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Hydrogen Chloride

Preparation And Uses

Hydrogen chloride can be prepared on an industrial scale from the reaction of salt with sulfuric acid. It is also formed rapidly above 482°F (250°C) by direct combination of the elements hydrogen and chlorine, and it is generated as a by-product during the manufacture of chlorinated hydrocarbons. Hydrochloric acid is obtained by passing hydrogen chloride gas into water.

Both hydrogen chloride and hydrochloric acid have many important practical applications. They are used in the manufacture of pharmaceutical hydrochlorides (water soluble drugs that dissolve when ingested), chlorine, and various metal chlorides, in numerous reactions of organic (carbon containing) compounds, and in the plastics and textiles industries. Hydrochloric acid is used for the production of fertilizers, dyes, artificial silk, and paint pigments; in the refining of edible oils and fats; in electro-plating, leather tanning, refining, and concentration of ores, soap production, petroleum extraction, cleaning of metals, and in the photographic and rubber industries.

Small quantities of hydrochloric acid occur in nature in emissions from active volcanos and in waters from volcanic mountain sources. The acid is also present in digestive juices secreted by glands in the stomach wall and is therefore an important component in gastric digestion. When too much hydrochloric acid is produced in the digestive system, gastric ulcers may form. Insufficient secretion of stomach acid can also lead to digestion problems.

See also Acids and bases.



Emsley, John. Nature's Building Blocks: An A-Z Guide to the Elements. Oxford: Oxford University Press, 2002.

Heiserman, D.L. Exploring the Chemical Elements and Their Compounds. Blue Ridge Summit, PA: Tab Publications, 1992.

Mahn, W.J. Academic Laboratory Chemical Hazards Guidebook. New York: Van Nostrand Rheinhold, 1991.

Salzberg, H.W. From Caveman to Chemist. Washington, DC: American Chemical Society, 1991.

Sittig, M. Handbook of Toxic and Hazardous Chemicals and Carcinogens. 3rd ed. Park Ridge, NJ: Noyes Publications, 1991.

Nicholas C. Thomas

Additional topics

Science EncyclopediaScience & Philosophy: Hydrazones to IncompatibilityHydrogen Chloride - Properties, Early Discovery Of Hydrogen Chloride, Preparation And Uses