Ammonia is found in small quantities in the atmosphere, being produced by the putrefaction of nitrogenous matter from plants and animals. Ammonia and ammonium salts are also found in small quantities in rainwater, where ammonium chloride and ammonium sulfate are found in volcanic areas; Ammonium bicarbonate crystals have been found in Patagonia, in guano. The kidney secretes ammonia to neutralize excess acid.[11] Ammonia salts are distributed throughout fertile soil and in the ocean. Ammonia is also found in other parts of the solar system: on Mars "Mars (planet)"), Jupiter "Jupiter (planet)"), Saturn "Saturn (planet)"), Uranus "Uranus (planet)"), Neptune "Neptune (planet)") and Pluto "Pluto (dwarf planet)"). Substances that contain ammonia, or those that are similar to it, are called ammoniacal.

Escapes of a flammable gas outside the structure that contains it are dangerous, as this gas could cause a serious deflagration when it comes into contact with a flame.

Contenido

El amoníaco es un gas incoloro con un olor desagradable y nauseabundo. Es más ligero que el aire, su densidad es 0.589 veces la del aire de la atmósfera. Se condensa fácilmente por sus fuertes puentes de hidrógeno entre las moléculas; el líquido hierve a –33.3 °C y se congela a los –77.7 °C en cristales blancos.[12]​.

El amoníaco se puede desodorizar fácilmente reaccionando con algún ácido. Así se forman sales de amonio sin olor, ya que se comporta como una base "Base (química)").

La simetría del cristal es cúbico, su símbolo pearson es CP16, grupo espacial P 213 No.198, constante de red 0.5125 nm.[13]​.

El amoníaco líquido posee fuertes fuerzas ionizantes reflejando su alta constante dieléctrica de 22. El amoníaco líquido tiene una muy alta entalpía de vaporización (23.35 kJ/mol, cf. agua 40.65 kJ/mol, metano 8.19 kJ/mol, fosfina 14.6 kJ/mol) y puede ser usado en laboratorios en vasos no aislados sin refrigeración.

El amoníaco es miscible con agua. En una solución acuosa puede separarse por ebullición. La solución acuosa de amoníaco es una base. La concentración máxima de amoníaco en agua tiene una densidad de 0.880 g/cm³ (880 kg/m³) y es frecuentemente conocido como 'amoníaco 0.880'.

El amoníaco casero o hidróxido de amonio es una solución de NH en agua. La concentración de dicha solución es medida en unidades de la Escala Baumé, con 26 grados baumé (cerca del 30 % por peso de amoníaco) como concentración típica del producto comercial.

El amoníaco no se quema ni sostiene la combustión por sí mismo, excepto en mezclas de combustible con el 15 a 25 % de aire.

Cuando se mezcla con oxígeno se quema con una llama de color verde amarillento pálido. A alta temperatura y en la presencia de un catalizador, el amoníaco se descompone en sus elementos constituyentes. La combustión ocurre cuando la clorina pasa a amonio, formando nitrógeno y cloruro de hidrógeno; si la clorina esta en exceso, se forma el explosivo tricloruro de nitrógeno o tricloramina (NCl).

Structure

The ammonia molecule has a trigonal pyramidal shape, as predicted by valence shell electron pair repulsion theory, with a given bond angle of 106.7°.[14] The central nitrogen atom has five outer electrons with an additional electron from each hydrogen atom. This gives a total of eight electrons, or four pairs of electrons that are arranged tetrahedrally. Three of those electron pairs are used as pair bonds, leaving one pair of electrons free. This pair more strongly repels bond pairs, so the bond angle is not 109.5° as would be expected for a tetrahedral arrangement, but rather 106.7°.[14] The nitrogen atom in the molecule has a lone pair of electrons, which causes ammonia to be a base, proton acceptor. This shape gives the molecule a dipole moment and makes it a polar molecule. The polarity of the molecule and, especially, its ability to form hydrogen bonds, makes ammonia highly miscible in water. Ammonia is moderately basic, a 1 M aqueous solution has a pH of 11.6 and if a strong acid is added to the solution until the solution reaches a neutral pH of (pH=7), 99.4%, the ammonia molecules are protonated. Temperature and salinity also affect the NH ratio. The resulting product has a regular shape and is isoelectronic with methane.

The ammonia molecule readily undergoes nitrogen inversion at room temperature; A useful analogy is that when an umbrella spins upside down in a strong wind. The energy barrier to this inversion is 24.7 kJ/mol, and the resonant frequency is 23.79 GHz, corresponding to microwave radiation with a wavelength of 1,260 cm. Absorption at this frequency was the first microwave spectroscopy observed.[15]​.

Amphotericity

One of the most important characteristics of ammonia is its basicity. Ammonia is considered a weak base. Combines with acids to form salts; with hydrochloric acid it forms ammonium chloride; with nitric acid, ammonium nitrate, etc. In any case, perfectly dry ammonia does not combine with completely dry hydrogen chloride; water is necessary for the reaction to take place[16] As a demonstration of the experiment, open bottles with concentrated ammonia and hydrochloric acid produce clouds of ammonium chloride, which seem to come "out of nowhere" while the salts form where the two diffusion clouds of the molecules meet, between the two bottles.

The salts produced by the action of ammonia in acids are known as ammonium compounds, which contain the ammonium ion. (NH).

Although ammonia is known as a weak base, it also functions as a very weak acid. It is a protic substance if it is capable of forming amines (which contain the NH ion). For example, lithium dissolved in liquid ammonia to give a lithium amine solution.

Self dissociation

Just like water, ammonia undergoes molecular autoionization to form its conjugate bases and acids.

At standard pressure and temperature, K=[][] = 10.

Combustion

The combustion of ammonia generates molecular nitrogen and water, and is an exothermic reaction:.

The heating value, ΔH°, expressed per mole of ammonia and forming water condensation, is -382.81 kJ/mol. Dinitrogen is the thermodynamic product of ammonia combustion: all nitrogen oxides are unstable with respect to N and O, which is the principle behind the catalytic conversion. However, nitrogen oxides can be formed by kinetic products in the presence of appropriate catalysis, a reaction of great industrial importance in the production of nitric acid:

A subsequent reaction leads to NO.

The combustion of ammonia in air is very difficult in the absence of a catalyst "Catalyst (chemistry)"), since the flame temperature is normally lower than the ignition temperature of the ammonia-air mixture. The flammable range of ammonia in air is 16% to 25%.[17]​.

Formation of other compounds

In organic chemistry, ammonia can act as a nucleophile in nucleophilic substitution reactions. Amines can be formed by the reaction of ammonia with haloalkanes, although the resulting -NH is also nucleophilic and secondary and tertiary amines are formed as byproducts. An excess of ammonia helps minimize multiple substitutions, and neutralizes the hydrogen halides formed. Methylamine is prepared commercially by the reaction of ammonia with chloromethane, and the reaction of ammonia with 2-bromopropanoic acid has been used to prepare racemic alanine in 70% yield. Ethanolamine is prepared by an oxidation reaction with ethylene: the reaction sometimes produces diethanolamine and triethanolamine.

Amides can be prepared by a reaction of ammonia with carboxylic acid derivatives. Acyl chloride is the most reactive, but ammonia must be present in at least twice as much to neutralize the hydrochloric acid formed. Esters and anhydrides also react with ammonia to form amides. Ammonium salts of carboxylic acids can be dehydrated to amides for so long that no thermally sensitive groups are present: temperatures of 150 °C to 200 °C are required.

The hydrogen in ammonia can be replaced by metals, so magnesium burns in the gas with the formation of magnesium nitride MgN, and when the gas passes over superheated sodium or potassium, sodamide, NaNH, and potasamide, KNH, are formed. Where necessarily in IUPAC nomenclature, "azane" is preferred as the name of the anomiac: therefore chloramine would be called "chloroazane", not chloroammonia.

Pentavalent ammonia is known as λ-amino, or more commonly as ammonium hydric. It is a crystalline solid that is stable only at high pressures, and decomposes back to trivalent ammonia and hydrogen gas under normal conditions. This substance has been investigated as a possible fuel in 1966.[18]​.

Ammonia as ligand

Ammonia can function as a ligand in transition metal complexes. It is a σ-donor, in the middle of the spectrochemical series, and shows intermediate hard-soft behavior. Some ammonia complexes include 'tetraamminediaquacopper'([Cu(NH)(HO)]), ([Ag(NH)]) which is the active species of Tollen's agent. The formation of this complex can also be distinguished between precipitates of different silver halides: silver chloride (AgCl) is soluble in a dilute ammonia solution (2M), silver bromide (AgBr) is soluble only in a concentrated ammonia solution, where silver iodide (AgI) is insoluble in liquid ammonia.

Chromium complexes were known in the 19th century, and formed the basis of Alfred Werner's revolutionary theory on the coordination structure of compounds. Werner noted only two isomers ("fac"- and "mer"-) of the [CrCl(NH)] complex can form, and concluded that the ligates must be arranged around the metal ions at the vertices") of an octahedron. This proposal has since been confirmed by X-ray crystallography.

An ammonia ligand bound to a metal ion is markedly more acidic than a free ammonia molecule, although deprotonation in an aqueous solution is still rare. An example is the Calomel reaction:

Ammonia in group theory

The point group for ammonia is C when the major axis goes through the vertical nitrogen. When the major axis is spun either clockwise or counterclockwise, by 120°, each hydrogen moves into the previous location of another hydrogen. Another aspect of the C strut group includes three vertical planes of symmetries that intercept the nitrogen and one of the hydrogens allowing the other two to reflect each other.

The mathematical matrix for this particular subgroup is complicated since matrices produced by rotations or reflections are reducible compared to other matrices that are irreducible. Therefore, a similar transformation must be done on each portion of the matrix that is reducible. The similar transformation for ammonia comes from calculations of the symmetry molecular orbital diagram adapted to a linear combination for the bonding contribution of each of the hydrogens.

Ammonia in solution

Ammonia and ammonium salts can be easily detected, in trace minutes, by adding Nessler's solution, which gives a yellow color in the presence of the slightest trace of ammonia or ammonium salts. The amount of ammonia in ammonium salts can be estimated quantitatively by distillation of salts with sodium hydroxide or potassium hydroxide, the ammonia evolves being absorbed in a known volume in standard sulfuric acid and the excess acid then determined by volumetric analysis; or ammonia can be absorbed into hydrochloric acid and ammonium chloride is formed as a precipitate as ammonium hexachloroplatinate, (NH)PtCl.

