Nitrous acid

Nitrous acid
Nitrous acid
Names
IUPAC name
Nitrous acid[1]
Identifiers
3D model (JSmol)
3DMet
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.029.057 Edit this at Wikidata
EC Number
  • 231-963-7
983
KEGG
MeSH Nitrous+acid
UNII
  • InChI=1S/HNO2/c2-1-3/h(H,2,3) checkY
    Key: IOVCWXUNBOPUCH-UHFFFAOYSA-N checkY
  • O=NO
Properties
HNO2
Molar mass 47.013 g/mol
Appearance Pale blue solution
Density Approx. 1 g/ml
Melting point Only known in solution or as gas
Acidity (pKa) 3.15[2]
Conjugate base Nitrite
Hazards
NFPA 704 (fire diamond)
Flash point Non-flammable
Related compounds
Other anions
Nitric acid
Other cations
Sodium nitrite
Potassium nitrite
Ammonium nitrite
Related compounds
Dinitrogen trioxide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Nitrous acid (molecular formula HNO
2
) is a weak and monoprotic acid known only in solution, in the gas phase, and in the form of nitrite (NO
2
) salts.[3] It was discovered by Carl Wilhelm Scheele, who called it "phlogisticated acid of niter". Nitrous acid is used to make diazonium salts from amines. The resulting diazonium salts are reagents in azo coupling reactions to give azo dyes.

  1. ^ "Nitrous Acid".
  2. ^ Perrin, D. D., ed. (1982) [1969]. Ionisation Constants of Inorganic Acids and Bases in Aqueous Solution. IUPAC Chemical Data (2nd ed.). Oxford: Pergamon (published 1984). Entry 156. ISBN 0-08-029214-3. LCCN 82-16524.
  3. ^ Cite error: The named reference G&E was invoked but never defined (see the help page).