Hydrazoic acid

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Hydrazoic acid
Structure, bonding and dimensions of the hydrogen azide molecule
Hydrazoic acid
General
Systematic name hydrogen azide
Other names hydrazoic acid
azoimide
azidic acid
diazoimide
hydrogen azide
hydronitric acid
triazoic acid
Molecular formula HN3
SMILES N=N=N
Molar mass 43.03 g/mol
Appearance Colourless liquid
CAS number [7782-79-8]
Properties:
Density and phase  ? g/cm3, ?
Solubility in water  ? g/100 ml (? °C)
Melting point −80 °C (193.15 K)
Boiling point 37 °C (310.15 K)
Acidity (pKa) 4.6 to 4.7
Viscosity  ? cP at ?°C
Structure
Molecular shape Linear
Dipole moment  ? D
Hazards
MSDS External MSDS
Main hazards Highly toxic, explosive.
NFPA 704
Flash point  ? °C
R/S statement R: R1, R2
S: ?
RTECS number  ?
Supplementary data page
Structure and
properties
n, εr, etc.
Thermodynamic
data
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
Related compounds
Other anions Hydrogen chloride
Other cations Sodium azide
Related acids Hydrochloric acid
hydrocyanic acid
Related compounds Hydrazine
Except where noted otherwise, data are given for
materials in their standard state (at 25 °C, 100 kPa)
Infobox disclaimer and references

Hydrazoic acid, HN3, is a colorless, volatile, and extremely explosive liquid at room temperature and pressure.

Contents

[edit] Applications

Hydrazoic acid is used primarily for preservation of stock solutions, and as a reagent.

[edit] History

It was first isolated in 1890 by Theodor Curtius (Berichte, 1890, 23, p. 3023).

[edit] Chemistry

It is soluble in water, and the solution dissolves many metals (e.g. zinc, iron) with liberation of hydrogen and formation of salts (azides, formerly also called azoimides or hydrazoates).

All the salts are explosive and readily interact with the alkyl iodides. In its properties it shows some analogy to the halogen acids, since it forms poorly soluble lead, silver and mercurous salts (in water). The metallic salts all crystallize in the anhydrous form and decompose on heating, leaving a residue of the pure metal. It is a weak acid (pKa 4.6-4.7).

[edit] Production

The acid is formed by acidification of an azide salt, usually sodium azide, or by adding water (which has a lower yield).

The pure acid may be obtained by fractional distillation as a colorless liquid of very unpleasant smell, boiling at ~30 °C., and extremely explosive.

[edit] Toxicity

Hydrazoic acid is volatile and highly poisonous. Its unbearable smell and the violent headache caused by breathing the vapor conspire to make accidental poisoning impossible. The compound acts a non-cumulative poison.

[edit] References

  • Dictionary of inorganic and organometallic compounds, Chapman & Hall

[edit] External links

This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain.