492. Ammonia

Nomenclature

CAS number: 7664-41-7
H3N; mol wt 17.03.
H 17.76%, N 82.25%.
NH3.

Description and references

Manufactured from water gas (obtained by blowing steam through incandescent coke) as source of hydrogen, and from producer gas (obtained from steam and air through incandescent coke), as source of nitrogen by the Haber-Bosch process. Manuf from natural gas: Faith, Keyes & Clark's Industrial Chemicals, F. A. Lowenheim, M. K. Moran, Eds. (Wiley-Interscience, New York, 4th ed., 1975) pp 83-92. Historical monograph: A. Mittasch, Geschichte der Ammoniaksynthese (Verlag Chemie, 1951). Reviews of prepn, properties and chemistry: Several authors in Mellor's Vol. VIII, supplement I, Nitrogen part 1 (1964) pp 240-369; Jones in Comprehensive Inorganic Chemistry Vol. 2, J. C. Bailar, Jr. et al., Eds. (Pergamon Press, Oxford, 1973) pp 199-227; J. R. LeBlanc et al., in Kirk-Othmer Encyclopedia of Chemical Technology vol. 2 (Wiley-Interscience, New York, 3rd ed., 1978) pp 470-516. Review of toxicology and human exposure: Toxicological Profile for Ammonia (PB2004-107331, 2004) 269 pp.

Properties

Colorless, non-flammable gas; very pungent odor (characteristic of drying urine). Lower limit of human perception: 0.04 g/cubic meter or 53 ppm. Poisonous, corrosive. One liter of the gas weighs 0.7714 g. d 0.5967 (air = 1). mp 77.7°. bp760 33.35°. Densities of liq NH3 (temp; press.): 0.6818 (33.35°; 1 atm); 0.6585 (15°; 2.332 atm); 0.6386 (0°; 4.238 atm); 0.6175 (15°; 7.188 atm); 0.5875 (35°; 13.321 atm). Critical temp 132.4°; critical press. 111.5 atm. Heat capacity (25°) 8.38 cal/mole/deg. Mixtures of ammonia and air will explode when ignited under favorable conditions: Angew. Chem. 43, 302 (1930), but ammonia is generally regarded as non-flammable. pH of 1.0N aq soln 11.6; of 0.1N aq soln 11.1; of 0.01N aq soln 10.6. Water at 0° holds 47%, at 15° 38%, at 20° 34%, at 25° 31%, at 30° 28%, at 50° 18%. d420 (aq solns): 0.9939 (1%); 0.9811 (4%); 0.9651 (8%); 0.9362 (16%); 0.9229 (20%); 0.9101 (24%); 0.8980 (28%). fp (aq solns): 2.9° (4%); 8.1° (8%); 23.1° (16%); 34.9° (20%); 44.5° (24%); 69.2° (28%). Solution of NH3 in water is exothermic. 95% alcohol at 20° holds 15%, at 30° 11%. Abs ethanol at 0° 20%, at 25° 10%. Methanol at 25° 16%. It is also sol in chloroform and ether. Liquid ammonia produces low temps by its own evaporation. Heat of vaporization: 5.581 kcal/mole. It is a good solvent for many elements and compds. Usually marketed in liquefied form in steel cylinders or as ammonia water (aqua ammonia, ammonium hydroxide) in drums and bottles.

Caution

Potential symptoms of overexposure are eye, nose and throat irritation; dyspnea, bronchospasm and chest pain; pulmonary edema; pink frothy sputum; skin burns, vesiculation; direct contact with liquid may cause frostbite. See NIOSH Pocket Guide to Chemical Hazards (DHHS/NIOSH 97-140, 1997) p 14. See also Patty's Industrial Hygiene and Toxicology vol. 2B, G. D. Clayton, F. E. Clayton, Eds. (Wiley-Interscience, New York, 3rd ed., 1981) pp 3045-3052.

Use

Fertilizer, corrosion inhibitor, purification of water supplies, component of household cleaners, as refrigerant. Manuf nitric acid, explosives, synthetic fibers, fertilizers. In pulp and paper, metallurgy, rubber, food and beverage, textile and leather industries.