Although nitrogen cannot be seen unless it is liquefied or frozen, the importance of this gas to humans and civilization is second only to oxygen and hydrogen. Nitrogen is used in a wide variety of human activities from medicine to the production of explosives. Hundreds of millions of tons of nitrogen and its derivatives are produced annually in the world. Here are just a few facts about how nitrogen was discovered, explored, produced and used:
1. At the end of the 17th century, three chemists at once - Henry Cavendish, Joseph Priestley and Daniel Rutherford - managed to get nitrogen. However, none of them understood the properties of the resulting gas enough to discover a new substance. Priestley even confused it with oxygen. Rutherford was the most consistent in describing the properties of a gas that does not support combustion and does not react with other substances, so he got the laurels of the discoverer.
Daniel Rutherford
2. Actually, Antoine Lavoisier called the gas “nitrogen”, using the ancient Greek word “lifeless”.
3. By volume, nitrogen is 4/5 of the earth's atmosphere. Significant amounts of nitrogen are contained in the world's oceans, the earth's crust and mantle, and in the mantle it is an order of magnitude greater than in the crust.
4. 2.5% of the mass of all living organisms on Earth is nitrogen. In terms of mass fraction in the biosphere, this gas is second only to oxygen, hydrogen and carbon.
5. Actually pure nitrogen as a gas is harmless, odorless and tasteless. Nitrogen is dangerous only in high concentrations - it can cause intoxication, suffocation and death. Nitrogen is also terrible in case of decompression sickness, when the blood of divers, as it rises quickly from a considerable depth, boils, as it were, and nitrogen bubbles rupture blood vessels. A person subjected to such a disease can rise to the surface alive, but at best lose limbs, and at worst die in a few hours.
6. Previously, nitrogen was obtained from various minerals, but now about a billion tons of nitrogen per year is extracted directly from the atmosphere.
7. Terminator 2 is frozen in liquid nitrogen, but this cinematic scene is pure fiction. Liquid nitrogen does indeed have a very low temperature, but the heat capacity of this gas is so low that the freezing time of even small objects is calculated in tens of minutes.
8. Liquid nitrogen is most actively used in various cooling units (inertness to other substances makes nitrogen an ideal refrigerant) and in cryotherapy - cold treatment. In recent years, cryotherapy has been actively used in sports.
9. The inertness of nitrogen is actively used in the food industry. Food can be stored for a very long time in storage and packaging with a pure nitrogen atmosphere.
Plant for creating a nitrogen atmosphere in a food warehouse
10. Nitrogen is sometimes used in beer bottling instead of traditional carbon dioxide. However, experts say that its bubbles are smaller, and this carbonation is not suitable for all beers.
11. Nitrogen is pumped into the chambers of aircraft landing gear for fire safety purposes.
12. Nitrogen is the most effective fire extinguishing agent. They rarely extinguish ordinary fires - it is difficult to quickly deliver the gas to the fire site in the city, and it quickly evaporates in open areas. But in mines, the method of extinguishing a fire by displacing oxygen with nitrogen from a burning mine is often used.
13. Nitric oxide I, better known as nitrous oxide, is used both as an anesthetic and as a substance that improves the performance of a car engine. It does not burn itself, but supports combustion well.
You can speed up...
14. Nitric oxide II is a very toxic substance. However, it is present in small amounts in all living organisms. In the human body, nitric oxide (as this substance is more often called) is produced to normalize the functioning of the heart and prevent hypertension and heart attacks. During these diseases, diets that include beets, spinach, arugula and other greens are used to stimulate the production of nitric oxide.
15. Nitroglycerin (a complex compound of nitric acid with glycerin), whose core tablets are placed under the tongue, and the strongest explosive of the same name, is really one and the same substance.
16. In general, the vast majority of modern explosives are made using nitrogen.
17. Nitrogen is also critical for fertilizer production. Nitrogen fertilizers, in turn, are of great importance for crop yields.
18. In the tube of a mercury thermometer are silver mercury and colorless nitrogen.
19. Nitrogen is found not only on Earth. The atmosphere of Titan, the largest moon, is composed almost entirely of nitrogen. Hydrogen, oxygen, helium and nitrogen are the four most common chemical elements in the universe.
Titan's nitrogen atmosphere is over 400 km thick
20. In November 2017, a girl was born in the United States as a result of a very unusual procedure. Her mother received an embryo that had been stored frozen in liquid nitrogen for 24 years. Pregnancy and childbirth went well, the girl was born healthy.
Nitrogen (general information)
Nitrogen
brief information
Nitrogen is an element of the 15th group of the second period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 7.
General information about nitrogen
Nitrogen is the most abundant gas in the Earth's atmosphere. In other words, the air around us is three-quarters nitrogen, not oxygen. In the periodic system of chemical elements of Mendeleev, nitrogen is denoted by the symbol N (from the Latin Nitrogenium), has atomic number 7 and occupies a place in the 15th group. Under normal conditions, nitrogen is a diatomic and highly inert gas. It has no color, taste and smell, therefore, it is not perceptible to humans. The formula of nitrogen gas is N2; it is in this molecular state that it fills the atmosphere of our planet by three-quarters.
Discovery history
At the end of the 18th century, several scientists at once came close to the discovery of a new chemical element, the properties of which had not yet been studied by science. So, Henry Cavendish in 1772 carried out the following experiment: he repeatedly passed air over hot coal, treated the coal with an alkaline solution, and ultimately obtained the remainder of a new substance. The chemist called this residue "suffocating air." Cavendish, in fact, received nitrogen - a new chemical element, but he could not guess about it. In the same year, experiments on obtaining "suffocating air" were continued by Cavendish's friend Professor Priestley. He also repeatedly received nitrogen in the course of his experiments, but mistakenly assumed that this gas was oxygen. Therefore, neither of the two scientists are considered the discoverers of nitrogen.
In parallel with these experiments, Daniel Rutherford set up his own experiments in the same 1772. It was he who correctly described the main properties of nitrogen in his master's work. In particular, the fact that it is not breathable, does not react with alkalis and does not support the combustion process. Most often it is Rutherford who is called the discoverer of nitrogen.
Nitrogen Properties
The physical properties of nitrogen under normal conditions characterize it as a colorless gas, odorless and not perceptible by the human senses. Nitrogen is slightly soluble in water, has a density of 1.2506 kg/m 3 . In its liquid state, nitrogen is a colorless and mobile liquid, visually similar to water. It boils at -195.8 °C. The density of liquid nitrogen is reduced to 808 kg/m 3 . At −209.86 °C, nitrogen passes into a solid state of aggregation, acquiring the form of large bright white crystals.
The free state of nitrogen is a diatomic N2 molecule with a triple bond between the molecules. This bond makes the nitrogen molecule extremely strong, and under normal conditions there is practically no dissociation of the molecules. As a result, nitrogen is a very inert gas: it practically does not enter into chemical reactions with other substances and, under normal conditions, is in a free state. The forces of intermolecular interaction are extremely weak, which is why, under normal conditions, nitrogen is a gas, and not a liquid or a solid.
Interesting Nitrogen Facts
The name nitrogen, which means "devoid of life", appeared with the light hand of Antoine Lavoisier at the end of the 18th century, when it was experimentally established that nitrogen could not support respiration and combustion. Now we know that, being "lifeless" in name, nitrogen is extremely important for keeping all creatures alive. The Latin name for nitrogen "nitrogenium" is translated as "saltpeter giving birth" and recalls the critical importance of this element for industry.
All living organisms cannot absorb nitrogen in its pure form. We absorb the necessary amount of it through protein foods. When a person breathes, he inhales the nitrogen in the air. It is not absorbed by the lungs in any way (unlike oxygen), so nitrogen is mainly present in our exhalation. Surprisingly, just the abundance of nitrogen in the atmosphere helps us not to consume oxygen in quantities that are fatal to the human body.
In science fiction, there is a story about freezing living creatures with nitrogen in order to preserve them for future generations. In reality, modern scientists cannot do this, since freezing with liquid nitrogen occurs slowly, and the body dies before it has time to “correctly” freeze.
Application of nitrogen
The use of nitrogen in industrial production is determined by its high inert properties. Liquid nitrogen is used as an industrial refrigerant. Nitrogen in the gaseous state is used as an antioxidant. Since pure gaseous nitrogen can replace air (which contains oxygen as an oxidizing agent), nitrogen is used to purge cavities in the electrical industry and in mechanical engineering as such. With its help, tanks and pipelines are purged, their operation is controlled at high pressure inside the tank.
Nitrogen is a raw material for the synthesis of important nitrogen-containing compounds. These include nitrogen fertilizers, which, together with phosphorus and potash fertilizers, are indispensable in crop production. Nitrogen is a component of ammonia, which is used in refrigeration equipment, as an industrial solvent, in medicine and in general is the most important chemical raw material. The production of most explosives on the planet is based on the chemical properties of oxygen and nitrogen.
Nitrogen can also be found in the food industry as a food additive E941. Nitrogen gas is needed to fill tire chambers for aircraft landing gear. It has now become fashionable to fill tires with nitrogen among motorists, although scientific evidence of the effectiveness of such use has not yet been given. Nitrogen and other gases are widely used in medicine: both in the development of new drugs and methods, and in the manufacture of high-precision medical equipment.
The leading gas supplier in Ukraine today is considered to be DP Air Gas.
In terms of importance for humans and their activities, nitrogen is in third place after oxygen and hydrogen. It cannot be seen if the gas is not frozen or liquefied, however, every year specialists receive several tons of the gas in question and its derivatives. Gas is used in many areas of human activity, from medicine to explosives. And today, any resident of Moscow and the Moscow region can purchase a bottle of nitrous oxide at an affordable price on the website www.zakisazot.ru.
It is impossible to tell everything about this gas. Here are just a few facts about him:
1. Gas was first discovered at the end of 1777 by three chemists - Daniel Rutherford, Henry Cavendish and Joseph Priestley. However, none of them was able to discover the properties of nitrogen, which did not allow it to be fully discovered as a new gas. At first, Priestley thought it was oxygen. Daniel Rutherford consistently discovered the properties of a gas that does not react with other substances and does not burn. That is why it is believed that nitrogen was discovered by this particular scientist.
2. The name "Nitrogen" comes from the ancient Greek word "lifeless". This is what Antoine Lavoisier called the gas.
3. In the Earth's atmosphere, nitrogen is contained in a percentage - 75.51%. The bulk of this gas is located in the earth's crust and in the space between it and the core. It is distinctive that in the latter it is much more than in the bark.
4. The composition of the mass of living organisms includes nitrogen in a percentage of 2.5%.
5. Without impurities, the substance in question has neither color nor odor, it is absolutely harmless. However, a large concentration of gas causes life-threatening consequences - suffocation and death. Nitrogen is also dangerous in case of decompression sickness - when divers quickly rise from depth to the surface, gas bubbles clog blood vessels. As a result, a person can stay alive, losing, for example, a limb, but there have been cases when divers died a few hours after rising to the surface.
6. Initially, the gas in question was obtained from various natural objects with a certain chemical composition and crystal structure, however, today it is extracted directly from the Earth's atmosphere.
7. In the second part of the film "Terminator" he froze in liquid nitrogen. This is pure fiction - even freezing an object that has a small area will take at least 10-15 minutes, which is to say about the Terminator.
8. Due to its unique properties, liquid nitrogen can be used as a refrigerant in special cooling devices, and it can also be used in cryotherapy. Cold treatment is actively used for injuries in athletes.
9. Nitrogen is also widely used in the food industry. By placing food in an atmosphere of liquid nitrogen, you can keep food fresh for a long time.
10. In some cases, nitrogen is used in the production of beer. Its rare use in the beer industry is due to the fact that gas bubbles are not suitable for all varieties of this drink.
11. Nitrogen is placed in the wheels of airliners, which is necessary to ensure fire safety.
12. The gas in question is effective in extinguishing fires. Under standard conditions, it is not used in case of fire, since it quickly evaporates in open spaces. However, in mines, when a fire occurs, nitrogen is used quite often.
13. In the medical field, nitrous oxide, or otherwise nitric oxide I, is used as anesthesia during surgery. Nitrous oxide is also used in the automotive industry - improving engine performance. The gas itself does not burn, however, it supports the ignition process well.
14. Nitric oxide II is dangerous to humans. Every body contains it in small amounts. In the human body, it is called nitric oxide. It is necessary to maintain the normal functioning of the heart, which protects against high blood pressure and heart attack. If a patient has heart problems, he is prescribed foods rich in nitric oxide - spinach, beets.
15. The compound of glycerol and nitric acid is called nitroglycerin. This substance is included not only in tablets for angina, but also in the composition of an explosive substance.
16. Almost all explosives are made with nitrogen.
17. Nitrogen plays an important role in the agricultural sector. Fertilizers are made from it, which in many respects increases the yield.
18. The composition of the thermometer for measuring temperature includes not only mercury, but also nitrogen.
19. The gas in question is not only part of the Earth's atmosphere. Almost all planetary systems contain a large amount of nitrogen.
20. At the beginning of 2017, an embryo was transplanted to a woman in America, which was stored in liquid nitrogen for 24 years. Pregnancy and childbirth were successful.
Further research on nitrogen by specialists is proceeding at a rapid pace. It is possible that in the future, the scope of its application will expand significantly.
Nitrogen / Nitrogenium (N), 7
(molar mass)
A. e.m. (g/mol)
13 (+5e) 171 (-3e) pm
3.04 (Pauling scale)
5, 4, 3, 2, 1, 0, −1, −2, −3
(first electron)
1401.5 (14.53) kJ/mol (eV)
0.808 g/cm³ (−195.8 °C); at n. y. 0.001251 g/cm³
63.29K (-209.86°C)
77.4K (-195.75°C)
(N2) 0.720 kJ/mol
(N2) 5.57 kJ/mol
29.125 (N2 gas) J/(K mol)
17.3 cm³/mol
cubic
(300 K) 0.026 W/(m K)
| 7 | Nitrogen |
| N 14,007 | |
| 2s22p3 | |
Nitrogen- an element of the 15th group (according to the outdated classification - the main subgroup of the fifth group) of the second period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 7. Refers to pnictogens. Indicated by the symbol N(lat. Nitrogenium). simple substance nitrogen- diatomic gas without color, taste and smell. One of the most common elements on earth. It is chemically very inert, but reacts with complex compounds of transition metals. The main component of air (78.09% of the volume), the separation of which produces industrial nitrogen (more than ¾ goes to the synthesis of ammonia). It is used as an inert medium for many technological processes; liquid nitrogen - refrigerant. Nitrogen is one of the main biogenic elements that make up proteins and nucleic acids.
