Hydrogen fluoride
Other names	Hydrogen fluoride Fluoric acid Hydrofluoride Hydrofluoric acid Fluorine monohydride
Molecular formula	HF
Molecular mass	20.01 g/mol
Physical state	Liquid
CAS number	7664-39-3
Density	0.922 kg m-3
Solubility (water)	miscible
Melting point	-84 °C (190 K, -118 ºF)
Boiling point	19.54 °C (293 K, 67.2 ºF)
NFPA 704	0 4 0
Disclaimer and references

Hydrogen fluoride is a chemical compound with the formula HF. Together with hydrofluoric acid, it is the principal industrial source of fluorine and hence the precursor to many important compounds including pharmaceuticals and polymers (e.g. Teflon). HF is widely used in the petrochemical industry and a component of many superacids. HF boils just below room temperature whereas the other hydrogen halides condense at much lower temperatures. Aqueous solutions of HF, called hydrofluoric acid, are strongly corrosive. Image File history File links No higher resolution available. ... Image File history File links Download high resolution version (1100x887, 174 KB) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Hydrofluoric acid Hydrogen fluoride ... Image File history File links Size of this preview: 800 × 322 pixelsFull resolution (1000 × 402 pixel, file size: 158 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ... A chemical formula (also called molecular formula) is a concise way of expressing information about the atoms that constitute a particular chemical compound. ... The molecular mass (abbreviated Mr) of a substance, formerly also called molecular weight and abbreviated as MW, is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ... In the physical sciences, a phase is a set of states of a macroscopic physical system that have relatively uniform chemical composition and physical properties (i. ... CAS registry numbers are unique numerical identifiers for chemical compounds, polymers, biological sequences and alloys. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... Solubility refers to the ability for a given substance, the solute, to dissolve in a solvent. ... This article describes water from a scientific and technical perspective. ... The melting point of a crystalline solid is the temperature at which it changes state from solid to liquid. ... The boiling point of a substance is the temperature at which it can change its state from a liquid to a gas throughout the bulk of the liquid at a given pressure. ... NFPA 704 is a standard maintained by the U.S. National Fire Protection Association. ... Image File history File links NFPA_704. ... A chemical compound is a chemical substance of two or more different chemically bonded chemical elements, with a fixed ratio determining the composition. ... This article or section does not cite any references or sources. ... Hydrofluoric acid is a solution of hydrogen fluoride in water. ... Teflon is polytetrafluoroethylene (PTFE), a polymer of fluorinated ethylene. ... A superacid is an acid with an acidity greater than that of 100% sulfuric acid. ... A halide is a binary compound, of which one part is a halogen atom and the other part is an element or radical that is less electronegative than the halogen, to make a fluoride, chloride, bromide, iodide, or astatide compound. ... Hydrofluoric acid is a solution of hydrogen fluoride in water. ...

Structure of HF

HF forms orthorhombic crystals, consisting of zig-zag chains of HF molecules. The HF molecules, with a short H-F bond of 0.95 Å, are linked to neighboring molecules by intermolecular H--F distances of 1.55 Å.^[1] Image File history File links Size of this preview: 800 × 274 pixelsFull resolution (1388 × 475 pixel, file size: 70 KB, MIME type: image/png) File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...

Liquid HF also consists of chains of HF molecules, but the chains are shorter, consisting on average of only five or six molecules.^[2] The higher boiling point of HF relative to analogous species, such as HCl, is attributed to hydrogen bonding between HF molecules, as indicated by the existence of chains even in the liquid state. In chemistry, a hydrogen bond is a type of attractive intermolecular force that exists between two partial electric charges of opposite polarity. ...

Acidity

Dilute hydrogen fluoride solution is a weak acid due to the extensive intermolecular H-bonds present. The molecules tend to remain in chains rather than ionize to form H⁺ and F⁻ ions.

But in a more concentrated hydrogen fluoride solution, F⁻ ions forms a soluble [HF₂]⁻(aq) complex with HF molecules. HF molecules remaining ionize to compensate the loss of F⁻ ions. More H⁺ ions are thus formed, making concentrated HF an effectively strong acid. The hydrogendifluoride anion The hydrogendifluoride ion is the hydrogen-bonded anion [HF2]−. It can be considered as a molecule of HF that is hydrogen bonded to an F− ion: [F−H···F]−. There is a high degree of covalency in this particularly strong hydrogen bond, and both F−H distances...

