Potassium azide
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| Names | |||
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| IUPAC name
Potassium azide
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| Identifiers | |||
3D model (JSmol)
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| ECHA InfoCard | 100.039.997 | ||
PubChem CID
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| UNII | |||
CompTox Dashboard (EPA)
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| Properties | |||
| KN3 | |||
| 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 | 0.1375 g/100 g in ethanol (16°C)[2] insoluble in ether | ||
| Thermochemistry | |||
Std enthalpy of
formation (ΔfH⦵298) |
-1.7 kJ/mol | ||
| Hazards | |||
| Occupational safety and health (OHS/OSH): | |||
Main hazards
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Very Toxic, explosive if strongly heated | ||
| NFPA 704 (fire diamond) | |||
| Lethal dose or concentration (LD, LC): | |||
LD50 (median dose)
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27 mg/kg (oral, rat)[3] | ||
| Related compounds | |||
Other cations
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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).
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Potassium azide is the inorganic compound having the formula KN3. 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.[4]
Structure
[edit]KN3, RbN3, CsN3, and TlN3 adopt the same structures. They crystallize in a tetragonal habit.[5] The azide is bound to eight cations in an eclipsed orientation. The cations are bound to eight terminal N centers.[6]
Synthesis and reactions
[edit]KN3 is prepared by treating potassium carbonate with hydrazoic acid, which is generated in situ.[7] In contrast, the analogous sodium azide is prepared (industrially) by the "Wislicenus process," which proceeds via the reaction sodium amide with nitrous oxide.[8]
Upon heating or upon irradiation with ultraviolet light, it decomposes into potassium metal and nitrogen gas.[9] The decomposition temperatures of the alkali metal azides are: NaN3 (275 °C), KN3 (355 °C), RbN3 (395 °C), CsN3 (390 °C).[10]
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.[11][12]
Health hazards
[edit]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.[8]
References
[edit]- ^ a b c Dale L. Perry; Sidney L. Phillips (1995). Handbook of inorganic compounds. CRC Press. p. 301. ISBN 0-8493-8671-3.
- ^ Jiri Hála (2004). "IUPAC-NIST Solubility Data Series. 79. Alkali and Alkaline Earth Metal Pseudohalides". J. Phys. Chem. Ref. Data. 33: 16. doi:10.1063/1.1563591.
- ^ "Substance Name: Potassium azide". chem.sis.nlm.nih.gov. Archived from the original on 2014-08-12. Retrieved 2014-08-11.
- ^ T. D. Hughes; L. F. Welch (1970). "Potassium Azide as a Nitrification Inhibitor". Agronomy Journal. 62 (5). American Society of Agronomy: 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. Bibcode:1982JRSp...12..300K. doi:10.1002/jrs.1250120319.
- ^ 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.
- ^ a b 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; Chariton, Stella; Prakapenka, Vitali B.; Oganov, Artem R.; Goncharov, Alexander F. (21 April 2022). "Stabilization of hexazine rings in potassium polynitride at high pressure". Nature Chemistry. 14 (7): 794–800. arXiv:2010.15995. Bibcode:2022NatCh..14..794W. doi:10.1038/s41557-022-00925-0. PMID 35449217. S2CID 226222305.
- ^ Laniel, Dominique; Trybel, Florian; Yin, Yuqing; Fedotenko, Timofey; Khandarkhaeva, Saiana; Aslandukov, Andrey; Aprilis, Georgios; Abrikosov, Alexei I.; Bin Masood, Talha; Giacobbe, Carlotta; Bright, Eleanor Lawrence; Glazyrin, Konstantin; Hanfland, Michael; Wright, Jonathan; Hotz, Ingrid (2023-03-06). "Aromatic hexazine [N6]4− anion featured in the complex structure of the high-pressure potassium nitrogen compound K9N56". Nature Chemistry. 15 (5): 641–646. Bibcode:2023NatCh..15..641L. doi:10.1038/s41557-023-01148-7. ISSN 1755-4330. PMID 36879075. S2CID 257377020.