This MedLibrary.org supplementary page on Baryta is provided directly from the open source Wikipedia as a service to our readers. Please see the note below on authorship of this content, as well as the Wikipedia usage guidelines. To search for other content from our encyclopedia supplement, please use the form below:
Related Sponsors
| Barium hydroxide | |
|---|---|
| Identifiers | |
| CAS number | [17194-00-2] |
| RTECS number | CQ9200000 |
| Properties | |
| Molecular formula | Ba(OH)2 |
| Molar mass | 171.342 g/mol (anhydrous) 189.36 g/mol (monohydrate) 315.46 g/mol (octahydrate) |
| Appearance | white solid |
| Melting point |
78 °C (octahydrate) |
| Boiling point |
780 °C |
| Solubility in water | 5.6 g/100 g (octahydrate & anhydrous) |
| Solubility in other solvents | low |
| Basicity (pKb) | -2.02 |
| Structure | |
| Crystal structure | octahedral |
| Thermochemistry | |
| Std enthalpy of formation ΔfH |
−944.7 kJ/mol |
| Hazards | |
| MSDS | External MSDS |
| EU classification | Harmful (Xn) |
| NFPA 704 |
 0
3
0
|
| R-phrases | R20/22 |
| S-phrases | (S2), S28 |
| Flash point | non-flammable |
| Related compounds | |
| Other anions | Barium oxide Barium peroxide |
| Other cations | Calcium hydroxide Strontium hydroxide |
| Supplementary data page | |
| Structure and properties |
n, εr, etc. |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | UV, IR, NMR, MS |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox references |
|
Barium hydroxide is the chemical compound with the formula Ba(OH)2. Also known as baryta, it is one of the principal compounds of barium. The white granular monohydrate is the usual commercial form.
Contents |
Preparation
Barium hydroxide can be prepared by dissolving barium oxide (BaO) in water.
- BaO + 9H2O → Ba(OH)2·8H2O
It crystallises as the octahydrate, which converts to the monohydrate upon heating in air. At 100 °C in a vacuum, the monohydrate gives BaO.[1]
Uses
Barium hydroxide is used in analytical chemistry for the titration of weak acids, particularly organic acids. Its clear aqueous solution is guaranteed to be free of carbonate, unlike those of sodium hydroxide and potassium hydroxide, as barium carbonate is insoluble in water. This allows the use of indicators such as phenolphthalein or thymolphthalein (with alkaline colour changes) without the risk of titration errors due to the presence of weakly basic carbonate ions.[2]
Barium hydroxide is used in organic synthesis as a strong base, for example for the hydrolysis of esters[3] and nitriles.[4][5][6]
It has been used to hydrolyse one of the two equivalent ester groups in dimethyl hendecanedioate.[7]
It is also used in the preparation of cyclopentanone,[8] diacetone alcohol[9] and D-Gulonic γ-lactone.[10]
Barium hydroxide is used in a demonstration of endothermic reactions since, when mixed with an ammonium salt, the reaction becomes cold as heat is absorbed from the surroundings.
Miscellaneous applications
- Under the name baryta it is used in homeopathic remedies.
- It is also used to clean up acid spills.
- Also under the name of baryta it is used in the production of photographic paper for printing.
Safety
Barium hydroxide presents the same hazards as other strong bases and as other water-soluble barium compounds: it is corrosive and toxic.
References
- ^ (1960). Gmelins Handbuch der anorganischen Chemie (8. Aufl.), Weinheim: Verlag Chemie, p. 289.
- ^ Mendham, J.; Denney, R. C.; Barnes, J. D.; Thomas, M.J.K.; Denney, R. C.; Thomas, M. J. K. Vogel's Quantitative Chemical Analysis (6th Edn.) New York:Prentice Hall. ISBN 0-582-22628-7.
- ^ Meyer, K.; Bloch, H. S. (1945). "Naphthoresorcinol". Org. Synth. 25: 73; Coll. Vol. 3: 637.
- ^ Brown, G. B. (1946). "Methylsuccinic acid". Org. Synth. 26: 54; Coll. Vol. 3: 615.
- ^ Ford, Jared H. (1947). "β-Alanine". Org. Synth. 27: 1; Coll. Vol. 3: 34.
- ^ Anslow, W. K.; King, H.; Orten, J. M.; Hill, R. M. (1925). "Glycine". Org. Synth. 4: 31; Coll. Vol. 1: 298.
- ^ Durham, L. J.; McLeod, D. J.; Cason, J. (1958). "Methyl hydrogen hendecanedioate". Org. Synth. 38:55; Coll. Vol. 4:635.
- ^ Thorpe, J. F.; Kon, G. A. R. (1925). "Cyclopentanone". Org. Synth. 5: 37; Coll. Vol. 1: 192.
- ^ Conant, J. B.; Tuttle, Niel. (1921). "Diacetone alcohol". Org. Synth. 1: 45; Coll. Vol. 1: 199.
- ^ Karabinos, J. V. (1956). "D-Gulonic γ-lactone". Org. Synth. 36: 38; Coll. Vol. 4: 506.
External links
Wikipedia content modification information:
- This page was last modified on 28 August 2008, at 00:58.
Wikipedia Authorship and Review
Wikipedia content provided here is not reviewed directly by MedLibrary.org. Wikipedia content is authored by an open community of volunteers and is not produced by or in any way affiliated with MedLibrary.org.
Wikipedia Usage Guidelines
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article on "Baryta".
The URL for this specific entry is:
All Wikipedia text is available under the terms of the GNU Free Documentation License. (See Copyrights for details). Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc.