Hydrofluoric acid is a chemical compound that is a colorless, pungent-smelling, fuming liquid or gas with the formula HF. The solution of hydrogen fluoride compound in water is called hydrofluoric acid. Hydrofluoric acid is a very strong and dangerous acid. It reacts with most metals, glass and silicate compounds. Skin contact can cause deep burns and poisoning. Inhalation can irritate the lungs. Hydrofluoric acid is used in many fields in industry and daily life. The chemical and physical properties of hydrofluoric acid are as follows:

• Its molecular weight is 20.01 g/mol.
• Its melting point is -83.6 °C.
• Boiling point is 19.5 °C.
• Its density is 1.15 g/L (gas), 1.13 g/mL (liquid).
• Solubility is high in water and alcohol, low in ether.
• pKa value is 3.17.

The production methods of hydrofluoric acid are as follows:

• Calcium fluoride method: This is the most common method of hydrofluoric acid production. Hydrofluoric acid is obtained by the reaction of fluorite, a calcium fluoride mineral, with concentrated sulfuric acid. This method also produces calcium sulfate.
• Fluorspar method: This is an alternative method of producing hydrofluoric acid. Hydrogen fluoride gas is produced by heating the fluorspar mineral calcium fluoride. This gas is then brought into contact with water to form hydrofluoric acid.
• Cryogenic method: This is an old method of producing hydrofluoric acid. Hydrogen fluoride gas is obtained by separating hydrogen and fluorine gases with an electric arc. This gas is then liquefied and mixed with water to make hydrofluoric acid.

Uses of hydrofluoric acid include the following:

• Glass industry Hydrofluoric acid is one of the most widely used abrasives in the glass industry. It attacks the silica component of glass, shaping rough glass into a smooth shape. For example, hydrofluoric acid is used to write on glass bottles or to pattern glass surfaces.
• Electronic industry: Hydrofluoric acid also plays an important role in the electronics industry. Hydrofluoric acid is used for cleaning, soldering and coating circuit boards.
• Food industry Hydrofluoric acid is also used in the food industry for various purposes. Hydrofluoric acid is used to sterilize milk and dairy equipment and to purify beer dispensing tubes and various parts.
• Ceramic industry Hydrofluoric acid is also used in the ceramic industry. Hydrofluoric acid is used for fermenting, firing and polishing ceramic paste.
• Petroleum industry Hydrofluoric acid is also used in the petroleum industry. Hydrofluoric acid is used for drilling oil wells, cleaning and protecting the oilfield refill water system.

Cleaning industry Hydrofluoric acid is also used as an effective substance in the cleaning industry. Hydrofluoric acid is used to remove rust from metal surfaces, clean lime stains and prevent bad odors.