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
CAS Number	7787-69-1 Y
3D model (JSmol)	Interactive image
ChemSpider	22994 Y
ECHA InfoCard	100.029.209
EC Number	232-130-0
PubChem CID	24592
RTECS number	FK9275000
UNII	06M25EDM3F
CompTox Dashboard (EPA)	DTXSID8064854
InChI InChI=1S/BrH.Cs/h1H;/q;+1/p-1 Y Key: LYQFWZFBNBDLEO-UHFFFAOYSA-M Y InChI=1/BrH.Cs/h1H;/q;+1/p-1 Key: LYQFWZFBNBDLEO-REWHXWOFAA
SMILES [Cs+].[Br-]
Properties
Chemical formula	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]
Solubility in water	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)
Magnetic susceptibility (χ)	−67.2·10−6 cm3/mol[2]
Refractive index (nD)	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
Crystal structure	CsCl, cP2
Space group	Pm3m, No. 221[4]
Lattice constant	a = 0.4291 nm
Lattice volume (V)	0.0790 nm3
Formula units (Z)	1
Coordination geometry	Cubic (Cs+) Cubic (Br−)
Hazards
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H315, H319, H335
Precautionary statements	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)	2 0 0
Flash point	Non-flammable
Lethal dose or concentration (LD, LC):
LD50 (median dose)	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). Y verify (what is YN ?) Infobox references

Synthesis

Caesium bromide can be prepared via following reactions:

• Neutralization:

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.