Ammonium nitrate

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Ammonium nitrate
Ammonium Nitrate.jpg
IUPAC name
Ammonium nitrate
3D model (JSmol)
ECHA InfoCard 100.026.680
EC Number
  • 229-347-8
PubChem CID
RTECS number
  • BR9050000
UN number 0222with > 0.2% combustible substances
1942with ≤ 0.2% combustible substances
Molar mass 80.043 g/mol
Appearancewhite/grey solid
Density 1.725 g/cm3 (20 °C)
Melting point 169.6 °C (337.3 °F; 442.8 K)
Boiling point approx.210 °C (410 °F; 483 K)decomposes
118 g/100 ml (0 °C)
150 g/100 ml (20 °C)
297 g/100 ml (40 °C)
410 g/100 ml (60 °C)
576 g/100 ml (80 °C)
1024 g/100 ml (100 °C) [1]
-33.6·10−6 cm3/mol
Explosive data
Shock sensitivity very low
Friction sensitivity very low
Detonation velocity 2500 m/s
Main hazards Explosive, Oxidizer
GHS pictograms GHS-pictogram-exclam.svg GHS-pictogram-rondflam.svg GHS-pictogram-explos.svg
GHS Signal word Danger
H201, H271, H319
P220, P221, P271, P280, P264, P372
NFPA 704 (fire diamond)
Flammability code 0: Will not burn. E.g. waterHealth code 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineReactivity code 3: Capable of detonation or explosive decomposition but requires a strong initiating source, must be heated under confinement before initiation, reacts explosively with water, or will detonate if severely shocked. E.g. hydrogen peroxideSpecial hazard OX: Oxidizer. E.g. potassium perchlorateAmmonium nitrate
Lethal dose or concentration (LD, LC):
2085–5300 mg/kg (oral in rats, mice) [2]
Related compounds
Other anions
Ammonium nitrite
Other cations
Sodium nitrate
Potassium nitrate
Hydroxylammonium nitrate
Related compounds
Ammonium perchlorate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Ammonium nitrate is a chemical compound, the nitrate salt of the ammonium cation. It has the chemical formula N H
, simplified to N2H4O3. It is a white crystalline solid and is highly soluble in water. It is predominantly used in agriculture as a high-nitrogen fertilizer. [4] Its other major use is as a component of explosive mixtures used in mining, quarrying, and civil construction. It is the major constituent of ANFO, a popular industrial explosive which accounts for 80% of explosives used in North America; similar formulations have been used in improvised explosive devices. Many countries are phasing out its use in consumer applications due to concerns over its potential for misuse. [5]



Ammonium nitrate is found as a natural mineral (gwihabaite – the ammonium analogue of saltpetre, which is correctly called niter, and other nitre minerals such as sodium nitrate known as nitratine) in the driest regions of the Atacama Desert in Chile, often as a crust on the ground and/or in conjunction with other nitrate, iodate, and halide minerals. Ammonium nitrate was mined there in the past, but virtually 100% of the chemical now used is synthetic.


The industrial production of ammonium nitrate entails the acid-base reaction of ammonia with nitric acid: [6]

HNO3 + NH3 → NH4NO3

Ammonia is used in its anhydrous form (i.e., gas form) and the nitric acid is concentrated. This reaction is violent owing to its highly exothermic nature. After the solution is formed, typically at about 83% concentration, the excess water is evaporated to an ammonium nitrate (AN) content of 95% to 99.9% concentration (AN melt), depending on grade. The AN melt is then made into "prills" or small beads in a spray tower, or into granules by spraying and tumbling in a rotating drum. The prills or granules may be further dried, cooled, and then coated to prevent caking. These prills or granules are the typical AN products in commerce.

The ammonia required for this process is obtained by the Haber process from nitrogen and hydrogen. Ammonia produced by the Haber process is oxidized to nitric acid by the Ostwald process. Another production method is a variant of the Odda process:

Ca(NO3)2 + 2 NH3 + CO2 + H2O 2 NH4NO3 + CaCO3

The products, calcium carbonate and ammonium nitrate, may be separately purified or sold combined as calcium ammonium nitrate.

