Hydrofluoric acid - wikipedia Hydrofluoric acid Hydrofluoric acid Names Other names Fluorhydric acid Hydronium fluoride Identifiers CAS Number 7664 - 39 - 3 3D model ( JSmol ) Interactive image ChEBI CHEBI : 29228 ChemSpider 14214 EC Number 231 - 634 - 8 PubChem CID 14917 RTECS number MW7875000 UNII RGL5YE86CZ InChI InChI = 1S / FH / h1H Key : KRHYYFGTRYWZRS - UHFFFAOYSA - N InChI = 1 / FH / h1H Key : KRHYYFGTRYWZRS - UHFFFAOYAC SMILES Properties Chemical 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 ( pK ) 3.17 Hazards Safety data sheet duPont MSDS GHS pictograms GHS signal word DANGER GHS hazard statements H280, H300, H310, H314, H318, H330 GHS precautionary statements P260, P262, P264, P270, P271, P280, P284, P301 + 310, P301 + 330 + 331, P302 + 350, P303 + 361 + 353, P304 + 340, P305 + 351 + 338, P310 NFPA 704 0 0 ACID Flash point Non-flammable Related compounds Other anions Hydrochloric acid Hydrobromic acid Hydroiodic acid Related compounds Hydrogen fluoride Except where otherwise noted, data are given for materials in their standard state ( at 25 ° C ( 77 ° F ), 100 kPa ). Y verify ( what is ? ) Infobox references Hydrofluoric acid is a solution of hydrogen fluoride ( HF ) in water. It is a precursor to almost all fluorine compounds, including pharmaceuticals such as fluoxetine ( Prozac ), diverse materials such as PTFE ( Teflon ), and elemental fluorine itself. It is a colourless solution that is highly corrosive, capable of dissolving many materials, especially oxides. Its ability to dissolve glass has been known since the 17th century, even before Carl Wilhelm Scheele prepared it in large quantities in 1771. Because of its high reactivity toward glass and moderate reactivity toward many metals, hydrofluoric acid is usually stored in plastic containers ( although PTFE is slightly permeable to it ). Hydrogen fluoride gas is an acute poison that may immediately and permanently damage lungs and the corneas of the eyes. Aqueous hydrofluoric acid is a contact - poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality, after contact with as little as 160 cm ( 25 square inches ) of skin. Contents 1 Acidity 2 Production 3 Uses 3.1 Oil refining 3.2 Production of organofluorine compounds 3.3 Production of fluorides 3.4 Etchant and cleaning agent 3.5 Niche applications 4 Health and safety 5 See also 6 References 7 External links Acidity Hydrofluoric acid is classified as a weak acid because of its lower dissociation constant compared to the strong acids. It ionizes in aqueous solutions in a similar fashion to other common acids : HF + H O ⇌ H O + F HF is the only hydrohalic acid that is not considered a strong acid, i.e. it does not fully ionize in dilute aqueous solutions. When the concentration of HF approaches 100 %, the acidity increases dramatically because of homoassociation : 3 HF ⇌ H F + FHF The bifluoride ( FHF ) anion is stabilized by the very strong hydrogen -- fluorine hydrogen bond. Production Hydrofluoric acid is produced by treatment of the mineral fluorite ( CaF ) with concentrated sulfuric acid. When combined at 265 ° C, these two substances react to produce hydrogen fluoride and calcium sulfate according to the following chemical equation : CaF + H SO → 2 HF + CaSO Although bulk fluorite is a suitable precursor and a major source of world HF production, HF is also produced as a by - product of the production of phosphoric acid, which is derived from the mineral apatite. Apatite sources typically contain a few percent of fluoroapatite, acid digestion of which releases a gaseous stream consisting of sulfur dioxide ( from the H SO ), water, and HF, as well as particulates. After separation from the solids, the gases are treated with sulfuric acid and oleum to afford anhydrous HF. Owing to the corrosive nature of HF, its production is accompanied by the dissolution of silicate minerals, and, in this way, significant amounts of fluorosilicic acid are generated. Uses Hydrofluoric acid has a variety of uses in industry and research. It is used as a starting material or intermediate in industrial chemistry, mining, refining, glass finishing, silicon chip manufacturing, and in cleaning. Oil