Formula Mole Weight Critical Pressure Critical Temperature
NH# 17.03 1636 Psia 270.2 F


General Description:

            As a gas, ammonia is toxic, colorless, and possesses a characteristic penetrating and irritating odor.  In its liquid state, ammonia is a weak base and thus has a soapy feel.  Aqueous ammonia (NH3) reacts readily with water to form its conjugate acid, the ammonium ion (NH4+).   The gas readily dissolves in water to form aqueous ammonia (i.e. ammonium hydroxide).  Ammonia gas is also released by bacterial breakdown of animal waste, by which nitrogen enters the nitrogen cycle (see NITROGEN).  Bacteria in the soil break down ammonia into nitrates, which are utilized by plants.        


            The most important commercial compound of nitrogen, over 34.50 billion pounds of ammonia are produced annually in the United States (Chemical and Engineering News, April 11, 1994).  Ammonia is easily prepared from N2 and H2 from natural gas, steam, and air via the Haber process.  Liquefied ammonia and ammonium salts are commonly used as household cleaner and fertilizer.  Also, ammonia may be converted to urea (NH2CONH2) for the use in fertilizers, livestock feed supplement, and plastic manufacturing. 


Pressure, psia 14.7 100 500
Temperature, F 60 200 300
Compressibility, (Z) 0.9893 0.9683 0.9006
Enthalpy, Btu/lb (h)  245.0 310.0 340.0
Entropy, Btu/lb-R (s) 2.7172 2.6088 2.4749
Specific Heat, Btu/mol-R(Cp) 0.5082 0.5596 0.6675
k, (Cp/Cv)  1.2976 1.2631 1.2116
Sonic velocity, ft/sec 1400 1546 1588
Specific volume, ft3/lb 22.0 4.02 0.862
Dynamic viscosity, lb/ft-sec 5.941E-06 7.407E-06 8.858E-06



1) Gas Flex, Flexware, Inc., Grapeville, PA, USA
2) Organic Chemistry, Paula Yurkanis Bruice, University of California, Prentice Hall, NJ, 1998
3) General Chemistry, Darrell D. Ebbing, Wayne State University, Houghton Mifflin Co., 1996
4) Chemistry:  The Central Science, Theodore L. Brown; H. Eugene LeMay; Bruce E. Bursten. Prentice Hall, NJ, 1991

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Flexware, Inc. 2005
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page updated May 21, 2005