Physical properties.
Under normal pressure, ammonia liquefies at -33 ° C and solidifies at -78 ° C. The heat of fusion of NH 3 is 6 kJ / mol. The critical temperature of ammonia is 132 ° C, the critical pressure is 112 atm. The cylinders containing it must be painted yellow and have a black inscription "Ammonia".
Ammonia is a colorless gas with a characteristic pungent odor ("ammonia"). Its solubility in water is greater than that of all other gases: one volume of water absorbs about 1200 at 0 ° C, and about 700 volumes of NH 3 at 20 ° C. Commercial concentrated solution usually has a density of 0.91 g / cm 3 and contains 25 wt.% NH 3 (ie, close to the composition NH 3 .3H 2 O).
Associated with the association of liquid ammonia is its high heat of vaporization (23.4 kJ / mol). Since the critical temperature of ammonia is high (+132 ° C) and when it evaporates, a lot of heat is taken away from the environment, liquid ammonia can serve as a working substance of refrigeration machines. r air = M NH 3 / M average air = 17/29 = 0.5862
Liquid ammonia is a good solvent for a very large number of organic compounds, as well as many inorganic ones. For example, elemental sulfur is readily soluble in liquid ammonia, strong solutions of which are red [and below +18 ° C they contain S (NH 3) 2 solvate]. Of the salts, derivatives of ammonium and alkali metals are best soluble than others, and the solubility of salts increases in the Cl-Br-I series. Examples are the following data (g / 100 g NH 3 at 25 ° C):
|
A similar course of change in the solubility of halides is characteristic of a number of other cations. Many nitrates (and KMnO 4) are also well soluble in liquid ammonia. In contrast, oxides, fluorides, sulfates and carbonates are generally insoluble in it.
Taking advantage of the difference in the solubility of salts in liquid NH 3 and water, it is sometimes possible to reverse the commonly observed ion exchange reactions. For example, the equilibrium according to the scheme:
2 AgNO 3 + BaBr 2 N 2 AgBr + Ba (NO 3) 2
In an aqueous medium, it almost completely shifts to the right (due to the insolubility of AgBr), and in an ammonia environment - to the left (due to the insolubility of BaBr 2).
A characteristic property of ammonia as an ionizing solvent is its pronounced leveling effect on the dissociation of various electrolytes. For example, HClO 4 and HCN in liquid ammonia, incommensurable with each other in dissociation in an aqueous medium, are characterized by almost the same dissociation constants (5 · 10 -3 and 2 · 10 -3). Salts behave in liquid ammonia as electrolytes of medium strength or weak (for example, K = 2 · 10 -3 for KBr). Chlorides are usually somewhat less dissociated, and iodides somewhat more dissociated, corresponding to bromides.
A feature of liquid ammonia is its ability to dissolve the most active metals, the latter being ionized. For example, a dilute sodium metal solution is blue, conducts an electric current similar to electrolyte solutions, and contains Na + cations (solvated with ammonia) and (NH 3) x - anions. The central part of such a complex anion is a free electron in polarization interaction with the environment (polaron). At higher Na concentrations, its solution takes on the form of bronze and exhibits metallic electrical conductivity, i.e., along with solvated ammonia, free electrons are also contained. Below -42 ° C, the blue and bronze phases can coexist without mixing. Long-term storage of sodium solutions in liquid ammonia is accompanied by their discoloration as a result of a very slow reaction according to the scheme:
2 Na + 2 NH 3 = 2 NaNH 2 + H 2 .
With cesium (solubility of 25 moles per 1000 g of NH 3 at -50 ° C), a similar reaction proceeds in a few minutes.
The metal dissolved in ammonia tends to split off valence electrons, which makes it possible to carry out a kind of displacement reactions. For example, using the solubility in liquid ammonia KCl and the insolubility of CaCl 2, it is possible to isolate potassium with calcium according to the following scheme:
2 КСl + Ca ® CaCl 2 + 2 K.
There is an interesting indication that impregnation with liquid ammonia greatly increases the ductility of wood. This makes it relatively easy to give it certain desired forms, which are retained after the removal of ammonia.
The dissolution of ammonia in water is accompanied by the release of heat (about 33 kJ / mol). The effect of temperature on solubility is illustrated by the following data showing the number of parts by weight of NH 3 absorbed by one part by weight of water (at atmospheric pressure of ammonia):
|
Temperature ° С |
-30 | 0 | 10 | 30 | 50 | 80 | 100 |
| Solubility | 2,78 | 0,87 | 0,63 | 0,40 | 0,23 | 0,15 | 0,07 |
Under normal conditions, the maximum electrical conductivity is approximately 3 N ammonia solution. Its solubility in organic solvents is much less than in water.
Chemical properties.