- 1 Discovery history
- 2 Origin of the name
- 3 Nitrogen in nature
- 3.1 Isotopes
- 3.2 Prevalence
- 3.3 Biological role
- 3.4 The nitrogen cycle in nature
- 3.5 Toxicology of nitrogen and its compounds
- 4 Getting
- 5 Properties
- 5.1 Physical properties
- 5.2 Chemical properties, molecular structure
- 5.2.1 Industrial fixation of atmospheric nitrogen
- 6 Nitrogen compounds
- 7 Application
- 8 Cylinder marking
- 9 Interesting Facts
- 10 See also
- 11 Comments
- 12 Notes
- 13 Literature
- 14 Links
Discovery history
In 1772, Henry Cavendish conducted the following experiment: he repeatedly passed air over hot coal, then processed it with alkali, resulting in a residue that Cavendish called suffocating (or mephitic) air. From the standpoint of modern chemistry, it is clear that in the reaction with hot coal, the oxygen of the air was bound into carbon dioxide, which was then absorbed by the alkali. The remainder of the gas was mostly nitrogen. Thus, Cavendish isolated nitrogen, but failed to understand that this is a new simple substance (chemical element). In the same year, Cavendish reported this experience to Joseph Priestley.
An interesting fact is that he managed to bind nitrogen with oxygen using electric current discharges, and after absorbing nitrogen oxides in the residue, he received a small amount of gas, absolutely inert, although, as in the case of nitrogen, he could not understand that he had isolated a new chemical element - inert gas argon.
Priestley at that time conducted a series of experiments in which he also bound the oxygen of the air and removed the resulting carbon dioxide, that is, he also received nitrogen, however, being a supporter of the phlogiston theory prevailing at that time, he completely misinterpreted the results obtained (in his opinion, the process was the opposite - not oxygen was removed from the gas mixture, but, on the contrary, as a result of firing, the air was saturated with phlogiston; he called the remaining air (nitrogen) saturated with phlogiston, that is, phlogistic). It is obvious that Priestley, although he was able to isolate nitrogen, failed to understand the essence of his discovery, and therefore is not considered the discoverer of nitrogen.
Simultaneously, similar experiments with the same result were carried out by Karl Scheele.
In 1772, nitrogen (under the name of “spoiled air”) as a simple substance was described by Daniel Rutherford, he published his master's thesis, where he indicated the main properties of nitrogen (does not react with alkalis, does not support combustion, unsuitable for breathing). It is Daniel Rutherford who is considered the discoverer of nitrogen. However, Rutherford was also a supporter of the phlogiston theory, so he also could not understand what he singled out. Thus, it is impossible to clearly identify the discoverer of nitrogen.
origin of name
The name "nitrogen" (French azote, according to the most common version, from ancient Greek ἄζωτος - lifeless), instead of the previous names ("phlogistic", "mephitic" and "spoiled" air) was proposed in 1787 by Antoine Lavoisier, who at that time, as part of a group of other French scientists, he developed the principles of chemical nomenclature, in the same year this proposal was published in the work "Method of Chemical Nomenclature". As shown above, at that time it was already known that nitrogen does not support combustion or respiration. This property was considered the most important. Although it later turned out that nitrogen, on the contrary, is essential for all living beings, the name has been preserved in French and Russian. Finally, in Russian, this version of the name was fixed after the publication of the book by G. Hess "Fundamentals of Pure Chemistry" in 1831.
There is another version. The word "nitrogen" was not coined by Lavoisier or his colleagues on the nomenclature commission; it entered alchemical literature already in the early Middle Ages and was used to denote the "primary matter of metals", which was considered the "alpha and omega" of all things. This expression is borrowed from the Apocalypse: "I am Alpha and Omega, the beginning and the end" (Rev. 1:8-10). The word is made up of the initial and final letters of the alphabets of three languages - Latin, Greek and Hebrew - considered "sacred", because, according to the Gospels, the inscription on the cross at the crucifixion of Christ was made in these languages (a, alpha, aleph and zet, omega, tav - AAAZOTH). The compilers of the new chemical nomenclature were well aware of the existence of this word; the initiator of its creation Guiton de Morvo noted in his "Methodological Encyclopedia" (1786) the alchemical meaning of the term.
