Title: Ammonia
CAS Registry Number: 7664-41-7
Molecular Formula: H3N
Molecular Weight: 17.03
Percent Composition: H 17.76%, N 82.25%
Line Formula: NH3
Literature 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 gas; very pungent odor (characteristic of drying urine). Lower limit of human perception: 0.04 g/cubic meter or 53 ppm. 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 nonflammable. Corrosive, alkaline gas. 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.
Melting point: mp -77.7°
Boiling point: bp760 -33.35°
Density: d 0.5967 (air = 1); 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); d420 (aq solns): 0.9939 (1%); 0.9811 (4%); 0.9651 (8%); 0.9362 (16%); 0.9229 (20%); 0.9101 (24%); 0.8980 (28%)
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.
Ammonia Water Ammoniacum Ammonium Acetate Ammonium Benzoate Ammonium Bicarbonate

Stereo structural formula of the ammonia molecule
Ball-and-stick model of the ammonia molecule Space-filling model of the ammonia molecule
CAS number 7664-41-7 YesY
PubChem 222 YesY
ChemSpider 217 YesY
UNII 5138Q19F1X YesY
EC number 231-635-3
UN number 1005
KEGG D02916 YesY
MeSH Ammonia
ChEBI CHEBI:16134 YesY
RTECS number BO0875000
Beilstein Reference 3587154
Gmelin Reference 79
3DMet B00004
Jmol-3D images Image 1
Molecular formula NH3
Molar mass 17.031 g/mol
Appearance Colourless gas
Odor strong pungent odor
Density 0.86 kg/m3 (1.013 bar at boiling point)
0.73 kg/m3 (1.013 bar at 15 °C)
681.9 kg/m3 at −33.3 °C (liquid)[1]
817 kg/m3 at −80 °C (transparent solid)[2]
Melting point −77.73 °C; −107.91 °F; 195.42 K
Boiling point −33.34 °C; −28.01 °F; 239.81 K
Solubility in water 47% (0 °C)
31% (25 °C)
28% (50 °C)[3]
Solubility soluble in chloroform, ether, ethanol, methanol
Vapor pressure 8573 h Pa
Acidity (pKa) 32.5 (−33 °C),[4] 10.5 (DMSO)
Basicity (pKb) 4.75
Refractive index (nD) 1.3327
Viscosity 0.276 cP (-40 °C)
Molecular shape Trigonal pyramid
Dipole moment 1.42 D
Std molar
entropy So298
193 J·mol−1·K−1[5]
Std enthalpy of
formation ΔfHo298
−46 kJ·mol−1[5]
MSDS External MSDS
GHS pictograms GHS-pictogram-bottle.svgGHS-pictogram-acid.svgGHS-pictogram-skull.svgGHS-pictogram-pollu.svg[6]
GHS hazard statements H221, H280, H314, H331, H400[6]
GHS precautionary statements P210, P261, P273, P280, P305+351+338, P310[6]
EU Index 007-001-00-5 (anhydrous)
007-001-01-2 (solutions)
EU classification Toxic T Corrosive C Dangerous for the Environment (Nature) N
R-phrases R10, R23, R34, R50
S-phrases (S1/2), S9, S16, S26, S36/37/39, S45, S61
NFPA 704
NFPA 704.svg
Flash point flammable gas (see text)
Autoignition temperature 651 °C; 1,204 °F; 924 K
Explosive limits 15–28%
U.S. Permissible
exposure limit (PEL)
50 ppm (25 ppm ACGIH- TLV; 35 ppm STEL)
LD50 0.015 mL/kg (human, oral)
Related compounds
Other cations Phosphine
Related nitrogen hydrides Hydrazine
Hydrazoic acid
Related compounds Ammonium hydroxide
Supplementary data page
Structure and
n, εr, etc.
Phase behaviour
Solid, liquid, gas
Spectral data UV, IR, NMR, MS
 YesY (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Ammonia, or azane, is a compound of nitrogen and hydrogen with the formula NH3. It is a colourless gas with a characteristic pungent smell. Ammonia contributes significantly to the nutritional needs of terrestrial organisms by serving as a precursor to food and fertilizers. Ammonia, either directly or indirectly, is also a building-block for the synthesis of many pharmaceuticals and is used in many commercial cleaning products. Although in wide use, ammonia is both caustic and hazardous. The global industrial production of ammonia for 2012 was anticipated to be 198 million tonnes,[7] a 35% increase over the estimated 2006 global output of 146.5 million tonnes.[8]

NH3 boils at −33.34 °C (−28.012 °F) at a pressure of 1 atmosphere, so the liquid must be stored under high pressure or at low temperature. Household ammonia or ammonium hydroxide is a solution of NH3 in water. The concentration of such solutions is measured in units of the Baumé scale (density), with 26 degrees baumé (about 30% (by weight) ammonia at 15.5 °C) being the typical high-concentration commercial product.[9]