Hydrofluoric acid (English: Hydrofluoric Acid ) is an aqueous solution of hydrogen fluoride gas, clear, colorless, fuming corrosive liquid with a strong irritating odor. Melting point -83.3℃, boiling point 19.54℃, flash point 112.2℃, density 1.15g/cm³. Soluble in water, ethanol, slightly soluble in ether.

Because of the relatively strong ability to combine between hydrogen and fluorine atoms and the existence of hydrogen bonds between hydrogen fluoride molecules in aqueous solution, which makes hydrofluoric acid in water can not be completely ionized, so theoretically the low concentration of hydrofluoric acid is a weak acid. It is extremely corrosive and can strongly corrode metals, glass and objects containing silicon. It can cause incurable burns if the vapor is inhaled or comes into contact with the skin. It is generally prepared in the laboratory from fluorite (the main component of which is calcium fluoride) and concentrated sulfuric acid, and needs to be sealed in a plastic bottle and kept in a cool place.

Areas of Application

Because of its ability to dissolve oxides, hydrofluoric acid plays an important role in the purification of aluminum and uranium. Hydrofluoric acid is also used to etch glass, which can be engraved, marked with scales and text; the semiconductor industry uses it to remove oxides from the surface of silicon, and in refineries it can be used as a catalyst for the alkylation of isobutane and n-butene, and it is also used in the process of “leaching” stainless steel to remove oxygen-containing impurities on the surface of the stainless steel. Hydrofluoric acid is also used in the synthesis of a variety of fluorine-containing organic compounds, such as Teflon (polytetrafluoroethylene) and Freon as a refrigerant.

Both hydrofluoric acid and molten sodium hydroxide can be used for the removal of the glass-coated layer on the surface of microfilaments, and the time for the removal of the glass-coated layer with a thickness of 10 μm is about 150 s for hydrofluoric acid at room temperature, and it takes about 10 s for molten sodium hydroxide; the composition and structure of the glass is an important factor affecting the corrosion resistance of glass-coated pure copper microfilaments. The glass-coated pure copper microfilaments were prepared by the melt spinning method, and the removal of the glass-coated layer on the surface of the microfilaments was experimentally investigated. The corrosion behavior of the microfilaments in hydrofluoric acid and molten sodium hydroxide was evaluated, and the corrosion resistance of the glass-coated pure copper microfilaments in strong acids and alkalis was analyzed to discuss the corrosion mechanism.

Another Name

Hydrofluoric acid, hydrogen fluoride, hydrogen fluoride solution

Formula

HF

Molecular Mass

20.0063

CAS Login Number

7664-39-3

EINECS Registration Number...

231-634-8

Melting Point

-83.3℃

Boiling

19.54℃

Solubility

Soluble in Water

Densities

1.15 g/mL

Appearances

Colorless transparent to light yellow smoke

Flash Point

112.2℃

Appliance

Strong acidic corrosive, analytical reagent, used for etching glass, pickling metal, etc.