Lead(II) bromide
Lead(II) bromide is the inorganic compound with the formula PbBr2. It is a white powder. It is produced in the burning of typical leaded gasolines.[4]
 | |
-bromide-xtal-3x3x3-3D-sf.png.webp) | |
| Names | |
|---|---|
| IUPAC name
Lead(II) bromide | |
| Other names
Lead dibromide | |
| Identifiers | |
3D model (JSmol) |
|
| ChemSpider | |
| ECHA InfoCard | 100.030.065 |
| EC Number |
|
PubChem CID |
|
| UNII | |
CompTox Dashboard (EPA) |
|
| |
| |
| Properties | |
| PbBr2 | |
| Molar mass | 367.01 g/mol |
| Appearance | white powder |
| Density | 6.66 g/cm3 [1] |
| Melting point | 370.6 °C (699.1 °F; 643.8 K) |
| Boiling point | 916 °C (1,681 °F; 1,189 K) (vaporizes) |
| 0.455 g/100 mL (0 °C) 0.973 g/100 mL (20 °C)[2] 4.41 g/100 mL (100 °C) | |
Solubility product (Ksp) |
1.86 x 10−5 (20 °C) |
| Solubility | insoluble in alcohol; soluble in ammonia, alkali, KBr, NaBr |
| −90.6·10−6 cm3/mol | |
| Structure[3] | |
| PbCl2 type (orthorhombic) | |
| Pnma (No. 62) | |
a = 805.90 pm, b = 954.0 pm, c = 473.19 pm | |
Formula units (Z) |
4 |
| Hazards | |
| GHS labelling: | |
   | |
| Danger | |
| H302, H332, H360, H373, H410 | |
| P201, P202, P260, P261, P264, P270, P271, P273, P281, P301+P312, P304+P312, P304+P340, P308+P313, P312, P314, P330, P391, P405, P501 | |
| NFPA 704 (fire diamond) | |
| Related compounds | |
Other anions |
Lead(II) fluoride, Lead(II) chloride, Lead(II) iodide |
Other cations |
Thallium(I) bromide, Tin(II) bromide Bismuth bromide |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Preparation and properties
It is typically prepared from treating solutions of lead salts (e.g., (lead(II) nitrate) with bromide salts. This process exploits its low solubility in water - only 0.455 g dissolves in 100 g of water at 0 °C. It is about ten times more soluble in boiling water.[5]
PbBr2 has the same crystal structure as lead chloride (cotunnite) – they are isomorphous. In this structure, Pb2+ is surrounded by nine Br− ions in a distorted tricapped trigonal prismatic geometry. Seven of the Pb-Br distances are shorter, in the range 2.9-3.3 Å, while two of them are longer at 3.9 Å. The coordination is therefore sometimes described as (7+2).[6][3]
Lead bromide was prevalent in the environment as the result of the use of leaded gasoline. Tetraethyl lead was once widely used to improve the combustion properties of gasoline. To prevent the resulting lead oxides from fouling the engine, gasoline was treated with 1,2-Dibromoethane, which converted lead oxides into the more volatile lead bromide, which was then exhausted from the engine into the environment.[4]
Safety
Like other compounds containing lead, lead(II) bromide is categorized as probably carcinogenic to humans (Category 2A), by the International Agency for Research on Cancer (IARC). Its release into the environment as a product of leaded gasoline was highly controversial.
References
- Lide, David R., ed. (2006). CRC Handbook of Chemistry and Physics (87th ed.). Boca Raton, FL: CRC Press. ISBN 0-8493-0487-3.
- NIST-data review 1980
- Lumbreras, M.; Protas, J.; Jebbari, S.; Dirksen, G. J.; Schoonman, J. (1986). "Structure and ionic conductivity of mixed lead halides PbCl2xBr2(1−x). II". Solid State Ion. 20 (4): 295–304. doi:10.1016/0167-2738(86)90049-4.
- Michael J. Dagani, Henry J. Barda, Theodore J. Benya, David C. Sanders "Bromine Compounds" in Ullmann's Encyclopedia of Industrial Chemistry" Wiley-VCH, Weinheim, 2000.doi:10.1002/14356007.a04_405
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 978-0-08-037941-8.
- Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. p. 382. ISBN 978-0-08-037941-8.