| Revision as of 03:47, 19 December 2010 editCheMoBot (talk | contribs)Bots141,565 edits Updating {{chembox}} (no changed fields - added verified revid - updated 'UNII_Ref', 'ChemSpiderID_Ref', 'StdInChI_Ref', 'StdInChIKey_Ref') per Chem/Drugbox validation (report [[Wikipedia_talk:Wi← Previous edit |
Latest revision as of 16:15, 19 January 2025 edit undoMinusBot (talk | contribs)Bots3,739 editsm →2) <sup>+</sup> + H<sub>2</sub>O → <sup>+</sup>: Proper minus signs and other cleanup. Report bugs, errors, and suggestions at User talk:MinusBotTag: AWB |
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{{chembox |
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| verifiedrevid = 354512904 |
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| verifiedrevid = 403121369 |
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| ImageFile = Kristallstruktur Uranylhydroxid.png |
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| ImageFile = Kristallstruktur Uranylhydroxid.png |
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| ImageFile_Ref = {{chemboximage|correct|??}} |
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| ImageName = Ball and stick model of crystalline uranyl hydroxide |
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| IUPACName = |
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|Section1={{Chembox Identifiers |
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| CASNo_Ref = {{cascite|changed|??}} |
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| Section1 = {{Chembox Identifiers |
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| CASNo = |
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| CASNo = 211573-15-8 |
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| PubChem = |
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| PubChem = 5465112 |
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| SMILES = |
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| ChemSpiderID = 4576989 |
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| ChemSpiderID_Ref = {{chemspidercite|changed|chemspider}} |
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| UNNumber = 2909 |
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| SMILES = O==O.. |
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| StdInChI = 1S/2H2O.2O.U/h2*1H2;;;/q;;;;+2/p-2 |
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| StdInChI_Ref = {{stdinchicite|changed|chemspider}} |
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| StdInChIKey = VWIQIIGYDAPONF-UHFFFAOYSA-L |
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| StdInChIKey_Ref = {{stdinchicite|changed|chemspider}} |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| U = 1 | O = 4 | H = 2 |
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| Formula = {{Chem|UH|2|O|4}} |
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| MolarMass = 304.0424 g mol<sup>−1</sup> |
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| Density = 5.73 - 6.73 g/cc |
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| Section3 = {{Chembox Hazards |
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| OtherCompounds = ]<br />]<br />] |
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'''Uranyl hydroxide''' is a ] of ] with the chemical formula UO<sub>2</sub>(OH)<sub>2</sub> in the monomeric form and (UO<sub>2</sub>)<sub>2</sub>(OH)<sub>4</sub> in the dimeric; both forms may exist in normal aqueous media. Uranyl hydroxide hydrate is precipitated as a ]al ] from oxidized ] liquors near neutral pH. |
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'''Uranyl hydroxide''' is a ] of ] with the chemical formula UO<sub>2</sub>(OH)<sub>2</sub> in the monomeric form and <sup>2-</sup> in the dimeric; both forms may exist in normal aqueous media. In aerobic conditions, up to 5 hydroxides can bind to Uranyl {<sup>3-</sup>}'''.''' Uranyl hydroxide hydrate is precipitated as a ]al ] from oxidized uranium liquors near neutral pH. |
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] hydroxide was once used in glassmaking and ]s in the colouring of the ] phases and the preparation of pigments for high temperature firing. The introduction of ] diuranates into ]es leads to yellow by transmission, green by reflection; moreover these glasses become ] and ] under ] rays. |
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] hydroxide was once used in glassmaking and ]s in the colouring of the ] phases and the preparation of pigments for high temperature firing. The introduction of ] di] (like ]) into ]es leads to yellow by transmission, green by reflection; moreover these glasses become ] and ] under ] rays. |
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Uranyl hydroxide is ] and ], and should be handled with the appropriate care. |
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Uranyl hydroxide is ] and ]. |
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== Formation == |
