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Hydrofluoric acid
Hydrogen fluoride.JPG
Other names fluoric acid; fluorhydric acid
CAS number 7664-39-3
EC number 231-634-8
RTECS number MW7875000
Molecular formula HF
Molar mass not applicable
(see hydrogen fluoride)
Appearance Colorless solution
Density 1.15 g/mL (for 48% soln.)
Melting point

not applicable
(see hydrogen fluoride)

Boiling point

not applicable
(see hydrogen fluoride)

Solubility in water Miscible.
Acidity (pKa) 3.15
EU classification Very toxic (T+)
Corrosive (C)
EU Index 009-003-00-1
NFPA 704

NFPA 704.svg

R-phrases R26/27/28, R35
S-phrases (S1/2), S7/9, S26, S36/37, S45
Flash point Non-flammable
Related compounds
Other anions Hydrochloric acid
Hydrobromic acid
Hydroiodic acid
Related compounds Hydrogen fluoride
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Hydrofluoric acid (HF) is a solution of hydrogen fluoride in water. Its chemical formula is HF. It is a weak acid, but very corrosive and extremely toxic. It can dissolve glass to make hexafluorosilicic acid. If it gets on the skin, it can kill you. It is made by reacting fluorite with sulfuric acid. It is used in the processing of petroleum. It is also used to make various other chemicals containing fluorine, such as teflon (the coating in a frying pan), freon (the cooling agent in an air conditioner), and fluorocarbons (used as propellants in aerosol cans). It is used to clean metals. It is very toxic because it bonds with calcium ions in the body and makes them so they cannot be used. As an acid, it can be deprotonated to produce fluorides, which are also the salts of hydrofluoric acid.

If someone gets Hydrofluoric acid on them, medical attention is necessary, as just small amounts are very toxic.

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