Lead(II) bromide is the
inorganic compound
An inorganic compound is typically a chemical compound that lacks carbon–hydrogen bondsthat is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as ''inorganic chemistry''.
Inorgan ...
with the formula PbBr
2. It is a white powder. It is produced in the burning of typical leaded gasolines.
[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.]
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.
PbBr
2 has the same
crystal structure
In crystallography, crystal structure is a description of ordered arrangement of atoms, ions, or molecules in a crystalline material. Ordered structures occur from intrinsic nature of constituent particles to form symmetric patterns that repeat ...
as
lead chloride (
cotunnite) – they are
isomorphous. In this structure, Pb
2+ 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).
Lead bromide was prevalent in the environment as the result of the use of leaded gasoline.
Tetraethyl lead
Tetraethyllead (commonly styled tetraethyl lead), abbreviated TEL, is an organolead compound with the formula Pb( C2H5)4. It was widely used as a fuel additive for much of the 20th century, first being mixed with gasoline beginning in the 192 ...
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
1,2-Dibromoethane, also known as ethylene dibromide (EDB), is an organobromine compound with the chemical formula . Although trace amounts occur naturally in the ocean, where it is probably formed by algae and kelp, substantial amounts are produc ...
, which converted lead oxides into the more volatile lead bromide, which was then exhausted from the engine into the environment.
[
]
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
The International Agency for Research on Cancer (IARC; ) is an intergovernmental agency forming part of the World Health Organization of the United Nations.
Its role is to conduct and coordinate research into the causes of cancer. It also cance ...
(IARC). Its release into the environment as a product of leaded gasoline was highly controversial.
References
{{bromides
Lead(II) compounds
Bromides
Metal halides