Gaseous ammonia

Sulfur sticks are burned to detect small leaks in ammonia refrigeration systems. Larger quantities can be detected by heating the salts with a caustic alkali or calcium oxide, when the characteristic odor of ammonia is apparent. Ammonia is an irritant and irritation increases with concentration; The permitted exposure limit is 25 ppm, and lethal above 500 ppm.[19] Higher concentrations are difficult to detect by conventional detectors, the type of defects is chosen according to the required sensitivity (semiconductor, catalytic, electrochemical). Holographic sensors have been proposed to detect concentrations above 12.5% ​​by volume.[20]​.

Ammoniacal nitrogen (NH3-N)

Ammoniacal nitrogen (NH-N) is a measure commonly used to examine the amount of ammonium ions, naturally derived from ammonia, and returned to ammonia by organic processes, in water or liquid waste. It is a measure used primarily to quantify values ​​in waste treatment and water purification systems, as well as measure the health of natural and man-made water reserves. It is measured in units of mg/L (milligrams/Liters).

The Romans gave the name 'sal ammoniacus' (ammonia salt) to the deposits of ammonia chloride collected near the temple of Amun (in Greek Ἄμμων" Ammon) in ancient Libya due to the proximity of the temple.[21] Ammonia salts have been known since ancient times; so the term "Hammoniacus sal" appears in the writings of Pliny,[22] although it is not known if the term is identical to the modern term "sal-ammoniac" (ammonium chloride).[23]​.

In the form of ammonia salt, ammonia was important in medieval alchemy, as in the 18th century, it was mentioned by Persian chemist Jābir ibn Hayyān,[24] and by alchemists since the 19th century, being mentioned by Albertus Magnus.[12] It was also used by dyers in the Middle Ages in the form of fermented urine to alter the color of vegetable dyes. In the 19th century, Basilius Valentinus demonstrated that ammonia could be obtained by the action of alkalis on ammonia salt. In a later period, when ammonia salts were obtained by distilling the hooves and horns of oxen and neutralizing the resulting carbonate with hydrochloric acid.[25]​.

Gaseous ammonia was first isolated by Joseph Priestley in 1774 and named by him as "alkaline air".[26] Eleven years later in 1785, Claude Louis Berthollet found its composition.[12]

The production of ammonia from nitrogen in the air (and hydrogen) was invented by Fritz Haber and Robert LeRossignol. The patent was submitted in 1909 (USPTO No. 1,202,995) and granted in 1916. Carl Bosch then developed industrial production (Haber-Bosch process). Its first use was on an industrial scale in Germany during World War I. Ammonia was used to produce explosives to sustain war reinforcements. The 1918 Nobel Prize in Chemistry was awarded to Fritz Haber "for the synthesis of ammonia from its elements." The process has become the main source of fixed nitrogen in the world, improving crop yields and alleviating hunger for millions of people on the planet.

Prior to the availability of cheap natural gas, hydrogen as a precursor to ammonia production was carried out with water electrolysis or using the chlor-alkali process.

Fertilizer

Approximately 83% of ammonia in 2004 was used as fertilizers or salts, solutions or anhydrides. When applied to soil, it helped increase the yield of crops such as corn and wheat. 30% of the agricultural nitrogen used in the United States is in the anhydride form and worldwide, 110 million tons are used each year.[28]​.

Nitrogen compound precursor

Ammonia is directly or indirectly the precursor of most nitrogen-containing compounds. Virtually all synthetic nitrogen compounds are derivatives of ammonia. One of the most important derivatives is nitric acid. The key material is generated thanks to the Ostwald process by oxidation of ammonia with air over a platinum catalyst, with a temperature between 700 °C and 800 °C and 9 atmospheres. Nitric oxide is an intermediate in this reaction.[29]​.

Nitric acid is used for the production of fertilizers, explosives, etc.

Cleaner

Household ammonia is a solution of NH in water (ammonia hydroxide) used for the purpose of cleaning surfaces. One of its most common uses is to clean some crystals or crystallographic systems, porcelain and stainless steel. It is also frequently used to clean ovens and absorb elements to soften dirt. Homemade ammonia has a weight concentration of 5 to 10% ammonia.

Fermentation

Ammonia solutions between 16% and 25% are used in industrial fermentations as a source of nitrogen for microorganisms and to adjust their pH during fermentation.

Antimicrobial agent for food

By 1895, ammonia was known to be a strong antiseptic. This is why 1.4 grams per liter is required to preserve the broth.[30]​ In one study, anhydride ammonia destroyed 99.999% of zoonotic bacteria (Zoonosis) in three types of animal feed.[31]​ Ammonia anhydride is currently used to eliminate microbial contamination.[32]​[33]​ Pink slime is made from fatty meat trimmings by removing the fat with heat and centrifugation, then treating it with ammonia to reduce the presence of E. coli at undetectable levels.[34]​ There have been concerns about the safety of the process, as well as consumer complaints about its taste and odor, as well as its toxicity.[35]​.

Agricultural fertilizer

In the form of anhydrous ammonia, it is used as a fertilizer, increasing soil nitrogen levels.

Minor and emerging uses

Thanks to the vaporization properties of ammonia, it is useful as a refrigerant.[7] It was commonly used before the popularization of the use of chlorofluorocarbon compounds. Anhydride ammonia is used tirelessly in the refrigeration industry and for hockey rinks due to its high energy conversion efficiency and low cost. However, it has the disadvantage of being toxic, which restricts its domestic and small-scale use. Along with its modern use of vapor compression refrigeration, it was used along with hydrogen and water in absorption refrigeration. The Kalina cycle depends largely on the boiling range of the ammonia-water mixture.

Ammonia is used to purify SO from hot fuels, and the resulting product is converted to ammonia sulfate for use as fertilizer. Ammonia neutralizes the pollution of nitrogen oxides (NO) emitted by diesel engines. This technology, called SCR (Selective Catalytic Reduction), is based on a vanadium-based catalyst.[36]​.

Ammonia can be used to mitigate phosgene gas spills.[37]​.

Ammonia was used during World War II as fuel for trucks in Belgium, and its motor and solar power since 1900. Liquid ammonia was also fuel for the XLR99 jet engines that would power X-15. Although it is not a strong fuel, it leaves no doubt in the use of the rocket engine and its approximate density coincides with the density of the oxidizer, liquid oxygen, which simplified the design of the aircraft.

Ammonia has been proposed as a practical alternative to fossil fuel for internal engine combustion.[38] The heating value of ammonia is 22.5 Mj/kg, which is approximately half that of diesel. A normal engine, in which water vapor does not condense, the calorific value of ammonia would be less than 21%.

Ammonia cannot be easily used in the Otto cycle due to its low octane levels. Although with the slightest modifications to the carburetors and a drastic reduction in the compression ratio, which would require new pistons, a gasoline engine can run exclusively on ammonia, at a low fraction of its power before conversion to more powerful fuels.

A car tank can store liquid ammonia as long as the tank is appropriately pressurized, depending on the temperature. Depending on the thermodynamic properties of ammonia are such that at -30 °C, the tank pressure would have to be 1,896 bar (27.5 psi), approximately the same as a vehicle tire. At 30°C it would have to be 11.72 bar (170 psi) to keep the ammonia liquid. If the tank pressure were released, the liquid ammonia would become gaseous and raise the pressure to that level. Common tire air compressors operate at this pressure, so that the tank pressure is not a barrier to fuel use.

However, there are other barriers to expanding its use. In terms of raw ammonia supplies, plants would have to be built to increase production levels, which would require greater monetary and energy investment. Even though it is the second most produced chemical compound, the scale of ammonia production is a small fraction of the oil used in the world. It can be a manufacturer of renewable energy, as well as nuclear energy. Norway produced ammonia with water electrolysis for many years starting in 1913, producing fertilizer for Europe. If produced from carbon, CO can be seized, but carbon capture and storage plants have not yet reached the prototype stage.

La Administración de Seguridad y Salud Ocupacional de los Estados Unidos, ha delimitado un máximo de 15 minutos a la exposición del amoníaco líquido en 35 ppm por volumen en el aire del ambiente y 8 horas a 25 ppm por volumen.[48]​ El Instituto Nacional para la Seguridad y Salud Ocupacional (NIOSH), recientemente redujo el riesgo inmediato de vida y salud de 500 a 300 basados en interpretaciones conservadoras más recientes de la investigación original en 1943. El riesgo inmediato a la vida y salud es el nivel en el que un trabajador sano pueda ser expuesto 30 minutos sin sufrir daños irreversibles a la salud. Otras organizaciones tienen niveles de exposición variante. Los estándares de la Marina estadounidense permitía concentraciones máximas de: Exposición continua (60 días) a 25 ppm, o una hora con 400 ppm.[49]​ El vapor de amoníaco tiene un hedor agudo, irritante y desagradable que actúa como prevención de potencial exposición peligrosa. El hedor promedio en el ambiente son 5 ppm, un nivel muy abajo de cualquier peligro o daño. La exposición a concentraciones muy altas de gas de amoníaco puede dar como resultado daño en los pulmones, y posiblemente la muerte.[48]​ Aun cuando el amoníaco es regulado en los Estados Unidos como un gas inflamable, entra en la definición de un gas tóxico al inhalarlo y requiere seguridad específica al transportarlo en cantidades más grandes a 3,500 galones.[50]​.

Toxicity

The toxicity of ammonia solutions does not usually cause problems for humans or other mammals, due to a specific mechanism that exists to prevent its storage in the blood. Ammonia is converted to carbonyl phosphate by the enzyme carbonyl phosphate synthetase, and then enters the Urea Cycle to be incorporated into amino acids or excreted in urine. In any case, fish and amphibians do not have this mechanism, as they normally eliminate ammonia from their bodies with direct excretion. Ammonia, even in dilute concentrations, is highly toxic to aquatic animals, and for that reason it is classified as "dangerous to the environment."