refining In a standard oil refinery process known as alkylation, isobutane is alkylated with low - molecular - weight alkenes ( primarily a mixture of propylene and butylene ) in the presence of the strong acid catalyst derived from hydrofluoric acid. The catalyst protonates the alkenes ( propylene, butylene ) to produce reactive carbocations, which alkylate isobutane. The reaction is carried out at mild temperatures ( 0 and 30 ° C ) in a two - phase reaction. Production of organofluorine compounds The principal use of hydrofluoric acid is in organofluorine chemistry. Many organofluorine compounds are prepared using HF as the fluorine source, including Teflon, fluoropolymers, fluorocarbons, and refrigerants such as freon. Production of fluorides Most high - volume inorganic fluoride compounds are prepared from hydrofluoric acid. Foremost are Na AlF, cryolite, and AlF, aluminium trifluoride. A molten mixture of these solids serves as a high - temperature solvent for the production of metallic aluminium. Given concerns about fluorides in the environment, alternative technologies are being sought. Other inorganic fluorides prepared from hydrofluoric acid include sodium fluoride and uranium hexafluoride. Etchant and cleaning agent Wet etching tanks In metalworking, hydrofluoric acid is used as a pickling agent to remove oxides and other impurities from stainless and carbon steels because of its limited ability to dissolve steel. It is used in the semiconductor industry as a major component of Wright Etch and buffered oxide etch, which are used to clean silicon wafers. In a similar manner it is also used to etch glass by reacting with silicon dioxide to form gaseous or water - soluble silicon fluorides. It can also be used to polish and frost glass. SiO + 4 HF → SiF ( g ) + 2 H O SiO + 6 HF → H SiF + 2 H O A 5 % to 9 % hydrofluoric acid gel is also commonly used to etch all ceramic dental restorations to improve bonding. For similar reasons, dilute hydrofluoric acid is a component of household rust stain remover, in car washes in `` wheel cleaner '' compounds, in ceramic and fabric rust inhibitors, and in water spot removers. Because of its ability to dissolve iron oxides as well as silica - based contaminants, hydrofluoric acid is used in pre-commissioning boilers that produce high - pressure steam. Niche applications Because of its ability to dissolve ( most ) oxides and silicates, hydrofluoric acid is useful for dissolving rock samples ( usually powdered ) prior to analysis. In similar manner, this acid is used in acid macerations to extract organic fossils from silicate rocks. Fossiliferous rock may be immersed directly into the acid, or a cellulose nitrate film may be applied ( dissolved in amyl acetate ), which adheres to the organic component and allows the rock to be dissolved around it. Diluted hydrofluoric acid ( 1 to 3 % wt. ) is used in the petroleum industry in a mixture with other acids ( HCl or organic acids ) in order to stimulate the production of water, oil, and gas wells specifically where sandstone is involved. Hydrofluoric acid is also used by some collectors of antique glass bottles to remove so - called ' sickness ' from the glass, caused by acids ( usually in the soil the bottle was buried in ) attacking the soda content of the glass. Offset printing companies use hydrofluoric acid to remove unwanted images from printing plates. Felt - tip markers called `` deletion pens '' are available to make the process safer for the worker. Health and Safety A hydrofluoric acid burn of the hand HF burns, not evident until a day after In addition to being a highly corrosive liquid, hydrofluoric acid is also a powerful contact poison. Because of the ability of hydrofluoric acid to penetrate tissue, poisoning can occur readily through exposure of skin or eyes, or when inhaled or swallowed. Symptoms of exposure to hydrofluoric acid may not be immediately evident, and this can provide false reassurance to victims, causing them to delay medical treatment. Despite having an irritating odor, HF may reach dangerous levels without an obvious odor. HF interferes with nerve function, meaning that burns may not initially