Kiến thức

Barium hydroxide-Wikipedia

Barium hydroxide

From Wikipedia, the free encyclopedia

Jump to navigation

Jump to search

Barium hydroxide

Ba(OH)2monohydrate.tif

Ba(OH)2 octahydrate.JPG

Identifiers

CAS Number

  • 17194-00-2

     checkY

  • 22326-55-2 (monohydrate) checkY
  • 12230-71-6 (octahydrate) checkY
3D model (

JSmol

)

  • Interactive image

ChEBI

  • CHEBI:32592

     checkY

ChemSpider

  • 26408

     checkY

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

     checkY

  • P27GID97XM

     (monohydrate) checkY

  • L5Q5V03TBN

     (octahydrate) checkY

CompTox Dashboard

(EPA)

  • DTXSID10892155

    Edit this at Wikidata

InChI

  • InChI=1S/Ba.2H2O/h;2*1H2/q+2;;/p-2 checkY
    Key: RQPZNWPYLFFXCP-UHFFFAOYSA-L checkY
  • 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)
20.94 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

Std enthalpy of
formation

fH298)

−944.7 kJ/mol
Hazards

Safety data sheet

See:

data page

GHS pictograms

GHS05: Corrosive

GHS07: Harmful

GHS Signal word

Danger

GHS hazard statements

H302, H314, H318, H332, H412

NFPA 704

(fire diamond)

3

0

0

Flash point

Non-flammable
Related compounds
Other

anions

Barium oxide

Barium peroxide

Other

cations

Calcium hydroxide

Strontium hydroxide

Supplementary data page

Structure and
properties

Refractive index

(n),

Dielectric constant

r), etc.

Thermodynamic
data

Phase behaviour

solid–liquid–gas

Spectral data

UV

,

IR

,

NMR

,

MS

Except where otherwise noted, data are given for materials in their

standard state

(at 25 °C [77 °F], 100 kPa).

☒N 

verify

 (

what is

 checkY☒N ?)

Infobox references

Chemical compound

Barium hydroxide is a

chemical compound

with the

chemical formula

Ba(OH)2(H2O)x. 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 form.

Preparation and structure[

edit

]

Barium hydroxide can be prepared by dissolving

barium oxide

(BaO) in water:

BaO + 9 H2O → 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 will yield BaO and water.

[2]

The monohydrate adopts a layered structure (see picture above). The Ba2+ centers adopt a square anti-prismatic geometry. Each Ba2+ center is bound by two water ligands and six hydroxide ligands, which are respectively doubly and triply bridging to neighboring Ba2+ centre sites.

[3]

In the octahydrate, the individual Ba2+ centers are again eight coordinate but do not share ligands.

[4]

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

Xem thêm: [C++] Tìm UCLN, BCNN của hai số bất kì-Blog lập trình Cơ Bản-Blog của nhóm Yêu Lập Trình

Uses[

edit

]

Industrially, barium hydroxide is used as the precursor to other barium compounds. The monohydrate is used to dehydrate and remove sulfate from various products.

[5]

This application exploits the very low solubility of barium sulfate. This industrial application is also applied to laboratory uses.

Laboratory uses[

edit

]

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

carbonate

ions, which are much less basic.

[6]

Barium hydroxide is occasionally used in

organic synthesis

as a strong base, for example for the hydrolysis of esters

[7]

and nitriles,

[8]

[9]

[10]

and as a base in

aldol condensations

.

Barium hydroxide-catalyzed 2-carboxy-1,3-dihydroxynaphthalene preparation.svg

Barium hydroxide-catalyzed methylsuccinic acid preparation.svg

It has been used to hydrolyse one of the two equivalent ester groups in dimethyl hendecanedioate.

[11]

Barium hydroxide is used, as well, in the decarboxylation of amino acids liberating barium carbonate in the process.

[12]

It is also used in the preparation of

cyclopentanone

,

[13]

diacetone alcohol

[14]

and

D-gulonic γ-lactone

.

