Hydrofluoric acid is an aqueous solution of hydrogen fluoride gas, with the chemical formula HF. Hydrofluoric acid is a colorless, transparent, and highly irritating corrosive liquid that emits smoke. Hydrofluoric acid has extremely strong corrosiveness and can corrode metals, glass, and silicon containing objects.
Hydrofluoric acid is made by dissolving hydrogen fluoride in water. The ability of hydrogen and fluorine atoms to bond is relatively strong, making hydrofluoric acid unable to completely ionize in water. At low concentrations, it has weak acidity due to the formation of hydrogen bonds, but at high concentrations (above 5mol/L), it undergoes self ionization and has strong acidity. Hydrofluoric acid reacts with silicon and silicon compounds to produce gaseous silicon tetrafluoride, which can continue to react with excess HF to form the strong binary acid fluorosilicic acid.
Hydrofluoric acid has a wide range of applications, including being used as a catalyst for the alkylation reaction of isobutane and n-butene in refineries; Plays an important role in the purification of aluminum and uranium; The semiconductor industry uses it to remove oxides from the surface of silicon; Removing surface oxygen-containing impurities during the pickling process of stainless steel; Used for etching glass, etc.
