Ammonia (anhydrous)

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A colorless, strong smelling gas that is the fifth highest volume chemical produced in the United States. Ammonia was also the first complex molecule to be identified in interstellar space. Gaseous ammonia was first isolated by Joseph Priestly in 1774. It is used for chemical synthesis and in the manufacture of explosives and fertilizers. Ammonia has also been used as a vapor phase neutralizing/alkalizing agent where it neutralizes effectively but provides no residual alkaline reserve (Book and Paper catalog). Ammonia is most often sold as an aqueous solution of Ammonium hydroxide. Ammmonia can off-gas from emulsion paints and adhesives as well as neutral cure silicone sealants.

Synonyms and Related Terms

ammonia gas; ammoniacal gas; alkaline air; ammoniac (Fr.); amoniak (Ces., Pol.); ammoniak (Dan., Ned., Sven.); Ammoniak (Deut.); amoníaco (Esp.); ammoniaca (It.); ammoniakk (Nor.); gás amoníaco (Port.); amônia (Port.); Nitrosil; Vaporole; spirit of hartshorn

Personal Risks

  • Toxic by inhalation.
  • Contact causes irritation to skin, eyes and membranes. TLV = 25 ppm.
  • Mixtures of ammonia and air can explode.
  • Airgas: SDS

=Collection Risks

  • Degradation of crystal growth on objects
  • Yellowing of linseed oil

Physical and Chemical Properties

Soluble in water, ethanol, methanol, ether, and chloroform.

Composition NH3
CAS 7664-41-7
Melting Point -77.7 C
Density 0.6813 g/L (gas)
Molecular Weight 17.03
Boiling Point -33.35 C

Resources and Citations

  • Jean Tétreault, 'Products used in Preventive Conservation' Technical Bulletin #2, CCI, 2017. Link
  • Ralph Mayer, A Dictionary of Art Terms and Techniques, Harper and Row Publishers, New York, 1969 (also 1945 printing)
  • Richard S. Lewis, Hawley's Condensed Chemical Dictionary, Van Nostrand Reinhold, New York, 10th ed., 1993
  • 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
  • Book and Paper Group, Paper Conservation Catalog, AIC, 1984, 1989
  • The Merck Index, Martha Windholz (ed.), Merck Research Labs, Rahway NJ, 10th edition, 1983 Comment: entry 517