[15]

Cyclopentanone prepn.png

Barium hydroxide-catalyzed diacetone alcohol preparation.svg

Reactions[

edit

]

Barium hydroxide decomposes to

barium oxide

when heated to 800 °C. Reaction with

carbon dioxide

gives

barium carbonate

. Its aqueous solution, being highly alkaline, undergoes neutralization reactions with 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.

[16]

Reactions of barium hydroxide with

ammonium

salts are strongly

endothermic

. The reaction of barium hydroxide octahydrate with

ammonium chloride

[17]

[18]

or

[19]

ammonium thiocyanate

[19]

[20]

is often used as a classroom chemistry demonstration, producing temperatures cold enough to freeze water and enough water to dissolve the resulting mixture.

Xem thêm: Phương pháp lập phương trình hóa học (có bài tập vận dụng Cơ bản và nâng cao)

Safety[

edit

]

Barium hydroxide presents the same hazards as the other

strong bases

and as other water-soluble barium compounds: it is corrosive and toxic.[

citation needed

]

See also[

edit

]

  • Baralyme

Xem thêm: Cho hàm số $fleft( x right){rm{ = }},{rm{a}}{x^3} + b{x^2} + cx + d$; $left( {a;b;c;d} right.$ là hằng số, $a ne?

References[

edit

]

  1. ^

    “Sortierte Liste: pKb-Werte, nach Ordnungszahl sortiert. – Das Periodensystem online”

    (in German).

  2. ^

    (1960). Gmelins Handbuch der anorganischen Chemie (8. Aufl.), Weinheim: Verlag Chemie, p. 289.

  3. ^

    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.

  4. ^

    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

  5. ^

    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

  6. ^

    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

  7. ^

    Meyer, K.; Bloch, H. S. (1945). “

    Naphthoresorcinol

    “.

    Org. Synth.

    25: 73; Coll. Vol. 3: 637.

  8. ^

    Brown, G. B. (1946). “

    Methylsuccinic acid

    “.

    Org. Synth.

    26: 54; Coll. Vol. 3: 615.

  9. ^

    Ford, Jared H. (1947). “

    β-Alanine

    “.

    Org. Synth.

    27: 1; Coll. Vol. 3: 34.

  10. ^

    Anslow, W. K.; King, H.; Orten, J. M.; Hill, R. M. (1925). “

    Glycine

    “.

    Org. Synth.

    4: 31; Coll. Vol. 1: 298.

  11. ^

    Durham, L. J.; McLeod, D. J.; Cason, J. (1958). “

    Methyl hydrogen hendecanedioate

    “.

    Org. Synth.

    38:55; Coll. Vol. 4:635.

  12. ^

    [1]

  13. ^

    Thorpe, J. F.; Kon, G. A. R. (1925). “

    Cyclopentanone

    “.

    Org. Synth.

    5: 37; Coll. Vol. 1: 192.

  14. ^

    Conant, J. B.; Tuttle, Niel. (1921). “

    Diacetone alcohol

    “.

    Org. Synth.

    1: 45; Coll. Vol. 1: 199.

  15. ^

    Karabinos, J. V. (1956). “

    γ-lactone

    “.

    Org. Synth.

    36: 38; Coll. Vol. 4: 506.

  16. ^

    Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002,

    ISBN

     

    0-07-049439-8

  17. ^

    “Endothermic Reactions of Hydrated Barium Hydroxide and Ammonium Chloride”

    . UC San Diego. Retrieved 2 April 2014.

  18. ^

    Endothermic Solid-Solid Reactions

  19. ^

    a

    b

    Camp, Eric.

    “Endothermic Reaction”

    . Univertist of Washington. Retrieved 2 April 2014.

  20. ^

    “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)

Retrieved from “

https://en.wikipedia.org/w/index.php?title=Barium_hydroxide&oldid=993844711

Chuyên mục: Kiến thức

Related Articles

Trả lời

Email của bạn sẽ không được hiển thị công khai. Các trường bắt buộc được đánh dấu *

Check Also
Close
Back to top button