Air is necessary for all living organisms: animals for breathing, and plants - for food. In addition, the air protects against the damaging ultraviolet radiation of the sun. The main components of air are nitrogen and oxygen. In the air there are also small impurities of noble gases, carbon dioxide and a certain amount of solid particles - soot, dust. Air is needed by all animals for breathing. About 21% of the air is oxygen. An oxygen molecule (O 2) consists of two linked oxygen atoms.

Air composition

The percentage of different gases in the air varies slightly depending on the place, time of year and day. Nitrogen and oxygen are the main components of air. One percent of the air is noble gases, carbon dioxide, water vapor, and pollution, such as nitrogen dioxide. Air gases can be separated by fractional distillation. The air is cooled until the gases become liquid (see the article “Solids, liquids and gases”). After that, the liquid mixture is heated. The boiling point of each liquid is different, and the gases formed during boiling can be collected separately. Oxygen, nitrogen and carbon dioxide constantly get from living air into living organisms and return to the air, i.e. there is a cycle. Animals breathe oxygen in the air and exhale carbon dioxide.

Oxygen

Nitrogen

More than 78% of the air is nitrogen. The proteins from which living organisms are built also contain nitrogen. The main industrial use of nitrogen is ammonia productionrequired for fertilizer. Nitrogen for this purpose is combined with hydrogen. Nitrogen is pumped into packages for meat or fish, because upon contact with ordinary air, products are oxidized and deteriorate. Human organs intended for transplantation are stored in liquid nitrogen because it is cold and chemically inert. The nitrogen molecule (N 2) consists of two linked nitrogen atoms.

Noble gases

Noble gases are 6 elements of the 8th group of the periodic table. They are extremely inert chemically. Only they exist in the form of individual atoms that do not form molecules. Because of their passivity, some of them are filled with lamps. Xenon is practically not used by humans, but argon is pumped into light bulbs, and fluorescent lamps are filled with krypton. Neon flashes red-orange light when passing an electrical discharge. It is used in sodium street lamps and neon lamps. Radon is radioactive. It is formed as a result of the decay of radium metal. No helium compounds are known to science, and helium is considered completely inert. Its density is 7 times less than the density of air, so they fill the airships. Balloons filled with helium are equipped with scientific equipment and launched into the upper atmosphere.

Greenhouse effect

This is the name of the present increase in carbon dioxide in the atmosphere and the resulting global warmingi.e. increase in average annual temperatures throughout the world. Carbon dioxide does not allow heat to leave the Earth, just as glass keeps high inside the greenhouse. As the carbon dioxide in the air becomes more and more, more and more heat is trapped in the atmosphere. Even a slight warming causes an increase in the level of the World Ocean, a change in the winds and the melting of a piece of ice at the poles. Scientists believe that if the carbon dioxide content grows just as quickly, then in 50 years the average temperature may increase by an amount from 1.5 ° C to 4 ° C.

We will make a reservation at once, nitrogen occupies a large part in the air, however, the chemical composition of the remaining fraction is very interesting and diverse. In short, the list of basic elements is as follows.

However, we will give a small explanation of the functions of these chemical elements.

1. Nitrogen

The nitrogen content in the air is 78% by volume and 75% by weight, that is, this element dominates in the atmosphere, has the title of one of the most common on Earth, and, moreover, is also contained outside the human habitat zone - Uranus, Neptune and in interstellar spaces. So, how much nitrogen in the air, we have already figured out, the question remains about its function. Nitrogen is necessary for the existence of living beings, it is part of:

• proteins;
• amino acids;
• nucleic acids;
• chlorophyll;
• hemoglobin and others

On average, about 2% of a living cell is just nitrogen atoms, which explains why so much nitrogen in the air is in percent of volume and mass.
Nitrogen is also one of the inert gases produced from atmospheric air. Ammonia is synthesized from it, used for cooling and for other purposes.