Ammonia toxicity is believed to be a cause of the still unexplored loss of fish in hatcheries. Excess ammonia can accumulate and cause metabolic alterations or increase the pH in the body of the exposed organism. Tolerance varies among different fish species.[51]​ At lower concentrations, around 0.05 mg/L, non-ionized ammonia is harmful to fish and can cause decreased growth, reduced fertility and fecundity, and increased stress and susceptibility to bacterial infections and diseases.[52]​ Upon exposure to excess ammonia, fish may suffer from loss of balance, hyperexcitability, increased respiratory activity, oxygen uptake, and increased heart rate.[51]​ At concentrations exceeding 2.00 mg/L, ammonia causes tissue damage, extreme lethargy, seizures, coma, and death.[51]​[53]​ Experiments have shown that the lethal concentration for fish generally ranges from 0.2 to 2.00 mg/L[53]​.

During the winter, when the feed given to aquaculture farms is reduced, ammonia levels can increase. Temperatures lower than ambient reduce the photosynthesis rate of algae, so less ammonia is removed by algae. In this type of environment, especially on a large scale, there are no quick fixes to treat high levels of ammonia. Prevention rather than correction is recommended to reduce damage to fish[53]​ and in open water systems, the surrounding environment.

Storage information

Similar to propane, anhydride ammonia boils below ambient temperature at standard pressure. An ammonia storage container capable of holding it at 250 psi is appropriate for storage.[54] Ammonia compounds should not come into contact with "Base (chemical)" bases (unless a specific chemical reaction is intended), as dangerous amounts of ammonia may be released.

Home use

Ammonia solutions (5-10% by weight) are used in household cleaners, particularly for glass. These solutions are irritating to the eyes and mucous membrane, and to a lesser extent to the skin. Caution should be taken to never mix these solutions with any liquid containing bleach, as it may cause a dangerous gas. Mixing it with products that contain chlorine or powerful oxidants, such as household bleach, can lead to the production of dangerous gases such as chloramine.[55]​.

Laboratory use of ammonia solutions

The dangers of ammonia solutions depend on their concentration: Solutions with "dilute" ammonia usually have between 5-10% by weight (5.62 mol/l); Concentrated solutions are usually prepared with approximately 25% by weight. At 25% by weight, the solution has a density of 0.907 g/cm³ (907 kg/m³), and a solution that has a lower density will be more concentrated. The following table classifies ammonia solutions.

Ammonia vapor from concentrated ammonia solutions are severely irritating to the eyes and respiratory tract, and these solutions can only be handled in a fume hood. Saturated solutions ("0.880") can develop significant pressure in a closed bottle in hot weather, and the bottle should be opened carefully; this is normally not a problem for 25% ("0.900") solutions.

Ammonia solutions should not be mixed with halogens, as toxic and/or explosive products are formed. Prolonged contact of ammonia solutions with salts of silver, mercury or iodine may also result in explosive products: such mixtures are normally formed in inorganic qualitative analyses, and must be slightly acidified but not concentrated before the analysis is completed.

Laboratory use of Ammonia Anhydride (gas or liquid)

Ammonia anhydride is classified as toxic ("T") and hazardous to the environment ("N"). The gas is flammable (Autoignition temperature: 651 °C) and can form explosive mixtures with air (16-25%). The permissible exposure in the United States is 50 ppm, while the concentration for immediate harm to life and health is estimated to be 300 ppm. Repeated exposure to lower levels of ammonia decreases sensitivity to the odor of the gas: normally the odor is detectable at concentrations less than 50 ppm, but desensitized individuals would not be able to detect it even at concentrations of 100 ppm. Ammonia anhydride corrodes copper and zinc alloys, so brass should not be used to store the gas. Liquid ammonia can also attack rubber and certain plastics.

Ammonia reacts violently with halogens. Nitrogen triiodide, a primary explosive, which is formed when ammonia comes into contact with iodine. Ammonia causes the explosive polymerization of ethylene oxide. It also forms explosive fulminating compounds with gold, silver, mercury, germanium or tellurium. Violent reactions have also been reported with solutions of acetaldehyde, hypochlorite, peroxides and potassium ferricyanide.

Chemical principles

NH is obtained by the method called the Haber-Bosch process (Fritz Haber and Carl Bosch received the Nobel Prize in Chemistry in 1918 and 1931). The process consists of the direct reaction between gaseous nitrogen and hydrogen.

N + 3H → 2NH ΔH° = -46.2 kJ/mol

ΔS° < 0.

25 °C K = 6.8.10¬5 atm

850 °C K = 7.8.10¬-2 atm

These values are obtained through the van't Hoff equation. It is a very slow reaction, since it has a high activation energy, a consequence of the stability of N. The solution to the problem was to use a catalyst (iron oxide that is reduced to Fe in the H atmosphere). Because the reaction has more moles on the reactant side (4 moles) than on the products side (2 moles), increasing the pressure favors the formation of the product. Although thermodynamically the reaction proceeds better at low temperatures, this synthesis is carried out at high temperatures to favor the kinetic energy of the molecules and thus increase the reaction rate. In addition, ammonia is removed as it is produced to further promote the synthesis of products.

Production from reform

The Haber-Bosch method uses two raw materials: hydrogen and nitrogen. The necessary hydrogen is produced from the reforming of natural gas, LPG or naphtha with water vapor, natural gas being the most common feed. The plant is divided into two sections: the front-end or front part of the plant, where the mixture of hydrogen and nitrogen necessary to synthesize ammonia is generated, and the back-end or rear part of the plant, which is the section where the product is converted from both reactants.

The plant usually consists of the following units:.

Front-end:.

Back-end:.

The back-end section mainly consists of a reactor (the ammonia converter) and a series of auxiliary equipment to cool the reactor output stream. It also has a compressor which raises the pressure of the stream coming from the front-end up to the working pressure required for ammonia synthesis. There are various reactor designs offered by different technologists (e.g. Haldor Topsoe, Casale, Kellogg, TVA type reactors, etc.) and each converter has its own characteristics, advantages and disadvantages. Some reactors are vertical, others horizontal; some have radial flow, others axial flow, and others mixed flow; some have one bed, others have two beds, etc. In any case, a characteristic common to all of them is that they require a catalyst for the reaction to take place, currently the one used in almost all iron-based plants and promoted with other compounds.[59] Reactors usually operate in a temperature range of 400-500 °C and at very high pressures, in the order of 200-350 kgf/cm²g. As explained previously, the reaction is strongly balanced towards the reactant side, and therefore the ammonia concentration is not too high: in a plant operating under stable conditions the concentration at the entrance to the converter is usually around 5% and at the exit 15%.

El amoníaco líquido es conocido y comúnmente estudiado como un solvente ionizante no-acuoso. Su propiedad más conspicua es la habilidad de disolver metales álcali para formar soluciones altamente coloradas y eléctricamente conductivas conteniendo electrones solvatados. Además de estas soluciones, mucha de la química en el amoníaco líquido puede ser clasificado por analogía con reacciones relacionadas en soluciones acuosas. La comparación de las propiedades físicas del NH con aquellas del agua, muestra que el NH tiene un menor punto de ebullición, de fusión, densidad, viscosidad y constante dieléctrica; esto es al menos en parte por los enlaces débiles del hidrógeno en NH y porque dicho enlace no puede formar redes reticuladas, pues cada molécula de NH tiene un solo par de electrones libres comparado con dos por cada molécula de HO. La constante de disociación del NH a -50 °C es 10 mol·l.

Solubility of salts

Liquid ammonia is an ionizing solvent, although less so than water, it dissolves many compounds, including nitrates, nitrites, cyanides and thiocyanates. Most ammonium salts are soluble and act as acids in liquid ammonia solutions. The solubility of halogen salts increases from fluorine to iodine. A saturated solution of ammonium nitrate contains 0.083 moles of solite per mole of ammonia and has a vapor pressure of less than 1 bar "Bar (pressure unit)") at 25 °C.

Metal solutions

Liquid ammonia dissolves alkali metals and other electropositive metals such as magnesium, calcium, strontium, barium, europium and ytterbium. At low concentrations, dark blue solutions are formed: these contain cations and solvated electrons, free electrons that are surrounded by a cage of ammonia molecules.

These solutions are very useful and strong reducing agents. At high concentrations, solutions are metallic in appearance and electrical conductivity. At low temperatures, the two types of solution can coexist as immiscible phases.

Redox properties of liquid ammonia

The range of thermodynamic stability of solutions with liquid ammonia is very narrow, as the oxidation potential to dinitrogen, normal electrode potential (N + 6NH + 6e 8NH), is only +0.04 V. In practice, the oxidation to dinitrogen and reduction of dihydrogen are slow. This is especially true in reducing solutions: the solutions of the alkali metals mentioned above are stable for several days, slowly decomposing the metal and dihydrogen amoeba. Most studies on liquid ammonia in solutions are done under reducing conditions; However, the oxidation of liquid ammonia is slow and there is a risk of explosion.

Inhalation

In high concentrations it irritates the throat, inflames the lungs, damages the respiratory tract and eyes. As the concentration increases, it can lead to pulmonary edema (Pulmonary edema is often caused by congestive heart failure. When the heart is not able to pump blood to the body efficiently, it can back up in the veins that carry blood through the lungs to the left side of the heart.

As the pressure in these blood vessels increases, fluid is pushed into the air spaces (alveoli) in the lungs. This fluid reduces the normal movement of oxygen through the lungs. This and the increased pressure can lead to difficulty breathing) or death when it exceeds 5000 ppm.

If the person inhaled the poison, immediately move them to a place where they can get fresh air, and then immediately go to the doctor quickly.

Contact with skin

Ammonia can cause skin irritation, especially if the skin is damp. In addition, it can burn and blister the skin after a few seconds of exposure to atmospheric concentrations greater than 300 ppm.

If the chemical is on the skin or in the eyes, rinse with plenty of water for at least 15 minutes, preferably with diluted vinegar or boric acid since the acids neutralize it.

Ingestion

This compound is gaseous under normal atmospheric conditions and its ingestion is unlikely. However, if it occurs, it can destroy the gastric mucosa, causing severe pathologies and even death. In fact, the bacteria Helicobacter pylori secretes ammonia from urea and for this reason the gastric or duodenal mucosa is destroyed, causing peptic ulcer.

If the person ingested the chemical, vomiting should not be induced; Medical evaluation should be requested immediately in an emergency unit.

