Chemistry:Potassium azide
| |||
| File:KN3viewCropped.tif | |||
| Names | |||
|---|---|---|---|
| IUPAC name
Potassium azide
| |||
| Identifiers | |||
3D model (JSmol)
|
|||
PubChem CID
|
|||
| UNII | |||
| |||
| |||
| Properties | |||
| KN 3 | |||
| Molar mass | 81.1184 g/mol | ||
| Appearance | Colorless crystals[1] | ||
| Density | 2.038 g/cm3 [1] | ||
| Melting point | 350 °C (662 °F; 623 K) (in vacuum)[1] | ||
| Boiling point | decomposes | ||
| 41.4 g/100 mL (0 °C) 50.8 g/100 mL (20 °C) 105.7 g/100 mL (100 °C) | |||
| Solubility | soluble in ethanol insoluble in ether | ||
| Thermochemistry | |||
Std enthalpy of
formation (ΔfH⦵298) |
-1.7 kJ/mol | ||
| Hazards | |||
| Main hazards | Very Toxic, explosive if strongly heated | ||
| NFPA 704 (fire diamond) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
|
27 mg/kg (oral, rat)[2] | ||
| Related compounds | |||
Other cations
|
Sodium azide, copper(II) azide, lead(II) azide, silver azide | ||
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |||
 verify (what is   ?)
| |||
| Infobox references | |||
Potassium azide is the inorganic compound having the formula KN
3. It is a white, water-soluble salt. It is used as a reagent in the laboratory.
It has been found to act as a nitrification inhibitor in soil.[3]
Structure
KN
3, RbN
3, CsN
3, and TlN
3 adopt the same structures. They crystallize in a tetragonal habit.[4] The azide is bound to eight cations in an eclipsed orientation. The cations are bound to eight terminal N centers.[5]
File:AzideCoordinationCropped.tif
Synthesis and reactions
KN
3 is prepared by treating potassium carbonate with hydrazoic acid, which is generated in situ.[6] In contrast, the analogous sodium azide is prepared (industrially) by the "Wislicenus process," which proceeds via the reaction sodium amide with nitrous oxide.[7]
Upon heating or upon irradiation with ultraviolet light, it decomposes into potassium metal and nitrogen gas.[8] The decomposition temperatures of the alkali metal azides are: NaN
3 (275 °C), KN
3 (355 °C), RbN
3 (395 °C), CsN
3 (390 °C).[9]
Under high pressures and high temperatures, potassium azide was found to transform into the K2N6 and K9N56 compounds, both containing hexazine rings: N2−6 and N64-, respectively.[10][11]
Health hazards
Like sodium azide, potassium azide is very toxic. The threshold limit value of the related sodium azide is 0.07 ppm. The toxicity of azides arise from their ability to inhibit cytochrome c oxidase.[7]
References
- ↑ 1.0 1.1 1.2 Dale L. Perry; Sidney L. Phillips (1995). Handbook of inorganic compounds. CRC Press. p. 301. ISBN 0-8493-8671-3.
- ↑ "Substance Name: Potassium azide". https://chem.nlm.nih.gov/chemidplus/rn/20762-60-1.
- ↑ T. D. Hughes; L. F. Welch (1970). "Potassium Azide as a Nitrification Inhibitor". Agronomy Journal (American Society of Agronomy) 62 (5): 595–599. doi:10.2134/agronj1970.00021962006200050013x.
- ↑ Khilji, M. Y.; Sherman, W. F.; Wilkinson, G. R. (1982). "Variable temperature and pressure Raman spectra of potassium azide". Journal of Raman Spectroscopy 12 (3): 300–303. doi:10.1002/jrs.1250120319. Bibcode: 1982JRSp...12..300K.
- ↑ Ulrich Müller "Verfeinerung der Kristallstrukturen von KN3, RbN3, CsN3 und TIN3" Zeitschrift für anorganische und allgemeine Chemie 1972, Volume 392, 159–166. doi:10.1002/zaac.19723920207
- ↑ P. W. Schenk "Alkali Azides from Carbonates" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 475.
- ↑ 7.0 7.1 Horst H. Jobelius, Hans-Dieter Scharff "Hydrazoic Acid and Azides" in Ullmann's Encyclopedia of Industrial Chemistry, 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a13_193
- ↑ Tompkins, F. C.; Young, D. A. (1982). "The Photochemical and Thermal Formation of Colour Centres in Potassium Azide Crystals". Proceedings of the Royal Society of London. Series A, Mathematical and Physical Sciences 236 (1204): 10–23.
- ↑ E. Dönges "Alkali Metals" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 475
- ↑ Wang, Yu; Bykov, Maxim; Chepkasov, Ilya; Samtsevich, Artem; Bykova, Elena; Zhang, Xiao; Jiang, Shu-qing; Greenberg, Eran et al. (21 April 2022). "Stabilization of hexazine rings in potassium polynitride at high pressure". Nature Chemistry 14 (7): 794–800. doi:10.1038/s41557-022-00925-0. PMID 35449217. Bibcode: 2022NatCh..14..794W.
- ↑ Laniel, Dominique; Trybel, Florian; Yin, Yuqing; Fedotenko, Timofey; Khandarkhaeva, Saiana; Aslandukov, Andrey; Aprilis, Georgios; Abrikosov, Alexei I. et al. (2023-03-06). "Aromatic hexazine [N64− anion featured in the complex structure of the high-pressure potassium nitrogen compound K9N56"] (in en). Nature Chemistry 15 (5): 641–646. doi:10.1038/s41557-023-01148-7. ISSN 1755-4330. PMID 36879075. Bibcode: 2023NatCh..15..641L. https://www.nature.com/articles/s41557-023-01148-7.
 |  |
