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Lithium hydride (Li
Lithium

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft alkali metal with a silver-white color. Under standard conditions for temperature and pressure, it is the lightest metal and the least dense solid element....
H
Hydride

Hydride is the name given to the Electric charge ion of hydrogen, H-. Although this ion does not exist except in extraordinary conditions, the term hydride is widely applied to describe Chemical compound of hydrogen with other chemical element, particularly those of Periodic table group 1–16....
) is the compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 of lithium
Lithium

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft alkali metal with a silver-white color. Under standard conditions for temperature and pressure, it is the lightest metal and the least dense solid element....
 and hydrogen. It is a colourless crystalline solid, although commercial samples appear gray. Characteristic of a salt-like, or ionic, hydride, it has a high melting point of 689 °C
Celsius

Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death....
 (1272 °F
Fahrenheit

Fahrenheit is a temperature scale named after the physicist Daniel Gabriel Fahrenheit , who proposed it in 1724. Today, the scale has largely been replaced by the Celsius scale; it is still in use for non-scientific purposes in the United States and a few other countries such as Belize....
). Its density is 780 kilograms per cubic metre. It has a standard heat capacity of 29.73 J/mol*k with thermal conductivity that varies with composition and pressure (from at least 10 to 5 W/m*K at 400 K) and decreases with temperature.

It is a flammable solid and very reactive with water, producing the corrosive compound lithium hydroxide
Lithium hydroxide

Lithium hydroxide is a corrosive alkali hydroxide. It is a white hygroscopic crystalline material. It is soluble in water, and slightly soluble in ethanol....
 as well as hydrogen.
LiH + H2O ?? LiOH + H2


s produced by reacting lithium metal with hydrogen gas:
2 Li + H2 2 LiH


has numerous uses, as a desiccant
Desiccant

A desiccant is a hygroscopic substance that induces or sustains a state of dryness in its local vicinity in a moderately-well sealed container.Commonly encountered pre-packaged desiccants are solids, and work through absorption or adsorption of water, or a combination of the two....
, as a precursor for the synthesis of lithium aluminium hydride
Lithium aluminium hydride

Lithium aluminium hydride , commonly abbreviated to LAH, is a reducing agent used in organic synthesis. It is more powerful than the related reagent sodium borohydride due to the weaker Al-H bond compared to the B-H bond....
, in hydrogen generators, as both a coolant and shielding in nuclear reactor
Nuclear reactor

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an explosion....
s, and in the manufacture of ceramic
Ceramic

File:Bridge from dental porcelain.jpgFile:Qing vase p1070256.jpgA ceramic is an inorganic, nonmetal solid prepared by the action of heat and subsequent cooling....
s.






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Encyclopedia


Lithium hydride (Li
Lithium

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft alkali metal with a silver-white color. Under standard conditions for temperature and pressure, it is the lightest metal and the least dense solid element....
H
Hydride

Hydride is the name given to the Electric charge ion of hydrogen, H-. Although this ion does not exist except in extraordinary conditions, the term hydride is widely applied to describe Chemical compound of hydrogen with other chemical element, particularly those of Periodic table group 1–16....
) is the compound
Chemical compound

A chemical compound is a Chemical substance consisting of two or more different chemical element Chemical bond together in a fixed mass ratio that can be split into simpler substances....
 of lithium
Lithium

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft alkali metal with a silver-white color. Under standard conditions for temperature and pressure, it is the lightest metal and the least dense solid element....
 and hydrogen. It is a colourless crystalline solid, although commercial samples appear gray. Characteristic of a salt-like, or ionic, hydride, it has a high melting point of 689 °C
Celsius

Celsius is a temperature scale that is named after the Swedish astronomer Anders Celsius , who developed a similar temperature scale two years before his death....
 (1272 °F
Fahrenheit

Fahrenheit is a temperature scale named after the physicist Daniel Gabriel Fahrenheit , who proposed it in 1724. Today, the scale has largely been replaced by the Celsius scale; it is still in use for non-scientific purposes in the United States and a few other countries such as Belize....
). Its density is 780 kilograms per cubic metre. It has a standard heat capacity of 29.73 J/mol*k with thermal conductivity that varies with composition and pressure (from at least 10 to 5 W/m*K at 400 K) and decreases with temperature.

