Difference between revisions of "Caesium hydroxide"

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'''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 (chemistry)|base]], much like other [[alkali hydroxide|alkali metal hydroxides]] such as [[sodium hydroxide]] and [[potassium hydroxide]]. In fact, caesium hydroxide is powerful enough to quickly corrode through glass.
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'''Caesium hydroxide''' (CsOH) is the product of the violent reaction between [[caesium]] and [[water]]:
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:2Cs + 2H<sub>2</sub>O → 2CsOH + H<sub>2</sub>
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It is a powerful [[base (chemistry)|base]], much like other alkali metal hydroxides such as [[sodium hydroxide]] and [[potassium hydroxide]], and will quickly corrode through glass. It is also extremely [[hygroscopic]], and laboratory caesium hydroxide is typically a [[Hydrate|monohydrate]].
  
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Due to its high reactivity, caesium hydroxide is extremely [[hygroscopic]].  Laboratory caesium hydoxide is typically a [[hydrate]].
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Caesium hydroxide is an anisotropic etchant of [[silicon]], exposing [[octahedron|octahedral]] planes. This technique can create pyramids and regularly-shaped etch pits for uses such as [[MEMS]]. It has a higher selectivity to etch highly p-doped silicon than the more commonly used [[potassium hydroxide]].{{fact}}
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It is an anisotropic etchant of [[silicon]], exposing [[octahedron|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]].{{fact}}
 
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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.
 
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Caesium hydroxide can be obtained by the following chemical reaction:
 
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:2Cs + 2H<sub>2</sub>O → 2CsOH + H<sub>2</sub>
 
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The above reaction occurs explosively with enough force to shatter a [[Pyrex]] beaker.
 
  
 
==References==
 
==References==

Latest revision as of 21:20, 25 August 2009

Caesium hydroxide
Identifiers
InChI InChI=1/Cs.H2O/h;1H2/q+1;/p-1
InChIKey HUCVOHYBFXVBRW-REWHXWOFAG
Standard InChI InChI=1S/Cs.H2O/h;1H2/q+1;/p-1
Standard InChIKey HUCVOHYBFXVBRW-UHFFFAOYSA-M
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[3]
Material safety data sheet (MSDS) ICSC 1592
EU index number not listed
GHS pictograms Acute Tox. (inhal.) 1Skin Corr. 1B, Eye Dam. 1Acute Tox. (oral) 4
GHS signal word DANGER
GHS hazard statements H330, H314, H318, H302
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 monohydrate
Identifiers
InChI InChI=1/Cs.2H2O/h;2*1H2/q+1;;/p-1
InChIKey ABSOMGPQFXJESQ-REWHXWOFAC
Standard InChI InChI=1S/Cs.2H2O/h;2*1H2/q+1;;/p-1
Standard InChIKey ABSOMGPQFXJESQ-UHFFFAOYSA-M
CAS number [35103-79-8]
EC number 244-344-1
ChemSpider 10620883
Properties
Chemical formula CsOH·H2O
Molar mass 167.93 g/mol
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

Caesium hydroxide (CsOH) is the product of the violent reaction between caesium and water:

2Cs + 2H2O → 2CsOH + H2

It is a powerful base, much like other alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and will quickly corrode through glass. It is also extremely hygroscopic, and laboratory caesium hydroxide is typically a monohydrate.

Caesium hydroxide 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 has a higher selectivity to etch highly p-doped silicon than the more commonly used potassium hydroxide.[ref. needed]

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.
  3. ↑ GHS classification – ID 812, <http://www.safe.nite.go.jp/english/ghs_index.html#results> (accessed 26 August 2009), Japanese GHS Inter-ministerial Committee, 2006.

Further reading

External links

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