Module:4
Lecture:21 Sodium bromide
Dr. N. K. Patel
Module: 4
Lecture: 21
SODIUM BROMIDE
INTRODUCTION
Sodium bromide (NaBr) is an inorganic compound. It is a high-melting
white, crystalline solid that resembles sodium chloride. It is a widely used
source of the bromide ion and has many applications. Sodium bromide is the
most available alkali bromide and salt of hydrobromic acid. It is available in
the form of crystals or powder. From aqueous solution sodium bromide
crystallizes as a dihydrate and NaBr2.H2O at below 510C, while above it
crystallizes as the anhydrous compound.
NaBr crystallizes in the same cubic motif as NaCl, NaF and NaI. The
anhydrous salt crystallizes above 50.70C. It is produced by treating sodium
hydroxide with hydrogen bromide.
MANUFACTURE
1. By neutralization of sodium hydroxide
Raw materials
Basis: 1000kg sodium bromide by neutralization of sodium hydroxide
Sodium hydroxide
380kg
Hydrobromic acid
760kg
Reaction
Manufacture process
Sodium bromide can be produced by neutralization method, in which
solution of sodium hydroxide or sodium carbonate was neutralized using
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Module:4
Lecture:21 Sodium bromide
Dr. N. K. Patel
hydrobromic acid which should be free of bromine. For neutralization
process, solution of sodium hydroxide was introduced into the reactor haning
stirrer where it was treated with hydrobromic acid at ambient temperature.
Mother liquor
Water vapor
Steam
out
Reactor
Evaporator
Steam
in
Crystallizer
Filter
Hydrobromic
acid
NaOH
solution
Cold
air out
Hot
air
Dryer
Sodium
bromide
Figure: Manufacture of sodium bromide by neutralization
Block diagram of manufacturing process
Diagram with process equipment
Animation
As the neutralization reaction proceed amount of water in system was
increased. After neutralization steps reaction mass is transfer to evaporating
tank where water vapour was removed. Concentrated sodium bromide
solution was send to the crystallizer tank where sodium bromide was
crystallized.
The temperature of the crystallizing system should be kept below 510C.
So hydrated sodium bromide crystals will obtained. While anhydrous sodium
bromide was obtained in the form of crystals if temperature was kept above
510C. Mother liquor was separated out via filtration and recycled to a
reactor. While crystals of sodium bromide was sent to a dryer and dried
product was then sent for packaging section.
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Module:4
Lecture:21 Sodium bromide
Dr. N. K. Patel
2. By using excess of bromine
Raw materials
Basis: 1000kg sodium bromide by using excess bromine
Excess bromine
1553kg
Sodium hydroxide
380kg
Reaction
Manufacture process
Generally this process is used for preparing commercial quantity of
sodium bromide.
Excess of bromine is added into a reaction kettle containing sodium
hydroxide solution under continuous stirring at ambient temperature. Then the
excessive bromine-NaOH solution was transfer to evaporating tank where it is
evaporated to dryness.
Activated carbon
or formic acid
Water vapor
Filter
Excess
bromine
NaOH
solution
Steam
out
Reactor
Evaporator
Steam
in
Reducing agent
for purification
Reducing
tank
Cold
air out
Hot
air
Dryer
Sodium
bromide
Figure: Manufacture of sodium bromide using excess bromine
Block diagram of manufacturing process
Diagram with process equipment
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Module:4
Lecture:21 Sodium bromide
Dr. N. K. Patel
Animation
After that it is treated with reducing agent in reducing tank. Generally
activated carbon or formic acid was used as reducing agent which convert
the sodium bromate into sodium bromide.
Health and safety factors
The LD50 for this compound taken orally by rats is 3.5gm/kg body
weight. The gastrointestinal and central nervous system of human can be
affected by sodium bromide. Gastrointestinal effects include nausea and
vomiting, foul breath, anorexia, weight loss, constipation and dehydration.
Due to exposure of large amounts of sodium bromide, immediate abdominal
pain may occur in a single dose. Neurological effects include the headache,
slurred speech, impaired memory and intellectual capacity and drowsiness.
PROPERTIES
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Molecular formula
Molecular weight
Appearance
Odour
Boiling point
Flashpoint
Melting point
 Density
 Refractive index
 Solubility
: NaBr
:102.89gm/mole
: White powder
: Odourless
: 13960C
: 8000C
: 7470C (anhydrous)
360C (dihydrate)
: 3.20gm/cm3 (anhydrous)
2.18gm/cm3 (dihydrate)
: 1.6459
: Soluble in water, methanol
USES
Sodium bromide is useful inorganic bromide in industry
As a hypnotic, anticonvulsant and sedative in medicine
Used in conjunction with chlorine as disinfectant for swimming pools
Used to prepare dense fluids used in oil wells
It can be used as a source of the chemical element bromine this can
be done by treating an aqueous solution of NaBr with chlorine gas.
 Used widely as a hypnotic, anticonvulsant and sedative in medicine.
 Its action is due to the bromide ion, and for this reason potassium
bromide is equally effective.
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