Lithium hydride, represented by the chemical formula LiH, is a crystalline or powdery inorganic compound ^[1]. The alkali metal hydride has a molecular mass less than 8 and is the lightest ionic compound ^{[1, 2]}.

Lithium Hydride Identification
CAS Number	7580-67-8 [1]
PubChem CID	62714 [1]
ChemSpider ID	56460 [3]
UN Number	1414 [1]
ICSC Number	0813 [1]
EC Number	231-484-3 [1, 4]
RTECS Number	OJ6300000 [1]
InChI Key	SRTHRWZAMDZJOS-UHFFFAOYSA-N [1]

How to make Lithium Hydride

LiH can be synthesized by the reaction of solid lithium with hydrogen gas, which is represented by the following chemical equation ^[5]:

2Li + H₂ → 2LiH

The reaction occurs rapidly at temperatures over 600 °C, and the yield is increased to 98% ^[5]. It can also occur at 29 °C, but the yield is much lower ^[5].

Lithium hydride is also produced by combining lithium aluminum hydride and sodium hydroxide through metathesis in tetrahydrofuran (THF) ^[6]:

LiAlH₄ + NaH → NaAlH₄ + LiH

Reactions with Other Compounds

LiH reacts with air to produce Li₂O, LiOH, and Li₂CO₃, while it forms nitrogenous compounds in moist air ^[5]. It spontaneously undergoes a chemical reaction with water which is given as follows ^[5]:

LiH + H₂O → Li⁺ + H₂ + OH^–

Lithium hydride reacts with sulfur dioxide to form lithium dithionite at a temperature above 50 °C ^[5]:

2LiH + 2SO₂ → Li₂S₂O₄ + H₂

When it reacts with acetylene, it produces hydrogen and lithium carbide ^[5]:

LiH + LiOH →Li₂O + H₂

Properties and Characteristics of Lithium Hydride

General Properties
Molar Mass/Molecular Weight	7.948 g/mol [1]
Physical Properties
Color and Appearance	Off-white, gray, or translucent; light bluish-gray lumps in commercial product [1]
Odor	Odorless [1]
Melting Point	680 °C, 1256 °F [1]
Boiling Point	900-1000 °C, 1650-1830 °F (decomposes) [1]
Density	0.76-0.8 g cm-3 [1]
State of matter at room temperature	Solid [1, 4]
Solubility	Somewhat soluble in dimethylformamide; it reacts with diethyl ether, ammonia, and ethanol
Solubility in Water	Reacts [1]
Magnetic Susceptibility (χ)	-4.6 X 10-6 cm3/mol
Heat Capacity (C)	3.51 J/(g.K)
Atomic Properties
Crystal Structure	Octahedral cubic (NaCl-type) [7]

What is It Used for

• Synthesis of hydrogen because LiH has the highest H₂ content of any hydride ^[4]
• Manufacturing catalysts used for polyolefin plastics ^[8]
• Missiles, aircraft, and rocket fuel ^[8]
• Degasification, deoxidization, and desulfurization in the metallurgical industry ^[8]
• Forming alloys with magnesium and aluminum for aerospace use ^[8]
• Shielding and absorbing neutrons in mobile nuclear reactors, used along with lithium-7 ^[9]

Is It Toxic

Repeated contact or overexposure can cause acute irritation of skin, mucous membranes, and eyes ^[1]. When burned, it forms irritating alkali fumes ^[1]. LiH forms dust clouds that may explode when they come in contact with heat, flame, or oxidizing materials ^[1].

References
1. Lithium Hydride – Pubchem.ncbi.nlm.nih.gov
2. Lithium Hydride – Chem.libretexts.org
3. Lithium Hydride – Chemspider.com
4. Lithium Hydride – Americanelements.com
5. Technical Memorandum Compilation Of The Properties Of Lithium Hydride – Ntrs.nasa.gov
6. Lithium Aluminium Hydride – Cs.Mcgill.ca
7. Lithium Hydride – Webelements.com
8. Lithium Hydride – Toxnet.nlm.nih.gov
9. Lithium Hydride – A Space Age Shielding Material – Ntrs.nasa.gov