Formation of a covalent bond by the donor-acceptor mechanism.
1. Ammonia - Lewis base. Its solution in water (ammonia water, ammonia) has an alkaline reaction (litmus - blue; phenolphthalein - raspberry) due to the formation of ammonium hydroxide.
NH 3 + H 2 O<-->NH 4 OH<-->NH 4 + + OH -
2. Ammonia reacts with acids to form ammonium salts.
NH 3 + HCl ® NH 4 Cl
2NH 3 + H 2 SO 4 ® (NH 4) 2 SO 4
NH 3 + H 2 O + CO 2® NH 4 HCO 3
Ammonia - reducing agent (oxidized to N 2 +1 O or N +2 O)
1. Decomposition on heating
2N -3 H 3 - t ° ® N 2 0 + 3H 2
2. Combustion in oxygen
a) without catalyst
4N -3 H 3 + 3O 2 ® 2N 2 0 + 6H 2 O
b) catalytic oxidation (kat = Pt)
4N -3 H 3 + 5O 2 ® 4N +2 O + 6H 2 O
3. Reduction of oxides of some metals
3Cu +2 O + 2N -3 H 3 ® 3Cu0 + N 2 0 + 3H 2 O
When a stream of ammonia is passed over heated CuO, it is oxidized to free nitrogen. Oxidation of ammonia with ozone leads to the formation of NH 4 NO 3. It is interesting that ordinary oxygen mixed with ozone apparently takes some part in such oxidation.
Ammonia is a good jet fuel. Like water, liquid ammonia is strongly associated, mainly through the formation of H-bonds. However, they are relatively weak (about 4.2 kJ / mol). The viscosity of liquid ammonia is almost seven times less than the viscosity of water. Its density (0.68 and 0.61 g / cm 3, respectively, at -33 and +20 ° C) is also significantly less than that of water. Liquid ammonia practically does not conduct electric current, since electrolytic dissociation according to the scheme:
NH 3 + NH 3 N NH 4 + + NH 2 -
Negligible: ionic product = 2 · 10 -33 (at -50 ° C).
Above 0 ° C (under pressure), liquid ammonia is mixed with water in any ratio. On strong solutions of water in ammonia at 30 ° C it was shown that its ionization is low. So, for a 9 M solution we have / = 1 · 10 -11.
For the chemical characterization of ammonia, three types of reactions are of primary importance: addition, hydrogen substitution, and oxidation.
The most typical addition reactions for ammonia. In particular, when it acts on many salts, crystalline ammonia compounds of the composition CaCl 2 · 8NH 3, CuSO 4 · 4NH 3, etc., are easily formed, which are similar to crystalline hydrates in terms of their formation and stability.
When ammonia is dissolved in water, a partial formation of ammonium hydroxide occurs:
NH 3 + H 2 O Ы NH 4 OH
In this compound, the ammonium (NH 4) radical plays the role of a monovalent metal. Therefore, the electrolytic dissociation of NH 4 OH proceeds according to the main type:
NH 4 OH Ы NH 4 + OH "
Combining both of these equations, we get a general idea of the equilibria that take place in an aqueous solution of ammonia:
NH 3 + H 2 O Ы NH 4 OH Ы NH 4 + OH "
Because of these equilibria, aqueous ammonia (often referred to simply as "ammonia") has a pungent odor. Due to the fact that the concentration of OH ions in the solution is low, NH 4 OH is considered as a weak base. Ammonium hydroxide is one of the most important chemical reagents, dilute solutions of which (“ammonia”) are also used in medicine and household (when washing clothes and removing stains).
Analysis of data on the distribution of NH 3 between water and organic liquids shows that more than 90% of all ammonia dissolved in water is in the hydrated form. For the vapor phase over an aqueous ammonia solution, the presence of equilibrium was established according to the following scheme:
2 NH 3 + H 2 O N 2 NH 3 · H 2 O + 75 kJ,
Characterized by the value of K = 1 · 10 -4 at 20 ° C.
Atom, molecule.
The NH 3 molecule has a triangular pyramid structure with a nitrogen atom at the top. R HNH = 107.3 °. The electrons of the H-N bonds are rather strongly displaced from hydrogen to nitrogen, therefore the ammonia molecule as a whole is characterized by significant polarity.
The pyramidal structure of ammonia is energetically more favorable than the flat one by 25 kJ / mol. The molecule is polar; the N-H bond is characterized by an energy of 389 kJ / mol, but for the energies of sequential dissociation of hydrogen atoms, values of 435, 397, and 339 kJ / mol are given. Ammonia molecules are linked by weak hydrogen bonds:
An interesting property of ammonia molecules is their ability to structural inversion, i.e. to "turning inside out" by the passage of a nitrogen atom through the plane of the base of the pyramid formed by hydrogen atoms. The potential barrier to this inversion is 25 kJ / mol; only molecules that are sufficiently rich in energy can carry it out. The inversion rate is relatively low - it is 1000 times less than the rate of orientation of NH 3 molecules by an electric field.
Receiving.
The transfer of free nitrogen in the air into a bound state is carried out mainly through the synthesis of ammonia:
N 2 + 3 H 2 N 2 NH 3 + 92 kJ.
The principle of displacement of equilibrium shows that the most favorable conditions for the formation of ammonia are the lowest possible temperature and the highest possible pressure. However, even at 700 ° C, the reaction rate is so slow (and therefore, equilibrium is established so slowly) that there can be no question of its practical use. On the contrary, at higher temperatures, when the equilibrium state is established quickly, the ammonia content in the system becomes negligible. Thus, the technical implementation of the process under consideration turns out to be impossible, since, accelerating the achievement of equilibrium with the help of heating, we simultaneously shift its position to the disadvantageous side.
There is, however, a means to accelerate the attainment of equilibrium without simultaneously shifting the equilibrium. An often helpful catalyst is a suitable catalyst. A suitable catalyst is metallic iron (doped with Al 2 O 3 and K 2 O). The process is usually carried out at a temperature of 400-600 ° C (on a catalyst) and pressures of 100-1000 atm. After the separation of ammonia from the gas mixture, the latter is again introduced into the cycle.
In the process of searching for a catalyst for the synthesis of ammonia, about 20 thousand different substances were tried. The widely used iron catalyst is usually prepared by heating an intimate mixture of FeO and Fe 2 O 3 (containing small impurities of Fe, Al 2 O 3 and KOH) in an atmosphere of the composition 3H 2 + N 2. Since Н 2 S, CO, CO 2, water vapor and oxygen quickly "poison" the catalyst, the nitrogen-hydrogen mixture supplied to it must be carefully freed from them. With the correct technological mode, the catalyst will operate without interruption for several years.
For the further development of the synthetic ammonia industry, it may turn out to be essential that at pressures of 2000 atm and higher, the synthesis of ammonia from a nitrogen-hydrogen mixture proceeds well even without a special catalyst. The practical yield of ammonia at 850 ° C and 4500 atm is 97%. Especially important is the fact that at ultrahigh pressures, the presence of various impurities in the initial gases does not affect the course of the process.
The synthesis of ammonia was practically realized in 1913, when in this way it was possible to obtain 7 tons of NH 3. At present, this synthesis is the main industrial method for obtaining bound nitrogen with an annual world production of tens of millions of tons.
In addition to the direct synthesis of ammonia from elements, some industrial value for the binding of nitrogen in the air is developed in 1905. cyanamide method... The latter is based on the fact that at 1000 ° C calcium carbide (obtained by calcining a mixture of lime and coal in an electric furnace) reacts with free nitrogen according to the equation:
CaC 2 + N 2 = CaCN 2 + C + 293 kJ.
The calcium cyanamide obtained in this way (Ca = N-Cє N) is a gray (from carbon impurity) powder. Under the action of superheated (i.e. heated above 100 ° C) water vapor, it decomposes with the release of ammonia:
CaCN 2 + 3 H 2 O = CaCO 3 + 2 NH 3 + 222 kJ.
Decomposition of calcium cyanamide with water is slow at normal temperatures. Therefore, it can be used as a nitrogen fertilizer, introducing it into the soil long before sowing. The presence of calcium makes it especially suitable for podzolic soils. "Cyanamide plays the role of not only nitrogenous, but also lime fertilizer, and lime is a free supplement to nitrogen" (DN Pryanishnikov).
Under laboratory conditions, NH 3 is obtained by treating solid NH 4 Cl with a saturated KOH solution. The released gas can be dried by passing it through a vessel with solid KOH or with freshly calcined calcium oxide (CaO). It is impossible to use H 2 SO 4 and CaCl 2 for drying, since ammonia forms compounds with them.
2NH 4 Cl + Ca (OH) 2 - t ° ® CaCl 2 + 2NH 3 + 2H 2 O
(NH 4) 2 SO 4 + 2KOH - t ° ® K 2 SO 4 + 2NH 3 + 2H 2 O
Ammonia can only be collected using method (A), because it is lighter than air and very soluble in water.
Action on the body.
Ammonia strongly irritates mucous membranes even at 0.5% content in the air. Acute ammonia poisoning causes eye and respiratory tract damage, shortness of breath and pneumonia. First aid means are fresh air, rinsing the eyes with plenty of water, and inhaling water vapor. Chronic ammonia poisoning causes indigestion, catarrh of the upper respiratory tract, and hearing impairment. The maximum permissible concentration of NH 3 in the air of industrial premises is 0.02 mg / l. Mixtures of ammonia with air containing from 16 to 28 vol.% Ammonia are explosive.
Application.
Because the decomposition of calcium cyanamide with water slowly proceeds at normal temperatures, then it can be used as a nitrogen fertilizer, introducing it into the soil long before sowing. The presence of calcium makes it especially suitable for podzolic soils. "Cyanamide plays the role of not only nitrogenous, but also lime fertilizer, and lime is a free supplement to nitrogen" (DN Pryanishnikov).
Commercial ammonia usually contains about 10% ammonia. It also finds medical use. In particular, inhalation of its vapors or ingestion (3-10 drops per glass of water) is used to relieve the state of severe intoxication. Lubricating the skin with ammonia weakens the effect of insect bites. It is convenient to wipe windows and floors painted with oil paint with very diluted ammonia, while it is more durable to remove traces of flies, to clean silver or nickel-plated objects.
When removing stains, good results are given in many cases by the following compositions (by volume): a) 4 parts of ammonia, 5 parts of ether and 7 parts of wine alcohol (denatured alcohol); b) 5 parts of ammonia, 2 parts of gasoline and 10 parts of wine alcohol; c) 10 parts of ammonia, 7 parts of wine alcohol, 3 parts of chloroform and 80 parts of gasoline; d) 5 parts of ammonia, 3 parts of acetone and 20 parts of an alcoholic solution of soap.
It is recommended to wipe off the oil paint that has got on the clothes with pieces of cotton wool, moistened first with turpentine, and then with ammonia. To remove ink stains, it is usually sufficient to treat it with ammonia and rinse with water.
Ammonia (NH 3) is one of the most common industrial chemicals used in industry and commerce.
Ammonia, why does our body need it? It turns out that it is constantly formed in all organs and tissues and is an irreplaceable substance in many biological processes, serves as a precursor for the formation of amino acids and the synthesis of nucleotides. In nature, ammonia is formed during the decomposition of nitrogen-containing organic compounds.
Chemical and physical properties of ammonia
- At room temperature, ammonia is a colorless, irritating gas with a pungent, suffocating odor;
- in its pure form it is known as anhydrous ammonia;
- hygroscopic (easily absorbs moisture);
- has alkaline properties, caustic easily dissolves in water;
- easily compresses and forms a transparent liquid under pressure.
Where is ammonia used?
About 80% of ammonia is used to make industrial products.
Ammonia is used in agriculture as a fertilizer.
Present in refrigeration plants for water purification.
It is used in the production of plastics, explosives, textiles, pesticides, dyes and other chemicals.
Found in many household and industrial cleaning solutions. Household products containing ammonia are made with the addition of 5-10% ammonia, the concentration of ammonia in industrial solutions is higher - 25%, which makes them more caustic.
How does ammonia affect the human body?
Most people are in contact with ammonia, inhaling it like gas or evaporation. Since ammonia exists in nature and is found in detergents, they can be sources of it.
The widespread use of ammonia in agricultural and industrial areas also means that an increase in its concentration in the air can occur during accidental emissions or deliberate terrorist attacks.
Anhydrous ammonia gas is lighter than air and therefore rises high, so it is generally dispersed and does not accumulate in the lowlands. However, in the presence of dampness (high relative humidity), liquefied anhydrous ammonia forms vapors heavier than air. These vapors can be carried over the ground or over lowlands.
How does ammonia work?
Ammonia begins to interact immediately after contact with moisture on the surface of the skin, eyes, mouth, respiratory tract and partially mucous surfaces and forms a very corrosive ammonium hydroxide ... Ammonium hydroxide causes tissue necrosis due to disruption of cell membranes, leads to cell destruction. Once the protein and cells are broken down, water is extracted in an inflammatory response, resulting in further damage.
What are the symptoms of ammonia poisoning?
Breath... The smell of ammonia in the nose is irritating and acrid. Exposure to high concentrations of ammonia in the air causes a burning sensation in the nose, throat and respiratory tract. This can lead to bronchiolar and alveolar edema and airway damage as a result of respiratory failure. Inhalation of low concentrations may cause coughing, nose and throat irritation. The smell of ammonia warns early enough of its presence, but ammonia also leads to a weakening of the sense of smell, which makes it less likely to be noticed in the air at low concentrations.
Children who are exposed to the same amount of ammonia as adults receive a higher dose because the surface of their lungs is much larger in relation to their body. In addition, they can be more exposed to ammonia due to their low growth - they are closer to the ground, where the concentration of vapors is higher.
