Where is nitrogen used? The biological role of nitrogen

17.01.2022

Nitrogen is a gas that is slightly soluble in water and is colorless, odorless and tasteless. In its free form, nitrogen can be used in various industries. Let us consider in more detail those industries where nitrogen is used.

Metallurgy

During annealing, sintering with powdered metal.
With neutral hardening, hard soldering.
When cyanidation (nitrogen is necessary to protect ferrous and non-ferrous metals).
Nitrogen also plays an important role in the operation of the charging device in a blast furnace, a fire cleaning machine for metals.
At the coke plant.

Chemistry, gas, oil

Gaseous nitrogen is used in the development of wells. With its help, the water level in the wells is lowered. This method is very promising, it is characterized by reliability, as well as ease of control and regulation of the process in a wide range of pressures and flow rates. With the help of gaseous nitrogen, deep wells are quickly emptied, fast and sharp, or slow and smooth decrease in pressure in the well. Nitrogen provides reservoir drainage and pressurized gas replenishment, which is necessary for fluid flowing.
Nitrogen is used to create an inert environment in various containers during unloading and loading operations. Nitrogen is also used to extinguish fires, during testing and purging pipelines.
Nitrogen in its pure form is used for the synthesis of ammonia, in the production of nitrogen-type fertilizers, as well as in the processing of associated gases and methane conversion.
Nitrogen is used to reduce deposits in oil refineries, to process high octane components to increase the productivity of oil cracking plants.

Firefighting

Nitrogen has inert properties, due to which it is possible to displace oxygen and prevent the oxidation reaction. Combustion is, in fact, rapid oxidation, due to the presence of oxygen in the atmosphere and a source of combustion, which can be a spark, an electric arc, or simply a chemical reaction with a large amount of heat released. By using nitrogen, this situation can be avoided. If the concentration of nitrogen in the environment is 90%, then ignition will not occur.
Both stationary nitrogen plants and mobile nitrogen production stations can effectively prevent fires. With their help, the source of ignition can also be successfully extinguished.

The medicine

In researches in laboratories, for hospital analyses.

mining industry

In coal mines, nitrogen is also needed for fire fighting.

pharmaceuticals

Nitrogen is used to package, transport and displace oxygen from a variety of product tanks.

food industry

Nitrogen is necessary for transshipment, storage, packaging of food products (especially cheeses and oil and fat products, which are very quickly oxidized by oxygen), to increase their shelf life, and also to preserve the taste of these products.
A mixture of nitrogen and carbon dioxide helps to stop the growth of bacteria.
Nitrogen, creating an inert environment, allows you to protect food from harmful insects.
Nitrogen acts as a diluent to create a gas mixture.

Pulp and paper industry

Nitrogen is used in cathode ray processes on paper, cardboard, and even some wood products to cure varnish coatings. This method allows to reduce the cost of photoinitiators, as well as reduce the emission of volatile compounds and improve the quality of processing.

Thus, there are many industries where nitrogen is used. And all this proves its versatility and relevance.

Nitrogen is a well-known chemical element, which is denoted by the letter N. This element, perhaps, is the basis of inorganic chemistry, it begins to be studied in detail in the 8th grade. In this article, we will consider this chemical element, as well as its properties and types.

The history of the discovery of a chemical element

Nitrogen is an element that was first introduced by the famous French chemist Antoine Lavoisier. But many scientists are fighting for the title of the discoverer of nitrogen, among them Henry Cavendish, Karl Scheele, Daniel Rutherford.

As a result of the experiment, he was the first to single out a chemical element, but did not understand that he received a simple substance. He reported on his experience, which also did a number of studies. Probably, Priestley also managed to isolate this element, but the scientist could not understand what exactly he received, therefore he did not deserve the title of discoverer. Karl Scheele simultaneously conducted the same research, but did not come to the desired conclusion.

In the same year, Daniel Rutherford managed not only to obtain nitrogen, but also to describe it, publish a dissertation and indicate the main chemical properties of the element. But even Rutherford did not fully understand what he had received. However, it is he who is considered the discoverer, because he was closest to the solution.