Judging by its annoying and penetrating odor, its ingestion is unlikely, however, it is very common in the case of ingesting foods such as decomposing fish or shellfish (whose proteins, when degraded, form this compound); which is why it is essential to take care of their quality and freshness in order to avoid food poisoning.

El amoníaco es una importante fuente de nitrógeno para sistemas vivos. Aunque el nitrógeno atmosférico abunda (más del 75 %), algunos seres vivos son capaces de usar el nitrógeno atmosférico en su forma diatómica, N gas. Entonces, la fijación de nitrógeno es requerida para la síntesis de aminoácidos, los cuales son la base de la proteína. Algunas plantas usan el amoníaco del nitrógeno atmosférico.[61]​.

Biosynthesis

In certain organisms, ammonia is produced by atmospheric nitrogen by the enzyme called nitrogenase. The general process is called nitrogen fixation. Although biomimetic methods are hardly competitive with the "Haber Process", an intense effort has been directed towards the biological mechanism of nitrogen fixation. Scientific interest in this problem is motivated by an unusual structure of the active site of the enzyme, which consists of a FeMoS assembly.

Ammonia is also a metabolic product of amino acids, catalyzed by enzymes such as glutamate dehydrogenase. Ammonia excretion is common in marine animals. In humans, it is easily converted to urea, which is less toxic as well as less basic. Urea is the largest component of the dry weight of urine. Most reptiles, birds, insects, and snails secrete uric acid as nitrogenous wastes.

in physiology

Ammonia also plays a role in normal and abnormal physiologies. It is biosynthesized through normal amino acid metabolism and is toxic at high concentrations.[62] The liver converts ammonia to urea through several series of reactions known as the urea cycle. Liver dysfunctions, such as cirrhosis, can lead to having a high amount of ammonia in the blood (hyperammonemia). Similarly, defects in the enzyme responsible for the urea cycle, such as ornithine transcarbamylase, can cause hyperammonemia. Hyperammonemia leads to confusion and a coma-like state of hepatic encephalopathy, as well as illnesses common in people with urea cycle problems.[63]​.

Ammonia is important for normal acid/base balance. After ammonium formation from glutamine, α-ketoglutarate can be degraded to produce two bicarbonate molecules, which subsequently function as buffers for dietary acids. Ammonia is excreted in the urine, losing acids. Ammonia can itself diffuse through the kidney tumuli, combined with hydrogen ions, to allow future excretion of acids.[64]​.

Excretion

Ammonia ions are toxic waste products of animal metabolism. In fish and aquatic invertebrates, it is excreted directly into the water. In mammals, sharks and amphibians, it is converted in the urea cycle to urea, because it is less toxic and is an efficient process. In birds, reptiles, and land snails, metabolic ammonium is converted to uric acid, which is solid, and is therefore excreted with minimal water loss[65]​.

El amoníaco se ha detectado en la atmósfera de los planetas de gas gigante, incluyendo Júpiter "Júpiter (planeta)"), junto con otros gases como el metano, hidrógeno y helio. En el interior de Saturno hay cristales congelados de amoníaco.[66]​ Se encuentra naturalmente en Deimos "Deimos (satélite)") y Fobos "Fobos (satélite)"), las dos lunas de Marte.

interstellar space

Ammonia was originally detected in space in 1968, based on microwave emissions from the direction of the galactic nucleus.[67] This was the first polyatomic molecule detected. The sensitivity of the molecule over a wide range of excitations and the ease with which it can be observed in a number of regions has made ammonia one of the most important molecules for studies of molecular clouds.[68] The relative intensity of ammonia lines can be used to measure the temperature of the emitting medium.

The following isotopic species of ammonia have been detected:

The detection of triple deuterium ammonia was considered a surprise because deuterium is relatively scarce. It is believed that low temperatures allow this molecule to survive and accumulate.[69]​.

Since its interstellar discovery, NH has proven to be an invaluable spectroscopy tool in the study of the interstellar medium. With a large number of transitions, it is sensitive to a wide range of excitation conditions, NH has been widely detected astronomically - its detection has been reported in hundreds of papers.

The study of interstellar ammonia has been important for various research areas in recent decades.

The interstellar abundance of ammonia has been measured in several environments. The ratio of [NH]/[H] has been estimated from 10 in small dark clouds[70]​ to 10 in the dense core of the Orion molecular cloud complex.[71]​ Although a total of 18 production routes have been proposed,[72]​ the main mechanism of interstellar NH formation is the following reaction:.

The change constant "k" in this reaction depends on the ambient temperature, with a value of 5.2×10 at 10 K.[73] The constant was calculated from the formula "k = a(T/300)". For the primary formation reaction, a = 1.05×10 and B = −0.47. Assuming an NH abundance of 3×10 and an electron abundance of 10 typical of molecular clouds, formation proceeds to a change of 1.6×10 cms in a molecular cloud with a total density of 10 cm.[74]​.

All other formation reaction proposals have constants with values ​​between 2 and 13 orders of magnitude smaller, making the contributions to ammonia abundance relatively insignificant.[75] As an example of one of the contributions mentioned is:.

It has a constant gear of 2.2×10. Assuming densities of 10 and NH/H ratio of 10 for H, this reaction proceeds at a rate of 2.2×10, more than 3 orders of magnitude slower than the previous primary reaction.

Some other possible formation reactions are:.

There are 113 proposed reactions that lead to the destruction of NH. Of these, 39 were tabulated in extensive chemistry tables along with carbon, nitrogen, and oxygen compounds.[76]​ A review of interstellar ammonia cites the following reactions as the main dissociation mechanisms:[68]​.

With constant changes of 4.39×10[77]​ and 2.2×10,[78]​ respectively. Equations (1,2) run with a change of 8.8×10 and 4.4×10, respectively. These calculations assume the given change in constants and abundances of [NH]/[H] = 10, [H]/[H] = 2×10, [HCO]/[H] = 2×10, and total densities of n = 10, typical of cold, dense, molecular clouds.[79] Clearly, between these two primary reactions, equation (1) is the dominant destruction reaction, with a change of ~10,000 times faster than equation (2). This is due to the relatively high abundance of H.

NH radio observations from the Effelsberg Radio Telescope revealed that the ammonia line is separated into two components – a rigid background and shapeless core. The background corresponds well with the previously detected location of CO.[80] The 25 m Chilbolton telescope in England detected radio signals from ammonia in H II regions, HNHO, H-H objects, and other objects associated with star formation. A comparison with the emission line indicates that turbulent or systematic velocities do not increase in the center of the core of molecular clouds[81]​.

Microwave radiation from ammonia was observed at various galactic objects including W3(OH), Orion (constellation "Orion (constellation)"), W43, W51, and five sources in the galactic center. The high detection of the change indicates that it is a common molecule in the interstellar medium and that high-density regions are common in the galaxy[82].

VLA observations in seven regions with high-velocity gaseous flows revealed condensations of less than 0.1 pc") in L1551, S140 and Cepheus (constellation). Three individual condensations were detected in Cepheus, one of them was a very elongated figure. They may play an important role in creating bipolar slacks in the region.[83]​.

Extragalactic ammonia was imaged using VLA in IC 342. The temperature of the hot gas is above 70 K, which was inferred from the ammonia radius lines and appears to be associated with innermost portions of the nuclear rod seen in CO.[84]​ NH was also monitored by VLA towards the sample of four ultra-compacted galactic HII regions: G9.62+0.19, G10.47+0.03, G29.96−0.02, and G31.41+0.31. Based on temperature and density diagnostics, it is generally concluded that such clusters are probably the sites of star formation in an early evolutionary phase before the development of an ultracompact HII region.[85]​.

Absorptions at 2.91 micrometers of solid ammonia were recorded from interstellar grains in the Becklin-Neugebauer Object and probably in NGC 2264-IR. This detection helped explain the physical form of the previously poorly understood ice absorption lines.[86]​.

A spectrum of Jupiter's ring was obtained from the Kuiper Airborne observatory, covering the 100 to 300 cm spectrum range. Spectrum analysis provides information on global properties of ammonia gas and ammonia ice mist.[87]​.

A total of 149 black cloud positions were checked for evidence of "dense cores" using the line inversion of (J,K) = (1,1) deNH. In general, the nuclei do not have a sphere shape, with radii ranging between 1.1 to 4.4. It was also found that nuclei with stars have broader lines than nuclei without stars.[88]​.

Ammonia was also detected in the Draco Nebula and in one or perhaps two molecular clouds, which are associated with the infrared cirrus.[89]​.

By balancing and stimulating an emission with a spontaneous emission, it is possible to build a relationship between the excitation temperature and the density. However, since the transient levels of ammonia can be approximated to level 2 in a low temperature system, this calculation is simple. This premise can be applied to black clouds, regions suspected of having extremely low temperatures and possible sites for future star formation. Ammonia detections in black clouds show narrow lines—indicating not only low temperatures, but also a low level of turbulence in the cloud. The line of radius calculations provides a measure of cloud temperature that is independent of previous CO observations. The ammonia observations were consistent with CO measurements of rotation temperatures of ~10 K. With this, densities can be determined, and have been calculated to range between 10 and 10 cm in black clouds. By mapping NH, we conclude that it has everyday cloud measurements of 0.1 pc and masses close to a single mass. These cold sites with dense cores are places where a star will form.

Ultra-compact HII regions are among the best tracers of high-mass star formation. The dense material around UCHII regions is primarily molecular. Since a complete study of massive star formation necessarily involves the cloud from which the star formed, ammonia is an invaluable tool for understanding this surrounding molecular material. Since this molecular material can be resolved spatially, it is possible to constrain the heat/ionizing resources, temperatures, masses, and size of the regions. The Doppler shifted velocity components allow the separation of distinct regions of molecular gas that can trace flows and hot cores originating from star formation.

Ammonia has been detected in external galaxies, and by simultaneously measuring several lines, it is possible to directly measure the temperature of the gas in these galaxies. The radius lines imply that the temperatures are hot (~ 50 K), originating from dense clouds with sizes of tens of pc. This image is consistent with the image of our Milky Way—hot, dense molecular nuclei form around forming stars embedded in clouds with molecular material on the scale of several hundred pc (giant molecular clouds).