be painful. Accidental exposures can go unnoticed, delaying treatment and increasing the extent and seriousness of the injury. Symptoms of HF exposure include irritation of the eyes, skin, nose, and throat, eye and skin burns, rhinitis, bronchitis, pulmonary edema ( fluid buildup in the lungs ), and bone damage. Once absorbed into blood through the skin, it reacts with blood calcium and may cause cardiac arrest. Burns with areas larger than 160 cm ( 25 square inches ) have the potential to cause serious systemic toxicity from interference with blood and tissue calcium levels. In the body, hydrofluoric acid reacts with the ubiquitous biologically important ions Ca and Mg. Formation of insoluble calcium fluoride is proposed as the etiology for both precipitous fall in serum calcium and the severe pain associated with tissue toxicity. In some cases, exposures can lead to hypocalcemia. Thus, hydrofluoric acid exposure is often treated with calcium gluconate, a source of Ca that sequesters the fluoride ions. HF chemical burns can be treated with a water wash and 2.5 % calcium gluconate gel or special rinsing solutions. However, because it is absorbed, medical treatment is necessary ; rinsing off is not enough. Intra-arterial infusions of calcium chloride have also shown great effectiveness in treating burns. Hydrogen fluoride is generated upon combustion of many fluorine - containing compounds such as products containing Viton and polytetrafluoroethylene ( Teflon ) parts. Hydrofluorocarbons in automatic fire suppression systems can release hydrogen fluoride at high temperatures, and this has led to deaths from acute respiratory failure in military personnel when a rocket - propelled grenade hit the fire suppression system in their vehicle. Hydrofluoric acid can be released from volcanoes, sea salt aerosol, and from welding or manufacturing processes. The general population is exposed to hydrofluoric acid through consumption of naturally or artificially fluoridated drinking water, coal burning, volcanic emissions and the resuspension of soil by wind. Major sources of industrial fluoride emissions are aluminum production plants and phosphate fertilizer plants. See also Vapour phase decomposition References Jump up ^ Harris, Daniel C. ( 2010 ). Quantitative Chemical Analysis ( 8th international ed. ). New York : W.H. Freeman. pp. AP14. ISBN 1429263091. Jump up ^ `` Hydrofluoric Acid ''. PubChem. National Institute of Health. Retrieved October 12, 2017. Jump up ^ Greenwood, Norman N. ; Earnshaw, Alan ( 1984 ). Chemistry of the Elements. Oxford : Pergamon Press. p. 921. ISBN 0 - 08 - 022057 - 6. ^ Jump up to : Aigueperse, J. et al. ( 2005 ) `` Fluorine Compounds, Inorganic '' in Ullmann 's Encyclopedia of Industrial Chemistry, Wiley - VCH, Weinheim, doi : 10.1002 / 14356007. a11_307 Jump up ^ Ayotte, P ; Hébert, M ; Marchand, P ( Nov 2005 ). `` Why is hydrofluoric acid a weak acid ? ''. J. Chem. Phys. 123 ( 18 ) : 184501. PMID 16292908. doi : 10.1063 / 1.2090259. ^ Jump up to : `` CDC - The Emergency Response Safety and Health Database : Systemic Agent : HYDROGEN FLUORIDE / HYDROFLUORIC ACID - NIOSH ''. www.cdc.gov. Retrieved 2015 - 12 - 04. Jump up ^ Powers, John M. and Sakaguchi, Ronald L. ( 2006 ) Craig 's Restorative Dental Materials, 12th ed., Mosby, ISBN 0323036066 Jump up ^ Strachan, John ( January 1999 ). `` A deadly rinse : The dangers of hydrofluoric acid ''. Professional Carwashing & Detailing. 23 ( 1 ). Archived from the original on April 25, 2012. Jump up ^ Edwards, D. ( 1982 ). `` Fragmentary non-vascular plant microfossils from the late Silurian of Wales ''. Botanical Journal of the Linnean Society. 