Caesium hydroxide

Cesium hydroxide
Names
	Other names Cesium hydrate
Identifiers
CAS Number	21351-79-1 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:33988 ;
ChemSpider	56494 ;
ECHA InfoCard	100.040.298
EC Number	244-344-1;
RTECS number	FK9800000;
UN number	2682
CompTox Dashboard (EPA)	DTXSID7066699 ;
	InChI InChI=1S/Cs.H2O/h;1H2/q+1;/p-1 Key: HUCVOHYBFXVBRW-UHFFFAOYSA-M ; InChI=1/Cs.H2O/h;1H2/q+1;/p-1 Key: HUCVOHYBFXVBRW-REWHXWOFAG;
	SMILES [OH-].[Cs+];
Properties
Chemical formula	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)
Solubility in water	300 g/100 mL at 30 °C
Solubility	Soluble in ethanol
Basicity (pKb)	-1.76
Thermochemistry
Heat capacity (C)	69.9 J·mol−1·K−1
Std molar; entropy (S⦵298)	104.2 J·K−1·mol−1
Std enthalpy of; formation (ΔfH⦵298)	−416.2 kJ·mol−1
Hazards
Flash point	Not flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	570 mg/kg (oral, rat)
	NIOSH (US health exposure limits):
PEL (Permissible)	none
REL (Recommended)	TWA 2 mg/m3
IDLH (Immediate danger)	N.D.
Safety data sheet (SDS)	ICSC 1592
Related compounds
Other anions	Caesium oxide; Cesium 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). verify (what is ?) Infobox references

Caesium hydroxide (CsOH) is a chemical compound consisting of an ion of caesium and a hydroxide ion. It is a strong base (pK_b=-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.

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

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

External links

[hand-1] Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 4–51, ISBN 0-8493-0594-2

[2] ttp://www.periodensystem-online.de/index.php?show=list&id=acid&prop=pKb-Werte&sel=oz&el=92

[3] ttp://www.inchem.org/documents/icsc/icsc/eics1592.htm

[hand2-4] Lide, David R. (1998), Handbook of Chemistry and Physics (87 ed.), Boca Raton, FL: CRC Press, pp. 5–14, ISBN 0-8493-0594-2

[PGCH-5] NIOSH Pocket Guide to Chemical Hazards. "#0111". National Institute for Occupational Safety and Health (NIOSH).

[6] ttp://chem.sis.nlm.nih.gov/chemidplus/rn/21351-79-1

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