Potassium azide

Potassium azide

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Names
IUPAC name Potassium azide
Identifiers
CAS Number	20762-60-1 Y
Jmol 3D model	Interactive image
PubChem	10290740
InChI InChI=1S/K.N3/c;1-3-2/q+1;-1 Key: TZLVRPLSVNESQC-UHFFFAOYSA-N
SMILES [N-]=[N+]=[N-].[K+]
Properties
Chemical formula	KN 3
Molar mass	81.1184 g/mol
Appearance	Colorless crystals
Density	2.038 g/cm3
Melting point	350 °C (662 °F; 623 K) (in vacuum)
Boiling point	decomposes
Solubility in water	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 (ΔfHo298)	-1.7 kJ/mol
Vapor pressure	{{{value}}}
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).
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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.

Structure

KN₃, RbN₃, CsN₃, and TlN₃ adopt the same structures. They crystallize in a tetragonal habit. The azide is bound to eight cations in an eclipsed orientation. The cations are bound to eight terminal N centers.

File:AzideCoordinationCropped.tif

Coordination sphere of azide in K,Rb,Cs,TlN₃.

Synthesis and reactions

KN₃ is prepared by treating potassium carbonate with hydrazoic acid, which is generated in situ. In contrast, the analogous sodium azide is prepared (industrially) by the "Wislicenus process," which proceeds via the reaction sodium amide with nitrous oxide.

Upon heating or upon irradiation with ultraviolet light, it decomposes into potassium metal and nitrogen gas. The decomposition temperatures of the alkali metal azides are: NaN₃ (275 °C), KN₃ (355 °C), RbN₃ (395 °C), CsN₃ (390 °C).

Health hazards

Like sodium azide, potassium azide is very toxic. The MAK value for the related sodium azide is 0.07 ppm. The toxicity of azides arise from their ability to inhibit cytochrome c oxidase.