Skin or eye contact... Contact with low concentrations of ammonia in air or liquids can cause rapid eye or skin irritation. Higher concentrations of ammonia can lead to serious injury and burns ... Contact with concentrated ammonia liquids such as industrial detergents can cause corrosive damage, including skin burns, eye damage, or blindness ... Severe damage to the eye may not be visible until a week after exposure. Contact with liquefied ammonia can also cause frostbite .
Eating with food... Getting a high concentration of ammonia through swallowing an ammonia solution can damage the mouth, throat, and stomach.
Hydrogen, under normal conditions - a colorless gas with a pungent characteristic odor (the smell of ammonia)
- Halogens (chlorine, iodine) form dangerous explosives with ammonia - nitrogen halides (nitrogen chloride, nitrogen iodide).
- With haloalkanes, ammonia enters into a nucleophilic addition reaction, forming a substituted ammonium ion (a method for producing amines):
- With carboxylic acids, their anhydrides, halides, esters and other derivatives, it gives amides. With aldehydes and ketones - Schiff bases, which can be reduced to the corresponding amines (reductive amination).
- At 1000 ° C, ammonia reacts with coal to form hydrocyanic acid HCN and partially decompose into nitrogen and hydrogen. It can also react with methane to form the same hydrocyanic acid:
Name history
Ammonia (in European languages its name sounds like "ammonia") owes its name to the Ammon oasis in North Africa, located at the crossroads of caravan routes. In hot climates, urea (NH 2) 2 CO, contained in animal waste products, decomposes especially quickly. One of the decomposition products is ammonia. According to other sources, ammonia got its name from the ancient Egyptian word amonian... This was the name of the people who worship the god Amon. During their ritual ceremonies, they smelled ammonia NH 4 Cl, which evaporates ammonia when heated.
Liquid ammonia
Liquid ammonia, albeit to a small extent, dissociates into ions (autoprotolysis), in which its similarity to water is manifested:
The self-ionization constant of liquid ammonia at −50 ° C is approximately 10 −33 (mol / l) ².
The metal amides resulting from the reaction with ammonia contain a negative ion NH 2 -, which is also formed during the self-ionization of ammonia. Thus, metal amides are analogs of hydroxides. The reaction rate increases when going from Li to Cs. The reaction is significantly accelerated in the presence of even small H 2 O impurities.
Metallic ammonia solutions have metallic electrical conductivity, in which metal atoms decay into positive ions and solvated electrons surrounded by NH 3 molecules. Metallic ammonia solutions, which contain free electrons, are the strongest reducing agents.
Complexation
Due to their electron-donating properties, NH 3 molecules can enter complex compounds as a ligand. Thus, the introduction of an excess of ammonia into solutions of d-metal salts leads to the formation of their amino complexes:
Complexation is usually accompanied by a color change in the solution. So, in the first reaction, the blue color (CuSO 4) turns into dark blue (the color of the complex), and in the second reaction, the color changes from green (Ni (NO 3) 2) to blue-violet. The strongest complexes with NH 3 form chromium and cobalt in the +3 oxidation state.
Biological role
Ammonia is the end product of nitrogen metabolism in humans and animals. It is formed during the metabolism of proteins, amino acids and other nitrogenous compounds. It is highly toxic to the body, so most of the ammonia during the ornithine cycle is converted by the liver into a more harmless and less toxic compound - carbamide (urea). The urea is then excreted by the kidneys, and some of the urea can be converted by the liver or kidneys back to ammonia.
Ammonia can also be used by the liver for the reverse process - the resynthesis of amino acids from ammonia and keto analogs of amino acids. This process is called "reductive amination". Thus, aspartic acid is obtained from oxaloacetic acid, glutamic from α-ketoglutaric acid, etc.
Physiological action
In terms of its physiological effect on the body, it belongs to a group of substances of asphyxiant and neurotropic action, capable of causing toxic pulmonary edema and severe damage to the nervous system during inhalation damage. Ammonia has both local and resorptive effects.
Ammonia vapors strongly irritate the mucous membranes of the eyes and respiratory system, as well as the skin. This is a person who perceives it as a pungent smell. Ammonia vapors cause profuse lacrimation, eye pain, chemical burns of the conjunctiva and cornea, loss of vision, coughing fits, redness and itching of the skin. When liquefied ammonia and its solutions come into contact with the skin, a burning sensation occurs, a chemical burn with blisters, ulceration is possible. In addition, the liquefied ammonia absorbs heat when it evaporates, and contact with the skin results in frostbite of varying degrees. The smell of ammonia is felt at a concentration of 37 mg / m³.
Application
Ammonia is one of the most important products of the chemical industry, its annual global production reaches 150 million tons. It is mainly used for the production of nitrogen fertilizers (ammonium nitrate and sulphate, urea), explosives and polymers, nitric acid, soda (by the ammonia method) and other chemical products. Liquid ammonia is used as a solvent.
