Potassium nitrate

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Powdered possium nitrate

Clear colorless crystals that are slightly Hygroscopic. Potassium nitrate has been used since the 1300s as an ingredient in Gunpowder. It was used in Gold smelting, Glass making, and Textile dyeing. In a closed environment, a saturated salt solution of potassium nitrate will form an equilibrium at a relative humidity of about 93% (20C).

Synonyms and Related Terms

niter; nitre; saltpeter; Bengal saltpeter ; sal prunella; kaliumnitrat (Dan., Deut.); salpêtre (Fr.); nitrato di potassio (It.); kaliumnitraat (Ned.); azotan potasu (Pol.); saletra potasowa (Pol.);



Chemical structure

Potassium nitrate.jpg


  • Dangerous fire and explosion risk when shocked, heated or in contact with organic materials.
  • Strong oxidizing agent.
  • ThermoFisher: SDS

Physical and Chemical Properties

Soluble in water, glycerol. Slightly soluble in ethanol.

Deliquescent point at 20C is 93.2 % RH (see Saturated salt solutions)

Composition KNO3
CAS 7757-79-1
Melting Point 333 C
Density 2.1062 g/ml
Molecular Weight mol. wt. = 101.1
Boiling Point 400 C (dec)

Resources and Citations

  • G.S.Brady, Materials Handbook, McGraw-Hill Book Co., New York, 1971 Comment: p. 632
  • Hermann Kuhn, Conservation and Restoration of Works of Art and Antiquities, Butterworths, London, 1986
  • Susan E. Schur, Conservation Terminology: A review of Past & Current Nomenclature of Materials, Technology and Conservation, Spring (p.34-39); Summer (p.35-38); Fall (p.25-36), 1985
  • Michael McCann, Artist Beware, Watson-Guptill Publications, New York City, 1979