Sodium fluoride
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{{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]]