Cesium oxide

Crystal structure
__ O 2−      __ Cs +
General
Surname	Cesium oxide
other names	Dicaesium oxide
Ratio formula	Cs 2 O
Brief description	orange to red solid
External identifiers / databases
CAS number 20281-00-9 EC number 243-679-0 ECHA InfoCard 100,039,693 PubChem 9903865 Wikidata Q417090
properties
Molar mass	281.81 g mol −1
Physical state	firmly
density	4.65 g cm −3
Melting point	490 ° C
solubility	reacts violently with water
safety instructions
GHS labeling of hazardous substances danger H and P phrases H: 314-318-411 P: ?
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Cesium oxide is a chemical compound of cesium and is one of the oxides . It is an orange solid.

Extraction and presentation

Cesium oxide cannot be obtained directly from the elements, as this creates cesium hyperoxide . Instead, cesium peroxide or cesium nitrate can be reacted with elemental cesium. The reaction of cesium nitrate with cesium azide to form cesium oxide and nitrogen is also possible.

${\displaystyle \mathrm {Cs_{2}O_{2}+2\ Cs\longrightarrow 2\ Cs_{2}O} }$

${\displaystyle \mathrm {CsNO_{3}+5\ CsN_{3}\longrightarrow 3\ Cs_{2}O+8\ N_{2}} }$

properties

Cesium oxide is an orange to red solid. When heated, the color deepens to almost black. In air dissolves it gradually under discoloration. In contrast to the other alkali metal oxides, it does not crystallize in an anti- fluorite , but in a trigonal anti- cadmium chloride structure with the space group R 3 m (space group no. 166) with the lattice parameters a = 4.256 Å and c = 18.99 Å.

The standard enthalpy of formation of cesium oxide is ΔH _f ⁰  = −346 kJ / mol.

use

Cesium oxide is a cocatalyst for vanadium oxide - titanium oxide catalysts, which are used for gas phase oxidations . With these, carboxylic acids and carboxylic acid anhydrides can be produced from aromatic hydrocarbons .

Photocathodes can be made from cesium oxide mixed with small silver particles .

Individual evidence

1. ^ ^{A b c} Jean d'Ans, Ellen Lax, Roger Blachnik: Pocket book for chemists and physicists . Springer DE, 1998, ISBN 3-642-58842-5 , pp. 414 ( limited preview in Google Book search).
2. ↑ ^{a b} cesium oxide at webelements.com.
3. ↑ There is not yet a harmonized classification for this substance . A labeling of dicesium oxide in the Classification and Labeling Inventory of the European Chemicals Agency (ECHA), which was accessed on December 28, 2019, is reproduced from a self-classification by the distributor .
4. ^ ^{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 , pp. 1285-1286.
5. ↑ Georg Brauer (Ed.), With the collaboration of Marianne Baudler a . a .: Handbook of Preparative Inorganic Chemistry. 3rd, revised edition. Volume II, Ferdinand Enke, Stuttgart 1978, ISBN 3-432-87813-3 , p. 954.
6. ^ AF Holleman , E. Wiberg , N. Wiberg : Textbook of Inorganic Chemistry . 101st edition. Walter de Gruyter, Berlin 1995, ISBN 3-11-012641-9 , p. 1176.
7. ↑ patent EP1654061 . ‌
8. ^ Yoshihiro Sayama: The Optical Theory of the Spectral Sensitivity of Cesium-Oxide Photocathode . In: Journal of the Physical Society of Japan . 2, No. 5, 1948, pp. 103-107 ( abstract ).