The chemical compound ammonium nitrate, the nitrate of ammonia with chemical formula NH4NO3, is commonly used in agriculture as a high-nitrogen fertilizer.
Ammonium nitrate has found many uses as a strong oxidizer, primarily as a component of explosives. In this case, it is mixed with a hydrocarbon, usually Diesel fuel (oil). Because of the ready availability in bulk of the raw materials, ammonium nitrate/fuel oil (ANFO) mixtures have occasionally been used for terrorist bombs, for example by the Provisional IRA and in the Oklahoma City bombing by Timothy McVeigh and Terry Nichols. It is also used in military explosives such as the daisy cutter bomb, and as a component of amatol. It has also found use as a solid rocket propellant, though ammonium perchlorate is frequently considered preferable due to higher performance and faster burn rates. It also finds use in gas generator applications such as airbags due to its low temperature, non-toxic decomposition products.
Ammonium nitrate decomposes into gases including oxygen when heated (non-explosive reaction); however, ammonium nitrate can be induced to decompose explosively by detonation. Large stockpiles of the material can be a major fire risk due to their supporting oxidation, and may also detonate, as happened in the Texas City disaster of 1947, which led to major changes in the regulations for storage and handling.
A heavy explosion, with 561 casualties, occurred in the city of Oppau (on the grounds of BASF near Ludwigshafen in Germany) on September 21, 1921. Another one occurred, 80 years later, at a plant in Toulouse, France, in September 21, 2001.
Ammonium nitrate is also used in instant cold packs, as it dissolves in water endothermically, absorbing 26.2 kilojoules per mole of heat to do so.
Ammonium nitrate is also used in the treatment of titanium ores.
Industrial production is quite easy. A simple reaction of ammonia with nitric acid easily gives a solution of ammonium nitrate. Another production method is used in the so called Odda process.