Lithium nitride
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| Lithium nitride | |
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| IUPAC name | lithium nitride |
| Other names | Trilithium nitride Trilithium amide |
| Identifiers | |
| CAS number | [26134-62-3] |
| PubChem | |
| EINECS number | |
| Properties | |
| Molecular formula | Li3N |
| Molar mass | 34.830(8) g mol−1 |
| Appearance | red, purple solid |
| Density | 1.270 g cm−3 |
| Melting point |
813 °C (1086 K) |
| Solubility in water | Reacts |
| Related compounds | |
| Other cations | Sodium nitride |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Lithium nitride is a compound of lithium and nitrogen with the formula Li3N. It is the only stable alkali metal nitride. The solid is a red or purple color, has a high melting point.
Li3N has an unusual crystal structure that consists of two types of layers, one sheet has the composition Li2N− contains 6 coordinate Li centers and the other sheet consist only of lithium cations. Solid lithium nitride is a fast ion conductor and has the highest conductivity of any inorganic lithium salt. It has been studied extensively as a solid electrolyte and an anode material for use in batteries.[1]. It can be formed by direct reaction of the elements, either by burning lithium metal in pure nitrogen gas or by reacting nitrogen gas with lithium dissolved in liquid sodium metal[2]. The second method gives a purer product. Lithium nitride reacts violently with water to produce ammonia:
Li3N (s) + 3 H2O (l) → 3 LiOH (aq) + NH3 (g)
Other alkali and alkaline earth nitrides react in this manner due to the high basicity of the nitride. The hypothetical nitride ion, N3−, would be an extremely strong Bronsted base, easily qualifying as a superbase. It is, in fact, a stronger base than the hydride ion, so deprotonates hydrogen itself:
Li3N (s) + 2 H2 (g) → LiNH2 (s) + 2 LiH (s)
Lithium nitride is being investigated as a potential storage medium for hydrogen gas, as the reaction is reversible at 270 °C. Up to 11.5% by weight absorption of hydrogen has been achieved.[3]
[edit] References
- WebElements
- Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
- ^ US patent 4888258 (1989)
- ^ Barker M.G., Blake A.J, Edwards P.P., Gregory D.H., Hamor T. A., Siddons D. J., Smith S. E. Chem. Commun., 1999, 1187–1188
- ^ Ping Chen, Zhitao Xiong, Jizhong Luo, Jianyi Lin and Kuang Lee Tan "Interaction of hydrogen with metal nitrides and imides" Nature volume 420, pp. 302-304, 2002. doi:10.1038/nature01210
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