Ammonium nitrate

Ammonium nitrate
Ammonium nitrate
Are common
Systematic ; name	Ammonium nitrate
Chem. formula	NH 4 NO 3
Physical properties
condition	solid
Molar mass	80.04 g / mol
Density	1,725 (IV modification)
Thermal properties
T. melt.	169.6 ° C
T. Kip.	235 ° C
T.	~ 210 ° C
Chemical properties
Water solubility	20 ° C - 190 g / 100 ml
Classification
Reg. CAS number	6484-52-2
Pubchem
Reg. EINECS number
SMILES
Inchi
RTECS
CHEBI
Chemspider

Ammonium nitrate (ammonium (ammonium) nitrate ) is a chemical compound NH ₄ NO ₃ , a salt of nitric acid . First obtained by Glauber in 1659 . It is used as a component of explosives and as a nitrogen fertilizer .

Content

Physical Properties

The crystallization of ammonium nitrate from a supersaturated solution

The crystalline substance is white. The melting point is 169.6 ° C, when heated above this temperature, a gradual decomposition of the substance begins, and at a temperature of 210 ° C, complete decomposition occurs. The boiling point under reduced pressure is 235 ° C. The molecular weight of 80.04 a. e. m. Speed of detonation 2570 m / s .

Solubility

Solubility in water :

Temperature, ° C	Solubility, g / 100ml
0	119
ten	150
25	212
50	346
80	599
100	1024

When dissolved, there is a strong absorption of heat (similar to potassium nitrate ), which significantly slows down the dissolution. Therefore, for the preparation of saturated solutions of ammonium nitrate is applied heating, while the solid substance is poured into small portions.

Also, the salt is soluble in ammonia , pyridine , methanol , ethanol .

Composition

The content of elements in ammonium nitrate in mass percent:

O - 60%,
N - 35%,
H - 5%.

Retrieval Methods

Basic Method

Anhydrous ammonia and concentrated nitric acid are used in industrial production:

{\mathsf {NH_{3}+HNO_{3}\rightarrow \ NH_{4}NO_{3}\downarrow }}

{\ displaystyle {\ mathsf {NH_ {3} + HNO_ {3} \ rightarrow \ NH_ {4} NO_ {3} \ downarrow}}}

The reaction proceeds rapidly with the release of a large amount of heat. Carrying out such a process in artisanal conditions is extremely dangerous (although under conditions of high water dilution, ammonium nitrate can be easily obtained). After the formation of the solution, usually with a concentration of 83%, excess water is evaporated to a melt state in which the content of ammonium nitrate is 95–99.5%, depending on the type of finished product. For use as a fertilizer, the melt is granulated in spray apparatuses, dried, cooled and coated with formulations to prevent caking. The color of the granules varies from white to colorless. Ammonium nitrate for use in chemistry is usually dehydrated, as it is very hygroscopic and the percentage of water in it is almost impossible to obtain.

Haber Method

According to the Haber method, ammonia is synthesized from nitrogen and hydrogen, part of which is oxidized to nitric acid and reacts with ammonia, resulting in the formation of ammonium nitrate:

{\mathsf {3H_{2}+N_{2}\longrightarrow \ 2NH_{3}}}

{\ displaystyle {\ mathsf {3H_ {2} + N_ {2} \ longrightarrow \ 2NH_ {3}}}}

at pressure, high temperature and catalyst

{\mathsf {NH_{3}+2O_{2}\longrightarrow \ HNO_{3}+H_{2}O}}

{\ displaystyle {\ mathsf {NH_ {3} + 2O_ {2} \ longrightarrow \ HNO_ {3} + H_ {2} O}}}

{\mathsf {HNO_{3}+NH_{3}\longrightarrow \ NH_{4}NO_{3}}}

{\ displaystyle {\ mathsf {HNO_ {3} + NH_ {3} \ longrightarrow \ NH_ {4} NO_ {3}}}

.

Nitrophosphate Method

This method is also known as the Odda method, named after the Norwegian city in which this process was developed. It is used directly for the production of nitrogen and nitrogen-phosphate fertilizers from widely available natural raw materials. In this case, the following processes occur:

Natural calcium phosphate ( apatite ) is dissolved in nitric acid:
- ${\mathsf {Ca_{3}(PO_{4})_{2}+6HNO_{3}\longrightarrow \ 2H_{3}PO_{4}+3Ca(NO_{3})_{2}}}$ ${\ displaystyle {\ mathsf {Ca_ {3} (PO_ {4}) _ {2} + 6HNO_ {3} \ longrightarrow \ 2H_ {3} PO_ {4} + 3Ca (NO_ {3}) _ {2}} }}$ .
The resulting mixture is cooled to 0 ° C, while calcium nitrate crystallizes in the form of tetrahydrate - Ca (NO ₃ ) ₂ · 4H ₂ O, and it is separated from phosphoric acid.
The resulting calcium nitrate , not purified from phosphoric acid, is affected by ammonia , resulting in ammonium nitrate:
- ${\mathsf {Ca(NO_{3})_{2}+4H_{3}PO_{4}+8NH_{3}\longrightarrow \ CaHPO_{4}\downarrow \ +2NH_{4}NO_{3}+3(NH_{4})_{2}HPO_{4}}}$ ${\ displaystyle {\ mathsf {Ca (NO_ {3}) _ {2} + 4H_ {3} PO_ {4} + 8NH_ {3} \ longrightarrow \ CaHPO_ {4} \ downarrow \ + 2NH_ {4} NO_ {3 } +3 (NH_ {4}) _ {2} HPO_ {4}}}}$ .

