Acids are defined as substances that have a sour taste, a low pH (<7), cause litmus paper to turn red, and react with bases, yielding water and ionic compounds called salts. Strong inorganic (also called mineral) acids can dissolve metals such as zinc and iron, producing hydrogen gas in the process.

Chemically, acids are molecules or ions that act as proton or hydrogen ion donors (Brønsted-Lowry acid) in non-aqueous solutions. In water, acids form hydronium ions (H3O+). Alternatively, acids act as Lewis acids, i.e., molecules or ions that can accept an electron pair.

In the laboratory, acids are used as reagents or catalysts in many types of chemical reactions. Almost all inorganic acids are strong and highly corrosive, the most common of which are hydrochloric, nitric, and sulfuric acids. The last is the most important industrial chemical—50 million tons of sulfuric acid are produced in North America annually. Also used in many industrial applications, organic acids are typically weak compared to inorganic acids. The most industrially important organic acids are the carboxylic acids, such as acetic acid (a component of vinegar and a precursor to solvents and coatings), acrylic, and methacrylic acids (precursors to polymers and adhesives).

Organic and inorganic acid products

Top acid categories

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