It is a flammable solid and very reactive with water, producing the corrosive compound lithium hydroxide
Lithium hydroxide

Lithium hydroxide is a corrosive alkali hydroxide. It is a white hygroscopic crystalline material. It is soluble in water, and slightly soluble in ethanol....
 as well as hydrogen.
LiH + H2O ?? LiOH + H2


Synthesis

It is produced by reacting lithium metal with hydrogen gas:
2 Li + H2 2 LiH


Uses

LiH has numerous uses, as a desiccant
Desiccant

A desiccant is a hygroscopic substance that induces or sustains a state of dryness in its local vicinity in a moderately-well sealed container.Commonly encountered pre-packaged desiccants are solids, and work through absorption or adsorption of water, or a combination of the two....
, as a precursor for the synthesis of lithium aluminium hydride
Lithium aluminium hydride

Lithium aluminium hydride , commonly abbreviated to LAH, is a reducing agent used in organic synthesis. It is more powerful than the related reagent sodium borohydride due to the weaker Al-H bond compared to the B-H bond....
, in hydrogen generators, as both a coolant and shielding in nuclear reactor
Nuclear reactor

A nuclear reactor is a device in which nuclear chain reactions are initiated, controlled, and sustained at a steady rate, as opposed to a nuclear bomb, in which the chain reaction occurs in a fraction of a second and is uncontrolled causing an explosion....
s, and in the manufacture of ceramic
Ceramic

File:Bridge from dental porcelain.jpgFile:Qing vase p1070256.jpgA ceramic is an inorganic, nonmetal solid prepared by the action of heat and subsequent cooling....
s. LiH has the highest hydrogen content (in mass percentage) of any saline hydride. The hydrogen content of LiH is three times that of NaH (though its stoichiometry
Stoichiometry

Stoichiometry is the calculation of quantitative relationships of the reactants and Product in a balanced chemical reaction .Etymology...
 is identical), because lithium
Lithium

Lithium is a chemical element with the symbol Li and atomic number 3. It is a soft alkali metal with a silver-white color. Under standard conditions for temperature and pressure, it is the lightest metal and the least dense solid element....
 is lighter than sodium
Sodium

Sodium is an element which has the symbol Na , atomic number 11, atomic mass 23 amu , and a common oxidation number +1. Sodium is a soft, silvery white, highly reactive element and is a member of the alkali metals within "group 1" ....
, making LiH of interest for hydrogen storage.

The corresponding lithium deuteride
Deuterium

Deuterium, also called heavy hydrogen, is a stable isotope of hydrogen with a natural abundance in the oceans of Earth of approximately one atom in 6500 of hydrogen ....
, formula LiD, is the fusion
Nuclear fusion

In nuclear physics and nuclear chemistry, nuclear fusion is the process by which multiple like-charged atomic nuclei join together to form a heavier nucleus....
 fuel in thermonuclear weapons. In warheads of the Teller-Ulam design
Teller-Ulam design

The Teller?Ulam design is a nuclear weapon design which is used in megaton-range thermonuclear weapons, and is more colloquially referred to as "the secret of the hydrogen bomb"....
, LiD is compressed and heated by the explosion of the fission primary to the point where fusion occurs. Lithium deuteride, unlike tritium
Tritium

Tritium is a radioactive isotope of hydrogen. The atomic nucleus of tritium contains one proton and two neutrons, whereas the nucleus of Hydrogen atom contains one proton and no neutrons....
, is non-radioactive.

Can also be used as a storage vessel for use in hydrogen vehicles.

Safety

LiH is flammable in air, and it reacts explosively with water to give corrosive LiOH together with hydrogen gas.

See also

  • Hydride
    Hydride

    Hydride is the name given to the Electric charge ion of hydrogen, H-. Although this ion does not exist except in extraordinary conditions, the term hydride is widely applied to describe Chemical compound of hydrogen with other chemical element, particularly those of Periodic table group 1–16....

Related compounds

  • Sodium hydride
    Sodium hydride

    Sodium hydride is the chemical compound with the formula NaH. It is primarily used as a strong base in organic synthesis. NaH is representative of the saline hydrides, meaning it is a salt-like hydride, composed of Na+ and H- ions, in contrast to the more molecular hydrides such as borane, methane, ammonia and water....


In popular culture

In Larry Niven
Larry Niven

Laurence van Cott Niven is a US science fiction author. Perhaps his best-known work is Ringworld , which received Hugo Award for Best Novel, Locus Award, Ditmar Award, and Nebula Award for Best Novel awards....
's science fiction book Protector, his character Brennan describes the by-products of a bussard ramjet
Bussard ramjet

The Bussard ramjet is a theoretical method of spacecraft propulsion proposed in 1960 by the physicist Robert W. Bussard, popularized by Larry Niven in his Known Space series of books, and referred to by Carl Sagan in the television series and Cosmos Cosmos: A Personal Voyage....
 as being an assortment of strange chemicals including "Lithium Hydride... a normally impossible chemical..." The book was published in 1973.

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