Caesium bromide

Caesium bromide or cesium bromide is an ionic compound of caesium and bromine with the chemical formula CsBr. It is a white or transparent solid with melting point at 636 °C that readily dissolves in water. Its bulk crystals have the cubic CsCl structure, but the structure changes to the rocksalt type in nanometer-thin film grown on mica, LiF, KBr or NaCl substrates.[6]

Caesium bromide
Names
IUPAC name
Cesium bromide
Other names
Cesium bromide,
Caesium(I) bromide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.029.209
EC Number
  • 232-130-0
RTECS number
  • FK9275000
UNII
  • InChI=1S/BrH.Cs/h1H;/q;+1/p-1 checkY
    Key: LYQFWZFBNBDLEO-UHFFFAOYSA-M checkY
  • InChI=1/BrH.Cs/h1H;/q;+1/p-1
    Key: LYQFWZFBNBDLEO-REWHXWOFAA
  • [Cs+].[Br-]
Properties
CsBr
Molar mass 212.809 g/mol[1]
Appearance White solid
Density 4.43 g/cm3[1]
Melting point 636 °C (1,177 °F; 909 K)[1]
Boiling point 1,300 °C (2,370 °F; 1,570 K)[1]
1230 g/L (25 °C)[1] Disputed.

420 g/L (11 °C) See References
560 /L (15°C)
1020 g/L (28.5 °C)
1180 g/L (31 °C)
1240 g/L (32.5 °C)
1380 g/L (35 °C)

-67.2·10−6 cm3/mol[2]
1.8047 (0.3 μm)
1.6974 (0.59 μm)
1.6861 (0.75 μm)
1.6784 (1 μm)
1.6678 (5 μm)
1.6439 (20 μm)[3]
Structure
CsCl, cP2
Pm3m, No. 221[4]
a = 0.4291 nm
0.0790 nm3
1
Cubic (Cs+)
Cubic (Br−)
Hazards
GHS labelling:
GHS07: Exclamation mark
Warning
H302, H315, H319, H335
P261, P264, P270, P271, P280, P301+P312, P302+P352, P304+P340, P305+P351+P338, P312, P321, P330, P332+P313, P337+P313, P362, P403+P233, P405, P501
NFPA 704 (fire diamond)
NFPA 704 four-colored diamond
2
0
0
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
1400 mg/kg (oral, rat)[5]
Related compounds
Other anions
 Caesium fluoride
Caesium chloride
Caesium iodide
Caesium astatide
Other cations
 Sodium bromide
Potassium bromide
Rubidium bromide
Francium bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
checkY verify (what is checkY☒N ?)
Infobox references

Synthesis

Caesium bromide can be prepared via following reactions:

CsOH (aq) + HBr (aq) → CsBr (aq) + H2O (l)
Cs2(CO3) (aq) + 2 HBr (aq) → 2 CsBr (aq) + H2O (l) + CO2 (g)
  • Direct synthesis:
2 Cs (s) + Br2 (g) → 2 CsBr (s)

The direct synthesis is a vigorous reaction of caesium with bromine. Due to its high cost, it is not used for preparation.

Uses

Caesium bromide is sometimes used in optics as a beamsplitter component in wide-band spectrophotometers.

References
  1. Haynes, p. 4.57
  2. Haynes, p. 4.132
  3. Haynes, p. 10.240
  4. Vallin, J.; Beckman, O.; Salama, K. (1964). "Elastic Constants of CsBr and CsI from 4.2K to Room Temperature". Journal of Applied Physics. 35 (4): 1222. Bibcode:1964JAP....35.1222V. doi:10.1063/1.1713597.
  5. Caesium bromide. nlm.nih.gov
  6. Schulz, L. G. (1951). "Polymorphism of cesium and thallium halides". Acta Crystallographica. 4 (6): 487–489. doi:10.1107/S0365110X51001641.


* Crystran Ltd experimental data July 2021

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