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26-490: When radon is heated to 400 °C with fluorine, radon difluoride is formed. Radon difluoride can be reduced to radon and hydrogen fluoride when heated with hydrogen gas at 500 °C. This inorganic compound –related article is a stub . You can help Misplaced Pages by expanding it . Hydrogen fluoride 15 (in DMSO) Hydrogen fluoride (fluorane) is an inorganic compound with chemical formula H F . It

52-433: A component of superacids . Due to strong and extensive hydrogen bonding , it boils at near room temperature, which is much higher of a temperature than other hydrogen halides . Hydrogen fluoride is an extremely dangerous gas, forming corrosive and penetrating hydrofluoric acid upon contact with moisture . The gas can also cause blindness by rapid destruction of the corneas . In 1771 Carl Wilhelm Scheele prepared

78-466: A discrete chemical species when dissolved in a particular solvent. Since fluoroantimonic acid is not a single chemical species, its p K a value is not well-defined. The gas-phase acidity (GPA) of individual species present in the mixture have been calculated using density functional theory methods. (Solution-phase p K a s of these species can, in principle, be estimated by taking into account solvation energies, but do not appear to be reported in

104-514: A short covalent H–F bond of 95 pm length, are linked to neighboring molecules by intermolecular H–F distances of 155 pm. Liquid HF also consists of chains of HF molecules, but the chains are shorter, consisting on average of only five or six molecules. Hydrogen fluoride does not boil until 20 °C in contrast to the heavier hydrogen halides, which boil between −85 °C (−120 °F) and −35 °C (−30 °F). This hydrogen bonding between HF molecules gives rise to high viscosity in

130-451: A temperature of 40 °C. As a superacid , fluoroantimonic acid solutions protonate nearly all organic compounds , often causing dehydrogenation, or dehydration. In 1967, Bickel and Hogeveen showed that 2HF·SbF 5 reacts with isobutane and neopentane to form carbenium ions: It is also used in the synthesis of tetraxenonogold complexes. HF/SbF 5 is a highly corrosive substance that reacts violently with water. Heating it

156-501: A weak acid, unlike the other hydrohalic acids, due to the formation of hydrogen-bonded ion pairs [ H 3 O ·F ]. However concentrated solutions are strong acids, because bifluoride anions are predominant, instead of ion pairs. In liquid anhydrous HF, self-ionization occurs: which forms an extremely acidic liquid ( H 0  = −15.1 ). Like water, HF can act as a weak base, reacting with Lewis acids to give superacids . A Hammett acidity function ( H 0 ) of −21

182-613: Is a mixture of hydrogen fluoride and antimony penta­fluoride , containing various cations and anions (the simplest being H 2 F and Sb F 6 ). This mixture is a superacid that, in terms of corrosiveness, is trillions of times stronger than pure sulfuric acid when measured by its Hammett acidity function . It even protonates some hydro­carbons to afford pentacoordinate carbo­cations ( carbonium ions ). Like its precursor hydrogen fluoride , it attacks glass, but can be stored in containers lined with PTFE (Teflon) or PFA . Fluoroantimonic acid

208-411: Is a very poisonous, colorless gas or liquid that dissolves in water to yield hydrofluoric acid . It is the principal industrial source of fluorine , often in the form of hydrofluoric acid, and is an important feedstock in the preparation of many important compounds including pharmaceuticals and polymers such as polytetrafluoroethylene (PTFE). HF is also widely used in the petrochemical industry as

234-526: Is dangerous as well, as it decomposes into toxic hydrogen fluoride gas . With superacids that are fuming and toxic, proper personal protective equipment should be used. In addition to the obligatory gloves and goggles , the use of a face shield and respirator are also required. Regular lab gloves are not recommended, as this acid can react with the gloves. Safety gear must be worn at all times when handling or going anywhere near this corrosive substance, as fluoroantimonic acid can protonate every compound in

260-447: Is fluorinated by HF to produce chlorodifluoromethane (R-22): Pyrolysis of chlorodifluoromethane (at 550-750 °C) yields TFE. HF is a reactive solvent in the electrochemical fluorination of organic compounds. In this approach, HF is oxidized in the presence of a hydrocarbon and the fluorine replaces C–H bonds with C–F bonds . Perfluorinated carboxylic acids and sulfonic acids are produced in this way. 1,1-Difluoroethane

286-417: Is formed by combining hydrogen fluoride and antimony pentafluoride : The speciation (i.e., the inventory of components) of fluoroantimonic acid is complex. Spectroscopic measurements show that fluoroantimonic acid consists of a mixture of HF-solvated protons, [ (HF) n H] (such as H 3 F + 2 ), and SbF 5 -adducts of fluoride, [(SbF 5 ) n F] (such as Sb 4 F − 21 ). Thus,

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312-399: Is highly corrosive and a powerful contact poison. Exposure requires immediate medical attention. It can cause blindness by rapid destruction of the corneas . Breathing in hydrogen fluoride at high levels or in combination with skin contact can cause death from an irregular heartbeat or from pulmonary edema (fluid buildup in the lungs). Fluoroantimonic acid Fluoroantimonic acid

338-558: Is in fact the strongest Brønsted base in the mixture, protonating to H 2 F in the same way water protonates to H 3 O in aqueous acid. It is the fluoronium ion that accounts for fluoroantimonic acid's extreme acidity. The protons easily migrate through the solution, moving from H 2 F to HF, when present, by the Grotthuss mechanism . Two related products have been crystallized from HF-SbF 5 mixtures, and both have been analyzed by single crystal X-ray crystallography . These salts have

