ba baoh2

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Barium hydroxide
Identifiers

CAS Number

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  • 17194-00-2 check
  • 22326-55-2 (monohydrate) check
  • 12230-71-6 (octahydrate) check

3D model (JSmol)

  • Interactive image
ChEBI
  • CHEBI:32592 check
ChemSpider
  • 26408 check
ECHA InfoCard 100.037.470 Edit this at Wikidata
EC Number
  • 241-234-5

Gmelin Reference

846955

PubChem CID

  • 28387
RTECS number
  • CQ9200000
UNII
  • 1OHB71MYBK check
  • P27GID97XM (monohydrate) check
  • L5Q5V03TBN (octahydrate) check

CompTox Dashboard (EPA)

  • DTXSID10892155 Edit this at Wikidata

InChI

  • InChI=1S/Ba.2H2O/h;2*1H2/q+2;;/p-2 check

    Key: RQPZNWPYLFFXCP-UHFFFAOYSA-L check

  • InChI=1/Ba.2H2O/h;2*1H2/q+2;;/p-2

    Key: RQPZNWPYLFFXCP-NUQVWONBAR

SMILES

  • [Ba+2].[OH-].[OH-]

Properties

Chemical formula

Ba(OH)2
Molar mass 171.34 g/mol (anhydrous)
189.355 g/mol (monohydrate)
315.46 g/mol (octahydrate)
Appearance white solid
Density 3.743 g/cm3 (monohydrate)
2.18 g/cm3 (octahydrate, 16 °C)
Melting point 78 °C (172 °F; 351 K) (octahydrate)
300 °C (monohydrate)
407 °C (anhydrous)
Boiling point 780 °C (1,440 °F; 1,050 K)

Solubility in water

mass of BaO (not Ba(OH)2):
1.67 g/100 mL (0 °C)
3.89 g/100 mL (20 °C)
4.68 g/100 mL (25 °C)
5.59 g/100 mL (30 °C)
8.22 g/100 mL (40 °C)
11.7 g/100 mL (50 °C)
đôi mươi.94 g/100 mL (60 °C)
101.4 g/100 mL (100 °C)[citation needed]
Solubility in other solvents low
Basicity (pKb) 0.15 (first OH), 0.64 (second OH)[1]

Magnetic susceptibility (χ)

−53.2·10−6 cm3/mol

Refractive index (nD)

1.50 (octahydrate)
Structure

Crystal structure

octahedral
Thermochemistry[2]

Std enthalpy of
formation fH298)

−944.7 kJ·mol−1

Enthalpy of fusion fHfus)

16 kJ·mol−1
Hazards
GHS labelling:

Pictograms

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GHS05: CorrosiveGHS07: Exclamation mark

Signal word

Danger

Hazard statements

H302, H314, H332, H412
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 3: Short exposure could cause serious temporary or residual injury. E.g. chlorine gasFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code

3

Flash point Non-flammable
Related compounds

Other anions

Barium oxide
Barium peroxide

Other cations

Calcium hydroxide
Strontium hydroxide
Supplementary data page
Barium hydroxide (data page)

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

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Infobox references

Barium hydroxide is a chemical compound with the chemical formula Ba(OH)2. The monohydrate (x = 1), known as baryta or baryta-water, is one of the principal compounds of barium. This white granular monohydrate is the usual commercial khuông.

Preparation and structure[edit]

Barium hydroxide can be prepared by dissolving barium oxide (BaO) in water:

BaO + H2O → Ba(OH)2

It crystallises as the octahydrate, which converts lớn the monohydrate upon heating in air. At 100 °C in a vacuum, the monohydrate will yield BaO and water.[3] The monohydrate adopts a layered structure (see picture above). The Ba2+ centers adopt a square antiprismatic geometry. Each Ba2+ center is bound by two water ligands and six hydroxide ligands, which are respectively doubly and triply bridging lớn neighboring Ba2+ centre sites.[4] In the octahydrate, the individual Ba2+ centers are again eight coordinate but vì thế not share ligands.[5]

Coordination sphere about an individual barium ion in Ba(OH)2.H2O.

Uses[edit]

Industrially, barium hydroxide is used as the precursor lớn other barium compounds. The monohydrate is used lớn dehydrate and remove sulfate from various products.[6] This application exploits the very low solubility of barium sulfate. This industrial application is also applied lớn laboratory uses.

Laboratory uses[edit]

Barium hydroxide is used in analytical chemistry for the titration of weak acids, particularly organic acids. Its aqueous solution, if clear, is guaranteed lớn be miễn phí 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 lớn the presence of carbonate ions, which are much less basic.[7]

Barium hydroxide is occasionally used in organic synthesis as a strong base, for example for the hydrolysis of esters[8] and nitriles,[9][10][11] and as a base in aldol condensations.

There are several uses for barium hydroxide such as lớn hydrolyse one of the two equivalent ester groups in dimethyl hendecanedioate.[12]

Barium hydroxide has also been used, as well, in the decarboxylation of amino acids liberating barium carbonate in the process.[13]

It is also used in the preparation of cyclopentanone,[14] diacetone alcohol[15] and D-gulonic γ-lactone.[16]

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Reactions[edit]

Barium hydroxide decomposes lớn barium oxide when heated lớn 800 °C. Reaction with carbon dioxide gives barium carbonate. Its aqueous solution, being highly alkaline, undergoes neutralization reactions with acids due lớn it being a strong base. It is especially useful on reactions that require the titrations of weak organic acids. Thus, it forms barium sulfate and barium phosphate with sulfuric and phosphoric acids, respectively. Reaction with hydrogen sulfide produces barium sulfide. Precipitation of many insoluble, or less soluble barium salts, may result from double replacement reaction when a barium hydroxide aqueous solution is mixed with many solutions of other metal salts.[17]

Reactions of barium hydroxide with ammonium salts are strongly endothermic. The reaction of barium hydroxide octahydrate with ammonium chloride[18][19] or[20] ammonium thiocyanate[20][21] is often used as a classroom chemistry demonstration, producing temperatures cold enough lớn freeze water and enough water lớn dissolve the resulting mixture.

Safety[edit]

Barium hydroxide presents the same hazards such as skin irritation and burns as well as eye damage, just as the other strong bases and as other water-soluble barium compounds: it is corrosive and toxic.[citation needed]

See also[edit]

  • Baralyme

References[edit]

  1. ^ "Sortierte Liste: pKb-Werte, nach Ordnungszahl sortiert. - Das Periodensystem online" (in German).
  2. ^ Lide, David R., ed. (2009). CRC Handbook of Chemistry and Physics (90th ed.). Boca Raton, Florida: CRC Press. ISBN 978-1-4200-9084-0.
  3. ^ (1960). Gmelins Handbuch der anorganischen Chemie (8. Aufl.), Weinheim: Verlag Chemie, p. 289.
  4. ^ Kuske, P..; Engelen, B.; Henning, J.; Lutz, H.D.; Fuess, H.; Gregson, D. "Neutron diffraction study of Sr(OH)2(H2O) and beta-Ba(OH)2*(H2O)" Zeitschrift für Kristallographie (1979-2010) 1988, vol. 183, p319-p325.
  5. ^ Manohar, H.; Ramaseshan, S. "The crystal structure of barium hydroxide octahydrate Ba (OH)2(H2O)8" Zeitschrift für Kristallographie, Kristallgeometrie, Kristallphysik, Kristallchemie 1964. vol. 119, p357-p374
  6. ^ Robert Kresse, Ulrich Baudis, Paul Jäger, H. Hermann Riechers, Heinz Wagner, Jochen Winkler, Hans Uwe Wolf, "Barium and Barium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, 2007 Wiley-VCH, Weinheim. doi:10.1002/14356007.a03_325.pub2
  7. ^ Mendham, J.; Denney, R. C.; Barnes, J. D.; Thomas, M. J. K. (2000), Vogel's Quantitative Chemical Analysis (6th ed.), New York: Prentice Hall, ISBN 0-582-22628-7
  8. ^ Meyer, K.; Bloch, H. S. (1945). "Naphthoresorcinol". Org. Synth. 25: 73; Coll. Vol. 3: 637.
  9. ^ Brown, G. B. (1946). "Methylsuccinic acid". Org. Synth. 26: 54; Coll. Vol. 3: 615.
  10. ^ Ford, Jared H. (1947). "β-Alanine". Org. Synth. 27: 1; Coll. Vol. 3: 34.
  11. ^ Anslow, W. K.; King, H.; Orten, J. M.; Hill, R. M. (1925). "Glycine". Org. Synth. 4: 31; Coll. Vol. 1: 298.
  12. ^ Durham, L. J.; McLeod, D. J.; Cason, J. (1958). "Methyl hydrogen hendecanedioate". Org. Synth. 38:55; Coll. Vol. 4:635.
  13. ^ Chaudhari, M. R.; Kulkarni, Y. A.; Gokhale, S. B. (6 October 2008). Biochemistry and Clinical Pathology. ISBN 9788185790169.
  14. ^ Thorpe, J. F.; Kon, G. A. R. (1925). "Cyclopentanone". Org. Synth. 5: 37; Coll. Vol. 1: 192.
  15. ^ Conant, J. B.; Tuttle, Niel. (1921). "Diacetone alcohol". Org. Synth. 1: 45; Coll. Vol. 1: 199.
  16. ^ Karabinos, J. V. (1956). "γ-lactone". Org. Synth. 36: 38; Coll. Vol. 4: 506.
  17. ^ Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN 0-07-049439-8
  18. ^ "Endothermic Reactions of Hydrated Barium Hydroxide and Ammonium Chloride". UC San Diego. Retrieved 2 April 2014.
  19. ^ Endothermic Solid-Solid Reactions
  20. ^ a b Camp, Eric. "Endothermic Reaction". Univertist of Washington. Retrieved 2 April 2014.
  21. ^ "Endothermic solid-solid reactions" (PDF). Classic Chemistry Demonstrations. The Royal Society of Chemistry. Archived from the original (PDF) on 7 April 2014. Retrieved 2 April 2014.

External links[edit]

  • Material Safety Data Sheet (MSDS)