Consumption rates per ton of ammonia
For the production of one ton of ammonia in Russia, an average of 1200 nm³ of natural gas is consumed, in Europe - 900 nm³.
Belarusian "Grodno Azot" consumes 1200 nm³ of natural gas per ton of ammonia, after modernization it is expected to decrease consumption to 876 nm³.
Ukrainian producers consume from 750 Nm³ to 1170 Nm³ of natural gas per ton of ammonia.
According to UHDE technology, the consumption of 6.7 - 7.4 Gcal of energy resources per ton of ammonia is declared.
Ammonia in medicine
For insect bites, ammonia is used externally in the form of lotions. A 10% aqueous solution of ammonia is known as ammonia.
Possible side effects: with prolonged exposure (inhalation use) ammonia can cause reflex respiratory arrest.
Local application is contraindicated in dermatitis, eczema, other skin diseases, as well as in open traumatic injuries of the skin.
In case of accidental damage to the mucous membrane of the eye, rinse with water (15 minutes every 10 minutes) or 5% boric acid solution. Oils and ointments are not used. In case of damage to the nose and throat - 0.5% citric acid solution or natural juices. In case of ingestion, drink water, fruit juice, milk, preferably 0.5% citric acid solution or 1% acetic acid solution until the contents of the stomach are completely neutralized.
Interaction with other drugs is unknown.
Ammonia producers
Ammonia producers in Russia
| Company | 2006, thousand tons | 2007, thousand tons |
|---|---|---|
| JSC "Togliattiazot"]] | 2 635 | 2 403,3 |
| OJSC NAK "Azot" | 1 526 | 1 514,8 |
| OJSC "Acron" | 1 526 | 1 114,2 |
| JSC "Nevinnomyssky Azot", Nevinnomyssk | 1 065 | 1 087,2 |
| OJSC "Minudobreniya" (Rossosh) | 959 | 986,2 |
| JSC "AZOT" | 854 | 957,3 |
| OJSC "Azot" | 869 | 920,1 |
| OJSC Kirovo-Chepetskiy Khim. combine " | 956 | 881,1 |
| OJSC Cherepovetskiy "Azot" | 936,1 | 790,6 |
| Kuibyshevazot CJSC | 506 | 570,4 |
| Gazprom Salavat neftekhim" | 492 | 512,8 |
| "Mineral fertilizers" (Perm) | 437 | 474,6 |
| OJSC "Dorogobuzh" | 444 | 473,9 |
| OJSC "Voskresensk Mineral Fertilizers" | 175 | 205,3 |
| JSC Shchekinoazot | 58 | 61,1 |
| LLC "MendeleevskAzot" | - | - |
| Total | 13 321,1 | 12 952,9 |
Russia accounts for about 9% of the world ammonia production. Russia is one of the world's largest exporters of ammonia. About 25% of the total volume of ammonia production is exported, which is about 16% of world exports.
Ammonia producers in Ukraine
- Jupiter's clouds are composed of ammonia.
see also
Notes (edit)
Links
- //
- // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
Literature
- Akhmetov N.S. General and inorganic chemistry. - M .: Higher school, 2001.
Hydrogen nitride with the formula NH 3 is called ammonia. It is a light (lighter than air) gas with a pungent odor. The structure of the molecule determines the physical and chemical properties of ammonia.
Structure
An ammonia molecule consists of one nitrogen atom and three hydrogen atoms. The bonds between hydrogen and nitrogen atoms are covalent. The ammonia molecule has the shape of a trigonal pyramid.
There are three free electrons in the 2p-orbital of nitrogen. Three hydrogen atoms hybridize with them, forming the type of hybridization sp 3.
Rice. 1. The structure of the ammonia molecule.
If one hydrogen atom is replaced by a hydrocarbon radical (C n H m), a new organic substance is obtained - an amine. Not only one hydrogen atom can be replaced, but all three. Depending on the number of substituted atoms, three types of amines are distinguished:
- primary(methylamine - CH 3 NH 2);
- secondary(dimethylamine - CH 3 -NH-CH 3);
- tertiary(trimethylamine - CH 3 -N- (CH 3) 2).
C 2 H 4, C 6 H 4, (C 2 H 4) 2 and other substances containing several carbon and hydrogen atoms can join the ammonia molecule.
Rice. 2. Formation of amines.
Ammonia and amines have a free pair of nitrogen electrons, so the properties of the two substances are similar.
Physical
Basic physical properties of ammonia:
- colorless gas;
- Strong smell;
- good solubility in water (for one volume of water 700 volumes of ammonia at 20 ° С, at 0 ° С - 1200);
- lighter than air.
