waterstoffluoride

Waterstoffluoride, known in English as hydrogen fluoride (HF), is a highly reactive hydrogen halide. In its anhydrous form it is a colorless gas at room temperature; when dissolved in water it forms hydrofluoric acid, a solution used in many industrial processes.

Physical and chemical properties: HF is highly corrosive and toxic. It forms hydrogen-bonded structures and, in solution, dissociates to fluoride ions and hydronium. The pure compound has a melting point of -83.6°C and a boiling point of 19.5°C, so it exists as a gas at most ambient conditions but readily liquefies near room temperature. HF is highly capable of dissolving silica and reacts with many materials, which is why it is stored in special plastic or fluoropolymer containers rather than glass.

Production and applications: Industrial HF is primarily produced by reacting fluorspar (calcium fluoride) with sulfuric acid:

CaF2 + H2SO4 → 2 HF + CaSO4.

Hydrofluoric acid is used to manufacture fluorinated compounds, including refrigerants and polymers, and to prepare fluoride salts. It is also employed for glass etching and surface pretreatment in the electronics industry, where it cleans silicon wafers and other materials.

Safety and handling: HF is exceptionally dangerous. Inhalation or skin contact can cause severe chemical burns and deep tissue damage; fluoride ions can interfere with calcium metabolism, leading to systemic toxicity. First aid emphasizes immediate removal from exposure and calcium-based antidotes (such as calcium gluconate) for burns. Strict engineering controls, corrosion-resistant equipment, and appropriate personal protective equipment are essential when working with HF.