Strontium bromide

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Strontium bromide
Names
IUPAC name
Strontium bromide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.030.868 Edit this at Wikidata
EC Number
  • 233-969-5
UNII
  • InChI=1S/2BrH.Sr/h2*1H;/q;;+2/p-2 checkY
    Key: YJPVTCSBVRMESK-UHFFFAOYSA-L checkY
  • InChI=1S/2BrH.Sr/h2*1H;/q;;+2/p-2
    Key: YJPVTCSBVRMESK-NUQVWONBAI
  • Key: YJPVTCSBVRMESK-UHFFFAOYSA-L
  • [Sr+2].[Br-].[Br-]
Properties
SrBr2
Molar mass 247.428 g/mol (anhydrous)
355.53 g/mol (hexahydrate)
Appearance white crystalline powder
Density 4.216 g/cm3 (anhydrous)
2.386 g/cm3 (hexahydrate)
Melting point 643 °C (1,189 °F; 916 K)
Boiling point 2,146 °C (3,895 °F; 2,419 K)
107 g/100 mL
Solubility Soluble in ethanol
Insoluble in diethyl ether
−86.6·10−6 cm3/mol
Structure[1]
Tetragonal
P4/n (No. 85)
a = 1160.42 pm, c = 713.06 pm
10
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
Corrosive
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 1: Normally stable, but can become unstable at elevated temperatures and pressures. E.g. calciumSpecial hazards (white): no code
1
0
1
Related compounds
Other anions
Other cations
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Strontium bromide is a chemical compound with a formula SrBr2. At room temperature it is a white, odourless, crystalline powder. Strontium bromide imparts a bright red colour in a flame test, showing the presence of strontium ions. It is used in flares and also has some pharmaceutical uses.

Preparation

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SrBr2 can be prepared from strontium hydroxide and hydrobromic acid.

Sr(OH)2 + 2 HBr → SrBr2 + 2 H2O

Alternatively strontium carbonate can also be used as strontium source.

SrCO3 + 2 HBr → SrBr2 + H2O + CO2(g)

These reactions give hexahydrate of strontium bromide (SrBr2·6H2O), which decomposes to dihydrate (SrBr2·2H2O) at 89 °C. At 180 °C anhydrous SrBr2 is obtained.[2]

Structure

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At room temperature, strontium bromide adopts a crystal structure with a tetragonal unit cell and space group P4/n. This structure is referred to as α-SrBr2 and is isostructural with EuBr2 and USe2. The compound's structure was initially erroneously interpreted as being of the PbCl2 type,[3] but this was later corrected.[4][1]

Around 920 K (650 °C), α-SrBr2 undergoes a first-order solid-solid phase transition to a much less ordered phase, β-SrBr2, which adopts the cubic fluorite structure. The beta phase of strontium bromide has a much higher ionic conductivity of about 1 S/cm, comparable to that of molten SrBr2, due to extensive disorder in the bromide sublattice.[1] Strontium bromide melts at 930 K (657 °C).

See also

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References

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  1. ^ a b c Hull, Stephen; Norberg, Stefan T.; Ahmed, Istaq; Eriksson, Sten G.; Mohn, Chris E. (2011). "High temperature crystal structures and superionic properties of SrCl2, SrBr2, BaCl2 and BaBr2". J. Solid State Chem. 184 (11): 2925–2935. Bibcode:2011JSSCh.184.2925H. doi:10.1016/j.jssc.2011.09.004.
  2. ^ Dale L. Perry, Sidney L. Phillips: Handbook of Inorganic Compounds. CRC Press, 1995, ISBN 978-0-8493-8671-8, (Strontium bromide, p. 387, at Google Books).
  3. ^ Kamermans, M. A. (1939-12-01). "The Crystal Structure of SrBr2". Zeitschrift für Kristallographie - Crystalline Materials. 101 (1–6). Walter de Gruyter GmbH: 406–411. doi:10.1524/zkri.1939.101.1.406. ISSN 2196-7105. S2CID 102183214.
  4. ^ R. L. Sass; et al. (1963). "The crystal structure of strontium bromide". J. Phys. Chem. 67 (12): 2862. doi:10.1021/j100806a516.