Brief introduction
Bromine, which symbol is Br, is a red-brown liquid at room
temperature. In fact, it was discovered by a chemist, Antoine J. Balard, in
1826. It is corrosive and toxic. It is an elements with the atomic number 35 and
atomic mass 79.904 amu. Bromine is in the halogen element group, with the
properties between chlorine and iodine. In nature, free bromine doesn’t occur, while it
would occur as colourless soluble crystalline mineral halide salts (similar to table
salt).
Existence on earth
Bromine is quite a rare element, while it is rarer than three-quarters of elements.
However, due to it high solubility, it accumulates in ocean. Besides, it easily extracted,
so nearly 556 000 tonnes of bromine were produced in 2007, the amount produced is
similar to an abundant element magnesium.
Physical property
Bromine is a slightly transparent red liquid in room temperature, while it is one of
the two elements that are liquid in exact room temperature (mercury is the another
one). The melting point of bromine is around -7.2℃, with the boiling point 58.78
℃, which means it evaporates easily in standard temperature and pressure to give an
orange vapour. The colour of the vapour is similar to nitrogen dioxide. It also have a
strongly unpleasant odor similar to chlorine.
Chemical property
Bromine is more reactive than iodine but less reactive with chlorine, it would
react vigorously with metals, especially in the presence of water. It is also reactive
towards some organic compounds. It would bond easily with many elements and
would give a strong bleaching action. Besides, Bromine is slightly soluble in water,
while it is highly soluble in organic solvents (acetic acids, etc.)
Applications
One of the major uses is as a water purifier and disinfectant, brominated
compounds are used for water treatment in swimming pools and hot tubs. It can also
be used to control algae and bacterial growth in industrial processes.
In agriculture, bromine compounds are effective pesticides, used as soil
fumigants, particularly fruit-growing, and as a fumigant to prevent pets from attacking
stored grain and other produce.
In the past, bromine compounds were used in leaded fuel. However, this use has
declined as lead has gradually been removed from fuel. Bromine compounds are now
being tested in batteries for electric cars. Such batteries can also be used as electricity
storage devices.
By the way, a key application of bromine compounds is in manufacturing
pharmaceuticals. Brominated substances are important ingredients of many
over-the-counter and prescription drugs, including analgesics, sedatives, etc. In fact,
bromine compounds are active ingredients in several drugs that treat pneumonia and
cocaine addiction. Currently, bromine are undergoing trials for new generations of
anti-cancer and AIDS drugs.
Moreover, bromine compounds have a number of applications in photography,
without the existence of bromine compound, photographs could not capture sufficient
light. Other bromine compounds are used as an ingredient in photo development.
Safety
Although bromine is an useful element, it is toxic and could cause burn. AS an
oxidising agent, it is incompatible with most organic and inorganic compounds. Cars
are needed to be taken when transporting bromine. It is commonly carried in steel
tanks lined with lead, supported by strong metal frames.
Reference: www.bromine-info.or
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