ClH

ClH is an uncommon notation that may be used to denote hydrogen chloride, the diatomic molecule consisting of chlorine and hydrogen. The standardized chemical formula is HCl; ClH is not widely adopted and is more likely to appear in older literature or in informal contexts.

Hydrogen chloride is a colorless gas at room temperature with a sharp, pungent odor. It is highly soluble in water, forming hydrochloric acid, a strong mineral acid. The molecule has a molecular weight of 36.46 g/mol, a boiling point of approximately -85.05 °C, and a melting point of about -114.2 °C. In the gas phase, HCl is polar and can participate in hydrogen bonding with water and other polar species.

Production and uses: Industrially, hydrogen chloride is produced by direct synthesis of hydrogen and chlorine or as a byproduct of various chlorination processes. In the laboratory, it can be prepared by reacting concentrated sulfuric acid with sodium chloride. It is widely used to produce hydrochloric acid for pH control and etching, and as a reagent in the synthesis of organic chlorides and other chemicals. It also plays a role in metal pickling and in the manufacture of vinyl chloride monomer and other chlorinated compounds.

Safety and handling: Hydrogen chloride gas and hydrochloric acid are highly corrosive to skin, eyes, and respiratory tissues. They can form corrosive fumes that irritate the throat and lungs. Handling is typically performed in well-ventilated areas or fume hoods, with appropriate PPE. HCl reacts with water to form acid, and it can react with certain metals to release hydrogen gas; storage and handling require compatibility with moisture-sensitive materials.

See also: Hydrochloric acid, Hydrogen chloride, Chlorine.