Origin of the name nitrogen

From the Greek "nitrogen" is translated as "lifeless". It was Lavoisier who worked on the rules of nomenclature and decided to name the element that way. In the 18th century, all that was known about this element was that it did not support either breathing. Therefore, this name was adopted.

In Latin, nitrogen is called "nitrogenium", which means "giving birth to saltpeter". From the Latin language, the designation of nitrogen appeared - the letter N. But the name itself did not take root in many countries.

Element abundance

Nitrogen is perhaps one of the most common elements on our planet, it ranks fourth in abundance. The element is also found in the solar atmosphere, on the planets Uranus and Neptune. The atmospheres of Titan, Pluto and Triton are composed of nitrogen. In addition, the Earth's atmosphere consists of 78-79 percent of this chemical element.

Nitrogen plays an important biological role, because it is necessary for the existence of plants and animals. Even the human body contains 2 to 3 percent of this chemical element. It is part of chlorophyll, amino acids, proteins, nucleic acids.

A liquid nitrogen

Liquid nitrogen is a colorless transparent liquid, it is one of the states of aggregation of chemical nitrogen is widely used in industry, construction and medicine. It is used in the freezing of organic materials, cooling equipment, and in medicine for the removal of warts (aesthetic medicine).

Liquid nitrogen is non-toxic and non-explosive.

Molecular nitrogen

Molecular nitrogen is an element that is contained in the atmosphere of our planet and forms a large part of it. The formula of molecular nitrogen is N 2 . Such nitrogen reacts with other chemical elements or substances only at very high temperatures.

Physical properties

Under normal conditions, the chemical element nitrogen is odorless, colorless, and practically insoluble in water. Liquid nitrogen in its consistency resembles water, it is also transparent and colorless. Nitrogen has another state of aggregation, at temperatures below -210 degrees it turns into a solid, forms many large snow-white crystals. Absorbs oxygen from the air.

Chemical properties

Nitrogen belongs to the group of non-metals and adopts properties from other chemical elements from this group. Generally, non-metals are not good conductors of electricity. Nitrogen forms various oxides, such as NO (monoxide). NO or nitric oxide is a muscle relaxant (a substance that significantly relaxes the muscles and does not have any harm or other effects on the human body). Oxides containing more nitrogen atoms, such as N 2 O, are laughing gas, slightly sweet in taste, which is used in medicine as an anesthetic. However, NO 2 oxide has nothing to do with the first two, because it is a rather harmful exhaust gas that is contained in car exhausts and seriously pollutes the atmosphere.

Nitric acid, which is formed by hydrogen, nitrogen and three oxygen atoms, is a strong acid. It is widely used in the production of fertilizers, jewelry, organic synthesis, the military industry (the production of explosives and the synthesis of poisonous substances), the production of dyes, medicines, etc. Nitric acid is very harmful to the human body, leaving ulcers and chemical burns on the skin.

People mistakenly believe that carbon dioxide is nitrogen. In fact, due to its chemical properties, an element reacts with only a small number of elements under normal conditions. And carbon dioxide is carbon monoxide.

Application of a chemical element

Liquid nitrogen is used in medicine for cold treatment (cryotherapy), as well as in cooking as a refrigerant.

This element has also found wide application in industry. Nitrogen is a gas that is explosion and fire safe. In addition, it prevents rotting and oxidation. Now nitrogen is used in mines to create an explosion-proof environment. Gaseous nitrogen is used in petrochemistry.

In the chemical industry, it is very difficult to do without nitrogen. It is used for the synthesis of various substances and compounds, such as some fertilizers, ammonia, explosives, dyes. Now a large amount of nitrogen is used for the synthesis of ammonia.

In the food industry, this substance is registered as a food additive.

Mixture or pure substance?

Even the scientists of the first half of the 18th century, who managed to isolate the chemical element, thought that nitrogen was a mixture. But there is a big difference between these concepts.

It has a whole complex of constant properties, such as composition, physical and chemical properties. A mixture is a compound that contains two or more chemical elements.

Now we know that nitrogen is a pure substance, since it is a chemical element.