Uses

HF is used for fluorinating polymers giving fluorocarbons, petroleum refining, glassmaking, aluminium manufacturing, titanium pickling, quartz purification, and metal finishing. It is also used to synthesize UF₆, which is key to separating uranium isotopes. A polymer is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ... Some important fluorocarbons. ... Pumpjack pumping an oil well near Lubbock, Texas Ignacy Łukasiewicz - inventor of the refining of kerosene from crude oil. ... General Name, Symbol, Number aluminium, Al, 13 Chemical series poor metals Group, Period, Block 13, 3, p Appearance silvery Standard atomic weight 26. ... General Name, Symbol, Number titanium, Ti, 22 Chemical series transition metals Group, Period, Block 4, 4, d Appearance silvery metallic Standard atomic weight 47. ... Quartz is one of the most common minerals in the Earths continental crust. ... Uranium hexafluoride, or UF6, is a compound used in the uranium enrichment process that produces fuel for nuclear reactors and nuclear weapons. ... General Name, Symbol, Number uranium, U, 92 Chemical series actinides Group, Period, Block n/a, 7, f Appearance silvery gray metallic; corrodes to a spalling black oxide coat in air Standard atomic weight 238. ... Isotopes are any of the several different forms of an element each having different atomic mass (mass number). ...

Hydrogen fluoride can be found in consumer products for removing rust, cleaning brass, and glass etching, although use in consumer products is discouraged^{[citation needed]} due to HF's corrosiveness and toxicity. Hydrogen fluoride is typically marketed in three common forms: anhydrous HF, aqueous 70% HF, aqueous 49% HF. HF is manufactured by the reaction of calcium fluoride (fluorspar) and sulfuric acid: A blacksmith removing rust with sand prior to welding Rust damage in automobiles can create hidden dangers. ... For other uses, see Brass (disambiguation). ... In industry, etching (sometimes called chemical milling or wet etching) is the process of using acids, bases or other chemicals to dissolve away unwanted materials such as metals, semiconductor materials or glass. ... // Toxic and Intoxicated redirect here – toxic has other uses, which can be found at Toxicity (disambiguation); for the state of being intoxicated by alcohol see Drunkenness. ... Calcium fluoride (CaF2) is an insoluble ionic compound of calcium and fluorine. ... Sulfuric (or sulphuric) acid, H2SO4, is a strong mineral acid. ...

CaF₂ + H₂SO₄ → CaSO₄ + 2 HF

The vapors from this reaction are a mixture of hydrogen fluoride, sulfuric acid, and a few minor byproducts, from which hydrogen fluoride can be isolated by distillation. Laboratory distillation set-up using, without a fractionating column 1: Heat source 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed...

Health effects

Hydrogen fluoride is toxic and can be fatal if even small amounts are ingested or absorbed through the skin. HF burns require immediate treatment beginning with washing with water but specialized care is indicated. HF acid burns are not similar to those produced by hydrogen chloride (HCl), or other common acids. Onset time of symptoms of HF burns are proportional to concentration. Above 50% instantaneous effects are apparent. Between 20% and 50% clinical symptoms may not appear for one to eight hours. Concentrations below 20% may not result in symptoms for 24 hours.

Entry routes include inhalation, ingestion, skin and eyes. Aside from burns to the eyes, skin, lungs, or digestive tract, the lowering of serum calcium (hypocalcemia) is one of the most serious consequences of HF exposure. As the free fluoride ion penetrates the skin it binds serum calcium forming covalent, nearly insoluble calcium fluoride (CaF₂). This has effects on nerve conduction and can lead to extreme throbbing pain, metabolic changes, and even death. In general terms, eating (formally, ingestion) is the process of consuming something edible, i. ... Blood plasma is the liquid component of blood, in which the blood cells are suspended. ... General Name, Symbol, Number calcium, Ca, 20 Chemical series alkaline earth metals Group, Period, Block 2, 4, s Appearance silvery white Standard atomic weight 40. ... In medicine, hypocalcaemia is the presence of less than a total calcium of 2. ... Calcium fluoride (CaF2) is an insoluble ionic compound of calcium and fluorine. ...

References

1. ^ Johnson, M. W.; Sándor, E.; Arzi, E. "The Crystal Structure of Deuterium Fluoride" Acta Crystallographica 1975, B31, pages 1998-2003. DOI: 10.1107/S0567740875006711].
2. ^ Sylvia E. McLain, S. E.; Benmore, C. J.; Siewenie, J. E.; Urquidi, J.; Turner, J. F. C. "On the Structure of Liquid Hydrogen Fluoride" Angewandte Chemie, International Edition, 2004, volume 43, pages 1952-55. DOI: 10.1002/anie.200353289

The United States Agency for Toxic Substance Disease Registry ,(ATSDR), is directed by congressional mandate to perform specific functions concerning the effect on public health of hazardous substances in the environment. ... May 14 is the 134th day of the year (135th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ... May 14 is the 134th day of the year (135th in leap years) in the Gregorian calendar. ... For the Manfred Mann album, see 2006 (album). ...

External links

• Links to external chemical sources