Caesium hydroxide

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Caesium hydroxide
Identifiers
InChI InChI=1/Cs.H2O/h;1H2/q+1;/p-1
Standard InChI InChI=1S/Cs.H2O/h;1H2/q+1;/p-1
CAS number [21351-79-1]
EC number 244-344-1
UN number 2682
RTECS FK9800000
ChemSpider 56494
Properties[1]
Chemical formula CsOH
Molar mass 149.91 g/mol
Appearance whitish-yellow solid, deliquescent
Density 3.675 g/cm3, solid
Melting point

273.3 °C

Solubility in water 395.5 g/100 ml at 15 °C
Solubility in ethanol soluble
Thermochemistry[2]
Std enthalpy of formation ΔfHo298 −416.2 kJ/mol
Standard molar entropy So298 104.2 J K−1 mol−1
Specific heat capacity C 69.9 J K−1 mol−1
Hazards
Material safety data sheet (MSDS) ICSC 1592
EU index number not listed
Flash point non-flammable
Related compounds
Other anions Caesium oxide
Other cations Lithium hydroxide
Sodium hydroxide
Potassium hydroxide
Rubidium hydroxide
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Caesium hydroxide (CsOH) is a chemical compound consisting of an atom of caesium and a hydroxide group (also known as hydroxyl). It is a powerful base, much like 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 hydoxide is typically a hydrate.

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

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 but reacts chemically stronger than they do.

Caesium hydroxide can be obtained by the following chemical reaction:

2Cs + 2H2O → 2CsOH + H2

The above reaction occurs explosively with enough force to shatter a Pyrex beaker.

References

  1. CRC Handbook of Chemistry and Physics, 62nd ed.; Weast, Robert C., Ed.; CRC Press: Boca Raton, FL, 1981; p B-92. ISBN 0-8493-0462-8.
  2. CRC Handbook of Chemistry and Physics, 87th ed.; Lide, David R., Ed.; CRC Press: Boca Raton, FL, 2006; p 5-14. ISBN 0-8493-0487-3.

Further reading

External links

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