Ammonia liquefies at -33 ° C and becomes solid at -78 ° C. The concentrated solution contains 25% ammonia and has a density of 0.91 g / cm 3. Liquid ammonia dissolves inorganic and organic substances, but does not conduct electricity.
In nature, ammonia is released during the decay and decomposition of organic substances containing nitrogen (proteins, urea).
Chemical
The oxidation state of nitrogen in the composition of ammonia is -3, hydrogen is +1. When ammonia is formed, hydrogen oxidizes nitrogen, taking three electrons away from it. Due to the remaining pair of nitrogen electrons and the easy separation of hydrogen atoms, ammonia is an active compound that reacts with simple and complex substances.
The main chemical properties are described in the table.
|
Interaction |
Reaction products |
The equation |
|
With oxygen |
Burns to form nitrogen or reacts with oxygen in the presence of a catalyst (platinum) to form nitric oxide |
4NH 3 + 3O 2 → 2N 2 + 6H 2 O; 4NH 3 + 5O 2 → 4NO + 6H 2 O |
|
With halogens |
Nitrogen, acid |
2NH 3 + 3Br 2 → N 2 + 6HBr |
|
Ammonium hydroxide or ammonia |
NH 3 + H 2 O → NH 4 OH |
|
|
With acids |
Ammonium salts |
NH 3 + HCl → NH 4 Cl; 2NH 3 + H 2 SO 4 → (NH 4) 2 SO 4 |
|
Replaces metal to form new salt |
2NH 3 + CuSO 4 → (NH 4) 2 SO 4 + Cu |
|
|
With metal oxides |
Reduces metal, nitrogen is formed |
2NH 3 + 3CuO → 3Cu + N 2 + 3H 2 O |
Rice. 3. Combustion of ammonia. Assessment of the report
Average rating: 4.3. Total ratings received: 297.
Hydrogen, under normal conditions - a colorless gas with a pungent characteristic odor (the smell of ammonia)
- Halogens (chlorine, iodine) form dangerous explosives with ammonia - nitrogen halides (nitrogen chloride, nitrogen iodide).
- With haloalkanes, ammonia enters into a nucleophilic addition reaction, forming a substituted ammonium ion (a method for producing amines):
- With carboxylic acids, their anhydrides, halides, esters and other derivatives, it gives amides. With aldehydes and ketones - Schiff bases, which can be reduced to the corresponding amines (reductive amination).
- At 1000 ° C, ammonia reacts with coal to form hydrocyanic acid HCN and partially decompose into nitrogen and hydrogen. It can also react with methane to form the same hydrocyanic acid:
Name history
Ammonia (in European languages its name sounds like "ammonia") owes its name to the Ammon oasis in North Africa, located at the crossroads of caravan routes. In hot climates, urea (NH 2) 2 CO, contained in animal waste products, decomposes especially quickly. One of the decomposition products is ammonia. According to other sources, ammonia got its name from the ancient Egyptian word amonian... This was the name of the people who worship the god Amon. During their ritual ceremonies, they smelled ammonia NH 4 Cl, which evaporates ammonia when heated.
Liquid ammonia
Liquid ammonia, albeit to a small extent, dissociates into ions (autoprotolysis), in which its similarity to water is manifested:
The self-ionization constant of liquid ammonia at −50 ° C is approximately 10 −33 (mol / l) ².
The metal amides resulting from the reaction with ammonia contain a negative ion NH 2 -, which is also formed during the self-ionization of ammonia. Thus, metal amides are analogs of hydroxides. The reaction rate increases when going from Li to Cs. The reaction is significantly accelerated in the presence of even small H 2 O impurities.
Metallic ammonia solutions have metallic electrical conductivity, in which metal atoms decay into positive ions and solvated electrons surrounded by NH 3 molecules. Metallic ammonia solutions, which contain free electrons, are the strongest reducing agents.
Complexation
Due to their electron-donating properties, NH 3 molecules can enter complex compounds as a ligand. Thus, the introduction of an excess of ammonia into solutions of d-metal salts leads to the formation of their amino complexes:
Complexation is usually accompanied by a color change in the solution. So, in the first reaction, the blue color (CuSO 4) turns into dark blue (the color of the complex), and in the second reaction, the color changes from green (Ni (NO 3) 2) to blue-violet. The strongest complexes with NH 3 form chromium and cobalt in the +3 oxidation state.
Biological role
Ammonia is the end product of nitrogen metabolism in humans and animals. It is formed during the metabolism of proteins, amino acids and other nitrogenous compounds. It is highly toxic to the body, so most of the ammonia during the ornithine cycle is converted by the liver into a more harmless and less toxic compound - carbamide (urea). The urea is then excreted by the kidneys, and some of the urea can be converted by the liver or kidneys back to ammonia.
