Caesium hydroxide

Caesium hydroxide
Names
Other names
Cesium hydrate
Identifiers
21351-79-1 Yes
ChEBI CHEBI:33988 Yes
ChemSpider 56494 Yes
EC-number 244-344-1
Jmol-3D images Image
RTECS number FK9800000
UN number 2682
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)[1]
300 g/100 mL at 30 °C
Solubility Soluble in ethanol[2]
Basicity (pKb) -1.76[3]
Thermochemistry
Specific
heat capacity (C)
 69.9 J·mol−1·K−1[4]
104.2 J·K−1·mol−1
Std enthalpy of
formation (ΔfHo298)
 −416.2 kJ·mol−1
Hazards
MSDS ICSC 1592
EU Index Not listed
Flash point Not flammable
570 mg/kg (oral, rat)[5]
US health exposure limits (NIOSH):
none[6]
TWA 2 mg/m3[6]
N.D.[6]
Related compounds
Other anions
 Caesium oxide
Caesium fluoride
Other cations
 Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Rubidium hydroxide
Except where noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

Caesium hydroxide (CsOH) is a chemical compound consisting of an ion of caesium and a hydroxide ion. It is a strong base (pKb=-1.76), much like the other alkali metal hydroxides such as sodium hydroxide and potassium hydroxide. In fact, caesium hydroxide is powerful enough to quickly corrode through glass.

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.

However, this compound is not usually used in experiments as the extraction of caesium is very expensive and the fact that it behaves very much like rubidium hydroxide and potassium hydroxide although it is more reactive than they are.

Caesium hydroxide can be obtained by the following chemical reaction:

2 Cs + 2 H2O → 2 CsOH + H2

The above reaction occurs explosively with enough force to shatter a Pyrex beaker. Caesium metal will react with ice above −116 °C.

References

  1. ↑ http://www.inchem.org/documents/icsc/icsc/eics1592.htm
  2. ↑ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 4–51, ISBN 0-8493-0594-2
  3. ↑ http://www.periodensystem-online.de/index.php?show=list&id=acid&prop=pKb-Werte&sel=oz&el=92
  4. ↑ Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 5–14, ISBN 0-8493-0594-2
  5. ↑ http://chem.sis.nlm.nih.gov/chemidplus/rn/21351-79-1
  6. ↑ 6.0 6.1 6.2 "NIOSH Pocket Guide to Chemical Hazards #0111". National Institute for Occupational Safety and Health (NIOSH).

External links