Ammonia is the basic building block of the nitrogen industry worldwide. Almost all ammonia is produced in the anhydrous form (free of water) by a catalytic reaction of nitrogen (from air) with hydrogen from a hydrocarbon source (usually natural gas). Ammonia is a colorless, pungent, nonflammable gas at normal pressure and temperature and is lighter than air. For storage at atmospheric pressure at sea level, ammonia must be cooled to 33ºC and stored as liquid. Lower temperatures are required at higher altitudes. In the usual atmospheric temperature range of 0–40ºC, the range of vapor pressure is about 4–15 atm. Approximately 10% of the ammonia produced never reaches the market, because of its volatility and losses, during conversion to other materials and during transportation and storage. Nitrogen fertilizer consumption accounts for more than 85% of the world ammonia market

Ammonia is a colorless gas with a characteristic pungent smell. It is lighter than air, its density being 0.589 times that of air. It is easily liquefied due to the strong hydrogen bonding between molecules; the liquid boils at -33.3 °C, and solidifies at -77.7 °C to white crystals. Liquid ammonia possesses strong ionizing powers reflecting its high “Dielectric Constant” of 22. Liquid ammonia has a very high standard enthalpy change of vaporization (23.35 kJ/mol,  cf.  water 40.65 kJ/mol, methane 8.19 kJ/mol, phosphine 14.6 kJ/mol) and can therefore be used in laboratories in non-insulated vessels without additional refrigeration

 

It is miscible with water. Ammonia in an aqueous solution can be expelled by boiling. The aqueous solution of ammonia is basic. The maximum concentration of ammonia in water (a saturated solution) has a density of 0.880 g /cm³ and is often known as '.880 Ammonia'. Ammonia does not burn readily or sustain combustion, except under narrow fuel-to-air mixtures of 15-25% air. When mixed with oxygen, it burns with a pale yellowish-green flame. At high temperature and in the presence of a suitable catalyst, ammonia is decomposed into its constituent elements. Ignition occurs when chlorine is passed into ammonia, forming nitrogen and hydrogen chloride; if ammonia is present in excess, then the highly explosive nitrogen trichloride (NCl3) is also formed.

The ammonia molecule readily undergoes nitrogen inversion at room temperature; a useful analogy is an umbrella turning itself inside out in a strong wind. The energy barrier to this inversion is 24.7 kJ/mol, and the resonance frequency is 23.79 GHz, corresponding to microwave radiation of a wavelength of 1.260 cm. The absorption at this frequency was the first microwave spectrum to be observed