Perhaps the word "nitrogen" came from one of two Arabic words - either from the word "az-zat" ("essence" or "inner reality"), or from the word "zibak" ("mercury").
The name "nitrogen", in addition to French and Russian, is accepted in Italian, Turkish and a number of Slavic languages, as well as in many languages of the peoples of the former USSR.
In Latin, nitrogen is called nitrogenium, that is, "giving birth to saltpeter", hence the symbol N. This name in the French form nitrogène was proposed by the French chemist J. Chaptal in 1790 in his book "Elements of Chemistry", but in French it did not take root, unlike many other languages (in particular, English, Spanish, Hungarian, Norwegian), where the name is derived from this word. the German language uses the name Stickstoff, which means "suffocating substance", similarly in Dutch; names similar in meaning are used in some Slavic languages (for example, Croatian dušik).
nitrogen in nature
isotopes
Main article: Isotopes of nitrogenNatural nitrogen consists of two stable isotopes 14N - 99.635% and 15N - 0.365%.
Fourteen radioactive isotopes of nitrogen with mass numbers from 10 to 13 and from 16 to 25 have been artificially obtained. All of them are very short-lived isotopes. The most stable of them, 13N, has a half-life of 10 minutes.
Spin of nuclei of stable isotopes of nitrogen: 14N - 1; 15N - 1/2.
Prevalence
Nitrogen is one of the most abundant elements on Earth. Outside the Earth, nitrogen is found in gaseous nebulae, the solar atmosphere, on Uranus, Neptune, interstellar space, etc. The atmospheres of the satellites Titan, Triton, and the dwarf planet Pluto also mainly consist of nitrogen. Nitrogen is the fourth most abundant element in the solar system (after hydrogen, helium and oxygen).
Nitrogen in the form of diatomic N2 molecules makes up most of the Earth's atmosphere, where its content is 75.6% (by mass) or 78.084% (by volume), that is, about 3.87 1015 tons.
The mass of nitrogen dissolved in the hydrosphere, taking into account that the processes of atmospheric nitrogen dissolution in water and its release into the atmosphere, are simultaneously taking place, is about 2 1013 tons, in addition, about 7 1011 tons of nitrogen are contained in the hydrosphere in the form of compounds.
Biological role
Nitrogen is a chemical element necessary for the existence of animals and plants, it is part of proteins (16-18% by weight), amino acids, nucleic acids, nucleoproteins, chlorophyll, hemoglobin, etc. The composition of living cells in terms of the number of nitrogen atoms is about 2%, by mass fraction - about 2.5% (fourth place after hydrogen, carbon and oxygen). In connection with this, a significant amount of bound nitrogen is contained in living organisms, "dead organic matter" and dispersed matter of the seas and oceans. This amount is estimated at approximately 1.9 1011 tons. As a result of the processes of decay and decomposition of nitrogen-containing organic matter, subject to favorable environmental factors, natural deposits of minerals containing nitrogen, for example, "Chile nitrate" (sodium nitrate with impurities of other compounds ), Norwegian, Indian saltpeter.
The nitrogen cycle in nature
Main article: nitrogen cycleAtmospheric nitrogen fixation in nature occurs in two main directions - abiogenic and biogenic. The first way involves mainly the reactions of nitrogen with oxygen. Since nitrogen is chemically quite inert, large amounts of energy (high temperatures) are required for oxidation. These conditions are achieved during lightning discharges, when the temperature reaches 25,000 °C or more. In this case, the formation of various nitrogen oxides occurs. There is also a possibility that abiotic fixation occurs as a result of photocatalytic reactions on the surfaces of semiconductors or broadband dielectrics (desert sand).
However, the main part of molecular nitrogen (about 1.4 108 t/year) is fixed biotically. For a long time, it was believed that only a small number of microorganism species (although widely distributed on the Earth’s surface) can bind molecular nitrogen: Azotobacter and Clostridium bacteria, Rhizobium nodule bacteria of leguminous plants, Anabaena, Nostoc cyanobacteria, etc. Now it is known that many other organisms in water and soil, for example, actinomycetes in tubers of alder and other trees (160 species in total). All of them convert molecular nitrogen into ammonium compounds (NH4+). This process requires a significant amount of energy (to fix 1 g of atmospheric nitrogen, bacteria in legume nodules spend about 167.5 kJ, that is, they oxidize about 10 g of glucose). Thus, the mutual benefit of the symbiosis of plants and nitrogen-fixing bacteria is visible - the former provide the latter with a “place to live” and supply the “fuel” obtained as a result of photosynthesis - glucose, the latter provide the nitrogen necessary for plants in the form they assimilate.