2. Oxygen

The oxygen content in the air is one of the most popular questions. Keeping the intrigue, let us digress for one funny fact: oxygen was opened twice - in 1771 and 1774, but because of the difference in the discovery publications, the English chemist Joseph Priestley, who in fact gave oxygen to the second, got the honors of opening the element. So, the proportion of oxygen in the air varies around 21% by volume and 23% by weight. Together with nitrogen, these two gases form 99% of all terrestrial air. However, the percentage of oxygen in the air is less than nitrogen, and at the same time we have no breathing problems. The fact is that the amount of oxygen in the air is optimally calculated precisely for normal breathing, in its pure form this gas acts on the body like poison, leads to difficulties in the nervous system, respiratory and circulatory failures. At the same time, the lack of oxygen also adversely affects health, causing oxygen starvation and all the unpleasant symptoms associated with it. Therefore, how much oxygen is in the air is needed for healthy full breathing.

3. Argon

Argon is third in the air; it is odorless, colorless and tasteless. No significant biological role of this gas has been identified, but it has a narcotic effect and is even considered doping. Argon extracted from the atmosphere is used in industry, medicine, to create an artificial atmosphere, chemical synthesis, fire extinguishing, creating lasers, etc.

4. Carbon dioxide

Carbon dioxide is the atmosphere of Venus and Mars, its percentage in the terrestrial air is much lower. At the same time, a huge amount of carbon dioxide is contained in the ocean, it is regularly supplied by all breathing organisms, and is released due to the work of industry. In human life, carbon dioxide is used in fire fighting, the food industry as a gas and as a food additive E290 - a preservative and baking powder. In solid form, carbon dioxide is one of the most well-known “dry ice” refrigerants.

5. Neon

The same mysterious light of disco lanterns, bright signs and modern lights use the fifth most common chemical element that a person also breathes - neon. Like many inert gases, neon has a narcotic effect on humans at a certain pressure, but it is this gas that is used in the preparation of divers and other people working at elevated pressure. Also, neon-helium mixtures are used in medicine for respiratory disorders, neon itself is used for cooling, in the production of signal lights and those same neon lamps. However, contrary to stereotype, neon light is not blue, but red. All other colors give lamps with other gases.

6. Methane

Methane and air have a very ancient history: in the primary atmosphere, even before the advent of man, methane was in much larger quantities. Now this gas, extracted and used as fuel and raw materials in production, is not so widespread in the atmosphere, but is still emitted from the Earth. Modern research establishes the role of methane in the respiration and vital functions of the human body, however, there is no authoritative data on this subject yet.

7. Helium

After seeing how much helium is in the air, anyone will understand that this gas is not among the most important ones. Indeed, it is difficult to determine the biological value of this gas. Apart from the amusing distortion of voice when helium is inhaled from a balloon 🙂 However, helium is widely used in industry: in metallurgy, food industry, for filling aeronautical vessels and meteorological probes, in lasers, nuclear reactors, etc.

8. Krypton

This is not about the birthplace of Superman. Тон Krypton is an inert gas that is three times heavier than air, chemically inert, is extracted from the air, is used in incandescent lamps, lasers, and is still being actively studied. Of the interesting properties of krypton, it is worth noting that at a pressure of 3.5 atmospheres, it has a narcotic effect on humans, and at 6 atmospheres it acquires a strong odor.

9. Hydrogen

Hydrogen in the air is 0.00005% by volume and 0.00008% by weight, but it is this that is the most common element in the Universe. It is quite possible to write a separate article about its history, production and use, so now we confine ourselves to a small list of industries: chemical, fuel, food industry, aviation, meteorology, electric power industry.

10. Xenon

The latter is composed of air, which was originally considered to be only an admixture to krypton. Its name translates as “alien”, and the percentage of content both on Earth and beyond its limits is minimal, which determined its high cost. Now, xenon does not do without: the production of powerful and pulsed light sources, diagnostics and anesthesia in medicine, spacecraft engines, rocket fuel. In addition, when inhaled, xenon significantly lowers the voice (the opposite effect of helium), and more recently, the inhalation of this gas is counted as a dope list.

That part of the atmosphere, which is adjacent to the Earth and which man breathes accordingly, is called the troposphere. The troposphere has a height of nine to eleven kilometers and is a mechanical mixture of various gases.