When studying chemistry, it is very important to understand that nitrogen is the basis of all chemistry. It forms various compounds that we all encounter, including laughing gas, brown gas, ammonia, and nitric acid. No wonder chemistry at school begins with the study of such a chemical element as nitrogen.

Nitrogen colorless and non-toxic, odorless and tasteless. Nitrogen exists in nature as a non-flammable gas at normal temperatures and pressures. This gas (nitrogen) is somewhat lighter than air, so its concentration increases with height. When cooled to the boiling point, nitrogen turns into a colorless liquid, which, under certain pressure and temperature, becomes a solid colorless crystalline substance. Nitrogen is slightly soluble in water and most other liquids, and is a poor conductor of electricity and heat.

Most uses of nitrogen are due to its inert properties. However, at high pressures and temperatures nitrogen reacts with some active metals such as lithium and magnesium to form nitrides, and also with some gases such as oxygen and hydrogen.

Basic facts about nitrogen: history of discovery and basic properties

Nitrogen (N2)- one of the most common substances on Earth. The atmosphere of our planet consists of 75% of it, while the proportion of oxygen in it is only 22%.

Oddly enough, scientists did not know about the existence of this gas for a long time. Only in 1772, the English chemist Daniel Rutherford described it as "spoiled air", unable to sustain combustion, not reacting with alkalis and unsuitable for breathing. The very word " nitrogen"(from the Greek -" lifeless ") suggested 15 years later Antoine Lavoisier.

Under normal conditions, it is a colorless, odorless and tasteless gas, heavier than air and practically inert. At a temperature of -195.8 ° C, it passes into a liquid state; at -209.9 ° C - crystallizes, resembling snow.

Nitrogen Applications

Currently, nitrogen found wide application in all spheres of human activity.

Thus, the oil and gas industry uses it to regulate the level and pressure in oil wells, displace oxygen from natural gas storage tanks, purge and test pipelines. The chemical industry needs it for the production of fertilizers and the synthesis of ammonia, metallurgy - for a number of technological processes. Thanks to nitrogen displaces oxygen, but does not support combustion, it is used in fire fighting. In the food industry, packaging products in a nitrogen atmosphere replaces the use of preservatives, prevents the oxidation of fats and the development of microorganisms. In addition, this substance is used in pharmaceuticals to obtain various drugs and in laboratory diagnostics - for a number of tests.

Liquid nitrogen can freeze anything in seconds without the formation of ice crystals. Therefore, doctors use it in cryotherapy to remove dead cells, as well as in the cryopreservation of sperm, eggs and tissue samples.

It's interesting that:

Instant ice cream made with liquid nitrogen was invented in 1998 by biologist Kurt Jones while fooling around with friends in the kitchen. Subsequently, he founded a company for the production of this dessert, which is in demand among American sweet teeth.
The world industry receives 1 million tons of this gas per year from the earth's atmosphere.
A human hand, immersed in a glass of liquid nitrogen for 1-2 seconds, will remain unharmed thanks to the “glove” of gas bubbles that form when the liquid boils at the points of contact with the skin.

Everyone knows that in order for an organism to exist, the presence of oxygen, hydrogen, carbon and nitrogen is necessary. It is clear that nitrogen is one of the main elements in the life of both plants and humans and animals. For plants, the source of nitrogen is naturally the soil. Depending on the type of soil, its “wear and tear”, the amount of nitrogen in it also changes. Most often, nitrogen deficiency is felt by various crops growing on sandy and sandy loamy soils. It is these types of soils that always need additional enrichment with nitrogen fertilizers so that the plants feel normal on them.

Mineral nitrogen-containing fertilizer. © agrihol

It has been established that a significant proportion of nitrogen in the earth is concentrated in its layer, called humus, it contains more than 5% nitrogen. Naturally, the thicker the humus layer, the greater the amount of nitrogen, therefore, plants feel better on such soil.

Humus is a very stable substance, the process of its decomposition is slow, therefore, the release of mineral substances from this layer also occurs rather slowly. Only one percent of the five that is in the soil is a mineral compound that is soluble in water, and therefore available for consumption by plants.

