| Lithium nitride | |
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| Identifiers | |
| CAS number | [] |
| PubChem | |
| EC number | |
| ChEBI | |
| InChI |
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| Properties | |
| Molecular formula | Li3N |
| Molar mass | 34.83 g/mol |
| Appearance | red, purple solid |
| Density | 1.270 g/cm3 |
| Melting point |
813 °C, 1086 K, 1495 °F |
| Solubility in water | reacts |
| log P | 3.24 |
| Hazards | |
| EU Index | Not listed |
| Main hazards | reacts with water to release ammonia |
| Related compounds | |
| Other anions | Lithium oxide |
| Other cations | Sodium nitride |
| Related compounds | Lithium amide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox 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 and 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 also react in this manner, due to the high basicity of the nitride. The hypothetical nitride ion, N3−, would be an extremely strong Brønsted base, easily qualifying as a superbase. It is, in fact, a stronger base than the hydride ion, and 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]
References
- WebElements
- Greenwood, Norman N.; Earnshaw, A. (1997), Chemistry of the Elements (2nd ed.), 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. (1999). "Novel layered lithium nitridonickelates; effect of Li vacancy concentration on N co-ordination geometry and Ni oxidation state". Chem. Commun.: 1187–1188. doi:.
- ^ Ping Chen, Zhitao Xiong, Jizhong Luo, Jianyi Lin and Kuang Lee Tan (2002). "Interaction of hydrogen with metal nitrides and imides". Nature 420: 302–304. doi:.
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