acid, found in animal fats and vegetable oils; and oxalic acid, found in rhubarb, spinach, and other edible plants.
Organic acids are used as food additives, in medicines, in dyeing and bleaching, in the tanning of leather, and in the manufacture of various chemicals.
Inorganic acids, which contain no carbon, are sometimes called mineral acids. In order of tonnage produced in the United States, the most important inorganic acids are sulfuric, phosphoric, and nitric. Inorganic acids are used in the manufacture of fertilizers, plastics, explosives, synthetic textiles, paints, dyes, solvents, and many other substances.