Therefore, even in the presence of a thick layer of humus, additional feeding is necessary for plants, although at lower doses.

Why do plants need nitrogen?

This element, it turns out, is not found in every organic compound. For example, there is no nitrogen in sugars, fiber, oil and starch. There is nitrogen in amino acids and proteins. Nitrogen is an important component of nucleic acid, which is the main component of literally any cell responsible for protein synthesis and duplication of hereditary data (duplication is the formation of additional hereditary material identical to that already in the genome).

Even chlorophyll, which is known to help plants absorb solar energy, also has nitrogen in its composition. In addition, nitrogen is found in various components of the organic environment, for example, in alkaloids, lipoids, and similar substances.

The entire above-ground mass of plants has nitrogen, and most of this element is contained in the very first leaf blades. With the completion of flowering and the beginning of the formation of the ovary, this substance flows to the reproductive organs of plants and accumulates there, forming proteins.

During the period of seed ripening, nitrogen is taken from the vegetative organs in the maximum amount, and they are greatly depleted. If there is a lot of nitrogen in the soil and the plant consumes it in large quantities, then this element will be distributed to almost all organs of the plant, which will lead to a rapid growth of the above-ground mass, delays in the ripening of berries and fruits, and a decrease in the total plant yield.

Only a balanced concentration of nitrogen in the soil can guarantee high yields and sufficient product quality.

Those plants that consume nitrogen in abundance, and not in excess, can fully develop, form standard leaf blades of a typical, often green, color, otherwise they will wither and form mediocre yields.

Corn treated with nitrogen fertilizers (background) and not treated. © Nora Nolden

Varieties of fertilizers containing nitrogen

Nitrogen fertilizers are substances that contain nitrogen compounds. In total there are several main groups of nitrogen fertilizers. These are nitrate fertilizers (calcium and sodium nitrate), ammonium fertilizers (ammonium chloride and ammonium sulfate), ammonium nitrate fertilizers (ammonium nitrate), amide fertilizers (urea), and liquid nitrogen fertilizers (ammonium water or anhydrous ammonium).

Nitrogen fertilizers, nitrate group

Let's start with calcium nitrate, is its chemical formula Ca(NO₃)₂. Externally, calcium nitrate is a snow-white granules, in which nitrogen contains up to 18%. This fertilizer is suitable for soils with high acidity. With the systematic and annual introduction of calcium nitrate into the soil with high acidity, an improvement in its properties is observed. Calcium nitrate is highly soluble in water, so you need to store the fertilizer in bags that do not let water through.

When making calcium nitrate, you need to remember that its mixing with phosphate fertilizers is unacceptable.

The next fertilizer is sodium nitrate, its chemical formula is NaNO₃. This fertilizer is crystalline, it contains a little less - up to 17% nitrogen. Sodium nitrate is highly soluble in water and is perfectly absorbed by plant roots. This fertilizer is universal and suitable for various crops. This fertilizer cannot be applied in the autumn period: the nitrogen contained in it will be actively washed off into groundwater.

Given the excellent solubility in water and hygroscopicity, this fertilizer should be stored in dry places.

Ammonium fertilizers

The next group is ammonium fertilizers. First in this group is ammonium sulfate, its chemical formula is (NH 4) 2 SO 4 . Externally, this fertilizer is a snow-white powder, which contains a little more than 20% nitrogen.

Ammonium sulfate can be used both as a basic nitrogen fertilizer and as an additional top dressing. The introduction of this fertilizer can be carried out in the autumn: nitrogen from it is fixed in the soil, without being washed off into groundwater.

With the annual and systematic application of ammonium sulfate to the soil, soil acidification may occur, for which this fertilizer must be mixed with lime or chalk in a ratio of one to two.

Ammonium sulfate is not hygroscopic, so storage is usually not a problem. The main thing to remember is that this fertilizer cannot be applied in combination with any alkaline top dressing, because there is a risk of suppressing nitrogen activity.

Ammonium chloride, is its chemical formula NH₄Cl. This fertilizer contains about 26% nitrogen. Externally, ammonium chloride is a yellow-white powder. When ammonium chloride is applied, it is not washed out of the soil, this fertilizer does not cake during storage, and even after many years of storage it does not require grinding. Nitrogen released from ammonium chloride into the soil is perfectly absorbed by plants.

The main disadvantage of this fertilizer is the chlorine contained in its composition. So, when 10 kg of nitrogen is added to the soil, in terms of the active substance, about twice as much chlorine gets into the soil, and it is considered poisonous for most plants. Taking this into account, the introduction of ammonium chloride should be carried out exclusively in the autumn period in order to deactivate the chlorine component, but along with this, up to 2% of nitrogen is lost.

Ammonium nitrate fertilizers

The next category is ammonium nitrate fertilizers, the leader in this group is ammonium nitrate. Chemical formula ammonium nitrate looks like this - NH₄NO₃. This fertilizer is in the form of a whitish granular powder. The fertilizer contains about 36% nitrogen. Ammonium nitrate can be used as a basic fertilizer or as an additional top dressing.

This fertilizer is categorized as a non-ballast substance, so its main use falls on regions with a deficit of water moisture. It is noteworthy that on soils with excess moisture, the effectiveness of the use of this fertilizer is reduced to a minimum, since the nitrogen contained in the fertilizer is almost completely washed off into groundwater.

Ammonium nitrate, due to its increased hygroscopicity, does not tolerate storage in damp rooms, where it quickly hardens and cakes. Of course, this does not mean that the fertilizer becomes unusable, just before applying it to the soil, it will be necessary to grind the saltpeter, which is sometimes quite difficult.

In the event that your plans include creating a mixture of ammonium nitrate and phosphate fertilizer, for example, then you should initially mix superphosphate with any neutralizing fertilizer, for example, dolomite flour, chalk or lime, and the next step is to mix it with ammonium nitrate.

Do not forget that the systematic and annual introduction of ammonium nitrate into the soil leads to an increase in its acidity. It is noteworthy that the level of soil acidity increases most actively with time, and at the initial stages of its introduction, the change in acidity is imperceptible.

In order to prevent acidification of the soil, ammonium nitrate must be applied together with chalk, dolomite flour and lime in a ratio of 1 to 2.

Interestingly, at present, pure ammonium nitrate is practically not sold, it is sold in the form of various kinds of mixtures. It is very popular and has good reviews when using a mixture consisting of 60% ammonium nitrate and 40% of various neutralizing components. In this ratio, the mixture contains approximately 19-21% nitrogen.

Nitrogen fertilizer granules - urea. © thechemco

Group - amide fertilizers

Urea, - its chemical formula is CH 4 N 2 O. Urea is called differently - carbamide, this fertilizer is considered one of the most effective. Urea contains about 47% nitrogen, sometimes - 1% less. Outwardly, these are snow-white granules. This fertilizer is characterized by an increased ability to acidify the soil, so it can only be applied with neutralizing substances - dolomite flour, chalk, lime. Urea is rarely used as the main fertilizer, it is usually used as an additional foliar top dressing. This is an excellent foliar fertilizer also because it does not burn leaf blades, but is well absorbed by plants.

In total, two brands of urea are known, which are called - A and B. The brand under the name A does not belong to the category of highly effective and is extremely rarely used in crop production. Typically grade A urea is used for animal feed additives, eg goats, cows, horses. The brand of urea with the name B is urea processed with additives, used specifically as fertilizers.

Liquid nitrogen fertilizers

Ammonia hydrate, or ammonium hydroxide (ammonia water or liquid ammonia). The chemical formula of ammonium hydroxide is NH 4 OH. Essentially, ammonia water is ammonia dissolved in water. In total, there are two types of liquid ammonia, the first contains nitrogen at least 19% and no more than 26%, and the second can contain from 15% nitrogen to 21%. Usually, ammonia water is applied with special equipment capable of planting this fertilizer into the soil to a depth of about 14-16 cm.