Ammonia is found in small quantities in the atmosphere, being produced by the putrefaction of nitrogenous matter from plants and animals. Ammonia and ammonium salts are also found in small quantities in rainwater, where ammonium chloride and ammonium sulfate are found in volcanic areas; Ammonium bicarbonate crystals have been found in Patagonia, in guano. The kidney secretes ammonia to neutralize excess acid.[11] Ammonia salts are distributed throughout fertile soil and in the ocean. Ammonia is also found in other parts of the solar system: on Mars "Mars (planet)"), Jupiter "Jupiter (planet)"), Saturn "Saturn (planet)"), Uranus "Uranus (planet)"), Neptune "Neptune (planet)") and Pluto "Pluto (dwarf planet)"). Substances that contain ammonia, or those that are similar to it, are called ammoniacal.

Escapes of a flammable gas outside the structure that contains it are dangerous, as this gas could cause a serious deflagration when it comes into contact with a flame.

Contenido

El amoníaco es un gas incoloro con un olor desagradable y nauseabundo. Es más ligero que el aire, su densidad es 0.589 veces la del aire de la atmósfera. Se condensa fácilmente por sus fuertes puentes de hidrógeno entre las moléculas; el líquido hierve a –33.3 °C y se congela a los –77.7 °C en cristales blancos.[12]​.

El amoníaco se puede desodorizar fácilmente reaccionando con algún ácido. Así se forman sales de amonio sin olor, ya que se comporta como una base "Base (química)").

La simetría del cristal es cúbico, su símbolo pearson es CP16, grupo espacial P 213 No.198, constante de red 0.5125 nm.[13]​.

El amoníaco líquido posee fuertes fuerzas ionizantes reflejando su alta constante dieléctrica de 22. El amoníaco líquido tiene una muy alta entalpía de vaporización (23.35 kJ/mol, cf. agua 40.65 kJ/mol, metano 8.19 kJ/mol, fosfina 14.6 kJ/mol) y puede ser usado en laboratorios en vasos no aislados sin refrigeración.

El amoníaco es miscible con agua. En una solución acuosa puede separarse por ebullición. La solución acuosa de amoníaco es una base. La concentración máxima de amoníaco en agua tiene una densidad de 0.880 g/cm³ (880 kg/m³) y es frecuentemente conocido como 'amoníaco 0.880'.

El amoníaco casero o hidróxido de amonio es una solución de NH en agua. La concentración de dicha solución es medida en unidades de la Escala Baumé, con 26 grados baumé (cerca del 30 % por peso de amoníaco) como concentración típica del producto comercial.

El amoníaco no se quema ni sostiene la combustión por sí mismo, excepto en mezclas de combustible con el 15 a 25 % de aire.

Cuando se mezcla con oxígeno se quema con una llama de color verde amarillento pálido. A alta temperatura y en la presencia de un catalizador, el amoníaco se descompone en sus elementos constituyentes. La combustión ocurre cuando la clorina pasa a amonio, formando nitrógeno y cloruro de hidrógeno; si la clorina esta en exceso, se forma el explosivo tricloruro de nitrógeno o tricloramina (NCl).

Structure

The ammonia molecule has a trigonal pyramidal shape, as predicted by valence shell electron pair repulsion theory, with a given bond angle of 106.7°.[14] The central nitrogen atom has five outer electrons with an additional electron from each hydrogen atom. This gives a total of eight electrons, or four pairs of electrons that are arranged tetrahedrally. Three of those electron pairs are used as pair bonds, leaving one pair of electrons free. This pair more strongly repels bond pairs, so the bond angle is not 109.5° as would be expected for a tetrahedral arrangement, but rather 106.7°.[14] The nitrogen atom in the molecule has a lone pair of electrons, which causes ammonia to be a base, proton acceptor. This shape gives the molecule a dipole moment and makes it a polar molecule. The polarity of the molecule and, especially, its ability to form hydrogen bonds, makes ammonia highly miscible in water. Ammonia is moderately basic, a 1 M aqueous solution has a pH of 11.6 and if a strong acid is added to the solution until the solution reaches a neutral pH of (pH=7), 99.4%, the ammonia molecules are protonated. Temperature and salinity also affect the NH ratio. The resulting product has a regular shape and is isoelectronic with methane.

The ammonia molecule readily undergoes nitrogen inversion at room temperature; A useful analogy is that when an umbrella spins upside down in a strong wind. The energy barrier to this inversion is 24.7 kJ/mol, and the resonant frequency is 23.79 GHz, corresponding to microwave radiation with a wavelength of 1,260 cm. Absorption at this frequency was the first microwave spectroscopy observed.[15]​.

Amphotericity

One of the most important characteristics of ammonia is its basicity. Ammonia is considered a weak base. Combines with acids to form salts; with hydrochloric acid it forms ammonium chloride; with nitric acid, ammonium nitrate, etc. In any case, perfectly dry ammonia does not combine with completely dry hydrogen chloride; water is necessary for the reaction to take place[16] As a demonstration of the experiment, open bottles with concentrated ammonia and hydrochloric acid produce clouds of ammonium chloride, which seem to come "out of nowhere" while the salts form where the two diffusion clouds of the molecules meet, between the two bottles.

The salts produced by the action of ammonia in acids are known as ammonium compounds, which contain the ammonium ion. (NH).

Although ammonia is known as a weak base, it also functions as a very weak acid. It is a protic substance if it is capable of forming amines (which contain the NH ion). For example, lithium dissolved in liquid ammonia to give a lithium amine solution.

Self dissociation

Just like water, ammonia undergoes molecular autoionization to form its conjugate bases and acids.

At standard pressure and temperature, K=[][] = 10.

Combustion

The combustion of ammonia generates molecular nitrogen and water, and is an exothermic reaction:.

The heating value, ΔH°, expressed per mole of ammonia and forming water condensation, is -382.81 kJ/mol. Dinitrogen is the thermodynamic product of ammonia combustion: all nitrogen oxides are unstable with respect to N and O, which is the principle behind the catalytic conversion. However, nitrogen oxides can be formed by kinetic products in the presence of appropriate catalysis, a reaction of great industrial importance in the production of nitric acid:

A subsequent reaction leads to NO.

The combustion of ammonia in air is very difficult in the absence of a catalyst "Catalyst (chemistry)"), since the flame temperature is normally lower than the ignition temperature of the ammonia-air mixture. The flammable range of ammonia in air is 16% to 25%.[17]​.

Formation of other compounds

In organic chemistry, ammonia can act as a nucleophile in nucleophilic substitution reactions. Amines can be formed by the reaction of ammonia with haloalkanes, although the resulting -NH is also nucleophilic and secondary and tertiary amines are formed as byproducts. An excess of ammonia helps minimize multiple substitutions, and neutralizes the hydrogen halides formed. Methylamine is prepared commercially by the reaction of ammonia with chloromethane, and the reaction of ammonia with 2-bromopropanoic acid has been used to prepare racemic alanine in 70% yield. Ethanolamine is prepared by an oxidation reaction with ethylene: the reaction sometimes produces diethanolamine and triethanolamine.

Amides can be prepared by a reaction of ammonia with carboxylic acid derivatives. Acyl chloride is the most reactive, but ammonia must be present in at least twice as much to neutralize the hydrochloric acid formed. Esters and anhydrides also react with ammonia to form amides. Ammonium salts of carboxylic acids can be dehydrated to amides for so long that no thermally sensitive groups are present: temperatures of 150 °C to 200 °C are required.

The hydrogen in ammonia can be replaced by metals, so magnesium burns in the gas with the formation of magnesium nitride MgN, and when the gas passes over superheated sodium or potassium, sodamide, NaNH, and potasamide, KNH, are formed. Where necessarily in IUPAC nomenclature, "azane" is preferred as the name of the anomiac: therefore chloramine would be called "chloroazane", not chloroammonia.

Pentavalent ammonia is known as λ-amino, or more commonly as ammonium hydric. It is a crystalline solid that is stable only at high pressures, and decomposes back to trivalent ammonia and hydrogen gas under normal conditions. This substance has been investigated as a possible fuel in 1966.[18]​.

Ammonia as ligand

Ammonia can function as a ligand in transition metal complexes. It is a σ-donor, in the middle of the spectrochemical series, and shows intermediate hard-soft behavior. Some ammonia complexes include 'tetraamminediaquacopper'([Cu(NH)(HO)]), ([Ag(NH)]) which is the active species of Tollen's agent. The formation of this complex can also be distinguished between precipitates of different silver halides: silver chloride (AgCl) is soluble in a dilute ammonia solution (2M), silver bromide (AgBr) is soluble only in a concentrated ammonia solution, where silver iodide (AgI) is insoluble in liquid ammonia.

Chromium complexes were known in the 19th century, and formed the basis of Alfred Werner's revolutionary theory on the coordination structure of compounds. Werner noted only two isomers ("fac"- and "mer"-) of the [CrCl(NH)] complex can form, and concluded that the ligates must be arranged around the metal ions at the vertices") of an octahedron. This proposal has since been confirmed by X-ray crystallography.

An ammonia ligand bound to a metal ion is markedly more acidic than a free ammonia molecule, although deprotonation in an aqueous solution is still rare. An example is the Calomel reaction:

Ammonia in group theory

The point group for ammonia is C when the major axis goes through the vertical nitrogen. When the major axis is spun either clockwise or counterclockwise, by 120°, each hydrogen moves into the previous location of another hydrogen. Another aspect of the C strut group includes three vertical planes of symmetries that intercept the nitrogen and one of the hydrogens allowing the other two to reflect each other.

The mathematical matrix for this particular subgroup is complicated since matrices produced by rotations or reflections are reducible compared to other matrices that are irreducible. Therefore, a similar transformation must be done on each portion of the matrix that is reducible. The similar transformation for ammonia comes from calculations of the symmetry molecular orbital diagram adapted to a linear combination for the bonding contribution of each of the hydrogens.

Ammonia in solution

Ammonia and ammonium salts can be easily detected, in trace minutes, by adding Nessler's solution, which gives a yellow color in the presence of the slightest trace of ammonia or ammonium salts. The amount of ammonia in ammonium salts can be estimated quantitatively by distillation of salts with sodium hydroxide or potassium hydroxide, the ammonia evolves being absorbed in a known volume in standard sulfuric acid and the excess acid then determined by volumetric analysis; or ammonia can be absorbed into hydrochloric acid and ammonium chloride is formed as a precipitate as ammonium hexachloroplatinate, (NH)PtCl.

Gaseous ammonia

Sulfur sticks are burned to detect small leaks in ammonia refrigeration systems. Larger quantities can be detected by heating the salts with a caustic alkali or calcium oxide, when the characteristic odor of ammonia is apparent. Ammonia is an irritant and irritation increases with concentration; The permitted exposure limit is 25 ppm, and lethal above 500 ppm.[19] Higher concentrations are difficult to detect by conventional detectors, the type of defects is chosen according to the required sensitivity (semiconductor, catalytic, electrochemical). Holographic sensors have been proposed to detect concentrations above 12.5% ​​by volume.[20]​.

Ammoniacal nitrogen (NH3-N)

Ammoniacal nitrogen (NH-N) is a measure commonly used to examine the amount of ammonium ions, naturally derived from ammonia, and returned to ammonia by organic processes, in water or liquid waste. It is a measure used primarily to quantify values ​​in waste treatment and water purification systems, as well as measure the health of natural and man-made water reserves. It is measured in units of mg/L (milligrams/Liters).

The Romans gave the name 'sal ammoniacus' (ammonia salt) to the deposits of ammonia chloride collected near the temple of Amun (in Greek Ἄμμων" Ammon) in ancient Libya due to the proximity of the temple.[21] Ammonia salts have been known since ancient times; so the term "Hammoniacus sal" appears in the writings of Pliny,[22] although it is not known if the term is identical to the modern term "sal-ammoniac" (ammonium chloride).[23]​.

In the form of ammonia salt, ammonia was important in medieval alchemy, as in the 18th century, it was mentioned by Persian chemist Jābir ibn Hayyān,[24] and by alchemists since the 19th century, being mentioned by Albertus Magnus.[12] It was also used by dyers in the Middle Ages in the form of fermented urine to alter the color of vegetable dyes. In the 19th century, Basilius Valentinus demonstrated that ammonia could be obtained by the action of alkalis on ammonia salt. In a later period, when ammonia salts were obtained by distilling the hooves and horns of oxen and neutralizing the resulting carbonate with hydrochloric acid.[25]​.

Gaseous ammonia was first isolated by Joseph Priestley in 1774 and named by him as "alkaline air".[26] Eleven years later in 1785, Claude Louis Berthollet found its composition.[12]

The production of ammonia from nitrogen in the air (and hydrogen) was invented by Fritz Haber and Robert LeRossignol. The patent was submitted in 1909 (USPTO No. 1,202,995) and granted in 1916. Carl Bosch then developed industrial production (Haber-Bosch process). Its first use was on an industrial scale in Germany during World War I. Ammonia was used to produce explosives to sustain war reinforcements. The 1918 Nobel Prize in Chemistry was awarded to Fritz Haber "for the synthesis of ammonia from its elements." The process has become the main source of fixed nitrogen in the world, improving crop yields and alleviating hunger for millions of people on the planet.

Prior to the availability of cheap natural gas, hydrogen as a precursor to ammonia production was carried out with water electrolysis or using the chlor-alkali process.

Fertilizer

Approximately 83% of ammonia in 2004 was used as fertilizers or salts, solutions or anhydrides. When applied to soil, it helped increase the yield of crops such as corn and wheat. 30% of the agricultural nitrogen used in the United States is in the anhydride form and worldwide, 110 million tons are used each year.[28]​.

Nitrogen compound precursor

Ammonia is directly or indirectly the precursor of most nitrogen-containing compounds. Virtually all synthetic nitrogen compounds are derivatives of ammonia. One of the most important derivatives is nitric acid. The key material is generated thanks to the Ostwald process by oxidation of ammonia with air over a platinum catalyst, with a temperature between 700 °C and 800 °C and 9 atmospheres. Nitric oxide is an intermediate in this reaction.[29]​.

Nitric acid is used for the production of fertilizers, explosives, etc.

Cleaner

Household ammonia is a solution of NH in water (ammonia hydroxide) used for the purpose of cleaning surfaces. One of its most common uses is to clean some crystals or crystallographic systems, porcelain and stainless steel. It is also frequently used to clean ovens and absorb elements to soften dirt. Homemade ammonia has a weight concentration of 5 to 10% ammonia.

Fermentation

Ammonia solutions between 16% and 25% are used in industrial fermentations as a source of nitrogen for microorganisms and to adjust their pH during fermentation.

Antimicrobial agent for food

By 1895, ammonia was known to be a strong antiseptic. This is why 1.4 grams per liter is required to preserve the broth.[30]​ In one study, anhydride ammonia destroyed 99.999% of zoonotic bacteria (Zoonosis) in three types of animal feed.[31]​ Ammonia anhydride is currently used to eliminate microbial contamination.[32]​[33]​ Pink slime is made from fatty meat trimmings by removing the fat with heat and centrifugation, then treating it with ammonia to reduce the presence of E. coli at undetectable levels.[34]​ There have been concerns about the safety of the process, as well as consumer complaints about its taste and odor, as well as its toxicity.[35]​.

Agricultural fertilizer

In the form of anhydrous ammonia, it is used as a fertilizer, increasing soil nitrogen levels.

Minor and emerging uses

Thanks to the vaporization properties of ammonia, it is useful as a refrigerant.[7] It was commonly used before the popularization of the use of chlorofluorocarbon compounds. Anhydride ammonia is used tirelessly in the refrigeration industry and for hockey rinks due to its high energy conversion efficiency and low cost. However, it has the disadvantage of being toxic, which restricts its domestic and small-scale use. Along with its modern use of vapor compression refrigeration, it was used along with hydrogen and water in absorption refrigeration. The Kalina cycle depends largely on the boiling range of the ammonia-water mixture.

Ammonia is used to purify SO from hot fuels, and the resulting product is converted to ammonia sulfate for use as fertilizer. Ammonia neutralizes the pollution of nitrogen oxides (NO) emitted by diesel engines. This technology, called SCR (Selective Catalytic Reduction), is based on a vanadium-based catalyst.[36]​.

Ammonia can be used to mitigate phosgene gas spills.[37]​.

Ammonia was used during World War II as fuel for trucks in Belgium, and its motor and solar power since 1900. Liquid ammonia was also fuel for the XLR99 jet engines that would power X-15. Although it is not a strong fuel, it leaves no doubt in the use of the rocket engine and its approximate density coincides with the density of the oxidizer, liquid oxygen, which simplified the design of the aircraft.

Ammonia has been proposed as a practical alternative to fossil fuel for internal engine combustion.[38] The heating value of ammonia is 22.5 Mj/kg, which is approximately half that of diesel. A normal engine, in which water vapor does not condense, the calorific value of ammonia would be less than 21%.

Ammonia cannot be easily used in the Otto cycle due to its low octane levels. Although with the slightest modifications to the carburetors and a drastic reduction in the compression ratio, which would require new pistons, a gasoline engine can run exclusively on ammonia, at a low fraction of its power before conversion to more powerful fuels.

A car tank can store liquid ammonia as long as the tank is appropriately pressurized, depending on the temperature. Depending on the thermodynamic properties of ammonia are such that at -30 °C, the tank pressure would have to be 1,896 bar (27.5 psi), approximately the same as a vehicle tire. At 30°C it would have to be 11.72 bar (170 psi) to keep the ammonia liquid. If the tank pressure were released, the liquid ammonia would become gaseous and raise the pressure to that level. Common tire air compressors operate at this pressure, so that the tank pressure is not a barrier to fuel use.

However, there are other barriers to expanding its use. In terms of raw ammonia supplies, plants would have to be built to increase production levels, which would require greater monetary and energy investment. Even though it is the second most produced chemical compound, the scale of ammonia production is a small fraction of the oil used in the world. It can be a manufacturer of renewable energy, as well as nuclear energy. Norway produced ammonia with water electrolysis for many years starting in 1913, producing fertilizer for Europe. If produced from carbon, CO can be seized, but carbon capture and storage plants have not yet reached the prototype stage.

La Administración de Seguridad y Salud Ocupacional de los Estados Unidos, ha delimitado un máximo de 15 minutos a la exposición del amoníaco líquido en 35 ppm por volumen en el aire del ambiente y 8 horas a 25 ppm por volumen.[48]​ El Instituto Nacional para la Seguridad y Salud Ocupacional (NIOSH), recientemente redujo el riesgo inmediato de vida y salud de 500 a 300 basados en interpretaciones conservadoras más recientes de la investigación original en 1943. El riesgo inmediato a la vida y salud es el nivel en el que un trabajador sano pueda ser expuesto 30 minutos sin sufrir daños irreversibles a la salud. Otras organizaciones tienen niveles de exposición variante. Los estándares de la Marina estadounidense permitía concentraciones máximas de: Exposición continua (60 días) a 25 ppm, o una hora con 400 ppm.[49]​ El vapor de amoníaco tiene un hedor agudo, irritante y desagradable que actúa como prevención de potencial exposición peligrosa. El hedor promedio en el ambiente son 5 ppm, un nivel muy abajo de cualquier peligro o daño. La exposición a concentraciones muy altas de gas de amoníaco puede dar como resultado daño en los pulmones, y posiblemente la muerte.[48]​ Aun cuando el amoníaco es regulado en los Estados Unidos como un gas inflamable, entra en la definición de un gas tóxico al inhalarlo y requiere seguridad específica al transportarlo en cantidades más grandes a 3,500 galones.[50]​.

Toxicity

The toxicity of ammonia solutions does not usually cause problems for humans or other mammals, due to a specific mechanism that exists to prevent its storage in the blood. Ammonia is converted to carbonyl phosphate by the enzyme carbonyl phosphate synthetase, and then enters the Urea Cycle to be incorporated into amino acids or excreted in urine. In any case, fish and amphibians do not have this mechanism, as they normally eliminate ammonia from their bodies with direct excretion. Ammonia, even in dilute concentrations, is highly toxic to aquatic animals, and for that reason it is classified as "dangerous to the environment."

