sulfuric acid

Chem.

a clear, colorless to brownish, dense, oily, corrosive, water-miscible liquid, H₂SO₄, usually produced from sulfur dioxide: used chiefly in the manufacture of fertilizers, chemicals, explosives, and dyestuffs and in petroleum refining. Also called oil of vitriol.

[1780-90]

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or oil of vitriol

Dense, colourless, oily, corrosive liquid inorganic compound (H₂SO₄).

A very strong acid, it forms ions of hydrogen or hydronium (H⁺ or H₃O⁺), hydrogen sulfate (HSO₄^-), and sulfate (SO₄^2-). It is also an oxidizing (see oxidation-reduction) and dehydrating agent and chars many organic materials. It is one of the most important industrial chemicals, used in various concentrations in manufacturing fertilizers, pigments, dyes, drugs, explosives, detergents, and inorganic salts and acids, in petroleum refining and metallurgical processes, and as the acid in lead-acid storage batteries. It is made industrially by dissolving sulfur trioxide (SO₃) in water, sometimes beyond the saturation point to make oleum (fuming sulfuric acid), used to make certain organic chemicals.

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▪ chemical compound

sulfuric also spelled  Sulphuric (H₂SO₄),  also called  Oil Of Vitriol, or Hydrogen Sulfate,  

      dense, colourless, oily, corrosive liquid; one of the most important of all chemicals, prepared industrially by the reaction of water with sulfur trioxide (see sulfur oxide), which in turn is made by chemical combination of sulfur dioxide and oxygen either by the contact process (q.v.) or the chamber process (q.v.). In various concentrations the acid is used in the manufacture of fertilizers, pigments, dyes, drugs, explosives, detergents, and inorganic salts and acids, as well as in petroleum refining and metallurgical processes. In one of its most familiar applications, sulfuric acid serves as the electrolyte in lead–acid storage batteries.

      Pure sulfuric acid has a specific gravity of 1.830 at 25° C (77° F); it freezes at 10.37° C (50.7° F). When heated, the pure acid partially decomposes into water and sulfur trioxide; the latter escapes as a vapour until the concentration of the acid falls to 98.3 percent. This mixture of sulfuric acid and water boils at a constant temperature of 338° C (640° F) at one atmosphere pressure. Sulfuric acid is commonly supplied at concentrations of 78, 93, or 98 percent.

      Sulfuric acid is a very strong acid; in aqueous solutions it ionizes completely to form hydronium ions (H₃O⁺) and hydrogen sulfate ions (HSO₄⁻). In dilute solutions the hydrogen sulfate ions also dissociate, forming more hydronium ions and sulfate ions (SO₄²⁻). In addition to being an oxidizing agent, reacting readily at high temperatures with many metals, carbon, sulfur, and other substances, concentrated sulfuric acid is also a strong dehydrating agent, combining violently with water; in this capacity, it chars many organic materials, such as wood, paper, or sugar, leaving a carbonaceous residue.

      The term fuming sulfuric acid, or oleum, is applied to solutions of sulfur trioxide in 100 percent sulfuric acid; these solutions, commonly containing 20, 40, or 65 percent sulfur trioxide, are used for the preparation of organic chemicals.

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