Hydrochloric Acid(HCL)
Abstract
Hydrochloric acid (HCl) is commonly used for the neutralization of alkaline agents, as a bleaching agent, in food, textile, metal, and rubber industries. It is neutralized if released into the soil and it rapidly hydrolyzes when exposed to water. Transport through soil may contaminate groundwater and will dissolve some of the soil materials. Exposure to HCl gas or solutions of HCl may cause eye irritation and permanent damage with loss of sight. Dermal exposure may cause burns. Inhalation of HCl immediately causes severe irritation with cough and choking sensation. HCl is not classifiable as to its carcinogenicity to humans.
Gaseous hydrogen chloride reacts with active metals and their oxides, hydroxides, and carbonates to produce chlorides. These reactions occur readily only in the presence of moisture. Completely dry hydrogen chloride is very unreactive. The reactions of hydrochloric acid are those of typical strong acids, such as: reactions with metals in which hydrogen gas is displaced, reactions with basic (metal) oxides and hydroxides that are neutralized with the formation of a metal chloride and water, and reactions with salts of weak acids in which the weak acid is displaced. Hydrochloric acid also enters into chemical reactions characteristic of the chloride ion, such as reactions with various inorganic and organic compounds in which hydrochloric acid is used as a chlorinating agent and reactions with metals and their oxides in which complex chloride-containing ions are formed (e.g., with platinum, [PtCl6]2−, or with copper, [CuCl4]2−). The latter type of reaction accounts for the ease of solution of certain metals and metallic compounds in hydrochloric acid although they are slowly dissolved in other acids of equal strength (e.g., sulfuric or nitric acid). For this reason, hydrochloric acid is used extensively in the industrial processing of metals and in the concentration of some ores.
Hydrochloric acid is present in the digestive juices of the human stomach. Excessive secretion of the acid causes gastric ulcers, while a marked deficiency of it impairs the digestive process and is sometimes the primary cause of deficiency anemias. Exposure to 0.1 percent by volume hydrogen chloride gas in the atmosphere may cause death in a few minutes. Concentrated hydrochloric acid causes burns and inflammation of the skin.
