Barium bromide

Barium bromide is the chemical compound with the formula BaBr₂. It is ionic and hygroscopic in nature.

Barium bromide

Barium bromide Space-filling model of the crystal structure
Identifiers
CAS Number	10553-31-8 (anhydrous) Y[PubChem] 7791-28-8 (dihydrate) Y[PubChem]
3D model (JSmol)	Interactive image Interactive image
ChemSpider	59728 Y
ECHA InfoCard	100.031.024
EC Number	234-140-0
PubChem CID	5462743 (anhydrous) 44537612 (dihydrate)
UNII	TI8NM689HW Y
CompTox Dashboard (EPA)	DTXSID2065123
InChI InChI=1S/Ba.2BrH/h;2*1H/q+2;;/p-2 Y Key: NKQIMNKPSDEDMO-UHFFFAOYSA-L Y InChI=1/Ba.2BrH/h;2*1H/q+2;;/p-2 Key: NKQIMNKPSDEDMO-NUQVWONBAE
SMILES Br[Ba]Br [Ba+2].[Br-].[Br-]
Properties
Chemical formula	BaBr2 (anhydrous) BaBr2·2H2O (dihydrate)
Molar mass	297.14 g/mol
Appearance	White solid
Density	4.78 g/cm3 (anhydrous) 3.58 g/cm3 (dihydrate)
Melting point	857 °C (1,575 °F; 1,130 K)
Boiling point	1,835 °C (3,335 °F; 2,108 K)
Solubility in water	92.2 g/100 mL (0°C)
Magnetic susceptibility (χ)	-92.0·10−6 cm3/mol
Structure
Crystal structure	PbCl2-type (orthorhombic, oP12)
Space group	Pnma (No. 62)
Thermochemistry
Std enthalpy of formation (ΔfH⦵298)	−181.1 kcal/mol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Toxic
GHS labelling:
Pictograms
Signal word	Warning
Hazard statements	H302, H332
Precautionary statements	P261, P264, P270, P271, P301+P312, P304+P312, P304+P340, P312, P330, P501
NFPA 704 (fire diamond)	3 0 0
Safety data sheet (SDS)	NIH BaBr
Related compounds
Other anions	Barium fluoride Barium chloride Barium iodide
Other cations	Beryllium bromide Magnesium bromide Calcium bromide Strontium bromide Radium bromide Lead bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). N verify (what is YN ?) Infobox references

Structure and properties

BaBr₂ crystallizes in the lead chloride (cotunnite) motif, giving white orthorhombic crystals that are deliquescent.^[1][2]

Coordination geometry of ions in barium bromide^[1][3][4]

Ion	Ba2+	Br− (tetrahedral)	Br− (trigonal)
Coordination sphere	{BaBr9}	{BrBa4}	{BrBa3}
Ball-and-stick model
Coordination number	9	4	3
Coordination geometry	(7+2) coordination[5] distorted tricapped trigonal prismatic	distorted tetrahedral	trigonal pyramidal

In aqueous solution BaBr₂ behaves as a simple salt.

Solutions of barium bromide reacts with the sulfate salts to produce a solid precipitate of barium sulfate.

BaBr₂ + SO²⁻
₄ → BaSO₄ + 2 Br⁻

Similar reactions occur with oxalic acid, hydrofluoric acid, and phosphoric acid, giving solid precipitates of barium oxalate, fluoride, and phosphate, respectively.

Preparation

Barium bromide can be prepared by treating barium sulfide or barium carbonate with hydrobromic acid:

BaS + 2 HBr → BaBr₂ + H₂S

BaCO₃ + 2 HBr → BaBr₂ + CO₂ + H₂O

Barium bromide crystallizes from concentrated aqueous solution in its dihydrate, BaBr₂·2H₂O. Heating this dihydrate to 120 °C gives the anhydrous salt.^[6]

Uses

Barium bromide is a precursor to chemicals used in photography and to other bromides.
Historically, barium bromide was used to purify radium in a process of fractional crystallization devised by Marie Curie. Since radium precipitates preferentially in a solution of barium bromide, the ratio of radium to barium in the precipitate would be higher than the ratio in the solution.^[7]

Safety

Barium bromide, along with other water-soluble barium salts (e.g. barium chloride), is toxic. However, there is no conclusive data available on its hazards.^[8]

In popular culture

The compound appears in the intro title card of Breaking Bad, where the first pairs of letters are replaced with Br³⁵ and Ba⁵⁶, the symbols and atomic numbers of bromine and barium respectively.