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Caesium hydroxide

Caesium hydroxide
CAS number 21351-79-1
RTECS number FK9800000
Molecular formula CsOH
Molar mass 149.91 g/mol
Appearance white solid,
Density 3.675 g/cm3, solid
Melting point

272.3°C 342°C?

Solubility in water 395.5 g/100 ml (15°C)
Solubility in ethanol Soluble
Basicity (pKb) -1.76
Std enthalpy of
−416.73 kJ/mol
Standard molar
98.74 J.K−1.mol−1
EU classification not listed
Flash point non flammable
Related Compounds
Other anions Caesium oxide
Other cations Potassium hydroxide
Rubidium hydroxide
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

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. Caesium hydroxide can corrode 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.

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 equation:

2 Cs + 2 H2O → 2 CsOH + H2

The above reaction occurs explosively. Caesium metal will react with ice above -116 °C.


    This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Caesium_hydroxide". A list of authors is available in Wikipedia.
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