LITHIUM AND ITS COMPOUNDS

Lithium

LITHIUM AND ITS COMPOUNDS

Lithium (from Greek: λίθος, translate. lithos, lit. ‘stone’) is a chemical element with symbol Li and atomic number 3. It is a soft, silvery-white alkali metal.
Under standard conditions, it is the lightest metal and the lightest solid element. Like all alkali metals, lithium is highly reactive and flammable, and is stored in mineral oil.
When cut, it exhibits a metallic luster, but moist air corrodes it quickly to a dull silvery gray, then black tarnish.
It never occurs freely in nature, but only in (usually ionic) compounds, such as pegmatitic minerals, which were once the main source of lithium.
Due to its solubility as an ion, it is present in ocean water and is commonly obtained from brines. Lithium metal is isolated electrolytically from a mixture of lithium chloride and potassium chloride.

GENERAL DESCRIPTION OF LITHIUM AND ITS COMPOUNDS

Lithium is a soft, the lightest, silver-white, highly reactive metallic element in Group 1 of periodic table; atomic number 3; atomic mass 6.941; melting point ca 180.5 C; boiling point ca 1,342 C; specific gravity 0.534 g/cm3 valence +1; electronic config. 2-1 or 1s 22s 1. Lithium metal is prepared by the electrolysis of a molten mixture of potassium and lithium chlorides.

It is used in various alloys with magnesium, copper, manganese, cadmium and aluminum to form a strong, low density material,as a heat transfer medium, in cooling system of nuclear reactor, and as a scavenger, in ceramics, glasses and in rocket fuel.
Lithium forms many important inorganic and organic compounds such as;

Li. Hydride (LiH):

Flammable, white, translucent solids; decomposes at 850 °C; reacts violently with water to yield hydrogen and lithium hydroxide; used as a hydrogen source or reducing agent to prepare other hydrides amides and 2H isotopic compound, as a shielding material for thermal neutrons.

Lithium Hydroxide (LiOH); white, hygroscopic, crystalline material; soluble in water, slightly soluble in ethanol and insoluble in ether; there are commercially forms of mono hydrate and anhydrous;

used for purification of gases and air (as a carbon dioxide absorbent), as a heat transfer medium, as a storage-battery electrolyte, as a catalyst for polymerization, in ceramics, manufacturing other lithium compounds and esterification specially for lithium stearate which is used as general purpose lubricating greases due to its high resistance to water and the useful at both high and low temperature.

white granular powder; slight soluble in water, melts at 723°C, decomposes above 1310°C; It is prepared commercially by treating the ore with sulphuric acid at 250°C and leaching the product to give a solution of lithium sulphate.
The carbonate is then obtained by precipitation with sodium carbonate solution; It is used as a flux in the aluminum, glass and ceramics production to improves the brightness of glazes and increases the firing range.
It is a source of Lithia, strong high temperature flux.
It is used as an additive in cement industry to improve acceleration and fast setting process.
It is used as an additive in floor screeds and tiles.
It is used for the production of other lithium chemicals and organic compounds as a catalyst.
Pharmaceutical grade of lithium carbonate is used for the primary treatment of depression and bipolar disordez

Li.Bromide (LiBr);

white powder with a bitter taste; melts at 547°C,soluble in water, alcohol and glycol;
used as an operating medium for air-conditioning and industrial drying system due to its very hygroscopic property.
and as a sedative and hypnotic in medicine.
It is also used in manufacturing pharmaceuticals and alkylation process. It is used as brazing and welding fluxes.
Lithium chloride; white hygroscopic deliquescent granule or powder having high melting point at 614°C.
Lithium chloride and bromide are the mostly periscopic materials used as an operating medium for air-conditioning and industrial drying system. It is used as brazing and welding fluxes. It is also used in as an intermediate for manufacturing other chemical compounds.

Li.Fluoride (LiF);

white poisonous powder melting at 870°C, boiling at 1670°C; slightly soluble in water, soluble in acids but insoluble in alcohol; t is used as a flux in the aluminum, glass and ceramics production to improves the brightness of glazes and increases the firing range. It is used as a flux for brazing and welding of zirconium, titanium and magnesium. It is used as a heat-exchange medium.
Lithium Iodide (LiI; LiI.3H2O) white to yellowish solid; soluble in water alcohol; there are commercially anhydrous form (melts at 446°C) and trihydrate form (loses water at 72°C); It is used in organic synthesis, manufacturing medicines and mineral waters.

Li. Stearate (LiC18H35O2);

white crystalline powder derived from lithium hydroxide with cooking tallow (or other animal fat); melting at 220 C; used as general purpose lubricating greases providing high resistance to water and the useful at both high and low temperature, which have found extensive applications in the automotive, aircraft and heavy machinery industry. It is also applied as a stabilizer in cosmetics as well as plastic industry. It is used as a corrosion inhibitor in petroleum.

Li. Molybdate (Li2MoO4);

white crystals melting at 705°C; soluble in water; used as a catalyst for petroleum cracking and as a mill additive for steel.
Lithia (Li2O); A white crystalline compound, melting at 1700°C. the main uses are in lubricating greases, ceramics, glass and refractories, and as a flux in brazing and welding.

Li. Carbide (Li2C2);
Li. Phosphate (Li3PO4);
Li. Sulphate (Li2SO4);

white crystalline material, soluble in water but insoluble in ethanol. It forms a mono-hydrate and an anhydrous form, the compound is prepared by the reaction of the hydroxide or carbonate with sulphuric acid. Lithium Tetrahydridoaluminate (Lithal, LiAlH4); A powerful reducing agent in synthetic organic chemistry; aldehydes, esters and ketones to the corresponding alcohols. nitriles to primary amines.

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