Ammonium nitrate can also be made via metathesis reactions:

(NH4)2SO4 + Ba(NO3)2 → 2 NH4NO3 + BaSO4
NH4Cl + AgNO3 → NH4NO3 + AgCl


Ammonium nitrate reacts with metal hydroxides, releasing ammonia and forming alkali metal nitrate:

NH4NO3 + MOH → NH3 + H2O + MNO3 (M = Na, K)

Ammonium nitrate leaves no residue when heated:

NH4NO3N2O + 2H2O

When rapidly heated or exploded the predominant reaction is:

2NH4NO3 → 2N2 + O2 + 4H2O

Ammonium nitrate is also formed in the atmosphere from emissions of NO, SO2, and NH3, and is a secondary component of some PM10 particulates. [7]

Crystalline phases

Transformations of the crystal states due to changing conditions (temperature, pressure) affect the physical properties of ammonium nitrate. These crystalline states have been identified:

SystemTemperature (°C)StateVolume change (%)
> 169.6liquid
I169.6 to 125.2cubic−2.1
II125.2 to 84.2tetragonal+1.3
III84.2 to 32.3α-rhombic−3.6
IV32.3 to −16.8β-rhombic+2.9
V< −16.8tetragonal

The type V crystal is a quasicubic form related to caesium chloride, the nitrogen atoms of the nitrate anions and the ammonium cations are at the sites in a cubic array where Cs and Cl would be in the CsCl lattice. [8]



Ammonium nitrate is an important fertilizer with the NPK rating 34-0-0 (34% nitrogen). [9] It is less concentrated than urea (46-0-0), giving ammonium nitrate a slight transportation disadvantage. Ammonium nitrate's advantage over urea is that it is more stable and does not rapidly lose nitrogen to the atmosphere.


Ammonium nitrate is not, in the form it is commonly sold, an explosive, [10] but it readily forms explosive mixtures with varying properties when combined with primary explosives such as azides or with fuels such as aluminium powder or fuel oil.

Mixture with fuel oil

ANFO is a mixture of 94% ammonium nitrate ("AN") and 6% fuel oil ("FO") widely used as a bulk industrial explosive. [11] :1 It is used in coal mining, quarrying, metal mining, and civil construction in undemanding applications where the advantages of ANFO's low cost and ease of use matter more than the benefits offered by conventional industrial explosives, such as water resistance, oxygen balance, high detonation velocity, and performance in small diameters. [11] :2


Ammonium nitrate-based explosives were used in the Sterling Hall bombing in Madison, Wisconsin, 1970, the Oklahoma City bombing in 1995, the 2011 Delhi bombings, the 2011 bombing in Oslo, and the 2013 Hyderabad blasts.

In November 2009, a ban on ammonium sulfate, ammonium nitrate, and calcium ammonium nitrate fertilizers was imposed in the former Malakand Division – comprising the Upper Dir, Lower Dir, Swat, Chitral, and Malakand districts of the North West Frontier Province (NWFP) of Pakistan – by the NWFP government, following reports that those chemicals were used by militants to make explosives. Due to these bans, "Potassium chlorate – the stuff that makes matches catch fire – has surpassed fertilizer as the explosive of choice for insurgents." [12]

Niche uses

Ammonium nitrate is used in some instant cold packs, as its dissolution in water is highly endothermic. It also was used, in combination with independently explosive "fuels" such as guanidine nitrate, [13] [14] as a cheaper (but less stable) alternative to 5-aminotetrazole in the inflators of airbags manufactured by Takata Corporation, which were recalled as unsafe after killing 14 people. [15]

The solution of ammonium nitrate with nitric acid, called Cavea-b showed promise for use in spacecraft as a more energetic alternative to the common monopropellant hydrazine. A number of trials were carried out in the sixties but the substance ended up not being adopted by NASA.

