Wikipedia:WikiProject Chemicals/Chembox validation/VerifiedDataSandbox and Uranium hexafluoride: Difference between pages

{{Expand German|Uran(VI)-fluorid|date=November 2012}}

{{Chembox

|Watchedfields = changed

|verifiedrevid = 476998888

|Name = Uranium hexafluoride

|ImageFile = Uranium-hexafluoride-2D-V2.svg

|ImageSize = 144px

|ImageFile1 = Uranium-hexafluoride-3D-vdW.png

|ImageSize1 = 150px

|ImageFile2 = Uranium-hexafluoride-crystal-3D-vdW.png

|ImageSize2 = 150px

|IUPACName = Uranium hexafluoride<br>Uranium(VI) fluoride

|Section1={{Chembox Identifiers

|Abbreviations = hex

|ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

|ChemSpiderID = 22966

|PubChem = 24560

|InChI = 1/6FH.U/h6*1H;/q;;;;;;+6/p-6/rF6U/c1-7(2,3,4,5)6

|InChIKey = SANRKQGLYCLAFE-IIYYNVFAAT

|ChEBI_Ref = {{ebicite|correct|EBI}}

|ChEBI = 30235

|EINECS = 232-028-6

|Gmelin = 2923

|SMILES = F[U](F)(F)(F)(F)F

|StdInChI_Ref = {{stdinchicite|correct|chemspider}}

|StdInChI = 1S/6FH.U/h6*1H;/q;;;;;;+6/p-6

|StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}

|StdInChIKey = SANRKQGLYCLAFE-UHFFFAOYSA-H

|CASNo = 7783-81-5

|CASNo_Ref = {{cascite|correct|CAS}}

|UNII_Ref = {{fdacite|correct|FDA}}

|UNII = N06GJ1D94J

|RTECS = YR4720000

|UNNumber = 2978 (<1% {{chem2|^{235}U}})<br>2977 (>1% {{chem2|^{235}U}})

|Section2={{Chembox Properties

|Formula = {{chem2|UF6}}

|MolarMass = {{nowrap|352.02 g/mol}}

|Appearance = Colorless solid

|Density = 5.09{{nbsp}}g/cm³, solid

|Solubility = Hydrolyzes

|SolubleOther = {{ubl|Soluble in [[chloroform]], [[carbon tetrachloride|{{chem2|CCl4}}]], liquid [[chlorine]], and [[bromine]]|Dissolves in [[nitrobenzene]];

151{{nbsp}}kPa<ref>{{cite web |url=http://www.ibilabs.com/Uranium%20Hexafluoride.htm |title=Uranium Hexafluoride |access-date=2013-08-08 |url-status=dead |archive-url=https://web.archive.org/web/20130916221434/http://ibilabs.com/Uranium%20Hexafluoride.htm |archive-date=2013-09-16}}</ref>}}

|BoilingPtC = 56.5

|BoilingPt_notes = (sublimes, at atmospheric pressure)}}

|Section3={{Chembox Structure

|CrystalStruct = [[Orthorhombic]], [[Pearson symbol|oP28]]

|SpaceGroup = Pnma, No. 62

|Coordination = Octahedral (''O_h'')

|Dipole = 0}}

|Section4={{Chembox Thermochemistry

|DeltaHf = {{ubl

|Solid, −2197.7±1.8{{nbsp}}[[Joule|kJ]]·mol⁻¹<ref name="Enthalpie">{{cite journal |last1=Johnson |first1=Gerald K. |year=1979 |title=The Enthalpy of Formation of Uranium Hexafluoride |journal=[[The Journal of Chemical Thermodynamics]] |volume=11 |issue=5 |pages=483–490 |doi=10.1016/0021-9614(79)90126-5}}</ref>

|Gaseous, −2148.1±1.8{{nbsp}}kJ·mol⁻¹<ref name="Enthalpie"/>

|Entropy = {{ubl

|Solid, 227.8±1.3{{nbsp}}J·K⁻¹·mol⁻¹<ref name="Enthalpie"/>

|Gaseous, 377.8±1.3{{nbsp}}J·K⁻¹·mol⁻¹<ref name="Enthalpie"/>

}}}}

|Section7={{Chembox Hazards

|MainHazards = Toxic, corrosive, radioactive<ref>Uranium(VI) fluoride</ref>

|ExternalSDS = [https://www.inchem.org/documents/icsc/icsc/eics1250.htm ICSC 1250]

|GHSPictograms = {{GHS skull and crossbones}}{{GHS health hazard}}{{GHS environment}}