Nitrogen in the form of ammonia and ammonium compounds, obtained in the processes of biogenic nitrogen fixation, is rapidly oxidized to nitrates and nitrites (this process is called nitrification). The latter, not bound by plant tissues (and further along the food chain by herbivores and predators), do not remain in the soil for long. Most nitrates and nitrites are highly soluble, so they are washed off by water and eventually enter the oceans (this flow is estimated at 2.5-8·107 t/year).
Nitrogen included in the tissues of plants and animals, after their death, undergoes ammonification (the decomposition of complex compounds containing nitrogen with the release of ammonia and ammonium ions) and denitrification, that is, the release of atomic nitrogen, as well as its oxides. These processes are entirely due to the activity of microorganisms in aerobic and anaerobic conditions.
In the absence of human activity, the processes of nitrogen fixation and nitrification are almost completely balanced by opposite reactions of denitrification. Part of the nitrogen enters the atmosphere from the mantle with volcanic eruptions, part is firmly fixed in soils and clay minerals, in addition, nitrogen is constantly leaking from the upper layers of the atmosphere into interplanetary space.
Toxicology of nitrogen and its compounds
By itself, atmospheric nitrogen is inert enough to have a direct effect on the human body and mammals. However, at elevated pressure, it causes anesthesia, intoxication or suffocation (with a lack of oxygen); with a rapid decrease in pressure, nitrogen causes decompression sickness.
Many nitrogen compounds are very active and often toxic.
Receipt
In laboratories, it can be obtained by the decomposition reaction of ammonium nitrite:
The reaction is exothermic, releasing 80 kcal (335 kJ), so cooling of the vessel is required during its course (although ammonium nitrite is required to start the reaction).
In practice, this reaction is carried out by adding dropwise a saturated solution of sodium nitrite to a heated saturated solution of ammonium sulfate, while the ammonium nitrite formed as a result of the exchange reaction instantly decomposes.
The gas released in this case is contaminated with ammonia, nitric oxide (I) and oxygen, from which it is purified by successively passing through solutions of sulfuric acid, iron (II) sulfate and over hot copper. The nitrogen is then dried.
Another laboratory method for obtaining nitrogen is by heating a mixture of potassium dichromate and ammonium sulfate (in a ratio of 2:1 by weight). The reaction goes according to the equations:
The purest nitrogen can be obtained by decomposition of metal azides:
The so-called "air", or "atmospheric" nitrogen, that is, a mixture of nitrogen with noble gases, is obtained by reacting air with hot coke, and the so-called "generator" or "air" gas is formed - raw materials for chemical synthesis and fuel . If necessary, nitrogen can be separated from it by absorbing carbon monoxide.
Molecular nitrogen is produced industrially by fractional distillation of liquid air. This method can also be used to obtain "atmospheric nitrogen". Nitrogen plants and stations that use the method of adsorption and membrane gas separation are also widely used.
One of the laboratory methods is passing ammonia over copper (II) oxide at a temperature of ~700 °C:
Ammonia is taken from its saturated solution by heating. The amount of CuO is 2 times more than the calculated one. Immediately before use, nitrogen is purified from oxygen and ammonia impurities by passing over copper and its oxide (II) (also ~700 °C), then dried with concentrated sulfuric acid and dry alkali. The process is rather slow, but worth it: the gas is very pure.
Properties
Physical properties
Optical emission spectrum of nitrogenUnder normal conditions, nitrogen is a colorless gas, odorless, slightly soluble in water (2.3 ml/100 g at 0°C, 1.5 ml/100 g at 20°C, 1.1 ml/100 g at 40 °C, 0.5 ml/100 g at 80 °C), density 1.2506 kg/m³ (N.S.).
In a liquid state (boiling point -195.8 ° C) - a colorless, mobile, like water, liquid. The density of liquid nitrogen is 808 kg/m³. Upon contact with air, it absorbs oxygen from it.
At −209.86 °C, nitrogen solidifies as a snow-like mass or large snow-white crystals. Upon contact with air, it absorbs oxygen from it, while melting, forming a solution of oxygen in nitrogen.
Three crystalline modifications of solid nitrogen are known. In the range of 36.61 - 63.29 K, there is a β-N2 phase with hexagonal close packing, space group P63/mmc, lattice parameters a=3.93 Å and c=6.50 Å. At temperatures below 36.61 K, the α-N2 phase with a cubic lattice is stable, having the space group Pa3 or P213 and period a=5.660 Å. Under a pressure of more than 3500 atmospheres and a temperature below 83 K, a hexagonal γ-N2 phase is formed.
Chemical properties, molecular structure
Nitrogen in the free state exists in the form of diatomic molecules N2, the electronic configuration of which is described by the formula σs²σs*2πx, y4σz², which corresponds to a triple bond between nitrogen atoms N≡N (bond length dN≡N = 0.1095 nm). As a result, the nitrogen molecule is extremely strong, for the dissociation reaction N2 ↔ 2N, the enthalpy change in the reaction ΔH°298=945 kJ/mol, the reaction rate constant K298=10−120, that is, the dissociation of nitrogen molecules under normal conditions practically does not occur (the equilibrium is almost completely shifted to the left). The nitrogen molecule is non-polar and weakly polarized, the forces of interaction between molecules are very weak, therefore, under normal conditions, nitrogen is gaseous.
