Xenon trioxide

Xenon trioxide

Structural formula, showing lone pair
Space-filling model
Names
IUPAC names Xenon trioxide Xenon(VI) oxide
Other names Xenic anhydride
Identifiers
CAS Number	13776-58-4 N
ChemSpider	21106493 N
Jmol 3D model	Interactive image
InChI InChI=1S/O3Xe/c1-4(2)3 N Key: ZWAWYSBJNBVQHP-UHFFFAOYSA-N N InChI=1/O3Xe/c1-4(2)3 Key: ZWAWYSBJNBVQHP-UHFFFAOYAR
SMILES O=[Xe](=O)=O
Properties
Chemical formula	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
Solubility in water	Soluble (with reaction)
Structure
Molecular shape	trigonal pyramidal (C3v)
Thermochemistry
Std enthalpy of formation (ΔfHo298)	402 kJ·mol−1
Vapor pressure	{{{value}}}
Related compounds
Related compounds	Xenon tetroxide Xenic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Xenon trioxide is an unstable compound of xenon in its +6 oxidation state. It is a very powerful oxidizing agent, and liberates oxygen from water slowly (and xenon), accelerated by exposure to sunlight. It is dangerously explosive upon contact with organic materials. When it detonates, it releases xenon and oxygen gas.

Chemistry

Xenon trioxide is a strong oxidising agent and can oxidise most substances that are at all oxidisable. However, it is slow-acting and this reduces its usefulness.

Above 25 °C, xenon trioxide is very prone to violent explosion:

2 XeO₃ → 2 Xe + 3 O₂

When it dissolves in water, an acidic solution of xenic acid is formed:

XeO₃ (aq) + H₂O → H₂XeO₄ ⇌ H⁺ + HXeO₄⁻

This solution is stable at room temperature and lacks the explosive properties of xenon trioxide. It oxidises carboxylic acids quantitatively to carbon dioxide and water.

Alternatively, it dissolves in alkaline solutions to form xenates. The HXeO⁻
₄ anion is the predominant species in xenate solutions. These are not stable and begin to disproportionate into perxenates (+8 oxidation state) and xenon and oxygen gas. Solid perxenates containing XeO⁴⁻
₆ have been isolated by reacting XeO
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 form MXeO
₃F.

Physical properties

Hydrolysis of xenon hexafluoride or xenon tetrafluoride yields a solution from which colorless XeO₃ crystals can be obtained by evaporation. The crystals are stable for days in dry air, but readily absorb water from humid air to form a concentrated solution. The crystal structure is orthorhombic with a = 6.163, b = 8.115, c = 5.234 Å and 4 molecules per unit cell. The density is 4.55 g/cm³.

200px	200px	180px
ball-and-stick model of part of the crystal structure of XeO3	space-filling model	coordination geometry of Xe

Safety

XeO₃ should be handled with great caution. Samples have detonated when undisturbed at room temperature. Dry crystals react explosively with cellulose.

External links

• Webelements periodic table: page on Xenon(VI) oxide