Lithium : Extraction, Physical and Chemical Properties, Uses

Extraction of Lithium

Extraction of Lithium - Electrolysis of Lithium chloride.

Lithium metal is obtained by the electrolysis of moisture free lithium chloride in a crucible of thick porcelain using gas-coke splinter anode and iron wire cathode. For the preparation of the metal on a large scale, a fused mixture of equal parts of lithium and potassium chloride is used, as it melts at a lower temperature of 720 K.

Lithium is also obtained by the electrolysis of a concentrated solution of lithium chloride in pyridine or acetone.

Properties of Lithium

Physical : Lithium is a silvery white metal and it is the lightest of all solid elements. It's vapours impart calamine red colour to the flame. It is a good conductor of heat and electricity. It gives alloys with number of metals and forms amalgam.

Chemical

1) With air: Lithium is not affected by dry air but in moist air it is readily oxidized. When heated in air above 450K, it burns to give lithium monoxide and lithium nitride

4 Li + O_{2 -- >} 2 Li₂O

6 Li + N_{2 -- >} 2 Li₃N

2) It decomposes cold water forming lithium hydroxide and hydrogen

2 Li + 2 H2O  -- >   2 LiOH + H2

3) Lithium is a strongly electropositive metal and displaces hydrogen from acid with the formation of corresponding lithium salts. Dilute and concentrated hydrochloric and dilute sulphuric acid react readily while concentrated sulphuric acid reacts slowly. With nitric acid, the action is violent and metal melts and catches fire.

Uses

1.     For the manufacture of alloys.

2.     As a deoxidizer in the preparation of copper and nickel.

3.     Lithium citrate and salicylate are used in the treatment of gout.

4.     LiAlH₄ is used as an reducing agent.

5.     Its compounds are used in glass and pottery manufacture.