Abstract

Hydrogen fluoride is the most important manufactured fluorine compound, having the greatest production volume and serving as the raw material for most other fluorine-containing chemicals. It is produced from sulfuric acid and fluorspar (calcium fluoride ore) at elevated temperatures in a rotating kiln. It is used for the production of fluorocarbons and inorganic fluorides, as a catalyst in the production of high octane gasoline, in aluminum manufacture, as an etchant in the electronic industry, in uranium fuel processing, and in stainless steel pickling. Hydrogen fluoride is a colorless liquid or gas that strongly associates to form polymers in both the liquid and gaseous states, and exhibits highly nonideal physical properties. It is a fairly weak acid as a solute, but is highly acidic as a solvent. Among its unusual chemical properties is its reactivity with silica and silicates, including glass. It is a corrosive, hazardous material, but can be handled safely provided rigorous safety precautions are followed. Properties of both the aqueous and anhydrous material are described.