The advantages of liquid fertilizers are their extremely low price, fast digestibility by plants, long period of action and even distribution of fertilizers in the soil. There are also disadvantages - this is a rather complicated transportation and storage, the possibility of severe burns on the leaves when fertilizer gets on their surface and the need for special equipment designed for applying liquid fertilizers.

Organic nitrogen fertilizers

As you know, nitrogen is present in organic compounds, but its amount there is small. So, for example, in the litter of cattle, nitrogen is not more than 2.6%. In bird droppings, which is quite toxic, it is up to 2.7%. Nitrogen is also present in the compost, but the amount of nitrogen there, depending on the "ingredients" of the compost, is very different. Most nitrogen in compost prepared from lake silt, leaf litter, green mass of weeds and lowland peat. Given the instability of the nitrogen content in organic fertilizers, its use as the main fertilizer is not desirable and threatens with nutritional deficiency and nitrogen starvation for plants. In addition, such fertilizers, although slowly, but still acidify the soil.

Crops for which nitrogen is especially important

In general, each crop needs nitrogen, however, the application rates for certain crops vary. Given this, all plants can be grouped into categories according to the need for nitrogen.

To the first category you can include plants that need to be fed with nitrogen before planting them in the ground to activate growth and development. For such crops, about 26-28 g of nitrogen are needed per square meter in terms of ammonium nitrate and per square meter of area. This category includes, from vegetable crops: potatoes, cabbage, bell peppers, eggplant, zucchini, pumpkin and rhubarb; from berries and fruits: plum, cherry, raspberry, blackberry and strawberry; from flowers: lilac, rose, dahlia, peony, violet, phlox, balsam, carnation, nasturtium and zinnia.

Second group These are crops that need less nitrogen. Usually only 18-19 g of nitrogen in terms of ammonium nitrate and per square meter of area is sufficient. From vegetable crops, this can include: tomatoes, parsley, cucumber, carrots, corn, beets and garlic; from fruits and berries: apple, currant, gooseberry; from flowers: all annuals and delphiniums.

Third category- these are plants that need nitrogen in moderation, not more than 10-12 g per square meter in terms of ammonium nitrate. From vegetables, this category can include: early ripening potatoes, salad crops, radishes and onions; from fruit - it is a pear; from flowers: bulbous, primrose, adonis, saxifrage and daisy.

Final category requires the introduction of a minimum amount of nitrogen per square meter, not more than 5-6 g in terms of ammonium nitrate. From vegetable crops, spicy herbs and legumes can be included here; from flowers - poppy, azalea, young, heather, stonecrop, erica, purslane, rhododendrons and cosmea.

Rules for the use of nitrogen fertilizers

Remember that only optimal doses of nitrogen fertilizers can positively affect the development and growth of various crops, and you need to be able to calculate top dressing based on the percentage of nitrogen in a particular fertilizer, and also apply them according to soil type, season and plant species.

So, for example, when nitrogen is introduced into the soil in autumn, there is a risk of it being washed off into groundwater. Therefore, the most suitable period for applying fertilizers containing nitrogen is spring.

If you plan to fertilize soils with high acidity, then be sure to mix nitrogen with various components that neutralize the acidifying effect - chalk, lime, dolomite flour. Thus, fertilizers will be absorbed better, and the soil will not acidify.

For residents of the steppe zone and forest-steppe, where the soils are predominantly dry, it is very important to apply nitrogen fertilizers periodically, without abrupt breaks, which can affect plants in the form of delays in growth, development, and a decrease in yield.

The introduction of nitrogen fertilizers into the chernozem soil is best done 11-12 days after the snow melts. It is desirable to carry out the first top dressing using urea, and when the plants enter the active phase of the growing season, add ammonium nitrate.

The consequences of a lack of nitrogen

We have already partially mentioned this, but nitrogen deficiency is not only manifested in growth inhibition. In addition, quite often the leaf blades of plants begin to acquire an atypical color, they turn yellow, and this is the first signal to fertilize. With a strong nitrogen deficiency, in addition to yellowing of the leaf blades, their tips slowly begin to dry out.

Can nitrogen fertilizers be harmful?

