Xenon tetroxide is a

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one element ...

xenon Xenon is a chemical element; it has symbol Xe and atomic number 54. It is a dense, colorless, odorless noble gas found in Earth's atmosphere in trace amounts. Although generally unreactive, it can undergo a few chemical reactions such as the ...

and

oxygen Oxygen is a chemical element; it has chemical symbol, symbol O and atomic number 8. It is a member of the chalcogen group (periodic table), group in the periodic table, a highly reactivity (chemistry), reactive nonmetal (chemistry), non ...

with molecular formula XeO₄, remarkable for being a relatively stable compound of a noble gas. It is a yellow

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macros ...

line

solid Solid is a state of matter where molecules are closely packed and can not slide past each other. Solids resist compression, expansion, or external forces that would alter its shape, with the degree to which they are resisted dependent upon the ...

that is stable below −35.9 ° C; above that temperature it is very prone to exploding and decomposing into elemental xenon and oxygen (O₂). All eight

valence electron In chemistry and physics, valence electrons are electrons in the outermost shell of an atom, and that can participate in the formation of a chemical bond if the outermost shell is not closed. In a single covalent bond, a shared pair forms with b ...

s of xenon are involved in the bonds with the oxygen, and the

oxidation state In chemistry, the oxidation state, or oxidation number, is the hypothetical Electrical charge, charge of an atom if all of its Chemical bond, bonds to other atoms are fully Ionic bond, ionic. It describes the degree of oxidation (loss of electrons ...

of the xenon atom is +8. Oxygen is the only element that can bring xenon up to its highest oxidation state; even

fluorine Fluorine is a chemical element; it has Chemical symbol, symbol F and atomic number 9. It is the lightest halogen and exists at Standard temperature and pressure, standard conditions as pale yellow Diatomic molecule, diatomic gas. Fluorine is extre ...

can only give XeF₆ (+6). Two other short-lived xenon compounds with an oxidation state of +8, XeO₃F₂ and XeO₂F₄, are accessible by the reaction of xenon tetroxide with

xenon hexafluoride Xenon hexafluoride is a noble gas compound with the formula XeF6. It is one of the three binary fluorides of xenon that have been studied experimentally, the other two being XeF2 and XeF4. All of them are exergonic and stable at normal temperatur ...

. XeO₃F₂ and XeO₂F₄ can be detected with

mass spectrometry Mass spectrometry (MS) is an analytical technique that is used to measure the mass-to-charge ratio of ions. The results are presented as a ''mass spectrum'', a plot of intensity as a function of the mass-to-charge ratio. Mass spectrometry is used ...

. The perxenates are also compounds where xenon has the +8 oxidation state. __TOC__

Reactions

At temperatures above −35.9 °C, xenon tetroxide is very prone to explosion, decomposing into xenon and oxygen gases with Δ''H'' = −643 kJ/mol: :XeO₄ → Xe + 2 O₂ Xenon tetroxide dissolves in water to form perxenic acid and in alkalis to form perxenate salts: :XeO₄ + 2 H₂O → H₄XeO₆ :XeO₄ + 4 NaOH → Na₄XeO₆ + 2 H₂O Xenon tetroxide can also react with

to give xenon oxyfluorides: :XeO₄ + XeF₆ → XeOF₄ + XeO₃F₂ :XeO₄ + 2XeF₆ → XeO₂F₄ + 2 XeOF₄

Synthesis

All syntheses start from the perxenates, which are accessible from the xenates through two methods. One is the

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation state. The reverse of disproportionatio ...

of xenates to perxenates and xenon: : 2 + 2 OH⁻ → + Xe + O₂ + 2 H₂O The other is oxidation of the xenates with

ozone Ozone () (or trioxygen) is an Inorganic compound, inorganic molecule with the chemical formula . It is a pale blue gas with a distinctively pungent smell. It is an allotrope of oxygen that is much less stable than the diatomic allotrope , break ...

in basic solution: : + O₃ + 3 OH⁻ → + O₂ + 2 H₂O Barium perxenate is reacted with

sulfuric acid Sulfuric acid (American spelling and the preferred IUPAC name) or sulphuric acid (English in the Commonwealth of Nations, Commonwealth spelling), known in antiquity as oil of vitriol, is a mineral acid composed of the elements sulfur, oxygen, ...

and the unstable perxenic acid is dehydrated to give xenon tetroxide: : + 2 → 2 + : → 2 + Any excess perxenic acid slowly undergoes a decomposition reaction to xenic acid and oxygen: : 2 → + 2 + 2

References

* {{DEFAULTSORT:Xenon Tetroxide Xenon(VIII) compounds Inorganic compounds Oxides