Ammonia toxicity is believed to be a cause of the still unexplored loss of fish in hatcheries. Excess ammonia can accumulate and cause metabolic alterations or increase the pH in the body of the exposed organism. Tolerance varies among different fish species.[51]​ At lower concentrations, around 0.05 mg/L, non-ionized ammonia is harmful to fish and can cause decreased growth, reduced fertility and fecundity, and increased stress and susceptibility to bacterial infections and diseases.[52]​ Upon exposure to excess ammonia, fish may suffer from loss of balance, hyperexcitability, increased respiratory activity, oxygen uptake, and increased heart rate.[51]​ At concentrations exceeding 2.00 mg/L, ammonia causes tissue damage, extreme lethargy, seizures, coma, and death.[51]​[53]​ Experiments have shown that the lethal concentration for fish generally ranges from 0.2 to 2.00 mg/L[53]​.

During the winter, when the feed given to aquaculture farms is reduced, ammonia levels can increase. Temperatures lower than ambient reduce the photosynthesis rate of algae, so less ammonia is removed by algae. In this type of environment, especially on a large scale, there are no quick fixes to treat high levels of ammonia. Prevention rather than correction is recommended to reduce damage to fish[53]​ and in open water systems, the surrounding environment.

Storage information

Similar to propane, anhydride ammonia boils below ambient temperature at standard pressure. An ammonia storage container capable of holding it at 250 psi is appropriate for storage.[54] Ammonia compounds should not come into contact with "Base (chemical)" bases (unless a specific chemical reaction is intended), as dangerous amounts of ammonia may be released.

Home use

Ammonia solutions (5-10% by weight) are used in household cleaners, particularly for glass. These solutions are irritating to the eyes and mucous membrane, and to a lesser extent to the skin. Caution should be taken to never mix these solutions with any liquid containing bleach, as it may cause a dangerous gas. Mixing it with products that contain chlorine or powerful oxidants, such as household bleach, can lead to the production of dangerous gases such as chloramine.[55]​.

Laboratory use of ammonia solutions

The dangers of ammonia solutions depend on their concentration: Solutions with "dilute" ammonia usually have between 5-10% by weight (5.62 mol/l); Concentrated solutions are usually prepared with approximately 25% by weight. At 25% by weight, the solution has a density of 0.907 g/cm³ (907 kg/m³), and a solution that has a lower density will be more concentrated. The following table classifies ammonia solutions.

Ammonia vapor from concentrated ammonia solutions are severely irritating to the eyes and respiratory tract, and these solutions can only be handled in a fume hood. Saturated solutions ("0.880") can develop significant pressure in a closed bottle in hot weather, and the bottle should be opened carefully; this is normally not a problem for 25% ("0.900") solutions.

Ammonia solutions should not be mixed with halogens, as toxic and/or explosive products are formed. Prolonged contact of ammonia solutions with salts of silver, mercury or iodine may also result in explosive products: such mixtures are normally formed in inorganic qualitative analyses, and must be slightly acidified but not concentrated before the analysis is completed.

Laboratory use of Ammonia Anhydride (gas or liquid)

Ammonia anhydride is classified as toxic ("T") and hazardous to the environment ("N"). The gas is flammable (Autoignition temperature: 651 °C) and can form explosive mixtures with air (16-25%). The permissible exposure in the United States is 50 ppm, while the concentration for immediate harm to life and health is estimated to be 300 ppm. Repeated exposure to lower levels of ammonia decreases sensitivity to the odor of the gas: normally the odor is detectable at concentrations less than 50 ppm, but desensitized individuals would not be able to detect it even at concentrations of 100 ppm. Ammonia anhydride corrodes copper and zinc alloys, so brass should not be used to store the gas. Liquid ammonia can also attack rubber and certain plastics.

Ammonia reacts violently with halogens. Nitrogen triiodide, a primary explosive, which is formed when ammonia comes into contact with iodine. Ammonia causes the explosive polymerization of ethylene oxide. It also forms explosive fulminating compounds with gold, silver, mercury, germanium or tellurium. Violent reactions have also been reported with solutions of acetaldehyde, hypochlorite, peroxides and potassium ferricyanide.

Chemical principles

NH is obtained by the method called the Haber-Bosch process (Fritz Haber and Carl Bosch received the Nobel Prize in Chemistry in 1918 and 1931). The process consists of the direct reaction between gaseous nitrogen and hydrogen.

N + 3H → 2NH ΔH° = -46.2 kJ/mol

ΔS° < 0.

25 °C K = 6.8.10¬5 atm

850 °C K = 7.8.10¬-2 atm

These values are obtained through the van't Hoff equation. It is a very slow reaction, since it has a high activation energy, a consequence of the stability of N. The solution to the problem was to use a catalyst (iron oxide that is reduced to Fe in the H atmosphere). Because the reaction has more moles on the reactant side (4 moles) than on the products side (2 moles), increasing the pressure favors the formation of the product. Although thermodynamically the reaction proceeds better at low temperatures, this synthesis is carried out at high temperatures to favor the kinetic energy of the molecules and thus increase the reaction rate. In addition, ammonia is removed as it is produced to further promote the synthesis of products.

Production from reform

The Haber-Bosch method uses two raw materials: hydrogen and nitrogen. The necessary hydrogen is produced from the reforming of natural gas, LPG or naphtha with water vapor, natural gas being the most common feed. The plant is divided into two sections: the front-end or front part of the plant, where the mixture of hydrogen and nitrogen necessary to synthesize ammonia is generated, and the back-end or rear part of the plant, which is the section where the product is converted from both reactants.

The plant usually consists of the following units:.

Front-end:.

Back-end:.

The back-end section mainly consists of a reactor (the ammonia converter) and a series of auxiliary equipment to cool the reactor output stream. It also has a compressor which raises the pressure of the stream coming from the front-end up to the working pressure required for ammonia synthesis. There are various reactor designs offered by different technologists (e.g. Haldor Topsoe, Casale, Kellogg, TVA type reactors, etc.) and each converter has its own characteristics, advantages and disadvantages. Some reactors are vertical, others horizontal; some have radial flow, others axial flow, and others mixed flow; some have one bed, others have two beds, etc. In any case, a characteristic common to all of them is that they require a catalyst for the reaction to take place, currently the one used in almost all iron-based plants and promoted with other compounds.[59] Reactors usually operate in a temperature range of 400-500 °C and at very high pressures, in the order of 200-350 kgf/cm²g. As explained previously, the reaction is strongly balanced towards the reactant side, and therefore the ammonia concentration is not too high: in a plant operating under stable conditions the concentration at the entrance to the converter is usually around 5% and at the exit 15%.

El amoníaco líquido es conocido y comúnmente estudiado como un solvente ionizante no-acuoso. Su propiedad más conspicua es la habilidad de disolver metales álcali para formar soluciones altamente coloradas y eléctricamente conductivas conteniendo electrones solvatados. Además de estas soluciones, mucha de la química en el amoníaco líquido puede ser clasificado por analogía con reacciones relacionadas en soluciones acuosas. La comparación de las propiedades físicas del NH con aquellas del agua, muestra que el NH tiene un menor punto de ebullición, de fusión, densidad, viscosidad y constante dieléctrica; esto es al menos en parte por los enlaces débiles del hidrógeno en NH y porque dicho enlace no puede formar redes reticuladas, pues cada molécula de NH tiene un solo par de electrones libres comparado con dos por cada molécula de HO. La constante de disociación del NH a -50 °C es 10 mol·l.

Solubility of salts

Liquid ammonia is an ionizing solvent, although less so than water, it dissolves many compounds, including nitrates, nitrites, cyanides and thiocyanates. Most ammonium salts are soluble and act as acids in liquid ammonia solutions. The solubility of halogen salts increases from fluorine to iodine. A saturated solution of ammonium nitrate contains 0.083 moles of solite per mole of ammonia and has a vapor pressure of less than 1 bar "Bar (pressure unit)") at 25 °C.

Metal solutions

Liquid ammonia dissolves alkali metals and other electropositive metals such as magnesium, calcium, strontium, barium, europium and ytterbium. At low concentrations, dark blue solutions are formed: these contain cations and solvated electrons, free electrons that are surrounded by a cage of ammonia molecules.

These solutions are very useful and strong reducing agents. At high concentrations, solutions are metallic in appearance and electrical conductivity. At low temperatures, the two types of solution can coexist as immiscible phases.

Redox properties of liquid ammonia

The range of thermodynamic stability of solutions with liquid ammonia is very narrow, as the oxidation potential to dinitrogen, normal electrode potential (N + 6NH + 6e 8NH), is only +0.04 V. In practice, the oxidation to dinitrogen and reduction of dihydrogen are slow. This is especially true in reducing solutions: the solutions of the alkali metals mentioned above are stable for several days, slowly decomposing the metal and dihydrogen amoeba. Most studies on liquid ammonia in solutions are done under reducing conditions; However, the oxidation of liquid ammonia is slow and there is a risk of explosion.

Inhalation

In high concentrations it irritates the throat, inflames the lungs, damages the respiratory tract and eyes. As the concentration increases, it can lead to pulmonary edema (Pulmonary edema is often caused by congestive heart failure. When the heart is not able to pump blood to the body efficiently, it can back up in the veins that carry blood through the lungs to the left side of the heart.

As the pressure in these blood vessels increases, fluid is pushed into the air spaces (alveoli) in the lungs. This fluid reduces the normal movement of oxygen through the lungs. This and the increased pressure can lead to difficulty breathing) or death when it exceeds 5000 ppm.

If the person inhaled the poison, immediately move them to a place where they can get fresh air, and then immediately go to the doctor quickly.

Contact with skin

Ammonia can cause skin irritation, especially if the skin is damp. In addition, it can burn and blister the skin after a few seconds of exposure to atmospheric concentrations greater than 300 ppm.

If the chemical is on the skin or in the eyes, rinse with plenty of water for at least 15 minutes, preferably with diluted vinegar or boric acid since the acids neutralize it.

Ingestion

This compound is gaseous under normal atmospheric conditions and its ingestion is unlikely. However, if it occurs, it can destroy the gastric mucosa, causing severe pathologies and even death. In fact, the bacteria Helicobacter pylori secretes ammonia from urea and for this reason the gastric or duodenal mucosa is destroyed, causing peptic ulcer.

If the person ingested the chemical, vomiting should not be induced; Medical evaluation should be requested immediately in an emergency unit.

