Xenon tetroxide
| |||
| Names | |||
|---|---|---|---|
| IUPAC names
xenon tetraoxide
xenon(VIII) oxide | |||
| Structure | |||
| Tetrahedral[1] | |||
| 0 D | |||
| Properties | |||
| XeO4 | |||
| Molar mass | 195.29 g mol−1 | ||
| Appearance | Yellow solid below −36°C | ||
| Density | ? g cm−3, solid | ||
| Melting point | −35.9 °C | ||
| Boiling point | 0 °C[2] | ||
| Thermochemistry | |||
Std molar
entropy (S⦵298) |
? J.K−1.mol−1 | ||
Std enthalpy of
formation (ΔfH⦵298) |
? kJ mol−1 | ||
| Related compounds | |||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
| |||
Xenon tetroxide is a chemical compound of xenon and oxygen with molecular formula XeO4, remarkable for being a relatively stable compound of a noble gas. It is a yellow crystalline solid that is stable below −35.9 °C; above that temperature it explodes, decomposing into xenon and oxygen (O2).[3][4]
All eight valence shell electrons of xenon are involved in the bonds with the oxygen, and the oxidation state of the xenon atom is +8. Oxygen is the only element that can bring xenon up to its highest oxidation state; even fluorine can only give XeF6, probably for steric reasons.
Reactions
A spontaneous explosion occurs at temperature above −35.9 °C , with ΔH = −643 kJ/mol.
- XeO4 → Xe + 2 O2
The two other short lived xenon compounds with an oxidation state of +8 are accessible by the reaction of xenon tetroxide with xenon hexafluoride. XeO3F2 and XeO2F4 can be detected with mass spectroscopy.
Synthesis
All syntheses start from the perxenates, which are accessible from the xenates through two methods. One is the disproportionation of xenates to perxenates and xenon:
- 2 XeO42− → XeO64− + Xe + O2.
The other is oxidation of the xenates with ozone:
- 2 XeO42− + 4 e− + 2 O3 → 2 XeO64− + 2 O2.
Barium perxenate is reacted with sulfuric acid and the unstable perxenic acid is dehydrated to give xenon tetroxide:
- Ba2XeO6 + 2 H2SO4 → 2 BaSO4 + (H4XeO6 → 2 H2O + XeO4).
The unstable perxenic acid slowly undergoes a disproportionation reaction to the xenic acid and oxygen:
- H4XeO6 → 1/2 O2 + H2XeO4 + H2O.
See also
References
- ^ G. Gundersen, K. Hedberg, J. L.Huston (1970). "Molecular Structure of Xenon Tetroxide, XeO4". J. Chem. Phys. 52: 812–815. doi:10.1063/1.1673060.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, p. 494, ISBN 0849305942
- ^
H.Selig , J. G. Malm , H. H. Claassen , C. L. Chernick , J. L. Huston (1964). "Xenon tetroxide -Preparation + Some Properties". Science. 143: 1322. doi:10.1126/science.143.3612.1322. PMID 17799234.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^
J. L. Huston, M. H. Studier, E.N. Sloth (1964). "Xenon tetroxide - Mass Spectrum". Science. 143: 1162. doi:10.1126/science.143.3611.1161-a. PMID 17833897.
{{cite journal}}: CS1 maint: multiple names: authors list (link)
- Lide, D. R., ed. (2002). CRC Handbook of Chemistry and Physics (83rd ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0483-0.