Safety, handling, and storage

Health and safety data are shown on the safety data sheets available from suppliers and found on the internet. [16] In response to several explosions resulting in the deaths of numerous people, U.S. agencies of Environmental Protection (EPA), Occupational Health and Safety (OSHA) and the Bureau of Alcohol, Tobacco and Firearms jointly issued safety guidelines. [17]

Heating or any ignition source may cause violent combustion or explosion. [18] Ammonium nitrate reacts with combustible and reducing materials as it is a strong oxidant. Although it is mainly used for fertilizer, it can be used for explosives. It was sometimes used to blast away earth to make farm ponds. [19] [20] Ammonium nitrate is also used to modify the detonation rate of other explosives, such as trinitrotoluene in the form of amatol.

Numerous safety guidelines are available for storing and handling ammonium nitrate. [21] It should not be stored near combustible substances. Ammonium nitrate is incompatible with certain substances such as chlorates, mineral acids and metal sulfides, contact with which can lead to vigorous or even violent decomposition. [22]

Ammonium nitrate has a critical relative humidity of 59.4%, above which it will absorb moisture from the atmosphere. Therefore, it is important to store ammonium nitrate in a tightly sealed container. Otherwise, it can coalesce into a large, solid mass. Ammonium nitrate can absorb enough moisture to liquefy. Blending ammonium nitrate with certain other fertilizers can lower the critical relative humidity. [23]

The potential for use of the material as an explosive has prompted regulatory measures. For example, in Australia, the Dangerous Goods Regulations came into effect in August 2005 to enforce licensing in dealing with such substances. [24] Licenses are granted only to applicants (industry) with appropriate security measures in place to prevent any misuse. [25] Additional uses such as education and research purposes may also be considered, but individual use will not. Employees of those with licenses to deal with the substance are still required to be supervised by authorized personnel and are required to pass a security and national police check before a license may be granted.

Health hazards

Health and safety data are shown on the material safety data sheets, which are available from suppliers and can be found on the internet. [26]

Ammonium nitrate is not hazardous to health and is usually used in fertilizer products. [26] [27] [28]

Ammonium nitrate has an LD50 of 2217 mg/kg, [29] which for comparison is about two-thirds that of table salt.


Ammonium nitrate decomposes into the gases nitrous oxide and water vapor when heated (not an explosive reaction); however, it 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.

Two major classes of incidents resulting in explosions are:

See also

Related Research Articles

Ammonia Chemical compound of nitrogen and hydrogen

Ammonia is a compound of nitrogen and hydrogen with the formula NH3. A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a characteristic pungent smell. It is a common nitrogenous waste, particularly among aquatic organisms, and it 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 pharmaceutical products and is used in many commercial cleaning products. It is mainly collected by downward displacement of both air and water. Ammonia is named for the Ammonians, worshipers of the Egyptian god Amun, who used ammonium chloride in their rituals.

Explosive Substance that can explode

An explosive is a reactive substance that contains a great amount of potential energy that can produce an explosion if released suddenly, usually accompanied by the production of light, heat, sound, and pressure. An explosive charge is a measured quantity of explosive material, which may either be composed solely of one ingredient or be a mixture containing at least two substances.

Nitrogen Chemical element with atomic number 7

Nitrogen is the chemical element with the symbol N and atomic number 7. It was first discovered and isolated by Scottish physician Daniel Rutherford in 1772. Although Carl Wilhelm Scheele and Henry Cavendish had independently done so at about the same time, Rutherford is generally accorded the credit because his work was published first. The name nitrogène was suggested by French chemist Jean-Antoine-Claude Chaptal in 1790, when it was found that nitrogen was present in nitric acid and nitrates. Antoine Lavoisier suggested instead the name azote, from the Greek ἀζωτικός "no life", as it is an asphyxiant gas; this name is instead used in many languages, such as French, Russian, Romanian and Turkish, and appears in the English names of some nitrogen compounds such as hydrazine, azides and azo compounds.

Nitric acid (HNO3), also known as aqua fortis (Latin for "strong water") and spirit of niter, is a highly corrosive mineral acid.

