Xenon trioxide

Chemistry

Synthesis of xenon trioxide is by aqueous hydrolysis of : : + 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.

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

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

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

:XeO3(aq) + H2O → H2XeO4 H+ +

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, 15-crown-5 coordinates to xenon trioxide to give a complex stable at room-temperature against mechanical shock.

Alternatively, it dissolves in alkaline solutions to form xenates. The 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.{{cite book | url-access = limited

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 Å, b = 8.115 Å, c = 5.234 Å, and 4 molecules per unit cell. The density is 4.55 g/cm3.

Safety

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

References

References

1. Zumdahl, Steven S.. (2009). "Chemical Principles 6th Ed.". Houghton Mifflin Company.
2. (1997). "Chemistry of the Elements". Butterworth-Heinemann.
3. (July 1966). "Titrimetric determination of some organic acids by xenon trioxide oxidation". Talanta.
4. "A stable crown ether complex with a noble-gas compound". Wiley-VCH.
5. (March 1970). "Vibrational spectra and structures of xenate(VI) and perxenate(VIII) ions in aqueous solution". Inorganic Chemistry.
6. (1998). "Recent Advances in Noble-gas Chemistry". Academic Press.
7. (1963). "Crystal and Molecular Structure of Xenon Trioxide". Journal of the American Chemical Society.
8. (1963). "Xenon Hydroxide: an Experimental Hazard". Science.