Yes, maybe, in case of an overabundance of them. Usually, with an excess of nitrogen, the above-ground mass of plants begins to develop too actively, the shoots thicken, the leaf blades increase, and the internodes become larger. The green mass acquires atypical splendor and softness, and flowering is either weak and short, or does not occur at all, therefore, the ovary does not form and fruits and berries do not form.

If there is a lot of nitrogen, then something like burns appears on the leaf blades, in the future such leaves die off and fall off ahead of time. The death of foliage sometimes leads to partial death of the root system, which is why the introduction of nitrogen must be strictly normalized.

Results. So, we realized that all plants need nitrogen fertilizers, but it is necessary to correctly determine their dosages and apply them in accordance with the recommended terms, relying, among other things, on the properties of the fertilizers themselves.

Nitrogen is a chemical element that is known to everyone. It is denoted by the letter N. It can be said to be the basis of inorganic chemistry, and therefore they begin to study it as early as the eighth grade. In this article, we will take a detailed look at nitrogen, as well as its characteristics and properties.

Element Discovery History

Compounds such as ammonia, nitrate, and nitric acid were known and used in practice long before the production of pure nitrogen in the free state.

During an experiment conducted in 1772, Daniel Rutherford burned phosphorus and other substances in a glass bell. He found that the gas remaining after the combustion of the compounds does not support combustion and respiration, and called it "suffocating air."

In 1787, Antoine Lavoisier established that the gases that make up ordinary air are simple chemical elements, and proposed the name "Nitrogen". A little later (in 1784), physicist Henry Cavendish proved that this substance is part of saltpeter (a group of nitrates). This is where the Latin name for nitrogen comes from (from the late Latin nitrum and the Greek gennao), proposed by J. A. Chaptal in 1790.

By the beginning of the 19th century, scientists had clarified the chemical inertness of the element in the free state and its exceptional role in compounds with other substances. Since that moment, the "binding" of nitrogen in the air has become the most important technical problem in chemistry.

Physical properties

Nitrogen is slightly lighter than air. Its density is 1.2506 kg / m³ (0 ° C, 760 mm Hg), melting point - -209.86 ° C, boiling point - -195.8 ° C. Nitrogen is difficult to liquefy. Its critical temperature is relatively low (-147.1 °C), while the critical pressure is quite high - 3.39 MN/m². Density in the liquid state - 808 kg / m³. In water, this element is less soluble than oxygen: 23.3 g of N can dissolve in 1 m³ (at 0 ° C) of H₂O. This figure is higher when working with some hydrocarbons.

When heated to low temperatures, this element interacts only with active metals. For example, with lithium, calcium, magnesium. With most other substances, nitrogen reacts in the presence of catalysts and/or at high temperatures.

Compounds of N with O₂ (oxygen) N₂O₅, NO, N₂O₃, N₂O, NO₂ have been well studied. Of these, during the interaction of elements (t - 4000 ° C), oxide NO is formed. Further, in the process of cooling, it is oxidized to NO₂. Nitrogen oxides are formed in the air during the passage of atmospheric discharges. They can be obtained by the action of ionizing radiation on a mixture of N and O₂.

When N₂O₃ and N₂O₅ are dissolved in water, respectively, the acids HNO₂ and HNO₂ are obtained, which form salts - nitrates and nitrites. Nitrogen combines with hydrogen exclusively in the presence of catalysts and at high temperatures, forming NH₃ (ammonia). In addition, other (they are quite numerous) compounds of N with H₂ are known, for example, diimide HN = NH, hydrazine H₂N-NH₂, octazone N₈H₁₄, acid HN₃ and others.

It is worth saying that most hydrogen + nitrogen compounds have been isolated exclusively in the form of organic derivatives. This element does not interact (directly) with halogens, so all its halides are obtained only indirectly. For example, NF₃ is formed when ammonia reacts with fluorine.

Most nitrogen halides are low-resistant compounds, oxyhalides are more stable: NOBr, NO₂F, NOF, NOCl, NO₂Cl. Direct connection of N with sulfur also does not occur, N₄S₄ is obtained during the reaction of ammonia + liquid sulfur. During the interaction of red-hot coke with N, cyanogen (CN)₂ is formed. In the process of heating C₂H₂ acetylene with nitrogen to 1500 °C, hydrogen cyanide HCN can be obtained. When N interacts with metals at relatively high temperatures, nitrides are formed (for example, Mg₃N₂).

