Barium chloride

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Barium chloride
Cotunnite structure.png
Barium chloride.jpg
Identifiers
CAS number 10361-37-2 YesY
10326-27-9 (dihydrate)
PubChem 25204
ChemSpider 23540 YesY
UNII 0VK51DA1T2 YesY
EC number 233-788-1
RTECS number CQ8750000 (anhydrous)
CQ8751000 (dihydrate)
Jmol-3D images Image 1
Properties
Molecular formula BaCl2
Molar mass 208.23 g/mol (anhydrous)
244.26 g/mol (dihydrate)
Appearance White solid
Density 3.856 g/cm3 (anhydrous)
3.0979 g/cm3 (dihydrate)
Melting point 962 °C
960 °C (dihydrate)
Boiling point 1560 °C
Solubility in water 31.2 g/100 mL (0 °C)
35.8 g/100 mL (20 °C)
59.4 g/100 mL (100 °C)
Solubility soluble in methanol, insoluble in ethanol, ethyl acetate[2]
Structure
Crystal structure orthogonal (anhydrous)
monoclinic (dihydrate)
Coordination
geometry
7-9
Thermochemistry
Std enthalpy of
formation
ΔfHo298
−858.56 kJ/mol
Hazards
MSDS External MSDS
EU Index 056-004-00-8
EU classification Toxic (T)
Harmful (Xn)
R-phrases R20, R25
S-phrases (S1/2), S45
NFPA 704
Flammability code 0: Will not burn. E.g., water Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point Non-flammable
Related compounds
Other anions Barium fluoride
Barium bromide
Barium iodide
Other cations Beryllium chloride
Magnesium chloride
Calcium chloride
Strontium chloride
Radium chloride
Lead chloride
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 (77 °F), 100 kPa)
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Infobox references

Barium chloride is the inorganic compound with the formula BaCl2. It is one of the most common water-soluble salts of barium. Like other barium salts, it is toxic and imparts a yellow-green coloration to a flame. It is also hygroscopic.

Structure and properties[edit]

BaCl2 crystallizes in two forms (polymorphs). One form has the cubic fluorite (CaF2) structure and the other the orthorhombic cotunnite (PbCl2) structure. Both polymorphs accommodate the preference of the large Ba2+ ion for coordination numbers greater than six.[3] The coordination of Ba2+ is 8 in the fluorite structure[4] and 9 in the cotunnite structure.[5] When cotunnite-structure BaCl2 is subjected to pressures of 7–10 GPa, it transforms to a third structure, a monoclinic post-cotunnite phase. The coordination number of Ba2+ increases from 9 to 10.[6]

In aqueous solution BaCl2 behaves as a simple salt; in water it is a 1:2 electrolyte and the solution exhibits a neutral pH. Its solutions react with sulfate ion to produce a thick white precipitate of barium sulfate.

Ba2+(aq) + SO42–(aq) → BaSO4(s)

Oxalate effects a similar reaction:

Ba2+(aq) + C2O42–(aq)BaC2O4(s)

When it is mixed with sodium hydroxide, it gives the dihydroxide, which is moderately soluble in water.

Preparation[edit]

Barium chloride can be prepared from barium hydroxide or barium carbonate, with barium carbonate being found naturally as the mineral witherite. These basic salts react with hydrochloric acid to give hydrated barium chloride. On an industrial scale, it is prepared via a two step process from barite (barium sulfate):[7]

BaSO4(aq) + 4 C(s) → BaS(s) + 4 CO(g)

This first step requires high temperatures.

BaS + CaCl2 → BaCl2 + CaS

The second step requires fusion of the reactants. The BaCl2 can then be leached out from the mixture with water. From water solutions of barium chloride, the dihydrate can be crystallized as white crystals: BaCl2·2H2O

Uses[edit]

As an inexpensive, soluble salt of barium, barium chloride finds wide application in the laboratory. It is commonly used as a test for sulfate ion (see chemical properties above). In industry, barium chloride is mainly used in the purification of brine solution in caustic chlorine plants and also in the manufacture of heat treatment salts, case hardening of steel, in the manufacture of pigments, and in the manufacture of other barium salts. BaCl2 is also used in fireworks to give a bright green color. However, its toxicity limits its applicability.

Safety[edit]

Barium chloride, along with other water-soluble barium salts, is highly toxic.[8] Sodium sulfate and magnesium sulfate are potential antidotes because they form the insoluble solid barium sulfate BaSO4, which is also toxic, but less harmful because of its insolubility.

References[edit]

  1. ^ https://play.google.com/books/reader?printsec=frontcover&output=reader&id=nKQ-AAAAYAAJ&pg=GBS.PA64
  2. ^ Handbook of Chemistry and Physics, 71st edition, CRC Press, Ann Arbor, Michigan, 1990.
  3. ^ Wells, A. F. (1984) Structural Inorganic Chemistry, Oxford: Clarendon Press. ISBN 0-19-855370-6.
  4. ^ Haase, A.; Brauer, G. (1978). "Hydratstufen und Kristallstrukturen von Bariumchlorid". Z. anorg. allg. Chem. 441: 181–195. doi:10.1002/zaac.19784410120.  edit
  5. ^ Brackett, E. B.; Brackett, T. E.; Sass, R. L. (1963). "The Crystal Structures of Barium Chloride, Barium Bromide, and Barium Iodide". J. Phys. Chem. 67 (10): 2132. doi:10.1021/j100804a038.  edit
  6. ^ Léger, J. M.; Haines, J.; Atouf, A. (1995). "The Post-Cotunnite Phase in BaCl2, BaBr2 and BaI2 under High Pressure". J. Appl. Cryst. 28 (4): 416. doi:10.1107/S0021889895001580.  edit
  7. ^ Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0080379419. 
  8. ^ The Merck Index, 7th edition, Merck & Co., Rahway, New Jersey, 1960.

External links[edit]