Uranium Oxide

U₃O₈

 uranium (V, VI) oxide

• Formula as commonly written: U₃O₈
• Hill system formula: O₈U₃
• CAS registry number: [1344-59-8]
• Formula weight: 842.082
• Class: oxide

Synonyms

• uranium (V, VI) oxide
• uranium oxide
• pitchblende
• triuranium octaoxide

Physical properties

• Colour: very dark green-black
• Appearance:
• Melting point: 1150°C; 1300°C (decomposes to UO₂)
• Boiling point:
• Density: 8380 kg m^-3

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IBILABS

Element analysis and oxidation numbers

For each compound, and where possible, a formal oxidation number for each element is given, but the usefulness of this number is limited, especially so for p-block elements in particular. Based upon that oxidation number, an electronic configuration is also given but note that for more exotic compounds you should view this as a guide only.

Element	%	Formal oxidation state	Formal electronic configuration
O	15.20	-2	[He].2s2.2p6
U	84.80

Synthesis

Not available

Solid state structure

• Geometry of uranium: 7 coordinate: pentagonal bipyramidal
• Prototypical structure:

 

Isotope pattern

What follows is the calculated isotope pattern for the U₃O₈ unit with the most intense ion set to 100%.

Formula: U₃O₈

mass  %836   0.0 837   0.0 838   0.0 839   2.2 _ 840   0.0 841   0.0 842 100.0 843   0.3 844   1.6 845   0.0 846   0.0

 

 

CAS #		Formula		Formula Weight
		U3O8		842.09
Color Crystalline Form	Specific Gravity		Melting Point		Boiling Point
olive-grn-blk	8.30		d 1300 to UO2
Solubility in 100 parts
Cold Water		Hot Water		Other Reagents
				s HNO3

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Uranium Oxide

Ingredient Name:        Uranium Oxide: U3O8CAS Number:              11344-57-6Percent:                       ca 100Exposure Limits:         * OSHA PEL: 0.05 mg/m3, 8‑hr TWA Appearance & Odor:  Uranium oxide is usually a dull, dark charcoal-gray or flat black colored                     powder (U308) with no detectable odor. Boiling point:  NA                                                                    Specific Gravity (H2O=l):       8.30 Vapor Density (Air=1):  NA                                                       Vapor Pressure:                        NA Water Solubility (%):  Insoluble                                                Melting Point:        >>1300 °C Evaporation Rate:  NA                                                              % Volatile By Volume:        NA Molecular Weight:  842.09 Melting point for oxides is much higher than for metal (1132 °C), U3O8 decomposes to UO2 at 1300°C. {UO2 specific gravity = 10.96, melting point = 2878 °C.} {UO3 specific gravity =  7.29  (melting point NA)} Meets ACS specifications