Even at 3000 °C, the degree of thermal dissociation of N2 is only 0.1%, and only at a temperature of about 5000 °C does it reach several percent (at normal pressure). photochemical dissociation of N2 molecules occurs in high layers of the atmosphere. Under laboratory conditions, atomic nitrogen can be obtained by passing gaseous N2 at a strong vacuum through the field of a high-frequency electric discharge. Atomic nitrogen is much more active than molecular nitrogen: in particular, at ordinary temperature it reacts with sulfur, phosphorus, arsenic, and a number of metals, such as mercury.
Due to the high strength of the nitrogen molecule, some of its compounds are endothermic (many halides, azides, oxides), that is, the enthalpy of their formation is positive, and nitrogen compounds are thermally unstable and rather easily decompose when heated. That is why nitrogen on Earth is mostly in a free state.
Due to its significant inertness, nitrogen under normal conditions reacts only with lithium:
when heated, it reacts with some other metals and non-metals, also forming nitrides:
Hydrogen nitride (ammonia) NH3, obtained by the interaction of hydrogen with nitrogen (see below), is of the greatest practical importance.
In an electric discharge, it reacts with oxygen, forming nitric oxide (II) NO.
Several tens of complexes with molecular nitrogen have been described.
Industrial fixation of atmospheric nitrogen
Nitrogen compounds are extremely widely used in chemistry, it is impossible even to list all the areas where substances containing nitrogen are used: this is the industry of fertilizers, explosives, dyes, medicines, and so on. Although colossal amounts of nitrogen are available in the literal sense of the word “from the air”, due to the strength of the nitrogen molecule N2 described above, the problem of obtaining compounds containing nitrogen from the air remained unsolved for a long time; most of the nitrogen compounds were extracted from its minerals, such as Chilean saltpeter. However, the reduction in the reserves of these minerals, as well as the growth in the demand for nitrogen compounds, made it necessary to speed up work on the industrial fixation of atmospheric nitrogen.
The most common ammonia method of binding atmospheric nitrogen. Reversible ammonia synthesis reaction:
exothermic (thermal effect 92 kJ) and goes with a decrease in volume, therefore, in order to shift the equilibrium to the right, in accordance with the Le Chatelier-Brown principle, it is necessary to cool the mixture and high pressures. However, from a kinetic point of view, lowering the temperature is unfavorable, since this greatly reduces the reaction rate - even at 700 °C, the reaction rate is too low for its practical use.
In such cases, catalysis is used, since a suitable catalyst allows the reaction rate to be increased without shifting the equilibrium. in the process of searching for a suitable catalyst, about twenty thousand different compounds were tried. In terms of the combination of properties (catalytic activity, resistance to poisoning, low cost), a catalyst based on metallic iron with impurities of aluminum and potassium oxides has received the greatest use. The process is carried out at a temperature of 400-600 °C and pressures of 10-1000 atmospheres.
It should be noted that at pressures above 2000 atmospheres, the synthesis of ammonia from a mixture of hydrogen and nitrogen proceeds at a high rate and without a catalyst. For example, at 850 °C and 4500 atmospheres, the product yield is 97%.
There is another, less common method of industrial binding of atmospheric nitrogen - the cyanamide method, based on the reaction of calcium carbide with nitrogen at 1000 ° C. The reaction occurs according to the equation:
The reaction is exothermic, its thermal effect is 293 kJ.
Approximately 1 106 tons of nitrogen are taken from the Earth's atmosphere annually by industrial means.
Nitrogen compounds
Nitrogen oxidation states in compounds −3, −2, −1, 0, +1, +2, +3, +4, +5.
- Nitrogen compounds in oxidation state −3 are represented by nitrides, of which ammonia is practically the most important;
- Nitrogen compounds in oxidation state −2 less typical, represented by pernitrides, of which the most important is hydrogen pernitride N2H4 or hydrazine (there is also an extremely unstable hydrogen pernitride N2H2, diimide);
- Nitrogen compounds in oxidation state −1 NH2OH (hydroxylamine) - an unstable base used, along with hydroxylammonium salts, in organic synthesis;
- Nitrogen compounds in oxidation state +1 nitric oxide (I) N2O (nitrous oxide, laughing gas);
- Nitrogen compounds in oxidation state +2 nitric oxide (II) NO (nitrogen monoxide);
- Nitrogen compounds in oxidation state +3 nitric oxide (III) N2O3, nitrous acid, derivatives of the anion NO2−, nitrogen trifluoride (NF3);
- Nitrogen compounds in oxidation state +4 nitric oxide(IV) NO2 (nitrogen dioxide, brown gas);
- Nitrogen compounds in oxidation state +5 nitric oxide (V) N2O5, nitric acid, its salts - nitrates and other derivatives, as well as tetrafluoroammonium NF4+ and its salts.
