Lithium hydride

Chembox new
Name = Lithium hydride
ImageFile = Lithium-hydride-3D-vdW.png ImageSize = 200px
ImageName = Space-filling model of part of the crystal structure of lithium hydride
Section1 = Chembox Identifiers
CASNo = 7580-67-8
Section2 = Chembox Properties
Formula = LiH
MolarMass = 7.95 g mol⁻¹
Appearance = colorless to gray solid
Density = 0.82 g cm⁻³ [ [http://www.sigmaaldrich.com/catalog/search/ProductDetail/FLUKA/62500 Sigma-Aldrich website] ] , solid
Solubility = Reacts
MeltingPt = 692 °C [Greenwood&Earnshaw, p. 65]
Section3 = Chembox Structure
Structure = fcc (NaCl-type)
Section7 = Chembox Hazards
ExternalMSDS =
EUClass = Flammable (F)
NFPA-H =
NFPA-F =
NFPA-R =
RPhrases =
SPhrases =
Section8 = Chembox Related
OtherCations = sodium hydride, potassium hydride
OtherCpds = lithium borohydride, lithium aluminium hydride

Lithium hydride (LiH) is the compound of lithium 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 (1272 °F). 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 as well as hydrogen.:LiH + H₂O →→ LiOH + H₂

ynthesis

It is produced by reacting lithium metal with hydrogen gas: [Cite web
url=http://www.lyon.edu/webdata/users/fbeckford/CHM%20120/Lecture%20Notes/Chapter-14.ppt
title=University of Lyon course online (powerpoint) slideshow
accessdate=2008-07-27
author=Dr. Floyd Beckford
quote=definitions:Slides 8-10 (Chapter 14)] : 2 Li + H₂ $ightarrow$ 2 LiH

Uses

LiH has numerous uses, as a desiccant, as a precursor for the synthesis of lithium aluminium hydride, in hydrogen generators, as both a coolant and shielding in nuclear reactors, and in the manufacture of ceramics. 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 is identical), because lithium is lighter than sodium, making LiH of interest for hydrogen storage.

The corresponding lithium deuteride, formula LiD, is the fusion fuel in thermonuclear weapons. In warheads of the Teller-Ulam design, LiD is compressed and heated by the explosion of the fission primary to the point where fusion occurs. Lithium deuteride, unlike tritium, is non-radioactive.

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

afety

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

ee also

* Hydride

Related compounds

* Sodium hydride

In popular culture

In Larry Niven's science fiction book "Protector", his character Brennan describes the by-products of a bussard ramjet as being an assortment of strange chemicals including "Lithium Hydride... a normally impossible chemical..." The book was published in 1973.

References

External links

* [http://www.webelements.com/webelements/compounds/text/Li/H1Li1-7580678.html Compounds of lithium: Lithium (I) Hydride]
* [http://yosemite.epa.gov/oswer/CeppoEHS.nsf/firstaid/7580-67-8?OpenDocument Emergency First Aid Treatment Guide - Lithium Hydride]
* [http://www.compchemwiki.org/index.php?title=Lithium_hydride Computational Chemistry Wiki]
* [http://www.mcis.soton.ac.uk/Site_Files/pdf/nuclear_history/Working_Paper_No_5.pdf University of Southampton, Mountbatten Centre for International Studies, Nuclear History Working Paper No5.]