When ordinary nitrogen is exposed to electrical discharges [at a pressure of 130–270 N/m² (corresponds to 1–2 mmHg)] and during the decomposition of Mg₃N₂, BN, TiNx and Ca₃N₂, as well as during electrical discharges in air, active nitrogen can be formed, with increased energy reserves. It, unlike the molecular one, interacts very vigorously with hydrogen, sulfur vapor, oxygen, some metals and phosphorus.

Nitrogen is part of quite a few important organic compounds, including amino acids, amines, nitro compounds, and others.

Obtaining nitrogen

In the laboratory, this element can be easily obtained by heating a concentrated solution of ammonium nitrite (formula: NH₄NO₂ = N₂ + 2H₂O). The technical method for obtaining N is based on the separation of preliminarily liquefied air, which is subsequently distilled.

Application area

The main part of the free nitrogen obtained is used in the industrial production of ammonia, which is then processed in fairly large quantities into fertilizers, explosives, etc.

In addition to the direct synthesis of NH₃ from elements, the cyanamide method developed at the beginning of the last century is used. It is based on the fact that at t = 1000 °C calcium carbide (formed by heating a mixture of coal and lime in an electric furnace) reacts with free nitrogen (formula: CaC₂ + N₂ = CaCN₂ + C). The resulting calcium cyanamide decomposes into CaCO₃ and 2NH₃ under the action of heated water vapor.

In its free form, this element is used in many industries: as an inert medium in various metallurgical and chemical processes, when pumping flammable liquids, to fill the space in mercury thermometers, etc. In the liquid state, it is used in various refrigeration units. It is transported and stored in steel Dewar vessels, and compressed gas - in cylinders.

Many nitrogen compounds are also widely used. Their production began to develop intensively after the First World War and at the moment has reached a truly enormous scale.

This substance is one of the main biogenic elements and is part of the most important elements of living cells - nucleic acids and proteins. However, the amount of nitrogen in living organisms is small (approximately 1–3% by dry weight). The molecular material present in the atmosphere is assimilated only by blue-green algae and some microorganisms.

Quite large reserves of this substance are concentrated in the soil in the form of various mineral (nitrates, ammonium salts) and organic compounds (in the composition of nucleic acids, proteins and their decay products, including not yet completely decomposed remains of flora and fauna).

Plants perfectly absorb nitrogen from the soil in the form of organic and inorganic compounds. Under natural conditions, special soil microorganisms (ammonifiers), which are able to mineralize soil organic N to ammonium salts, are of great importance.

The nitrate nitrogen of the soil is formed during the vital activity of nitrifying bacteria, discovered by S. Vinogradsky in 1890. They oxidize ammonium salts and ammonia to nitrates. Part of the material assimilated by flora and fauna is lost due to the action of denitrifying bacteria.

Microorganisms and plants perfectly assimilate both nitrate and ammonium N. They actively convert inorganic material into various organic compounds - amino acids and amides (glutamine and asparagine). The latter are part of many proteins of microorganisms, plants and animals. The synthesis of asparagine and glutamine by amidation (enzymatic) of aspartic and glutamic acids is carried out by many representatives of flora and fauna.

The production of amino acids occurs through the reductive amination of a number of keto acids and aldehyde acids, which arise through enzymatic transamination, as well as as a result of the oxidation of various carbohydrates. The end products of the assimilation of ammonia (NH₃) by plants and microorganisms are proteins that are part of the cell nucleus, protoplasm, and are also deposited in the form of so-called storage proteins.

Man and most animals can synthesize amino acids only to a fairly limited extent. They are not able to produce eight essential compounds (lysine, valine, phenylalanine, tryptophan, isoleucine, leucine, methionine, threonine), and therefore the main source of nitrogen for them is the proteins consumed with food, that is, ultimately, the own proteins of microorganisms and plants.