TNT Chemical compound

Trinitrotoluene (; TNT), or more specifically 2,4,6-trinitrotoluene, is a chemical compound with the formula C6H2(NO2)3CH3. This yellow solid is sometimes used as a reagent in chemical synthesis, but it is best known as an explosive material with convenient handling properties. The explosive yield of TNT is considered to be the standard measure of bombs and the power of explosives. In chemistry, TNT is used to generate charge transfer salts.

Urea, also known as carbamide, is an organic compound with chemical formula CO(NH2)2. This amide has two –NH2 groups joined by a carbonyl (C=O) functional group.

Fertilizer Substance added to soils to supply plant nutrients for a better growth

A fertilizer or fertiliser is any material of natural or synthetic origin that is applied to soil or to plant tissues to supply one or more plant nutrients essential to the growth of plants. Many sources of fertilizer exist, both natural and industrially produced.

Picric acid Explosive chemical compound

Picric acid is an organic compound with the formula (O2N)3C6H2OH. Its IUPAC name is 2,4,6-trinitrophenol (TNP). The name "picric" comes from the Greek πικρός (pikros), meaning "bitter", reflecting its bitter taste. It is one of the most acidic phenols. Like other highly nitrated organic compounds, picric acid is an explosive, hence its primary use. It has also been used in medicine (antiseptic, burn treatments) and dyes.

ANFO explosive

ANFO is a widely used bulk industrial explosive. Its name is commonly pronounced as "an-fo".

The nitrophosphate process was a method for the industrial production of nitrogen fertilizers invented by Erling Johnson in the municipality of Odda, Norway around 1927.

Nitrogen trichloride chemical compound

Nitrogen trichloride, also known as trichloramine, is the chemical compound with the formula NCl3. This yellow, oily, pungent-smelling and explosive liquid is most commonly encountered as a byproduct of chemical reactions between ammonia-derivatives and chlorine (for example, in swimming pools). Alongside monochloramine and dichloramine, trichloramine is responsible for the distinctive 'chlorine smell' associated with swimming pools, where the compound is readily formed as a product from hypochlorous acid reacting with ammonia and other nitrogenous substances in the water.

Ammonium sulfate chemical compound

Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen and 24% sulfur.

Oppau explosion 1921 industrial disaster in the Weimar Republic

The Oppau explosion occurred on September 21, 1921, when a tower silo storing 4500 tonnes of a mixture of ammonium sulfate and ammonium nitrate fertilizer exploded at a BASF plant in Oppau, now part of Ludwigshafen, Germany, killing 500–600 people and injuring about 2,000 more.

The Kjeldahl method or Kjeldahl digestion (Danish pronunciation: [ˈkʰɛltæːˀl]) in analytical chemistry is a method for the quantitative determination of nitrogen contained in organic substances plus the nitrogen contained in the inorganic compounds ammonia and ammonium (NH3/NH4+). Without modification, other forms of inorganic nitrogen, for instance nitrate, are not included in this measurement. This method was developed by Johan Kjeldahl in 1883.

When heated, ammonium nitrate decomposes non-explosively into gases including oxygen; however, it 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.

Urea nitrate chemical compound

Urea nitrate is a fertilizer-based high explosive that has been used in improvised explosive devices in Afghanistan, Pakistan, Iraq, and various other terrorist acts elsewhere in the world, like the 1993 World Trade Center bombings. It has a destructive power similar to better-known ammonium nitrate explosives, with a velocity of detonation between 11,155 ft/s (3,400 m/s) and 15,420 ft/s (4,700 m/s).

Methylammonium nitrate chemical compound

Methylammonium nitrate is an explosive chemical with the molecular formula CH6N2O3, alternately CH3NH3+NO3. It is the salt formed by the neutralization of methylamine with nitric acid. This substance is also known as methylamine nitrate and monomethylamine nitrate, not to be confused with methyl nitramine or monomethyl nitramine.

Sable Chemicals

Sable Chemical Industries Limited is the sole manufacturer of ammonium nitrate (NH4NO3) in Zimbabwe.

Calcium ammonium nitrate or CAN, also known as nitro-limestone or nitrochalk, is a widely used inorganic fertilizer, accounting for 4% of all nitrogen fertilizer used worldwide in 2007.