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The formation of uranyl hydroxide hydrate can occur via hydrated uranyl fluoride <sub>7</sub>·4H<sub>2</sub>O which is not stable at an elevated water vapor pressure. A complete loss of fluorine is undergone and the formation of uranyl hydroxide hydrate (·5H<sub>2</sub>O) occurs. This uranyl hydroxide species is structurally similar to the uranyl hydroxide hydrate minerals schoepite and metaschoepite. X-ray diffraction data was gathered and found that this species has expanded interlayer spacing suggesting there may be additional water molecules in between uranyl layers. Unlike metaschoepite, however, this species does not form UO<sub>2</sub>(OH)<sub>2</sub> upon dehydration.<ref>{{Cite journal |last1=Kirkegaard |first1=Marie C. |last2=Spano |first2=Tyler L. |last3=Ambrogio |first3=Michael W. |last4=Niedziela |first4=J. L. |last5=Miskowiec |first5=Andrew |last6=Shields |first6=Ashley E. |last7=Anderson |first7=Brian B. |date=2019 |title=Formation of a uranyl hydroxide hydrate via hydration of 7 ·4H 2 O |url=https://xlink.rsc.org/?DOI=C9DT02835H |journal=Dalton Transactions |language=en |volume=48 |issue=36 |pages=13685–13698 |doi=10.1039/C9DT02835H |pmid=31468045 |osti=1607115 |issn=1477-9226}}</ref> |
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== Reactions == |
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{{Empty section|date=December 2024}} |
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== 1) (UO<sub>2</sub>(OH)<sup>+</sup> + H<sub>2</sub>O → <sup>+</sup> == |
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{{Empty section|date=December 2024}} |
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== 2) <sup>+</sup> + H<sub>2</sub>O → <sup>+</sup> == |
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UO<sub>2</sub>(OH)<sub>2</sub> reacts with water in a hydration reaction to form <sup>+</sup> and the monohydrate form also reacted with water to form dihydrates <sup>+</sup> and trihydrates <sup>+</sup>. The hydration reaction to form the monohydrate was significantly slower than if the hydroxide were replaced with acetate or nitrate. This could be due to the strongly basic (OH)<sup>−</sup> reducing the Lewis acidity of U or because the more complex acetate and nitrate anions provide more degrees of freedom. However, it was found that the formation of the dihydrate uranyl hydroxide hydrate (2) was nearly three times faster than the monohydrate (1).<ref>{{Cite journal |last1=Chien |first1=Winnie |last2=Anbalagan |first2=Victor |last3=Zandler |first3=Melvin |last4=Van Stipdonk |first4=Michael |last5=Hanna |first5=Dorothy |last6=Gresham |first6=Garold |last7=Groenewold |first7=Gary |date=2004-06-01 |title=Intrinsic hydration of monopositive uranyl hydroxide, nitrate, and acetate cations |url=https://pubs.acs.org/doi/10.1016/j.jasms.2004.01.013 |journal=Journal of the American Society for Mass Spectrometry |language=en |volume=15 |issue=6 |pages=777–783 |doi=10.1016/j.jasms.2004.01.013 |pmid=15144967 |bibcode=2004JASMS..15..777C |issn=1044-0305}}</ref> |
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== Mechanisms == |
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A mechanism for oxygen exchange between the UO<sub>2</sub><sup>2+</sup> cations in a highly alkaline solution was proposed and investigated by Shamov et al. in the ''Journal of the American Chemical Society''.<ref>{{Cite journal |last1=Shamov |first1=Grigory A. |last2=Schreckenbach |first2=Georg |date=2008-10-15 |title=Theoretical Study of the Oxygen Exchange in Uranyl Hydroxide. An Old Riddle Solved? |url=https://pubs.acs.org/doi/10.1021/ja804742f |journal=Journal of the American Chemical Society |language=en |volume=130 |issue=41 |pages=13735–13744 |doi=10.1021/ja804742f |pmid=18808120 |bibcode=2008JAChS.13013735S |issn=0002-7863}}</ref> An equilibrium between <sup>2-</sup>] and <sup>3-</sup>] was observed followed by the formation of the stable <sup>3−</sup>] intermediate that formed from <sup>3-</sup>] via intramolecular water elimination. |
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==References== |
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==References== |
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{{reflist}} |
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* Alexander, C.A. (2005) ''Journal of Nuclear Materials,'' '''346,''' 312–318. |
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* Alexander, C.A. (2005) ''Journal of Nuclear Materials,'' '''346,''' 312–318. |
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{{Uranium compounds}} |
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==External links== |
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{{Hydroxides}} |
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{{Uranium compounds}} |
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{{Inorganic-compound-stub}} |
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