Cesium carbide
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| Surname | Cesium carbide | |||||||||
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| Molecular formula | Cs 2 C 2 | |||||||||
| Brief description |
white solid |
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| Molar mass | 289.83 g mol −1 | |||||||||
| Physical state |
firmly |
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| As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions . | ||||||||||
Cesium carbide is a chemical compound of cesium from the group of carbides .
Extraction and presentation
Cesium carbide can be obtained by reacting ethyne with an ammoniacal solution of cesium and subsequent rapid heating of the intermediate product cesium hydrogen acetylide Cs 2 C 2 · C 2 H 2 or 2 CsHC 2 .
When heated slowly, the intermediate product decomposes into cesium, carbon and ethyne.
In addition to cesium carbide Cs 2 C 2 , another cesium carbide is known, CsC 8 , which is obtained by reacting graphite with cesium vapor at 300 ° C under reduced pressure. The compound decomposes at around 400 ° C.
properties
Cesium carbide is a white solid that is very sensitive to air. In a vacuum, the compound decomposes to cesium and carbon at 700 to 800 ° C. On contact with water it decomposes to ethyne and ceasium hydroxide.
Like rubidium carbide, cesium carbide comes in two modifications that can coexist with one another. The hexagonal modification ( space group P 6 2 m (space group no. 189) , Z = 3) crystallizes in the familiar sodium peroxide type with two crystallographically independent layers for the C 2 2– dumbbells. In this modification, each cesium ion is coordinated by four C 2 2− ions. The orthorhombic modification ( space group Pnma (space group no. 62) , Z = 4), on the other hand, is a previously unknown structure type that is related to the lead (II) chloride type , whereby the lead layers are characterized by ordered C 2 2– - Units are replaced.
Individual evidence
- ↑ a b c d T. Y. Kosolapova: Carbides Properties, Production, and Applications . Springer Science & Business Media, 2012, ISBN 978-1-4684-8006-1 , p. 65 ( limited preview in Google Book search).
- ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
- ↑ a b Norbert Auner, Wolfgang A. Herrmann, Uwe Klingebiel: Synthetic Methods of Organometallic and Inorganic Chemistry, Volume 2, 1996 Volume 2: Groups 1,2, 13 and 14 . Georg Thieme Verlag, 2014, ISBN 3-13-179171-3 , p. 44 ( limited preview in Google Book search).
- ↑ Monographs on Applied Electrochemistry . W. Knapp, January 1, 1914 ( books.google.de ).
- ↑ U. Ruschewitz, P. Müller, W. Kockelmann: On the crystal structure of Rb 2 C 2 and Cs 2 C 2 . In: Journal of Inorganic and General Chemistry. 627, p. 513, doi : 10.1002 / 1521-3749 (200103) 627: 3 <513 :: AID-ZAAC513> 3.0.CO; 2-I .