Xenon (VIII) oxide

Structural formula
General
Surname	Xenon (VIII) oxide
other names	Xenon tetroxide
Molecular formula	XeO 4
Brief description	as a solid: yellow, easily exploding crystals
External identifiers / databases
Wikidata	Q411822
properties
Molar mass	195.29 g mol −1
Physical state	gaseous
Melting point	−39.5 ° C
safety instructions
GHS hazard labeling ; no classification available
GHS hazard labeling ; no classification available
Thermodynamic properties
ΔH f 0	643 kJ / mol
	As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Xenon (VIII) oxide is an oxide of the noble gas xenon and thus a noble gas compound . It is a colorless gas under standard conditions.

Extraction and presentation

Solutions of xenates in the form of HXeO ₄^- are used as the starting material for the production of xenon (VIII) oxide . These can be oxidized by disproportionation or with the help of ozone to perxenates of the form HXeO ₆³⁻ and precipitated as barium perxenate Ba ₂ XeO ₆ . With the help of concentrated sulfuric acid , the unstable intermediate stage perxenonic acid H ₄ XeO ₆ xenon (VIII) oxide can be obtained:

{\ displaystyle \ mathrm {Ba_ {2} XeO_ {6} +2 \ H_ {2} SO_ {4} \ rightarrow 2 \ BaSO_ {4} + (H_ {4} XeO_ {6}),}}

Formation of the intermediate stage

{\ displaystyle \ mathrm {(H_ {4} XeO_ {6}) \ rightarrow XeO_ {4} +2 \ H_ {2} O.}}

Formation of xenon (VIII) oxide

These reactions are carried out at −5 ° C, whereby the product xenon tetraoxide escapes as a gas.

properties

Xenon (VIII) oxide has a positive enthalpy of formation of 643 kJ / mol and is therefore a strongly endothermic compound. As a result, it tends to break down explosively with the formation of elemental xenons and molecular oxygen. In the solid state below −39.5 ° C, it is a yellowish, crystalline mass of considerably greater stability. Occasionally it can also explode at low temperatures (−40 ° C), which is why xenon tetraoxide must be handled with great care and at the lowest possible temperatures ( nitrogen cooling ). A sudden explosion is triggered when the heat of reaction accumulated or (oxygen) radicals accelerate the further reaction due to gradual decomposition .

Aqueous solution

In aqueous solution, xenon (VIII) oxide is present in the form of HXeO ₆³⁻ ions, which can be derived from the inconsistent and non-isolable perxenonic acid H ₄ XeO ₆ . The reason for their instability lies in the decomposition of perxenonic acid to xenonic acid and oxygen . The decomposition takes place slowly in the basic and very quickly in the acidic . On the other hand, a large number of salts that are derived from perxenonic acid and are called perxenates are stable . Examples are barium perxenate Ba ₂ XeO ₆ or sodium perxenate Na ₄ XeO ₆

Individual evidence

↑ Entry on xenon connections. In: Römpp Online . Georg Thieme Verlag, accessed on July 14, 2014.
^ ^A ^b A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 .
↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
^ H. Selig, JG Malm, HH Claassen, CL Chernick, JL Huston: Xenon tetroxide - Preparation and Some Properties. In: Science. 143 (1964), p. 1322.

[roempp-1] Entry on xenon connections. In: Römpp Online . Georg Thieme Verlag, accessed on July 14, 2014.

[HoWi-2] A ^b A. F. Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 102nd edition. Walter de Gruyter, Berlin 2007, ISBN 978-3-11-017770-1 .

[NV-3] This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.

[4] H. Selig, JG Malm, HH Claassen, CL Chernick, JL Huston: Xenon tetroxide - Preparation and Some Properties. In: Science. 143 (1964), p. 1322.