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| Names | |
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| Other names
Uranium(V,VI) oxide
Pitchblende C.I. 77919 | |
| Identifiers | |
3D model (JSmol)
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| ChemSpider | |
| ECHA InfoCard | 100.014.275 |
| EC Number |
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PubChem CID
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CompTox Dashboard (EPA)
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| Properties | |
| U3O8 | |
| Molar mass | 842.08 g/mol |
| Melting point | 1,150 °C (2,100 °F; 1,420 K) |
| Boiling point | decomposes to UO2 at 1,300 °C (2,370 °F; 1,570 K) |
| Solubility in other solvents | Insoluble in water;
Soluble in nitric and sulfuric acids. |
| Thermochemistry | |
Std molar
entropy (S⦵298) |
282 J·mol−1·K−1[1] |
Std enthalpy of
formation (ΔfH⦵298) |
−3575 kJ·mol−1[1] |
| Hazards | |
| GHS labelling: | |
  
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| Danger | |
| H300, H330, H373, H411 | |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Triuranium octoxide (U3O8)[2] is a compound of uranium. It is present as an olive green to black, odorless solid. It is one of the more popular forms of yellowcake and is shipped between mills and refineries in this form.
U3O8 has potential long-term stability in a geologic environment. In the presence of oxygen (O2), uranium dioxide (UO2) is oxidized to U3O8, whereas uranium trioxide (UO3) loses oxygen at temperatures above 500 °C and is reduced to U3O8. The compound can be produced by any one of three primary chemical conversion processes, involving either uranium tetrafluoride (UF4) or uranyl fluoride (UO2F2) as intermediates. It is generally considered to be the more attractive form for disposal purposes because, under normal environmental conditions, U3O8 is one of the most kinetically and thermodynamically stable forms of uranium. Its particle density is 8.3 g cm−3.[citation needed]
Triuranium octoxide is converted to uranium hexafluoride for the purpose of uranium enrichment.[citation needed]
- ^ a b Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 978-0-618-94690-7.
- ^ "triuranium octaoxide". webbook.nist.gov. Retrieved 2022-12-20.