Identifiers | |
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3D model (Jmol)
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ChemSpider | |
ECHA InfoCard | 100.028.623 |
PubChem CID
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RTECS number | OJ6300000 |
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Properties | |
LiH | |
Molar mass | 7.95 g/mol |
Appearance | colorless to gray solid |
Density | 0.78 g/cm3 |
Melting point | 688.7 °C (1,271.7 °F; 961.9 K) |
Boiling point | decomposes at 900–1000 °C |
reacts | |
Solubility | slightly soluble in dimethylformamide reacts with ammonia, diethyl ether, ethanol |
−4.6·10−6 cm3/mol | |
Refractive index (nD)
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1.9847 |
Structure | |
fcc (NaCl-type) | |
a = 0.40834 nm
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6.0 D | |
Thermochemistry | |
3.51 J/(g·K) | |
Std molar
entropy (S |
170.8 J/mol K |
Std enthalpy of
formation (ΔfH |
-90.65 kJ/mol |
Gibbs free energy (ΔfG˚)
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-68.48 kJ/mol |
Hazards | |
Safety data sheet | ICSC 0813 |
NFPA 704 | |
200 °C (392 °F; 473 K) | |
Lethal dose or concentration (LD, LC): | |
LD50 (median dose)
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77.5 mg/kg (oral, rat) |
LC50 (median concentration)
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22 mg/m3 (rat, 4 hr) |
US health exposure limits (NIOSH): | |
PEL (Permissible)
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TWA 0.025 mg/m3 |
REL (Recommended)
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TWA 0.025 mg/m3 |
IDLH (Immediate danger)
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0.5 mg/m3 |
Related compounds | |
Other cations
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Sodium hydride Potassium hydride Rubidium hydride Caesium hydride |
Related compounds
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Lithium borohydride Lithium aluminium hydride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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what is ?) | (|
Infobox references | |
Lithium hydride is an inorganic compound with the formula LiH. This alkali metal hydride is a colorless solid, although commercial samples are grey. Characteristic of a salt-like, or ionic, hydride, it has a high melting point and is not soluble but reactive with all organic and protic solvents; it is soluble and non-reactive with certain molten salts such as lithium fluoride, lithium borohydride, and sodium hydride. 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 ×10−5 Ω−1cm−1 at 443 °C to 0.18 Ω−1cm−1 at 754 °C; there is no discontinuity in this increase through the melting point. The 2dielectric constant of LiH decreases from 13.0 (static, low frequencies) to 3.6 (visible light frequencies). LiH is a soft material with a 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.
LiH is produced by treating lithium metal with hydrogen gas: