 | |
 | |
| Names | |
|---|---|
| IUPAC names Xenon trioxide Xenon(VI) oxide | |
| Other names Xenic anhydride | |
| Identifiers | |
3D model (JSmol) | |
| ChemSpider |
|
| UNII | |
| |
| |
| Properties | |
| XeO3 | |
| Molar mass | 179.288 g/mol |
| Appearance | colourless crystalline solid |
| Density | 4.55 g/cm3, solid |
| Melting point | 25 °C (77 °F; 298 K)Violent decomposition |
| Soluble (with reaction) | |
| Structure | |
| trigonal pyramidal (C3v) | |
| Thermochemistry | |
Std enthalpy of formation(ΔfH⦵298) | 402 kJ·mol−1[1] |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Related compounds | |
Related compounds | Xenon tetroxide Xenic acid |
Except where otherwise noted, data are given for materials in theirstandard state (at 25 °C [77 °F], 100 kPa). | |
Xenon trioxide is an unstablecompound ofxenon in its +6oxidation state. It is a very powerfuloxidizing agent, and liberates oxygen from water slowly, accelerated by exposure to sunlight. It is dangerously explosive upon contact with organic materials. When it detonates, it releases xenon and oxygen gas.
Synthesis of xenon trioxide is by aqueous hydrolysis ofXeF
6:[2]
The resulting xenon trioxide crystals are a strong oxidising agent and can oxidise most substances that are at all oxidisable. However, it is slow-acting and this reduces its usefulness.[3]
Above 25 °C, xenon trioxide is very prone to violent explosion:
When it dissolves in water, an acidic solution ofxenic acid is formed:
This solution is stable at room temperature and lacks the explosive properties of xenon trioxide. It oxidisescarboxylic acids quantitatively tocarbon dioxide andwater.[4]
Alternatively,15-crown-5 coordinates to xenon trioxide to give a complex stable at room-temperature against mechanical shock.[5]
Alternatively, it dissolves in alkaline solutions to formxenates. TheHXeO−
4 anion is the predominant species in xenate solutions.[6] These are not stable and begin todisproportionate intoperxenates (+8 oxidation state) and xenon and oxygen gas.[7] Solid perxenates containingXeO4−
6 have been isolated by reactingXeO
3 with an aqueous solution of hydroxides. Xenon trioxide reacts with inorganic fluorides such as KF, RbF, or CsF to form stable solids of the formMXeO
3F.[8]
Hydrolysis ofxenon hexafluoride orxenon tetrafluoride yields a solution from which colorless XeO3 crystals can be obtained by evaporation.[2] The crystals are stable for days in dry air, but readily absorb water from humid air to form a concentrated solution. The crystal structure isorthorhombic witha = 6.163 Å,b = 8.115 Å,c = 5.234 Å, and 4 molecules per unit cell. The density is 4.55 g/cm3.[9]
 |  |  |
| ball-and-stick model of part of the crystal structure of XeO3 | space-filling model | coordination geometry of XeO3 |
XeO3 should be handled with great caution. Samples have detonated when undisturbed at room temperature. Dry crystals react explosively withcellulose.[9][10]