Deepak Fertilisers and Petrochemicals Corporation Limited (DFPCL) is an Indian manufacturer of industrial and agricultural chemicals, crop nutrients, and fertilizers that also owns real estate. The company was established in 1979 by Chimanlal Mehta as a private limited company and became public limited in 1982. The company has marketed fertilizers under the brand name of "Mahadhan" since 1990.


  1. Pradyot Patnaik. Handbook of Inorganic Chemicals. McGraw-Hill, 2002, ISBN   0-07-049439-8
  2. Martel, B.; Cassidy, K. (2004). Chemical Risk Analysis: A Practical Handbook. Butterworth–Heinemann. p. 362. ISBN   1-903996-65-1.
  3. "Archived copy". Archived from the original on 2015-02-17. Retrieved 2015-03-13.CS1 maint: archived copy as title (link)
  4. Karl-Heinz Zapp "Ammonium Compounds" in Ullmann's Encyclopedia of Industrial Chemistry 2012, Wiley-VCH, Weinheim. doi : 10.1002/14356007.a02_243
  5. Ammonium nitrate sold by ton as U.S. regulation is stymied.The Dallas Morning News
  6. "Archived copy" (PDF). Archived from the original (PDF) on 2012-01-23. Retrieved 2008-11-11.CS1 maint: archived copy as title (link)
  7. Int Panis, LLR (2008). "The Effect of Changing Background Emissions on External Cost Estimates for Secondary Particulates" (PDF). Open Environmental Sciences. 2: 47–53. doi:10.2174/1876325100802010047.[ permanent dead link ]
  8. Choi, C. S.; Prask, H. J. (1983). "The structure of ND4NO3 phase V by neutron powder diffraction". Acta Crystallographica B. 39 (4): 414–420. doi:10.1107/S0108768183002669.
  9. "Nutrient Content of Fertilizer Materials" (PDF). Archived from the original (PDF) on 2012-12-24. Retrieved 2012-06-27.
  10. Manhattan Bombs Provide Trove of CluesThe New York Times
  11. 1 2 Cook, Melvin A. (1974). The Science of Industrial Explosives. IRECO Chemicals. p. 1. ASIN   B0000EGDJT.
  12. Brook, Tom Vanden. "Afghan bomb makers shifting to new explosives for IEDs". USA TODAY.
  13. US 5531941
  14. Airbag Compound Has Vexed Takata for YearsThe New York Times
  15. A Cheaper Airbag, and Takata’s Road to a Deadly Crisis.The New York Times
  16. "Ammonium nitrate MSDS".
  17. Chemical Advisory: Safe Storage, Handling, and Management of Ammonium Nitrate United States Environmental Protection Agency
  18. Pradyot Patnaik (2002). Handbook of Inorganic Chemicals. McGraw-Hill. ISBN   0-07-049439-8.
  19. "Pothole pond" (PDF).
  20. Progressive Farmer Magazine
  21. "Storing and handling ammonium nitrate" (PDF).
  22. "Chemical Engineering Transactions" (PDF). Archived from the original (PDF) on April 14, 2016.
  23. Fertilizers Europe (2006). "Guidance for Compatibility of Fertilizer Blending Materials" (PDF).
  24. "Dangerous Goods (HCDG) Regulations" (PDF).
  25. Ammonium Nitrate-Regulating its use, Balancing Access & Protection from "Worksafe Victoria". Archived from the original on 2011-03-11.
  26. 1 2 CF Industries. "Ammonium nitrate MSDS" (PDF). Archived from the original (PDF) on 2014-03-27.
  27. "Chemicalland21 – Ammonium Nitrate". Archived from the original on 2012-01-10.
  28. "Ammonium Nitrate". Paton Fertilizers Pty Ltd. 2005.
  29. "Material Safety Data Sheet, Ammonium nitrate MSDS".


  • Properties: UNIDO and International Fertilizer Development Center (1998), Fertilizer Manual, Kluwer Academic Publishers, ISBN   0-7923-5032-4.
Salts and covalent derivatives of the nitrate ion