Application
Low-boiling liquid nitrogen in a metal glass.Liquid nitrogen is used as a refrigerant and for cryotherapy.
Industrial applications of nitrogen gas are due to its inert properties. Gaseous nitrogen is fire and explosion-proof, prevents oxidation, decay. In the petrochemical industry, nitrogen is used to purge tanks and pipelines, test the operation of pipelines under pressure, and increase the production of deposits. In mining, nitrogen can be used to create an explosion-proof environment in mines, to burst rock layers. Nitrogen is used in the electronics industry to purge areas that do not allow the presence of oxidizing oxygen. If oxidation or rotting are negative factors in a process traditionally using air, nitrogen can successfully replace air.
An important field of application of nitrogen is its use for the further synthesis of a wide variety of compounds containing nitrogen, such as ammonia, nitrogen fertilizers, explosives, dyes, etc. More than ¾ of industrial nitrogen is used for the synthesis of ammonia. Large amounts of nitrogen are used in coke production (“dry coke quenching”) when unloading coke from coke oven batteries, as well as for “squeezing” fuel in rockets from tanks to pumps or engines.
In the food industry, nitrogen is registered as a food additive. E941, as a gas medium for packaging and storage, a refrigerant, and liquid nitrogen is used when bottling oils and non-carbonated drinks to create overpressure and an inert atmosphere in soft containers.
Nitrogen gas fills the tire chambers of the landing gear of aircraft. In addition, filling tires with nitrogen has recently become popular among car enthusiasts, although there is no unequivocal evidence of the effectiveness of using nitrogen instead of air to fill car tires.
Liquid nitrogen is often shown in films as a substance that can instantly freeze large enough objects. This is a widespread misconception. Even freezing a flower takes a long time. This is partly due to the very low heat capacity of nitrogen. For the same reason, it is very difficult to cool, say, locks to -196 ° C and crack them with one blow.
A liter of liquid nitrogen, evaporating and heating up to 20 ° C, forms approximately 700 liters of gas. For this reason, liquid nitrogen is stored in special open-type vacuum insulated Dewars or cryogenic pressure vessels. The principle of extinguishing fires with liquid nitrogen is based on the same fact. Evaporating, nitrogen displaces the oxygen necessary for combustion, and the fire stops. Since nitrogen, unlike water, foam or powder, simply evaporates and vanishes, nitrogen fire extinguishing is the most effective fire extinguishing mechanism in terms of the preservation of valuables.
Freezing liquid nitrogen of living beings with the possibility of their subsequent defrosting is problematic. The problem lies in the inability to freeze (and unfreeze) the creature quickly enough that the heterogeneity of freezing does not affect its vital functions. Stanislav Lem, fantasizing about this topic in the book "Fiasco", came up with an emergency nitrogen freezing system, in which a nitrogen hose, knocking out teeth, stuck into the astronaut's mouth and a plentiful flow of nitrogen was supplied into it.
As an alloying addition to silicon, it forms a high-strength compound (ceramic) silicon nitride, which has high viscosity and strength.
Cylinder marking
Main article: Coloring and marking of gas cylindersCylinders with nitrogen are painted black, must have a yellow inscription and a brown strip (according to PB 03-576-03), while GOST 26460-85 does not require a strip, but the inscription must contain information about the purity of nitrogen (special purity, high purity , high purity).
Quote from the Great Soviet Encyclopedia of the 1952 edition (volume 1, p. 452, article "Nitrogen"):
Nitrogen in addition to capitalism is war, destruction, death. Nitrogen combined with socialism means a high harvest, high labor productivity, and a high material and cultural level of the working people.
see also
- Soil nitrogen exchange
- cryogenic cutting
- nitrogen rule
- nitrogen station
- Liquid nitrogen vehicles
In terms of importance for humans and their activities, nitrogen is in third place after oxygen and hydrogen. It cannot be seen if the gas is not frozen or liquefied, however, every year specialists receive several tons of the gas in question and its derivatives. Gas is used in many areas of human activity, from medicine to explosives.
Read some interesting facts about him:
1. Gas was first discovered at the end of 1777 by three chemists - Daniel Rutherford, Henry Cavendish and Joseph Priestley. However, none of them was able to discover the properties of nitrogen, which did not allow it to be fully discovered as a new gas. At first, Priestley thought it was oxygen. Daniel Rutherford consistently discovered the properties of a gas that does not react with other substances and does not burn. That is why it is believed that nitrogen was discovered by this particular scientist.