|GHSSignalWord = Danger

|HPhrases = {{H-phrases|300|330|373|411}}

|PPhrases = {{P-phrases|}}

|NFPA-H = 4

|NFPA-F = 0

|NFPA-R = 2

|NFPA-S = W+OX

|FlashPt = Non-flammable

}}

|Section9={{Chembox Related

|OtherAnions = [[Uranium hexachloride]]

|OtherCations = {{ubl|[[Neptunium hexafluoride]]|[[Plutonium hexafluoride]]|[[Americium hexafluoride]]|[[Curium hexafluoride]]|[[Tungsten hexafluoride]]}}

|OtherFunction = {{ubl|[[Uranium(III) fluoride]]|[[Uranium(IV) fluoride]]|[[Uranium(V) fluoride]]}}

|OtherFunction_label = uranium fluorides

}}

}}

'''Uranium hexafluoride''', sometimes called '''hex''', is an [[inorganic compound]] with the formula {{chem2|UF6|auto=1}}. Uranium hexafluoride is a volatile and toxic white solid that [[hydrolysis|reacts with water]], releasing corrosive [[hydrofluoric acid]]. The compound reacts mildly with [[aluminium]], forming a thin surface layer of [[aluminium fluoride|{{chem2|AlF3}}]] that resists any further reaction from the compound. {{chem2|UF6}} is used in the process of [[enriched uranium|enriching uranium]], which produces fuel for [[nuclear reactor]]s and [[nuclear weapon]]s.

==Preparation==

Milled uranium ore—{{chem2|U3O8}} or "[[yellowcake]]"—is dissolved in [[nitric acid]], yielding a solution of [[uranyl nitrate]] {{chem2|UO2(NO3)2}}. Pure uranyl nitrate is obtained by [[solvent extraction]], then treated with [[ammonia]] to produce [[ammonium diuranate]] ("ADU", {{chem2|[NH4]2U2O7}}). Reduction with [[hydrogen]] gives {{chem2|UO2}}, which is converted with [[hydrofluoric acid]] (HF) to [[uranium tetrafluoride]], {{chem2|UF4}}. Oxidation with [[fluorine]] yields {{chem2|UF6}}.

The [[Honeywell Uranium Hexafluoride Processing Facility]] uses a different process.

During [[nuclear reprocessing#Fluoride volatility|nuclear reprocessing]], uranium is reacted with [[chlorine trifluoride]] to give {{chem2|UF6}}:

:{{chem2|U + 2 ClF3 → UF6 + Cl2}}

==Properties==

=== Physical properties ===

At [[atmospheric pressure]], {{chem2|UF6}} [[sublimation (phase transition)|sublimes]] at 56.5&nbsp;°C.<ref>{{cite journal |last1=Brickwedde |first1=Ferdinand G. |last2=Hoge |first2=Harold J. |last3=Scott |first3=Russell B. |year=1948 |title=The Low Temperature Heat Capacities, Enthalpies, and Entropies of UF₄ and UF₆ |journal=[[J. Chem. Phys.]] |volume=16 |issue=5 |pages=429–436 |doi=10.1063/1.1746914 |bibcode=1948JChPh..16..429B|doi-access=free}}</ref>

[[File:Uranium hexafluoride crystals sealed in an ampoule.jpg|thumb|center|upright=1.5|{{chem2|UF6}} in a glass [[ampoule]]]]

The solid-state structure was determined by [[neutron diffraction]] at 77 K and 293 K.<ref>{{cite journal |author1=J. H. Levy |author2=John C. Taylor |author3=Paul W. Wilson |title=Structure of Fluorides. Part XII. Single-Crystal Neutron Diffraction Study of Uranium Hexafluoride at 293 K |journal=J. Chem. Soc., Dalton Trans. |year=1976 |pages=219–224 |doi=10.1039/DT9760000219 |issue=3}}</ref><ref>{{cite journal |author=J. H. Levy, J. C. Taylor and A. B. Waugh |title=Neutron Powder Structural Studies of UF₆, MoF₆ and WF₆ at 77 K |journal=Journal of Fluorine Chemistry |year=1983 |pages=29–36 |volume=23 |doi=10.1016/S0022-1139(00)81276-2}}</ref>

<gallery class="center" widths="180" heights="200">

File:Uranium-hexafluoride-unit-cell-3D-balls.png|[[Ball-and-stick model]] of the unit cell of uranium hexafluoride<ref name="UF6_1973">J. C. Taylor, P. W. Wilson, J. W. Kelly: „The structures of fluorides. I. Deviations from ideal symmetry in the structure of crystalline UF₆: a neutron diffraction analysis", ''[[Acta Crystallogr.]]'', '''1973''', ''B29'', p.&nbsp;7–12; {{doi|10.1107/S0567740873001895}}.</ref>

