Lithium Bromide

Lithium bromide is an ionic compound of lithium and bromine. Lithium is an alkali metal that has 3 electrons. The electronic configuration of lithium is 2,1. Thus, it has 1 electron in its valence shell. On the other hand, bromine is a non – metal that has 35 electrons in its single atom. Its electronic configuration is 2,8,18,7. Thus, it has 7 electrons in its valence shell. Lithium can attain electronic configuration like nearest noble gas He by donating one electron while bromine can attain electronic configuration like nearest noble gas Kr by accepting one electron. So, Li donates one electron to bromine and forms an ionic bond. Thus, both the elements get stability by attaining electronic configuration like nearest noble gas and form a new compound LiBr. 

An Interesting Salt Lithium Bromide (LiBr)

Lithium (Li) is the 3rd element in a series of elements as mentioned in a periodic table. It can chemically combine with the Bromine (Br)element to form a chemical compound called Lithium bromide (Libr). It is a type of salt as sodium chloride (NaCl) but what differs it from other salts is that it is extremely hygroscopic in nature. This property of Lithium bromide makes it a very useful substance in various places. Though it is available naturally due to its large amount of use, it is now being produced artificially by industrial methods.  To produce Lithium bromide lithium carbonate and hydrobromic acid are used. Both the compounds are suspended in water to come closer and react. In this mechanism, Lithium Bromide precipitates down in that aqueous solution. 

The most popular use of Lithium bromide is its use in Air conditioning systems as a desiccant and rarely in absorption refrigerators as a heat-absorbing salt.  The other uses of Lithium bromide include its use as a catalyst for oxidation and hydroformylation of organic compounds or sometimes for their deprotonation and dehydration. In medical science, it is also used for the purification of various steroids that are used for treating ailments or suppressing pain. Lithium bromide is also infamous as a  sedative of the early 2oth century. So it can be said that Lithium bromide has some psychoactive properties. Another great use of Lithium bromide is that it is used as a drug to treat bipolar disorder.

Properties of Lithium Bromide 

Physical and chemical properties of lithium bromide are listed below –

• Its chemical formula is LiBr

• Boiling point of lithium bromide is 1265 oC.

• Melting point of lithium bromide is 552 oC.

• It is a hygroscopic white solid. 

• Its molar mass is 86.845 g/mol.

• Its density is 3.464 g/cm3.

• It is soluble in water. Its solubility in water increases, as the temperature increases. For example, its solubility in water is 143 g/100 ml at 0 oC and as the temperature reaches up to 20 oC, its solubility becomes 166.7 g/100ml. 

• It is also soluble in methanol, ethanol, ether, acetone etc. It is slightly soluble in pyridine. 

• It is not flammable. 

• It can dissolve many polar organic compounds such as cellulose.

• It is stable in nature and generally, does not react easily. 

• Its anhydrous form forms cubic crystals like NaCl.

• Reaction with chlorine – Lithium bromide reacts with the chlorine molecule and forms lithium chloride salt and bromine gas. Reaction is given below –

Cl2 + 2LiBr → Br2 + 2LiCl 

• Reaction with silver nitrate – Lithium bromide reacts with silver nitrate and forms lithium nitrate and silver bromide.

Structure of Lithium Bromide 

In lithium bromide, an ionic bond is formed by the transfer of an electron from lithium to bromine. As lithium donates an electron so it forms a cation or gets a positive charge Li+. While bromine accepts an electron, it forms an anion or gets a negative charge Br-. The crystal structure of lithium bromide is cubic.

Production of Lithium Bromide 

Lithium bromide can be prepared by many methods. A few of them are listed below –

• By the reaction of lithium carbonate and hydrobromic acid – Lithium bromide can be prepared by reaction of lithium carbonate with hydrobromic acid. The reaction is given below 

Li2CO3 + 2HBr → 2LiBr + H2CO3

• By the reaction of lithium hydroxide and hydrobromic acid – Lithium bromide can also be prepared by reaction of lithium hydroxide with aqueous solution hydrogen bromide or hydrobromic acid. The reaction is given below

  LiOH + HBr → LiBr + H2O

Uses of Lithium Bromide 

Lithium bromide is used in many fields. A few of its uses are listed below –

• It is used in air – Conditioning machines as a desiccant due to its hygroscopic nature. It is used with water in absorption chilling in air conditioners. 

• It is used in the synthesis of many organic compounds. 

• It is used in pharmaceuticals in the synthesis of many drugs.

• It is used to produce many inorganic compounds as well such as lithium chloride etc. 

• It was used as a sedative in the early 1900s but due to some adverse effects on the heart, doctors stopped using it as a sedative. 

• Lithium chloride and lithium bromide were used for the treatment of bipolar disorder. 

• It is used in the synthesis of olefins for catalytic dehydrohalogenation.

• It is used in refrigerators as a non - CFC alternative as due to its hygroscopic nature it can easily absorb excess vapor. Thus, it makes the system environmentally friendly. 

• It is used in emulsions as it is soluble in ether and other organic solvents.