- Barium hydroxide
Name = Barium hydroxide
Section1 = Chembox Identifiers
CASNo = 17194-00-2
RTECS = CQ9200000
Section2 = Chembox Properties
Formula = Ba(OH)2
MolarMass = 171.342 g/mol (anhydrous)
189.36 g/mol (monohydrate)
315.46 g/mol (octahydrate)
Appearance = white solid
Solubility = 5.6 g/100 g (octahydrate & anhydrous)
Solvent = other solvents
SolubleOther = low
MeltingPt = 78 °C (octahydrate)
>408 °C (anhydrous)
BoilingPt = 780 °C
pKb = -2.02
Section3 = Chembox Structure
CrystalStruct = octahedral
Section4 = Chembox Thermochemistry
DeltaHf = −944.7 kJ/mol
Section7 = Chembox Hazards
EUClass = Harmful (Xn)
NFPA-H = 3
RPhrases = R20/22
SPhrases = S2, S28
FlashPt = non-flammable
Section8 = Chembox Related
Barium oxide Barium peroxide
Calcium hydroxide Strontium hydroxide
Barium hydroxide can be prepared by dissolving
barium oxide(BaO) in water.:BaO + 9H2O → Ba(OH)2·8H2OIt crystallises as the octahydrate, which converts to the monohydrate upon heating in air. At 100 °C in a vacuum, the monohydrate gives BaO. [(1960). "Gmelins Handbuch der anorganischen Chemie (8. Aufl.)", Weinheim: Verlag Chemie, p. 289.]
Barium hydroxide is used in
analytical chemistryfor the titration of weak acids, particularly organic acids. Its clear aqueous solution is guaranteed to be free of carbonate, unlike those of sodium hydroxideand potassium hydroxide, as barium carbonateis insoluble in water. This allows the use of indicators such as phenolphthaleinor thymolphthalein(with alkaline colour changes) without the risk of titration errors due to the presence of weakly basic carbonateions. [VogelQuantitative]
Barium hydroxide is used in organic synthesis as a strong base, for example for the hydrolysis of esters [Meyer, K.; Bloch, H. S. (1945). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0637 Naphthoresorcinol] ". "
Org. Synth." 25: 73; "Coll. Vol." 3: 637.] and nitriles. [Brown, G. B. (1946). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0615 Methylsuccinic acid] ". " Org. Synth." 26: 54; "Coll. Vol." 3: 615.] [Ford, Jared H. (1947). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv3p0034 β-Alanine] ". " Org. Synth." 27: 1; "Coll. Vol." 3: 34.] [Anslow, W. K.; King, H.; Orten, J. M.; Hill, R. M. (1925). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0298 Glycine] ". " Org. Synth." 4: 31; "Coll. Vol." 1: 298.]
It has been used to hydrolyse one of the two equivalent ester groups in dimethyl hendecanedioate. [Durham, L. J.; McLeod, D. J.; Cason, J. (1958). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv4p0635 Methyl hydrogen hendecanedioate] ". "
Org. Synth." 38:55; "Coll. Vol." 4:635.]
It is also used in the preparation of
cyclopentanone, [Thorpe, J. F.; Kon, G. A. R. (1925). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0192 Cyclopentanone] ". " Org. Synth." 5: 37; "Coll. Vol." 1: 192.] diacetone alcohol[Conant, J. B.; Tuttle, Niel. (1921). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv1p0199 Diacetone alcohol] ". " Org. Synth." 1: 45; "Coll. Vol." 1: 199.] and D-Gulonic γ-lactone. [Karabinos, J. V. (1956). " [http://www.orgsyn.org/orgsyn/prep.asp?prep=cv4p0506D-Gulonic γ-lactone] ". " Org. Synth." 36: 38; "Coll. Vol." 4: 506.]
Barium hydroxide is used in a demonstration of
endothermic reactions since, when mixed with an ammonium salt, the reaction becomes cold as heatis absorbed from the surroundings.
*Under the name baryta it is used in homeopathic remedies.
*It is also used to clean up acid spills.
Barium hydroxide presents the same hazards as other strong bases and as other water-soluble barium compounds: it is corrosive and toxic.
* [http://www.jtbaker.com/msds/englishhtml/b0422.htm Material Safety Data Sheet (MSDS)]
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