File:Uranium hexafluoride dimensions.svg|Bond lengths and angles of gaseous uranium hexafluoride<ref name="UF6_1968">{{cite journal |last1=Kimura |first1=Masao |last2=Schomaker |first2=Werner |last3=Smith |first3=Darwin W. |last4=Bernard |year=1968 |title=Electron-Diffraction Investigation of the Hexafluorides of Tungsten, Osmium, Iridium, Uranium, Neptunium, and Plutonium |url=https://authors.library.caltech.edu/71173/ |journal=[[J. Chem. Phys.]] |volume=48 |issue=8 |pages=4001–4012 |doi=10.1063/1.1669727 |bibcode=1968JChPh..48.4001K |access-date=2020-10-10 |archive-date=2023-01-11 |archive-url=https://web.archive.org/web/20230111083844/https://authors.library.caltech.edu/71173/ |url-status=dead }}</ref>

</gallery>

===Chemical properties===

It has been shown that uranium hexafluoride is an [[oxidant]]<ref>{{cite journal |author1=G. H. Olah |author2=J. Welch |title=Synthetic methods and reactions. 46. Oxidation of organic compounds with uranium hexafluoride in haloalkane solutions |journal=[[J. Am. Chem. Soc.]] |year=1978 |pages=5396–5402 |volume=100 |issue=17 |doi=10.1021/ja00485a024}}</ref> and a [[Lewis acids and bases|Lewis acid]] that is able to bind to [[fluoride]]; for instance, the reaction of [[copper(II) fluoride]] with uranium hexafluoride in [[acetonitrile]] is reported to form copper(II) heptafluorouranate(VI), {{chem2|Cu(2+)[UF7−]2}}.<ref>{{cite journal |author1=J. A. Berry |author2=R. T. Poole |author3=A. Prescott |author4=D. W. A. Sharp |author5=J. M. Winfield |title=The oxidising and fluoride ion acceptor properties of uranium hexafluoride in acetonitrile |journal=J. Chem. Soc., Dalton Trans. |year=1976 |pages=272–274 |doi=10.1039/DT9760000272 |issue=3}}</ref>

[[Polymer]]ic uranium(VI) fluorides containing organic cations have been isolated and characterized by X-ray diffraction.<ref>{{cite journal |author1=S. M. Walker |author2=P. S. Halasyamani |author3=S. Allen |author4=D. O'Hare |title=From Molecules to Frameworks: Variable Dimensionality in the UO₂(CH₃COO)₂·2H₂O/HF(aq)/Piperazine System. Syntheses, Structures, and Characterization of Zero-Dimensional (C₄N₂H₁₂)UO₂F₄·3H₂O, One-Dimensional (C₄N₂H₁₂)₂U₂F₁₂·H₂O, Two-Dimensional (C₄N₂H₁₂)₂(U₂O₄F₅)₄·11H₂O, and Three-Dimensional (C₄N₂H₁₂)U₂O₄F₆ |journal=J. Am. Chem. Soc. |year=1999 |pages=10513–10521 |volume=121 |issue=45 |doi=10.1021/ja992145f}}</ref>

==Application in the fuel cycle==

[[File:Uranium hexafluoride phase diagram.gif|thumb|left|250px|[[Phase diagram]] of {{chem2|UF6}}]]

As one of the most [[volatility (chemistry)|volatile]] compounds of uranium, uranium hexafluoride is relatively convenient to process and is used in both of the main uranium [[nuclear enrichment|enrichment]] methods, namely [[gaseous diffusion]] and the [[gas centrifuge]] method. Since the [[triple point]] of {{chem2|UF6}}; 64 °C(147 °F; 337 K) and 152 kPa (22 psi; 1.5 atm);<ref>{{cite web |title=Uranium Hexafluoride: Source: Appendix A of the PEIS (DOE/EIS-0269): Physical Properties |url=https://web.evs.anl.gov/uranium/guide/ucompound/propertiesu/hexafluoride.cfm |access-date=2022-08-18 |website=web.evs.anl.gov}}</ref> is close to ambient conditions, phase transitions can be achieved with little [[work (thermodynamics)|thermodynamic work]].

