Uranium trioxide

Uranium trioxide (UO3), also called uranyl oxide, uranium(VI) oxide, and uranic oxide, is an oxide of uranium. UO3 is a hexavalent oxide, which means that the uranium in the compound has an oxidation state of +6. It can be formed by heating uranyl nitrate to 400 °C.

Uranium trioxide
UO3 gamma lattice.png
IUPAC name Uranium trioxide
Uranium(VI) oxide
Other names Uranyl oxide
Uranic oxide
Identifiers
CAS number 1344-58-7
Properties
Molecular formula UO3
Molar mass 286.29 g/mol
Appearance yellow-orange powder
Density 5.5–8.7 g/cm3
Melting point

~200–650 °C (decomposes)

Solubility in water Partially soluble
Structure
Crystal structure see text
Space group I41/amd (γ-UO3)
Thermochemistry
Std enthalpy of
formation
ΔfHo298
−1230 kJ·mol−1[1]
Standard molar
entropy
So298
99 J·mol−1·K−1[1]
Hazards
EU classification Very toxic (T+)
Dangerous for the environment (N)
NFPA 704

NFPA 704.svg

0
4
1
 
R-phrases R26/28, R33, R51/53
S-phrases (S1/2), S20/21, S45, S61
Flash point Non-flammable
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

UO3 is a poisonous and slightly radioactive substance. It can be harmful if it is breathed in, ingested, or makes contact with skin.

Uranium Trioxide Media

References

  1. 1.0 1.1 Zumdahl, Steven S. (2009). Chemical Principles 6th Ed. Houghton Mifflin Company. p. A23. ISBN 978-0-618-94690-7.