Hydrofluoric acid is a colourless solution of hydrogen fluoride in water. It acts as a precursor in almost all the fluorine compounds. It is highly corrosive and can dissolve many materials (especially oxides). Because it is highly reactive towards glass & moderate activity towards many metals, it is generally stored in plastic containers. Hydrogen fluoride gas and concentrated acid is highly toxic and can lead to cardiac arrest and fatality. Here are some important uses/applications of hydrofluoric acid:
1. Oil refining
It is used as an acid catalyst in a standard oil refinery process.
2. In production of organofluorine compounds
Hydrofluoric acid is highly used in organofluorine chemistry. It acts as a fluorine source in the production of organofluorine compounds such as Teflon, fluorocarbons, fluoropolymers and refrigerants like freon.
3. In production of fluorides
Hydrofluoric acid is used for producing most of the high-volume inorganic fluoride compounds such as cryolite, aluminium trifluoride, etc.
4. Pickling and cleaning agent
In metalworking, it acts as a pickling agent to remove oxides and other impurities from carbon steels and stainless steel. A dilute solution of hydrofluoric acid acts as a household rust stain remover.
5. Niche applications
Hydrofluoric acid is useful to dissolve rock samples (generally powdered) because of its ability to dissolve most of the silicates and the oxides.