Hydrogen fluoride is an inorganic compound with the chemical formula HF. It is a very poisonous colorless gas or liquid that dissolves in water to produce hydrofluoric acid. It is the main industrial source of fluorine, often in the form of hydrofluoric acid, and underlies the fluorine value chain, which includes aluminum fluoride, refrigerants, fluoropolymers, pharmaceuticals, and lithium-ion battery material.
Historically it is produced industrially by reaction between acid-grade fluorspar and sulfuric acid. A number of industrial plants using process technology from FSA have recently been built in China and the United States.
