Hydride is the isolated atomic hydrogen anion, H- or any compound containing
hydrogen and another element, more electropositive element or group. Hydride
consists of a singly charged positive nucleus and two electrons of which one
electron is weakly held and readily donative ˇ°extraˇ±. There are some types of hydrides according to their bonding.
hydrides (saline hydrides): the hydrogen obtains an electron from a more
electropositive metal, usually one of the alkali metals, to be an anion, H- ,
and behaves like a halogen. Ionic hydrides react vigorously with water with
removing hydrogen gas (H2). Compounds that have hydrogen and one other element
only is called binary hydrides with general form of MH or MH2 such as sodium
hydride (NaH), lithium hydride (LiH), calcium hydride (CaH2), magnesium hydride
- Covalent hydrides: The hydrogen shares one or more pairs of
electrons with more electronegative elements (such as boron and aluminium) or
nonmetallic elements. Water, ammonia, hydrogen sulfide (H2S), hydrocarbons
(alkane, alkene and alkyne), and hydrazine belong to nonmetallic covalent
hydrides which behave as molecules and are normally gas or volatile liquids.
Hydrogen halides, boranes, silane, phosphines belong to covalent hydrides.
- Metallic hydrides: They are alloylike materials which have individual
properties of metals. Their bondings are vary from element to element.
- Polymeric hydrides: the hydrogen has bridges forming three center bond with
other atoms such as boron, aluminum, and beryllium.
Hydrides which carry
hydrogen can provide large amounts of energy when burned. They can be used as an exotic fuel. They are less flammable and less volatile
than hydrocarbon fuels. They are relatively environmentally friendly because
they degrade quickly in the environment. Hydrides and
hydrido complexes containing this easily polarized ion are highly reactive,
strongly basic and powerfully reducing in synthetic reactions. They are
important reducing agents in industrial reactions though they are easily
destroyed in the relatively acidic compound water (H2O) and in air containing
- Lithium Hydride:
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 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
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;
Lithium 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
Lithium Hydroxide (LiOH);
white, hygroscopic, crystalline material;
soluble in water, slightly soluble in
ethanol and insoluble in ether; there are commercially forms of monohydrate 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
esterfication 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.
Lithium Carbonate (Li2CO3) ; 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 aluminium, 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
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 disorder.
Lithium 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
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.
having high melting point at 614°C.
Lithium chloride and bromide are the mostly
used as a 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.
Lithium 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 aluminium, 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.
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
It is also applied as a stabilizer in cosmetics
as well as plastic industry. It is used as a corrosion inhibitor in petroleum.
Lithium Molybdate (Li2MoO4);
melting at 705°C; soluble in water; used as a catalyst for petroleum cracking and as a
mill additive for steel.
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.
Lithium Carbide (Li2C2);
Lithium Phosphate (Li3PO4);
(Li2SO4); white crystalline material, soluble in water but
insoluble in ethanol. It forms a monohydrate 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.