84 ( 3 ) : 223 -- 256. doi : 10.1111 / j. 1095 - 8339.1982. tb00536. x. ^ Jump up to : Yamashita M, Yamashita M, Suzuki M, Hirai H, Kajigaya H ; Yamashita ; Suzuki ; Hirai ; Kajigaya ( 2001 ). `` Ionophoretic delivery of calcium for experimental hydrofluoric acid burns ''. Crit. Care Med. 29 ( 8 ) : 1575 -- 8. PMID 11505130. doi : 10.1097 / 00003246 - 200108000 - 00013. CS1 maint : Multiple names : authors list ( link ) Jump up ^ `` CDC - NIOSH Pocket Guide to Chemical Hazards - Hydrogen fluoride ''. www.cdc.gov. Retrieved 2015 - 11 - 28. ^ Jump up to : `` Recommended Medical Treatment for Hydrofluoric Acid Exposure '' ( PDF ). Honeywell Specialty Materials. Archived from the original ( PDF ) on March 25, 2009. Retrieved 2009 - 05 - 06. Jump up ^ Hoffman, Robert S. et al. ( 2007 ) Goldfrank 's Manual of Toxicologic Emergencies. New York : McGraw - Hill Professional, p. 1333, ISBN 0071509577. Jump up ^ el Saadi MS, Hall AH, Hall PK, Riggs BS, Augenstein WL, Rumack BH ; Hall ; Hall ; Riggs ; Augenstein ; Rumack ( 1989 ). `` Hydrofluoric acid dermal exposure ''. Vet Hum Toxicol. 31 ( 3 ) : 243 -- 7. PMID 2741315. CS1 maint : Multiple names : authors list ( link ) Jump up ^ Roblin I, Urban M, Flicoteau D, Martin C, Pradeau D ; Urban ; Flicoteau ; Martin ; Pradeau ( 2006 ). `` Topical treatment of experimental hydrofluoric acid skin burns by 2.5 % calcium gluconate ''. J Burn Care Res. 27 ( 6 ) : 889 -- 94. PMID 17091088. doi : 10.1097 / 01. BCR. 0000245767.54278. 09. CS1 maint : Multiple names : authors list ( link ) Jump up ^ `` Calcium Gluconate Gel as an Antidote to HF Acid Burns ''. Northwestern University. Archived from the original on April 8, 2009. Retrieved 2012 - 10 - 01. Jump up ^ Hultén P, Höjer J, Ludwigs U, Janson A ; Höjer ; Ludwigs ; Janson ( 2004 ). `` Hexafluorine vs. standard decontamination to reduce systemic toxicity after dermal exposure to hydrofluoric acid ''. J. Toxicol. Clin. Toxicol. 42 ( 4 ) : 355 -- 61. PMID 15461243. doi : 10.1081 / CLT - 120039541. CS1 maint : Multiple names : authors list ( link ) Jump up ^ `` News & Views ''. Chemical Health and Safety. 12 ( 5 ) : 35 -- 37. September -- October 2005. doi : 10.1016 / j. chs. 2005.07. 007. Jump up ^ Siegel DC, Heard JM ; Heard ( March 1992 ). `` Intra-arterial calcium infusion for hydrofluoric acid burns ''. Aviat Space Environ Med. 63 ( 3 ) : 206 -- 11. PMID 1567323. Jump up ^ Koch, Ernst - Christian ( 2002 ). `` Metal - Fluorocarbon - Pyrolants IV : Thermochemical and Combustion Behaviour of Magnesium / Teflon / Viton ( MTV ) ''. Propellants, Explosives, Pyrotechnics. 27 ( 6 ) : 340 -- 351. doi : 10.1002 / prep. 200290004. Jump up ^ Chauviere, Matt ; Zierold, Dustin ( 2011 - 09 - 17 ). `` Hydrogen Fluoride Inhalation Injury from a Fire Suppression System ''. NATO. Retrieved 2013 - 08 - 22. Jump up ^ `` Hydrogen Fluoride ( Hydrofluoric Acid ) '' ( PDF ). Hazards Summary from EPA Air Toxics. US Environmental Protection Agency. Retrieved October 12, 2017. External links Wikimedia Commons has media related to Hydrogen fluoride. International Chemical Safety Card 0283 NIOSH Pocket Guide to Chemical Hazards CID 14917 from PubChem ( HF ) CID 144681 from PubChem ( 5HF ) CID 141165 from PubChem ( 6HF ) CID 144682 from PubChem ( 7HF ) Hydrofluoric Acid Burn, The New England Journal of Medicine Acid burn case study GND : 4209062 - 3 Retrieved from `` https://en.wikipedia.org/w/index.php?title=Hydrofluoric_acid&oldid=807343773 '' Categories : Fluorides Nonmetal halides Mineral acids Acid catalysts Hidden categories : CS1 maint : Multiple names : authors list Articles without KEGG source Chembox having DSD data Chembox having GHS data Articles containing unverified chemical infoboxes All articles with unsourced statements Articles with unsourced statements from March 2014 Articles with unsourced statements from October 2009 Articles with unsourced statements from February 2011 Articles with unsourced statements from July 2015 PubChem ID ( CID ) same as Wikidata PubChem ID ( CID ) different from Wikidata Wikipedia articles with GND identifiers Talk Contents About Wikipedia Беларуская Bosanski Català Čeština Dansk Deutsch Eesti Ελληνικά Español Esperanto Euskara فارسی Français Gaeilge 한국어 Հայերեն Hrvatski Italiano עברית Қазақша Latviešu മലയാളം मराठी 日本 語 Norsk Norsk nynorsk Occitan Polski Português Română Русский Scots Simple English Slovenčina Slovenščina Српски / srpski Srpskohrvatski / српскохрватски Suomi Svenska తెలుగు ไทย Türkçe Українська Tiếng Việt Winaray 中文 Edit links This page was last edited on 27 October 2017, at 11 : 01. 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Question: which acid is used to write on glass
Answer: hydrofluoric acid