Strontium bromide

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

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

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

References

  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.