Xenon trioxide

Source: Wikipedia, the free encyclopedia.
Xenon trioxide
Structural formula, showing lone pair
Space-filling model
Names
IUPAC names
Xenon trioxide
Xenon(VI) oxide
Other names
Xenic anhydride
Identifiers
3D model (
JSmol
)
ChemSpider
UNII
  • InChI=1S/O3Xe/c1-4(2)3 checkY
    Key: ZWAWYSBJNBVQHP-UHFFFAOYSA-N checkY
  • InChI=1/O3Xe/c1-4(2)3
    Key: ZWAWYSBJNBVQHP-UHFFFAOYAR
  • [O-] [Xe+3]([O-])[O-]
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)
NFPA 704 four-colored diamondHealth 4: Very short exposure could cause death or major residual injury. E.g. VX gasFlammability 0: Will not burn. E.g. waterInstability 4: Readily capable of detonation or explosive decomposition at normal temperatures and pressures. E.g. nitroglycerinSpecial hazard OX: Oxidizer. E.g. potassium perchlorate
4
0
4
OX
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 checkY☒N ?)

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, accelerated by exposure to sunlight. It is dangerously explosive upon contact with organic materials. When it detonates, it releases xenon and oxygen gas.

Chemistry

Synthesis of xenon trioxide is by aqueous hydrolysis of XeF
6:[2]

XeF
6 + 3 H
2O → XeO
3 + 6 HF

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:

2 XeO3 → 2 Xe + 3 O2  (ΔfH = −403 kJ/mol)

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

XeO3(aq) + H2O → H2XeO4 ⇌ H+ + HXeO−
4

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.[4]

Alternatively, it dissolves in alkaline solutions to form xenates. The HXeO−
4 anion is the predominant species in xenate solutions.[5] These are not stable and begin to disproportionate into perxenates (+8 oxidation state) and xenon and oxygen gas.[6] 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.[7]

Physical properties

Hydrolysis of

orthorhombic with a = 6.163 Å, b = 8.115 Å, c = 5.234 Å, and 4 molecules per unit cell. The density is 4.55 g/cm3.[8]

ball-and-stick model of part of
the crystal structure of XeO3		 space-filling model coordination geometry of XeO3

Safety

XeO3 should be handled with great caution. Samples have detonated when undisturbed at room temperature. Dry crystals react explosively with cellulose.[8][9]

References

  1. ISBN 978-0-618-94690-7
    .
  2. ^
    ISBN 0-12-023646-X
    .
  3. ^ Greenwood, N.; Earnshaw, A. (1997). Chemistry of the Elements. Oxford: Butterworth-Heinemann.
  4. PMID 18959958
    .
  5. doi:10.1021/ic50085a037
    .
  6. ISBN 0-85404-617-8
    .
  7. ISBN 0-12-352651-5
    .
  8. ^
    doi:10.1021/ja00889a037
    .
  9. PMID 17843880
    .

External links
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