Judging by its annoying and penetrating odor, its ingestion is unlikely, however, it is very common in the case of ingesting foods such as decomposing fish or shellfish (whose proteins, when degraded, form this compound); which is why it is essential to take care of their quality and freshness in order to avoid food poisoning.

El amoníaco es una importante fuente de nitrógeno para sistemas vivos. Aunque el nitrógeno atmosférico abunda (más del 75 %), algunos seres vivos son capaces de usar el nitrógeno atmosférico en su forma diatómica, N gas. Entonces, la fijación de nitrógeno es requerida para la síntesis de aminoácidos, los cuales son la base de la proteína. Algunas plantas usan el amoníaco del nitrógeno atmosférico.[61]​.

Biosynthesis

In certain organisms, ammonia is produced by atmospheric nitrogen by the enzyme called nitrogenase. The general process is called nitrogen fixation. Although biomimetic methods are hardly competitive with the "Haber Process", an intense effort has been directed towards the biological mechanism of nitrogen fixation. Scientific interest in this problem is motivated by an unusual structure of the active site of the enzyme, which consists of a FeMoS assembly.

Ammonia is also a metabolic product of amino acids, catalyzed by enzymes such as glutamate dehydrogenase. Ammonia excretion is common in marine animals. In humans, it is easily converted to urea, which is less toxic as well as less basic. Urea is the largest component of the dry weight of urine. Most reptiles, birds, insects, and snails secrete uric acid as nitrogenous wastes.

in physiology

Ammonia also plays a role in normal and abnormal physiologies. It is biosynthesized through normal amino acid metabolism and is toxic at high concentrations.[62] The liver converts ammonia to urea through several series of reactions known as the urea cycle. Liver dysfunctions, such as cirrhosis, can lead to having a high amount of ammonia in the blood (hyperammonemia). Similarly, defects in the enzyme responsible for the urea cycle, such as ornithine transcarbamylase, can cause hyperammonemia. Hyperammonemia leads to confusion and a coma-like state of hepatic encephalopathy, as well as illnesses common in people with urea cycle problems.[63]​.

Ammonia is important for normal acid/base balance. After ammonium formation from glutamine, α-ketoglutarate can be degraded to produce two bicarbonate molecules, which subsequently function as buffers for dietary acids. Ammonia is excreted in the urine, losing acids. Ammonia can itself diffuse through the kidney tumuli, combined with hydrogen ions, to allow future excretion of acids.[64]​.

Excretion

Ammonia ions are toxic waste products of animal metabolism. In fish and aquatic invertebrates, it is excreted directly into the water. In mammals, sharks and amphibians, it is converted in the urea cycle to urea, because it is less toxic and is an efficient process. In birds, reptiles, and land snails, metabolic ammonium is converted to uric acid, which is solid, and is therefore excreted with minimal water loss[65]​.

El amoníaco se ha detectado en la atmósfera de los planetas de gas gigante, incluyendo Júpiter "Júpiter (planeta)"), junto con otros gases como el metano, hidrógeno y helio. En el interior de Saturno hay cristales congelados de amoníaco.[66]​ Se encuentra naturalmente en Deimos "Deimos (satélite)") y Fobos "Fobos (satélite)"), las dos lunas de Marte.

interstellar space

Ammonia was originally detected in space in 1968, based on microwave emissions from the direction of the galactic nucleus.[67] This was the first polyatomic molecule detected. The sensitivity of the molecule over a wide range of excitations and the ease with which it can be observed in a number of regions has made ammonia one of the most important molecules for studies of molecular clouds.[68] The relative intensity of ammonia lines can be used to measure the temperature of the emitting medium.

The following isotopic species of ammonia have been detected:

The detection of triple deuterium ammonia was considered a surprise because deuterium is relatively scarce. It is believed that low temperatures allow this molecule to survive and accumulate.[69]​.

Since its interstellar discovery, NH has proven to be an invaluable spectroscopy tool in the study of the interstellar medium. With a large number of transitions, it is sensitive to a wide range of excitation conditions, NH has been widely detected astronomically - its detection has been reported in hundreds of papers.

The study of interstellar ammonia has been important for various research areas in recent decades.

The interstellar abundance of ammonia has been measured in several environments. The ratio of [NH]/[H] has been estimated from 10 in small dark clouds[70]​ to 10 in the dense core of the Orion molecular cloud complex.[71]​ Although a total of 18 production routes have been proposed,[72]​ the main mechanism of interstellar NH formation is the following reaction:.

The change constant "k" in this reaction depends on the ambient temperature, with a value of 5.2×10 at 10 K.[73] The constant was calculated from the formula "k = a(T/300)". For the primary formation reaction, a = 1.05×10 and B = −0.47. Assuming an NH abundance of 3×10 and an electron abundance of 10 typical of molecular clouds, formation proceeds to a change of 1.6×10 cms in a molecular cloud with a total density of 10 cm.[74]​.

All other formation reaction proposals have constants with values ​​between 2 and 13 orders of magnitude smaller, making the contributions to ammonia abundance relatively insignificant.[75] As an example of one of the contributions mentioned is:.

It has a constant gear of 2.2×10. Assuming densities of 10 and NH/H ratio of 10 for H, this reaction proceeds at a rate of 2.2×10, more than 3 orders of magnitude slower than the previous primary reaction.

Some other possible formation reactions are:.

There are 113 proposed reactions that lead to the destruction of NH. Of these, 39 were tabulated in extensive chemistry tables along with carbon, nitrogen, and oxygen compounds.[76]​ A review of interstellar ammonia cites the following reactions as the main dissociation mechanisms:[68]​.

With constant changes of 4.39×10[77]​ and 2.2×10,[78]​ respectively. Equations (1,2) run with a change of 8.8×10 and 4.4×10, respectively. These calculations assume the given change in constants and abundances of [NH]/[H] = 10, [H]/[H] = 2×10, [HCO]/[H] = 2×10, and total densities of n = 10, typical of cold, dense, molecular clouds.[79] Clearly, between these two primary reactions, equation (1) is the dominant destruction reaction, with a change of ~10,000 times faster than equation (2). This is due to the relatively high abundance of H.

NH radio observations from the Effelsberg Radio Telescope revealed that the ammonia line is separated into two components – a rigid background and shapeless core. The background corresponds well with the previously detected location of CO.[80] The 25 m Chilbolton telescope in England detected radio signals from ammonia in H II regions, HNHO, H-H objects, and other objects associated with star formation. A comparison with the emission line indicates that turbulent or systematic velocities do not increase in the center of the core of molecular clouds[81]​.

Microwave radiation from ammonia was observed at various galactic objects including W3(OH), Orion (constellation "Orion (constellation)"), W43, W51, and five sources in the galactic center. The high detection of the change indicates that it is a common molecule in the interstellar medium and that high-density regions are common in the galaxy[82].

VLA observations in seven regions with high-velocity gaseous flows revealed condensations of less than 0.1 pc") in L1551, S140 and Cepheus (constellation). Three individual condensations were detected in Cepheus, one of them was a very elongated figure. They may play an important role in creating bipolar slacks in the region.[83]​.

Extragalactic ammonia was imaged using VLA in IC 342. The temperature of the hot gas is above 70 K, which was inferred from the ammonia radius lines and appears to be associated with innermost portions of the nuclear rod seen in CO.[84]​ NH was also monitored by VLA towards the sample of four ultra-compacted galactic HII regions: G9.62+0.19, G10.47+0.03, G29.96−0.02, and G31.41+0.31. Based on temperature and density diagnostics, it is generally concluded that such clusters are probably the sites of star formation in an early evolutionary phase before the development of an ultracompact HII region.[85]​.

Absorptions at 2.91 micrometers of solid ammonia were recorded from interstellar grains in the Becklin-Neugebauer Object and probably in NGC 2264-IR. This detection helped explain the physical form of the previously poorly understood ice absorption lines.[86]​.

A spectrum of Jupiter's ring was obtained from the Kuiper Airborne observatory, covering the 100 to 300 cm spectrum range. Spectrum analysis provides information on global properties of ammonia gas and ammonia ice mist.[87]​.

A total of 149 black cloud positions were checked for evidence of "dense cores" using the line inversion of (J,K) = (1,1) deNH. In general, the nuclei do not have a sphere shape, with radii ranging between 1.1 to 4.4. It was also found that nuclei with stars have broader lines than nuclei without stars.[88]​.

Ammonia was also detected in the Draco Nebula and in one or perhaps two molecular clouds, which are associated with the infrared cirrus.[89]​.

By balancing and stimulating an emission with a spontaneous emission, it is possible to build a relationship between the excitation temperature and the density. However, since the transient levels of ammonia can be approximated to level 2 in a low temperature system, this calculation is simple. This premise can be applied to black clouds, regions suspected of having extremely low temperatures and possible sites for future star formation. Ammonia detections in black clouds show narrow lines—indicating not only low temperatures, but also a low level of turbulence in the cloud. The line of radius calculations provides a measure of cloud temperature that is independent of previous CO observations. The ammonia observations were consistent with CO measurements of rotation temperatures of ~10 K. With this, densities can be determined, and have been calculated to range between 10 and 10 cm in black clouds. By mapping NH, we conclude that it has everyday cloud measurements of 0.1 pc and masses close to a single mass. These cold sites with dense cores are places where a star will form.

Ultra-compact HII regions are among the best tracers of high-mass star formation. The dense material around UCHII regions is primarily molecular. Since a complete study of massive star formation necessarily involves the cloud from which the star formed, ammonia is an invaluable tool for understanding this surrounding molecular material. Since this molecular material can be resolved spatially, it is possible to constrain the heat/ionizing resources, temperatures, masses, and size of the regions. The Doppler shifted velocity components allow the separation of distinct regions of molecular gas that can trace flows and hot cores originating from star formation.

Ammonia has been detected in external galaxies, and by simultaneously measuring several lines, it is possible to directly measure the temperature of the gas in these galaxies. The radius lines imply that the temperatures are hot (~ 50 K), originating from dense clouds with sizes of tens of pc. This image is consistent with the image of our Milky Way—hot, dense molecular nuclei form around forming stars embedded in clouds with molecular material on the scale of several hundred pc (giant molecular clouds).