Caesium hydroxide

Caesium hydroxide
Names
Other names
Cesium hydrate
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.040.298 Edit this at Wikidata
EC Number
  • 244-344-1
RTECS number
  • FK9800000
UNII
UN number 2682
  • InChI=1S/Cs.H2O/h;1H2/q+1;/p-1 checkY
    Key: HUCVOHYBFXVBRW-UHFFFAOYSA-M checkY
  • InChI=1/Cs.H2O/h;1H2/q+1;/p-1
    Key: HUCVOHYBFXVBRW-REWHXWOFAG
  • [OH-].[Cs+]
Properties
CsOH
Molar mass 149.912 g/mol
Appearance Whitish-yellow deliquescent crystals
Density 3.675 g/cm3
Melting point 272 °C (522 °F; 545 K)[3]
300 g/100 mL at 30 °C
Solubility Soluble in ethanol[1]
Acidity (pKa) 15.76 [2]
Thermochemistry
69.9 J·mol−1·K−1[4]
104.2 J·K−1·mol−1
−416.2 kJ·mol−1
Hazards
GHS labelling:
GHS05: CorrosiveGHS08: Health hazard
Danger
H302, H314, H361, H373
P201, P202, P260, P264, P270, P280, P281, P301+P312, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P308+P313, P310, P314, P321, P330, P363, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazard ALK: Alkaline
3
0
1
ALK
Flash point Not flammable
Lethal dose or concentration (LD, LC):
570 mg/kg (oral, rat)[6]
NIOSH (US health exposure limits):
PEL (Permissible)
 none[5]
REL (Recommended)
 TWA 2 mg/m3[5]
IDLH (Immediate danger)
 N.D.[5]
Safety data sheet (SDS) ICSC 1592
Related compounds
Other anions
 Cæsium oxide
Cæsium fluoride
Other cations
 Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Rubidium hydroxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Caesium hydroxide is a strong base (pKa= 15.76) containing the highly reactive alkali metal caesium, much like the other alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. It is the strongest of the five alkali metal hydroxides.[7] Fused Caesium hydroxide dissolves glass by attacking silica framework and it has applications in bringing glass samples into a solution for analytical purposes in commercial glass industry and defense waste processing facility. The melting process is carried out in a nickel or zirconium crucible.[8] Caesium hydroxide fusion at 750°C produces complete dissolution of glass pellets.[8]

Due to its high reactivity, caesium hydroxide is extremely hygroscopic. Laboratory caesium hydroxide is typically a hydrate.

It is an anisotropic etchant of silicon, exposing octahedral planes. This technique can form pyramids and regularly shaped etch pits for uses such as Microelectromechanical systems. It is known to have a higher selectivity to etch highly p-doped silicon than the more commonly used potassium hydroxide.

This compound is not commonly used in experiments due to the high extraction cost of caesium and its reactive behaviour. It acts in similar fashion to the compounds rubidium hydroxide and potassium hydroxide, although more reactive.

References

  1. ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, Florida: CRC Press, pp. 4–51, ISBN 0-8493-0594-2
  2. ^ "Sortierte Liste: pKb-Werte, nach Ordnungszahl sortiert. – Das Periodensystem online".
  3. ^ "ICSC 1592 - Cesium Hydroxide".
  4. ^ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, Florida: CRC Press, pp. 5–14, ISBN 0-8493-0594-2
  5. ^ a b c NIOSH Pocket Guide to Chemical Hazards. "#0111". National Institute for Occupational Safety and Health (NIOSH).
  6. ^ Gigiena Truda i Professional'nye Zabolevaniya. Labor Hygiene and Occupational Diseases., 21(1)(29), 1977
  7. ^ Considine, Douglas M.; Considine, Glenn D. (2013-12-11). Van Nostrand's Scientific Encyclopedia. Springer Science & Business Media. ISBN 978-1-4757-6918-0.
  8. ^ a b Coleman, C.J; Spencer, W.A. (April 1998). "CsOH is a very strong base that attacks the silica framework of glass under fusion conditions. Cesium Hydroxide Fusion Dissolution of Analytical Reference Glass-1 in Both Powder and Shard Form" (PDF). Westinghouse Savannah River Company. CsOH is a very strong base that attacks the silica framework of glass under fusion conditions.