Ammonia can also be used by the liver for the reverse process - the resynthesis of amino acids from ammonia and keto analogs of amino acids. This process is called "reductive amination". Thus, aspartic acid is obtained from oxaloacetic acid, glutamic from α-ketoglutaric acid, etc.
Physiological action
In terms of its physiological effect on the body, it belongs to a group of substances of asphyxiant and neurotropic action, capable of causing toxic pulmonary edema and severe damage to the nervous system during inhalation damage. Ammonia has both local and resorptive effects.
Ammonia vapors strongly irritate the mucous membranes of the eyes and respiratory system, as well as the skin. This is a person who perceives it as a pungent smell. Ammonia vapors cause profuse lacrimation, eye pain, chemical burns of the conjunctiva and cornea, loss of vision, coughing fits, redness and itching of the skin. When liquefied ammonia and its solutions come into contact with the skin, a burning sensation occurs, a chemical burn with blisters, ulceration is possible. In addition, the liquefied ammonia absorbs heat when it evaporates, and contact with the skin results in frostbite of varying degrees. The smell of ammonia is felt at a concentration of 37 mg / m³.
Application
Ammonia is one of the most important products of the chemical industry, its annual global production reaches 150 million tons. It is mainly used for the production of nitrogen fertilizers (ammonium nitrate and sulphate, urea), explosives and polymers, nitric acid, soda (by the ammonia method) and other chemical products. Liquid ammonia is used as a solvent.
Consumption rates per ton of ammonia
For the production of one ton of ammonia in Russia, an average of 1200 nm³ of natural gas is consumed, in Europe - 900 nm³.
Belarusian "Grodno Azot" consumes 1200 nm³ of natural gas per ton of ammonia, after modernization it is expected to decrease consumption to 876 nm³.
Ukrainian producers consume from 750 Nm³ to 1170 Nm³ of natural gas per ton of ammonia.
According to UHDE technology, the consumption of 6.7 - 7.4 Gcal of energy resources per ton of ammonia is declared.
Ammonia in medicine
For insect bites, ammonia is used externally in the form of lotions. A 10% aqueous solution of ammonia is known as ammonia.
Possible side effects: with prolonged exposure (inhalation use) ammonia can cause reflex respiratory arrest.
Local application is contraindicated in dermatitis, eczema, other skin diseases, as well as in open traumatic injuries of the skin.
In case of accidental damage to the mucous membrane of the eye, rinse with water (15 minutes every 10 minutes) or 5% boric acid solution. Oils and ointments are not used. In case of damage to the nose and throat - 0.5% citric acid solution or natural juices. In case of ingestion, drink water, fruit juice, milk, preferably 0.5% citric acid solution or 1% acetic acid solution until the contents of the stomach are completely neutralized.
Interaction with other drugs is unknown.
Ammonia producers
Ammonia producers in Russia
| Company | 2006, thousand tons | 2007, thousand tons |
|---|---|---|
| JSC "Togliattiazot"]] | 2 635 | 2 403,3 |
| OJSC NAK "Azot" | 1 526 | 1 514,8 |
| OJSC "Acron" | 1 526 | 1 114,2 |
| JSC "Nevinnomyssky Azot", Nevinnomyssk | 1 065 | 1 087,2 |
| OJSC "Minudobreniya" (Rossosh) | 959 | 986,2 |
| JSC "AZOT" | 854 | 957,3 |
| OJSC "Azot" | 869 | 920,1 |
| OJSC Kirovo-Chepetskiy Khim. combine " | 956 | 881,1 |
| OJSC Cherepovetskiy "Azot" | 936,1 | 790,6 |
| Kuibyshevazot CJSC | 506 | 570,4 |
| Gazprom Salavat neftekhim" | 492 | 512,8 |
| "Mineral fertilizers" (Perm) | 437 | 474,6 |
| OJSC "Dorogobuzh" | 444 | 473,9 |
| OJSC "Voskresensk Mineral Fertilizers" | 175 | 205,3 |
| JSC Shchekinoazot | 58 | 61,1 |
| LLC "MendeleevskAzot" | - | - |
| Total | 13 321,1 | 12 952,9 |
Russia accounts for about 9% of the world ammonia production. Russia is one of the world's largest exporters of ammonia. About 25% of the total volume of ammonia production is exported, which is about 16% of world exports.
Ammonia producers in Ukraine
- Jupiter's clouds are composed of ammonia.
see also
Notes (edit)
Links
- //
- // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
- // Encyclopedic Dictionary of Brockhaus and Efron: In 86 volumes (82 volumes and 4 additional). - SPb. , 1890-1907.
Literature
- Akhmetov N.S. General and inorganic chemistry. - M .: Higher school, 2001.