Chemical Properties

Thermal decomposition of ammonium nitrate can occur in different ways, depending on temperature:

Temperature below 200 ° C:
- ${\mathsf {NH_{4}NO_{3}\longrightarrow \ N_{2}O\uparrow \ +2H_{2}O+Q}}$ ${\ displaystyle {\ mathsf {NH_ {4} NO_ {3} \ longrightarrow \ N_ {2} O \ uparrow \ + 2H_ {2} O + Q}}}$ .
Temperature above 350 ° C, or detonation:
- ${\mathsf {2NH_{4}NO_{3}\longrightarrow \ 2N_{2}+O_{2}+4H_{2}O}}$ ${\ displaystyle {\ mathsf {2NH_ {4} NO_ {3} \ longrightarrow \ 2N_ {2} + O_ {2} + 4H_ {2} O}}}$ .

Crystal states of ammonium nitrate

Changes in the crystalline state of ammonium nitrate under the influence of temperature and pressure change its physical properties. The following conditions are usually distinguished:

**Crystalline states of ammonium nitrate** ^[1]
System	Temperature range (° C)	condition	Volume change (%)
-	> 169.6	liquid
I	169.6 - 125.2	cubic	−2.13
II	125.5 - 84.2	tetragonal	−1.33
III	84.2 - 32.3	α-rhombic (monoclinic)	+0.8
IV	32.3 - −16.8	β-rhombic (bipyramidal)	−3.3
V	−50 - −16.8	tetragonal	+1.65
VI	exists at high pressures
VII	170
Viii	exists at high pressures
Ix	exists at high pressures

Phase transition from IV to III at 32.3 ° C brings trouble to fertilizer producers, because changes in density lead to the destruction of particles during storage and use. This is especially important in tropical countries where ammonium nitrate undergoes cyclical changes leading to granule breakdown, caking, increased dusting and the risk of explosion .

Application

Fertilizers

Ammonium Nitrate Fertilizer

Most of the ammonium nitrate is used either directly as a good nitrogenous fertilizer or as an intermediate for other fertilizers. To prevent the creation of ammonium nitrate-based explosives, commercially available fertilizers add components that reduce the explosiveness and detonation properties of pure ammonium nitrate, such as chalk ( calcium carbonate ).

In Australia, China, Afghanistan, Ireland and some other countries, the free sale of ammonium nitrate even in the form of fertilizers is prohibited or restricted. After the terrorist attack in Oklahoma City, restrictions on the sale and storage of ammonium nitrate were introduced in some US states ^[2] .

Explosives

The most widely used in industry and mining are mixtures of ammonium nitrate with various types of hydrocarbon combustible materials, other explosives, as well as multicomponent mixtures:

Ammonium nitrate / diesel fuel formulations ( ASDT )
liquid ammonium nitrate / hydrazine mixture ( Astrolite )
water filled industrial explosives ( Aquanal , Aquanit , etc.)
mixtures with other explosives ( Ammonite , Detonite , etc.)
mixture with aluminum powder ( ammonal )

In its pure form, ammonium nitrate is significantly inferior to most explosives in terms of explosion energy, but its explosion hazard must be taken into account during transportation and storage. The explosion hazard of granulated nitrate increases with its moisture content and with temperature drops leading to recrystallization ^[3] .

Safe Composition

In 2013, Sandia National Laboratories employees announced the development of a safe and effective composition based on a mixture of ammonium nitrate with iron sulfate , which cannot be used to create explosives based on it. During the decomposition of the composition, the ion SO ₄ ^{2– is} bound to the ammonium ion, and the iron ion is bound to the nitrate ion, which prevents an explosion. The introduction of iron sulfate fertilizer into the composition can also improve the technological characteristics of the fertilizer, especially on acidified soils. The authors refused to protect the fertilizer formula with a patent so that this compound could be quickly distributed in regions with a high terrorist risk ^[4] .

Additional Information

World production of ammonium nitrate in 1980 was 14 million tons, in terms of nitrogen.

Notes

↑ Industrial explosives (1988) L.V. Dubnov | Technical literature (neopr.) . booktech.ru. The appeal date is September 17, 2015.
↑ Homeland Security to Regulate Fertilizer Chemical Used in Oklahoma City, Norway Bombings (Eng.) . Associated Press (August 2, 2011). Date of appeal September 30, 2013.
↑ Directory of Nitrogen / under total. ed. E. Ya. Melnikova . - 2nd ed., Pererabat .. - M .: Chemistry, 1987. - p. 157, 159. - 464 p.
News Fertilizer (News release) (April 23, 2013). Date of appeal September 30, 2013.

Literature

Technology of ammonium nitrate , ed. V.M. Olevskogo, M., 1978.
Salts of nitric acid , Miniovich M.A., M., 1964.
Olevsky V. M., Ferd M. L., “ J. Vses. chemical about them D. I. Mendeleev ", 1983, v. 28, No. 4, p. 27—39.
Dubnov L.V., Baharevich N.S., Romanov A.I. Industrial explosives. - 3rd ed., Pererab. and add. - M .: Nedra, 1988 .-- 358 p.

Links

Ammonium Nitrate in Chemical Dictionary

[1] Industrial explosives (1988) L.V. Dubnov | Technical literature (neopr.) . booktech.ru. The appeal date is September 17, 2015.

[2] Homeland Security to Regulate Fertilizer Chemical Used in Oklahoma City, Norway Bombings (Eng.) . Associated Press (August 2, 2011). Date of appeal September 30, 2013.

[3] Directory of Nitrogen / under total. ed. E. Ya. Melnikova . - 2nd ed., Pererabat .. - M .: Chemistry, 1987. - p. 157, 159. - 464 p.

[Sandia42313-4] News Fertilizer (News release) (April 23, 2013). Date of appeal September 30, 2013.