Sodium fluoride 1224339 226178049 2008-07-17T04:47:27Z Inrain 7489188 /* Safety */ link fix {{Chembox new | Name = Sodium fluoride | ImageFile = Sodium-fluoride-3D-ionic.png <!-- | ImageSize = 150px --> | ImageName = Sodium fluoride | IUPACName = Sodium fluoride | Section1 = {{Chembox Identifiers | CASNo = 7681-49-4 }} | Section2 = {{Chembox Properties | Formula = NaF | MolarMass = 41.99 g/mol | Appearance = White solid | Density = 2.558 g/cm³, solid | Solubility = 4.13 g/100 g at 25 °C | MeltingPt = 993 °C | BoilingPt = 1700 °C }} | Section7 = {{Chembox Hazards | ExternalMSDS = | EUClass = Toxic ('''T''') | RPhrases = {{R25}}, {{R32}},<br /> {{R36}}, {{R38}} | SPhrases = {{S22}}, {{S36}}, {{S45}} | NFPA-H = 2 | NFPA-F = | NFPA-R = | FlashPt = Non-flammable. }} | Section8 = {{Chembox Related | OtherAnions = [[sodium chloride]]</br>[[sodium bromide]]</br>[[sodium iodide]] | OtherCations = [[potassium fluoride]]</br> [[calcium fluoride]]<br />[[caesium fluoride]] | Function = [[base (chemistry)|base]]s | OtherFunctn = None listed. | OtherCpds = [[TASF reagent]] }} }} '''Sodium fluoride''' is an [[ionic compound]] with the formula NaF. This colourless solid is the main source of the [[fluoride]] ion in diverse applications. NaF is less expensive and less [[hygroscopy|hygroscopic]] than [[potassium fluoride]] (KF). ==Production== NaF is prepared by neutralizing waste [[hydrofluoric acid]] resulting from the production of [[superphosphate]] fertilizer. It is also generated by treating [[sodium hydroxide]] and [[sodium carbonate]] with hydrofluoric acid, followed by concentrating the resulting solutions, sometimes with the addition of alcohols to precipitate the NaF: :HF + NaOH → NaF + H<sub>2</sub>O Using an excess of HF gives the bifluoride NaHF<sub>2</sub>. Heating the latter releases HF and gives NaF. :HF + NaF {{unicode|⇌}} NaHF<sub>2</sub> In a 1986 report, the annual, worldwide consumption of NaF was estimated to be several million tonnes.<ref name=Aigueperse>Jean Aigueperse, Paul Mollard, Didier Devilliers, Marius Chemla, Robert Faron, Renée Romano, Jean Pierre Cuer, “Fluorine Compounds, Inorganic” in Ullmann’s Encyclopedia of Industrial Chemistry 2005 Wiley-VCH, Weinheim. DOI 10.1002/14356007.a11 307</ref> ==Structure, properties, Uses== NaF crystallizes in the [[sodium chloride]] motif where both Na<sup>+</sup> and F<sup>−</sup> occupy octahedral coordination sites.<ref>Wells, A.F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.</ref> [[Image:Sodium fluoride tablets.jpg|thumb|left|Sodium fluoride is sold in tablets for cavity prevention.]] NaF is used as a cleaning agent, often to remove iron stains. A variety of specialty chemical applications exist in synthesis and extractive metallurgy. NaF is a reagent for the synthesis of [[fluorocarbon]]s. Representative substrates include electrophilic chlorides including [[acyl chloride]]s, sulfur chlorides, and phosphorus chloride.<ref>Halpern, D. F. “Sodium Fluoride” Encyclopedia of Reagents for Organic Synthesis, 2001, John Wiley & Sons. DOI: 10.1002/047084289X.rs071.</ref> Like other fluorides, NaF finds use in desilylation in [[organic synthesis]]. Fluoride salts were used widely to enhance the strength of teeth by the formation of [[fluoroapatite]], a naturally occurring component of tooth enamel. In some areas in the United States, NaF was once used to [[Water fluoridation|fluoridate]] drinking water but its use has been displaced by [[hexafluorosilicic acid]] (H<sub>2</sub>SiF<sub>6</sub>) or its sodium salt (Na<sub>2</sub>SiF<sub>6</sub>). [[Toothpaste]] often contains sodium fluoride under the claim that it prevents [[dental caries|cavities]]. The efficacy and [[Risk-benefit_analysis|risk vs. benefit]] of its use in toothpaste is a topic of controversy. In the United States, a toothpaste product with sodium fluoride is required to have a [[Poison_control_center|poison control]] safety warning, due to fluoride's toxicity. ==Safety== {{see also|Fluoride poisoning|Water fluoridation|water fluoridation controversy|Dental fluorosis}} Sodium fluoride is toxic. Ingested, a lethal dose of fluoride for a 70 kg human could be around 5 to 10 g<ref name=Aigueperse/>; however, the [[minimum lethal dose]] is approximately 5 mg per 1 kg in body weight<ref>{{cite web | url = http://www.emedicine.com/emerg/TOPIC181.HTM | title = eMedicine - Toxicity, Fluoride | author = Geofrey Nochimson, MD}}</ref>, which is 350 mg (0.35 g) fluoride for a 70 kg human. Even so, [[acute toxicity]] can occur in much lower doses.<ref>{{cite web | url = http://www.fluoride-journal.com/97-30-2/302-89.htm | title = Re-examination of acute toxicity of fluoride | author = Kenji Akiniwa}}</ref> A tube of toothpaste may generally contain anywhere from 1000 ppm to 5000 ppm (1000 mg to 5000 mg) of sodium fluoride. ==See also== *[[Fluorine]] *[[Fluoride]] *[[Water fluoridation]] *[[Fluoride poisoning]] *[[Caries]] *[[Osteoporosis]] *[[Insecticide]] *[[Cryolite]] *[[Light metals]] ==References== <references/> ==External links== *[http://www.chemistry.org/portal/a/c/s/1/acsdisplay.html?DOC=HomeMolecule%5Carchive%5Cmotw_sodiumfluoride_arch.html Sodium Fluoride] at chemistry.org ([[American Chemical Society]]) *[http://www.scorecard.org/chemical-profiles/summary.tcl?edf_substance_id=7681-49-4 Chemical Profile for Sodium Fluoride (CAS Number: 7681-49-4)] at Scorecard, the pollution information site {{Stomatological preparations}} {{Mineral supplements}} [[Category:Fluorides]] [[Category:Metal halides]] [[Category:Sodium compounds]] [[Category:Inorganic compounds]] [[ar:فلوريد صوديوم]] [[ca:Fluorur de sodi]] [[de:Natriumfluorid]] [[fr:fluorure de sodium]] [[it:Fluoruro di sodio]] [[hu:Nátrium-fluorid]] [[nl:Natriumfluoride]] [[ja:フッ化ナトリウム]] [[pl:Fluorek sodu]] [[pt:Fluoreto de sódio]] [[ro:Fluorură de sodiu]] [[fi:Natriumfluoridi]] [[zh:氟化鈉]]