364-407: Is more common industrially than its aqueous solution, hydrofluoric acid . Its main uses, on a tonnage basis, are as a precursor to organofluorine compounds and a precursor to cryolite for the electrolysis of aluminium. HF reacts with chlorocarbons to give fluorocarbons. An important application of this reaction is the production of tetrafluoroethylene (TFE), precursor to Teflon . Chloroform

390-438: Is obtained with antimony pentafluoride (SbF 5 ), forming fluoroantimonic acid . Hydrogen fluoride is typically produced by the reaction between sulfuric acid and pure grades of the mineral fluorite : About 20% of manufactured HF is a byproduct of fertilizer production, which generates hexafluorosilicic acid . This acid can be degraded to release HF thermally and by hydrolysis: In general, anhydrous hydrogen fluoride

416-449: Is produced by adding HF to acetylene using mercury as a catalyst. The intermediate in this process is vinyl fluoride or fluoroethylene, the monomeric precursor to polyvinyl fluoride . The electrowinning of aluminium relies on the electrolysis of aluminium fluoride in molten cryolite. Several kilograms of HF are consumed per ton of Al produced. Other metal fluorides are produced using HF, including uranium tetrafluoride . HF

442-418: Is so reactive that it is challenging to identify media with which it is unreactive. Materials compatible with fluoroantimonic acid as a solvent include SO 2 ClF , and sulfur dioxide ; some chlorofluorocarbons have also been used. Containers for HF/SbF 5 are made of PTFE . Fluoroantimonic acid solutions decompose when heated, generating free hydrogen fluoride gas and liquid antimony pentafluoride at

468-418: Is the precursor to elemental fluorine , F 2 , by electrolysis of a solution of HF and potassium bifluoride . The potassium bifluoride is needed because anhydrous HF does not conduct electricity. Several thousand tons of F 2 are produced annually. HF serves as a catalyst in alkylation processes in refineries. It is used in the majority of the installed linear alkyl benzene production facilities in

494-428: Is −15. A solution of HF containing 1 mol % of SbF 5 is −20. The H 0 is −21 for 10 mol%. For > 50 mol % SbF 5 , the H 0 is between −21 and −23. The lowest attained H 0 is about -28. The following H 0 values show that fluoroantimonic acid is stronger than other superacids. Increased acidity is indicated by smaller (in this case, more negative) values of H 0 . Of

520-434: The above, only the carborane acids , whose H 0 could not be directly determined due to their high melting points, may be stronger acids than fluoroantimonic acid. The H 0 value measures the protonating ability of the bulk, liquid acid, and this value has been directly determined or estimated for various compositions of the mixture. The p K a on the other hand, measures the equilibrium of proton dissociation of

546-484: The aqueous solution, hydrofluoric acid in large quantities, although hydrofluoric acid had been known in the glass industry before then. French chemist Edmond Frémy (1814–1894) is credited with discovering hydrogen fluoride (HF) while trying to isolate fluorine . HF is diatomic in the gas-phase. As a liquid, HF forms relatively strong hydrogen bonds , hence its relatively high boiling point. Solid HF consists of zig-zag chains of HF molecules. The HF molecules, with

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572-399: The formula " [H 2 F] [SbF 6 ] " is a convenient but oversimplified approximation of the true composition. Nevertheless, the extreme acidity of this mixture is evident from the inferior proton-accepting ability of the species present in the solution. Hydrogen fluoride, a weak acid in aqueous solution that is normally not thought to have any appreciable Brønsted basicity at all,

598-510: The formulas [H 2 F ] [Sb 2 F 11 ] and [H 3 F 2 ] [Sb 2 F 11 ] . In both salts, the anion is Sb 2 F 11 . As mentioned above, SbF 6 is weakly basic; the larger anion Sb 2 F 11 is expected to be a still weaker base. Fluoroantimonic acid is the strongest superacid based on the measured value of its Hammett acidity function ( H 0 ), which has been determined for various ratios of HF:SbF 5 . The H 0 of HF

624-475: The liquid phase and lower than expected pressure in the gas phase. HF is miscible with water (dissolves in any proportion). In contrast, the other hydrogen halides exhibit limiting solubilities in water. Hydrogen fluoride forms a monohydrate HF H 2 O with melting point −40 °C (−40 °F), which is 44 °C (79 °F) above the melting point of pure HF. Aqueous solutions of HF are called hydrofluoric acid . When dilute, hydrofluoric acid behaves like

650-496: The literature as of 2019.) For example, the ion-pair [H 2 F] · SbF 6 was estimated to have a GPA of 254 kcal/mol. For comparison, the commonly encountered superacid triflic acid , TfOH, is a substantially weaker acid by this measure, with a GPA of 299 kcal/mol. However, certain carborane superacids have GPAs lower than that of [H 2 F] · SbF 6 . For example, H(CHB 11 Cl 11 ) has an experimentally determined GPA of 241 kcal/mol. Fluoroantimonic acid solution

676-668: The world. The process involves dehydrogenation of n -paraffins to olefins, and subsequent reaction with benzene using HF as catalyst. For example, in oil refineries "alkylate", a component of high- octane petrol ( gasoline ), is generated in alkylation units, which combine C 3 and C 4 olefins and iso -butane . Hydrogen fluoride is an excellent solvent. Reflecting the ability of HF to participate in hydrogen bonding, even proteins and carbohydrates dissolve in HF and can be recovered from it. In contrast, most non-fluoride inorganic chemicals react with HF rather than dissolving. Hydrogen fluoride

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