Lithium hydride

CAS number : 7580-67-8

Molecular weight :7.95

Molecular formula/chemical symbol :HLi

Description :

Lithium hydride is the inorganic compound with the formula LiH. It is a colorless solid, although commercial samples are gray. Characteristic of a salt-like, or ionic, hydride, it has a high melting point and is not soluble in any solvent with which it does not react. With a molecular mass of slightly less than 8, it is the lightest ionic compound.

LiH is a diamagnetic and an ionic conductor with a conductivity gradually increasing from 2×10^?5 Ohm^?1cm^?1 at 443 °C to 0.18 Ohm^?1cm^?1 at 754 °C; there is no discontinuity in this increase through the melting point. The dielectric constant of LiH decreases from 13.0 (static, low frequencies) to 3.6 (visible light frequencies). LiH is a soft material with the Mohs hardness of 3.5. Its compressive creep (per 100 hours) rapidly increases from <1% at 350 °C to >100% at 475 °C meaning that LiH can‘t provide mechanical support when heated.

The thermal conductivity of LiH decreases with temperature and depends on morphology: the corresponding values are 0.125 W/(cm K) for crystals and 0.0695 W/(cm K) for compacts at 50 °C, and 0.036 W/(cm K) for crystals and 0.0432 W/(cm K) for compacts at 500 °C. The linear thermal expansion coefficient is 4.2×10^?5/°C at room temperature.

Lithium hydride
Identifiers
CAS number	7580-67-8 Y
PubChem	62714
ChemSpider	56460 Y
RTECS number	OJ6300000
Jmol-3D images	Image 1
Properties
Molecular formula	LiH
Molar mass	7.95 g/mol
Appearance	colorless to gray solid[1]
Density	0.78 g/cm3[1]
Melting point	688.7 °C[1]
Boiling point	decomposes at 900–1000 °C[2]
Solubility in water	reacts
Refractive index (nD)	1.9847[3]
Structure
Lattice constant	a = 0.40834 nm[4]
Dipole moment	6.0 D[5]
Thermochemistry
Std enthalpy of formation ΔfHo298	-11.39 kJ/g
Specific heat capacity, C	3.51 J/(g·K)
Hazards
MSDS	ICSC 0813
EU Index	Not listed
Autoignition temperature	200 °C
Related compounds
Other cations	Sodium hydride Potassium hydride Rubidium hydride Caesium hydride
Related compounds	Lithium borohydride Lithium aluminium hydride
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

ile:"
?:D?У@?DMINI~1\LOCALS~1\Temp\msohtml1\01\clip_image007.png" o:href="http://upload.wikimedia.org/wikipedia/en/thumb/f/fb/Yes_check.svg/10px-Yes_check.svg.png"/> Y/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)

USES :

The military used as a hydrogen source. Organic synthesis is used as the reducing agent, used as a desiccant, the hydrogen generating agent and the organic synthesis of a reducing agent