Difference between revisions of "Lithium hydride"
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==Preparation== | ==Preparation== | ||
| − | Can be prepared by reacting molten lithium metal with hydrogen. The reaction takes place in a [[nickel]] [[crucible]], between 450-500 °C, and the hydrogen used must be air and water-free. The yield of this reaction is 95%.<ref>[http://actachemscand.org/pdf/acta_vol_03_p1050-1057.pdf Brandt, P.; Acta Chemica Scandinavica (1947-1973); vol. 3; (1949); p. 1050 - 1057]</ref> | + | Can be prepared by reacting molten [[lithium metal]] with [[hydrogen]]. The reaction takes place in a [[nickel]] [[crucible]], between 450-500 °C, and the hydrogen used must be air and water-free. The yield of this reaction is 95%.<ref>[http://actachemscand.org/pdf/acta_vol_03_p1050-1057.pdf Brandt, P.; Acta Chemica Scandinavica (1947-1973); vol. 3; (1949); p. 1050 - 1057]</ref> |
| − | However, the reaction can proceed at temperatures as low as 29 °C. The yield is 60% at 99 °C and 85% at 125 °C, and the rate depends significantly on the surface condition of LiH. | + | However, the reaction can proceed at temperatures as low as 29 °C. The yield is 60% at 99 °C and 85% at 125 °C, and the rate depends significantly on the surface condition of LiH and the purity of the inert gas used as inert conditions. |
Hydrogenolysis of n-butyllithium at normal temperature and atmospheric pressure in the absence of catalyst will yield LiH.<ref>Gilman, H.; Jacoby, A. L.; Ludeman, H.; Journal of the American Chemical Society; vol. 60; (1938); p. 2336 - 2338</ref> | Hydrogenolysis of n-butyllithium at normal temperature and atmospheric pressure in the absence of catalyst will yield LiH.<ref>Gilman, H.; Jacoby, A. L.; Ludeman, H.; Journal of the American Chemical Society; vol. 60; (1938); p. 2336 - 2338</ref> | ||
Revision as of 17:32, 13 September 2018
| Names | |
|---|---|
| IUPAC name
Lithium hydride
| |
| Other names
Lithium monohydride
| |
| Properties | |
| LiH | |
| Molar mass | 7.95 g/mol |
| Appearance | White or light gray samples |
| Odor | Odorless |
| Density | 0.78 g/cm3 |
| Melting point | 688.7 °C (1,271.7 °F; 961.9 K) |
| Boiling point | 900 °C (1,650 °F; 1,170 K) (decomposes) |
| Reacts | |
| Solubility | Reacts with alcohols, aldehydes, amines, ammonia, carboxylic acids, DMSO, esters, ethers, halocarbons, ketones Soluble in molten lithium borohydride, lithium fluoride and sodium hydride Slightly soluble in dimethylformamide Insoluble in hydrocarbons |
| Vapor pressure | ~0 mmHg |
| Thermochemistry | |
| Std molar
entropy (S |
170.8 J·mol-1K-1 |
| Std enthalpy of
formation (ΔfH |
-90.65 kJ/mol |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Related compounds | |
| Related compounds
|
Sodium hydride Calcium hydride |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
| Infobox references | |
Lithium hydride is an inorganic compound with the formula LiH.
Contents
Properties
Chemical
Lithium hydride reacts with water to release hydrogen.
- LiH + H2O → LiOH + H2
Physical
Lithium hydride is an odorless white or slight grayish solid, which reacts with most solvents and is insoluble in those with which it doesn't react, like hydrocarbons.
Availability
Lithium hydride is sold by chemical suppliers, though it's not cheap.
Preparation
Can be prepared by reacting molten lithium metal with hydrogen. The reaction takes place in a nickel crucible, between 450-500 °C, and the hydrogen used must be air and water-free. The yield of this reaction is 95%.[1]
However, the reaction can proceed at temperatures as low as 29 °C. The yield is 60% at 99 °C and 85% at 125 °C, and the rate depends significantly on the surface condition of LiH and the purity of the inert gas used as inert conditions.
Hydrogenolysis of n-butyllithium at normal temperature and atmospheric pressure in the absence of catalyst will yield LiH.[2]
Projects
- Desiccant
- Make lithium aluminium hydride
Handling
Safety
Lithium hydride is very reactive towards most common solvents, it will even slowly attack ethers. It may spontaneously ignite in moist air.
Storage
Lithium hydride must be kept in air-tight containers, in an inert atmosphere, away from moisture. Schlenk flasks are good storage containers.
Disposal
Lithium hydride can be safely neutralized by slowly adding it in a large volume of alcohol, followed by slow addition of water.
References
- ↑ Brandt, P.; Acta Chemica Scandinavica (1947-1973); vol. 3; (1949); p. 1050 - 1057
- ↑ Gilman, H.; Jacoby, A. L.; Ludeman, H.; Journal of the American Chemical Society; vol. 60; (1938); p. 2336 - 2338
Relevant Sciencemadness threads
- Articles containing unverified chemical infoboxes
- Chembox articles without image
- Chemical compounds
- Inorganic compounds
- Lithium compounds
- Hydrogen compounds
- Metal hydrides
- Bases
- Insoluble compounds
- Reducing agents
- Desiccants
- Materials unstable in acidic solution
- Materials that react with water
- Irritants
- Air-sensitive materials
- Pyrophoric materials