Fluorine has only a single naturally occurring stable isotope, so [[isotopologue]]s of {{chem2|UF6}} differ in their molecular weight based solely on the uranium [[isotope]] present.<ref>{{cite web |title=Uranium Enrichment and the Gaseous Diffusion Process |publisher=USEC Inc |url=http://www.usec.com/v2001_02/HTML/Aboutusec_enrichment.asp |access-date=2007-09-24 |url-status=dead |archive-url=https://web.archive.org/web/20071019081831/http://www.usec.com/v2001_02/HTML/Aboutusec_enrichment.asp |archive-date=2007-10-19}}</ref> This difference is the basis for the physical separation of isotopes in enrichment.

All the other uranium fluorides are nonvolatile solids that are [[coordination polymer]]s.

The conversion factor for the {{chem2|^{238}U}} isotopologue of {{chem2|UF6}} ("hex") to "U mass" is 0.676.<ref>{{cite web

|website=TranslatorsCafé

|date=1 February 2021

|title=Unit converter molar mass calculator

|url=https://www.translatorscafe.com/unit-converter/en-US/molar-mass/?q=UF6

|publisher=ANVICA Software Development

|location=Mississauga, Ontario, Canada

}}</ref>

Gaseous diffusion requires about 60 times as much energy as the gas centrifuge process: gaseous diffusion-produced nuclear fuel produces 25 times more energy than is used in the diffusion process, while centrifuge-produced fuel produces 1,500 times more energy than is used in the centrifuge process.

In addition to its use in enrichment, uranium hexafluoride has been used in an advanced reprocessing method ([[fluoride volatility]]), which was developed in the [[Czech Republic]]. In this process, [[spent nuclear fuel]] is treated with fluorine gas to transform the oxides or elemental metals into a mixture of fluorides. This mixture is then distilled to separate the different classes of material. Some [[fission product]]s form nonvolatile fluorides which remain as solids and can then either be prepared for storage as nuclear waste or further processed either by [[solvation]]-based methods or [[electrochemistry|electrochemically]].

Uranium enrichment produces large quantities of [[depleted uranium hexafluoride]] (D{{chem2|UF6}} or D-{{chem2|UF6}}) as a waste product. The long-term storage of D-{{chem2|UF6}} presents environmental, health, and safety risks because of its chemical instability. When {{chem2|UF6}} is exposed to moist air, it reacts with the water in the air to produce {{chem2|UO2F2}} ([[uranyl fluoride]]) and HF ([[hydrogen fluoride]]) both of which are highly corrosive and toxic. In 2005, 686,500 tonnes of D-{{chem2|UF6}} was housed in 57,122 storage cylinders located near [[Portsmouth, Ohio]]; [[Oak Ridge, Tennessee]]; and [[Paducah, Kentucky]].<ref>{{cite web |work=Depleted UF₆ FAQs |title=How much depleted uranium hexafluoride is stored in the United States? |url=https://web.evs.anl.gov/uranium/faq/mgmt/faq23.cfm |publisher=[[Argonne National Laboratory]]}}</ref><ref>{{cite web |title=Depleted UF₆ Management Program Documents |url=https://web.evs.anl.gov/uranium/documents/ |access-date=2006-05-17 |url-status=live |archive-url=https://web.archive.org/web/20080216013118/http://web.ead.anl.gov/uranium/documents/index.cfm |archive-date=2008-02-16}}</ref> Storage cylinders must be regularly inspected for signs of corrosion and leaks. The estimated lifetime of the steel cylinders is measured in decades.<ref>{{cite web |publisher=Institute for Energy and Environmental Research |date=2007-09-24 |title=What is DUF₆? Is it dangerous and what should we do with it? |url=http://www.ieer.org/sdafiles/vol_5/5-2/deararj.html}}</ref>

== Accidents and disposal ==

There have been several accidents involving uranium hexafluoride in the US, including a cylinder-filling accident and material release at the [[Sequoyah Fuels Corporation]] in 1986 where an estimated 29 500 pounds of gaseous {{chem2|UF6}} escaped.<ref>{{cite journal | pmc=1963288 | date=2007 | last1=Brugge | first1=D. | last2=Delemos | first2=J. L. | last3=Bui | first3=C. | title=The Sequoyah Corporation Fuels Release and the Church Rock Spill: Unpublicized Nuclear Releases in American Indian Communities | journal=American Journal of Public Health | volume=97 | issue=9 | pages=1595–1600 | doi=10.2105/AJPH.2006.103044 | pmid=17666688 }}</ref> <ref>

{{cite web |work=Depleted UF₆ FAQs |title=Have there been accidents involving uranium hexafluoride? |url=http://web.ead.anl.gov/uranium/faq/health/faq30.cfm |publisher=Argonne National Laboratory |archive-url=https://web.archive.org/web/20170609171651/http://web.ead.anl.gov/uranium/faq/health/faq30.cfm |archive-date=2017-06-09}}</ref> The U.S. government has been converting D{{chem2|UF6}} to solid [[uranium oxides]] for disposal.<ref>{{cite web |work=Depleted UF₆ FAQs |title=What is going to happen to the uranium hexafluoride stored in the United States? |url=https://web.evs.anl.gov/uranium/faq/storage/faq22.cfm |publisher=Argonne National Laboratory}}</ref> Such disposal of the entire D{{chem2|UF6}} stockpile could cost anywhere from $15 million to $450 million.<ref>{{cite web |work=Depleted UF₆ FAQs |title=Are there any currently-operating disposal facilities that can accept all of the depleted uranium oxide that would be generated from conversion of DOE's depleted UF₆ inventory? |url=http://web.evs.anl.gov/uranium/faq/mgmt/faq27.cfm |publisher=Argonne National Laboratory}}</ref>

{{Gallery

|width=250

|height=180

|File:UF6 cylinder rupture bw.png

|Ruptured 14-ton {{chem2|UF6}} shipping cylinder. 1 fatality, dozens injured. ~29500&nbsp;lbs of material released. Sequoyah Fuels Corporation 1986.

|File:DUF6 storage yard far.jpg

|D{{chem2|UF6}} storage yard from afar

|File:Corroded DUF6 cylinder.jpg

|D{{chem2|UF6}} cylinders: painted (left) and corroded (right)<!-- (The left image is available on Commons; have to find the right image and then can make it look better as currently the images are not sized correctly.) -->

}}

==References==

{{Reflist}}

==Further reading==

* ''[[Gmelins Handbuch der anorganischen Chemie]]'', System Nr. 55, Uran, Teil A, p.&nbsp;121–123.

* ''Gmelins Handbuch der anorganischen Chemie'', System Nr. 55, Uran, Teil C&nbsp;8, p.&nbsp;71–163.

* R. DeWitt: ''Uranium hexafluoride: A survey of the physico-chemical properties'', Technical report, GAT-280; Goodyear Atomic Corp., Portsmouth, Ohio; 12.&nbsp;August 1960; {{doi|10.2172/4025868}}.

* Ingmar Grenthe, Janusz Drożdżynński, Takeo Fujino, Edgar C. Buck, [[Thomas E. Albrecht-Schmitt]], Stephen F. Wolf: [http://radchem.nevada.edu/classes/rdch710/files/Uranium.pdf Uranium] {{Webarchive|url=https://web.archive.org/web/20120118213655/http://radchem.nevada.edu/classes/rdch710/files/Uranium.pdf |date=2012-01-18}}, in: Lester R. Morss, Norman M. Edelstein, Jean Fuger (Hrsg.): ''The Chemistry of the Actinide and Transactinide Elements'', Springer, Dordrecht 2006; {{ISBN|1-4020-3555-1}}, p.&nbsp;253–698; {{doi|10.1007/1-4020-3598-5_5}} (p.&nbsp;530–531, 557–564).

* US-Patent 2535572: [https://www.freepatentsonline.com/2535572.html Preparation of UF₆]; 26. December 1950.

* US-Patent 5723837: [https://www.freepatentsonline.com/5723837.html Uranium Hexafluoride Purification]; 3. March 1998.

==External links==

{{Commons category}}

* Simon Cotton (Uppingham School, Rutland, UK): [http://www.chm.bris.ac.uk/motm/uf6/uf6v.htm Uranium Hexafluoride].

* [https://web.evs.anl.gov/uranium/guide/uf6/ Uranium Hexafluoride (UF₆) – Physical and chemical properties of UF₆, and its use in uranium processing – Uranium Hexafluoride and Its Properties]

* [https://www.webelements.com/compounds/uranium/uranium_hexafluoride.html Uranium Hexafluoride] at WebElements

* [http://ecoperestroika.ru/english/details-import-of-uranium-tails-2013-and-our-protests/ Import of Western depleted uranium hexafluoride (uranium tails) to Russia] [dead link 30 June 2017]

{{Hexafluorides}}

{{Uranium compounds}}

{{Fluorides}}

{{Actinide halides}}

[[Category:Actinide halides]]

[[Category:Hexafluorides]]

[[Category:Nuclear materials]]

[[Category:Octahedral compounds]]

[[Category:Uranium(VI) compounds]]