The composition of the air does not possess constancy. Depending on the geographical location, terrain, weather conditions, the air may have different composition and different properties. The air can be gassed or discharged, fresh or heavy - all this means that it contains certain impurities.

Nitrogen — 78.9 percent;

Oxygen - 20.95 percent;

Carbon dioxide - 0.3 percent.

In addition, in the atmosphere there are other gases (helium, argon, neon, xenon, krypton, hydrogen, radon, ozone), as well as their sum is slightly less than one percent.

It is also worth pointing to the presence in the air of some permanent impurities of natural origin, in particular, some gaseous products, which are formed as a result of both biological and chemical processes. Ammonia deserves a special mention among them (the air composition far from populated areas includes about three to five thousandths of a milligram per cubic meter), methane (its level is on average two to ten thousandths of a milligram per cubic meter), nitrogen oxides (in the atmosphere their concentration reaches approximately fifteen ten-thousandths of a milligram per cubic meter), hydrogen sulfide and other gaseous products.

In addition to vaporous and gaseous impurities, the chemical composition of air usually includes dust of cosmic origin, which falls to the surface of the Earth in the amount of seven hundred thousand tons per square kilometer during the year, as well as dust particles that come during volcanic eruptions.

However, the air composition changes most of all (and not for the better) and the so-called ground (plant, soil) dust and forest fire smoke pollutes the troposphere. Especially a lot of such dust in the continental air masses, originating in the deserts of Central Asia and Africa. That is why it can be said with confidence that there is simply no perfectly clean air environment, and it is a concept that exists only theoretically.

The composition of air tends to change constantly, and its natural changes usually play a fairly small role, especially in comparison with the possible consequences of its artificial disturbances. Such violations are mainly associated with the production activities of mankind, the use of devices for consumer services, as well as vehicles. These violations can lead to air denaturation, that is, to pronounced differences in its composition and properties from the corresponding indicators of the atmosphere.

These and many other types of human activity led to the fact that the basic composition of the air began to undergo slow and insignificant, but nonetheless absolutely irreversible changes. For example, scientists have calculated that over the past fifty years, mankind has used about as much oxygen as the previous million years, and as a percentage - two tenths of a percent of its total stock in the atmosphere. At the same time, emissions to air will increase accordingly. According to the latest data, this emission has reached almost four hundred billion tons over the past hundred years.

Thus, the composition of the air is changing for the worse, and it is difficult to guess what it will become in a few decades.

It is known that air for the most part consists of nitrogen. The amount of nitrogen in the air  is about 75.6% by weight and 78% by volume. Nitrogen is needed to maintain the plant and animal life. Any living thing needs nitrogen. Nitrogen is present in the composition of proteins, which, in turn, are an indispensable material in the composition of the human body. Without this substance, tissue regeneration, wound healing is impossible, growth is impossible.

The amount of nitrogen in the air  if calculated per kilometer the square surface of the Earth is approximately 12,500,000 tons.

Nitrogen is a colorless gas, odorless and tasteless. It dissolves very badly in water. Under conditions of high pressure or too low a temperature, nitrogen becomes liquid. Under normal conditions of atmospheric pressure, the nitrogen is converted into a liquid with a temperature of -210 ° C.

On the one hand, this amount of nitrogen in the air should be sufficient for plants and living beings. But in fact, only plants of the legume family in nature can absorb nitrogen from the air. Other living organisms, like humans, do not have the ability to assimilate pure nitrogen. In order to recreate the required amount of nitrogen, a person must consume protein foods that are prepared from certain types of herbivores or plants.

When breathing, we breathe a certain amount of nitrogen in the air. However, unlike oxygen, nitrogen cannot be absorbed by the human lungs, and the gas simply goes out of them. But the presence of nitrogen in the atmosphere contributes to the fact that there is no oversaturation of oxygen. Since an excess of oxygen is as dangerous for a person as a lack.

Other living things absorb nitrogen as compounds with other elements. Plants get nitrogen from the soil, and animals from other animals, or from plants.

It is very difficult for nitrogen to interact with other elements. For example, oxygen with nitrogen in nature can react when lightning flashes in a thunderstorm. Due to the fact that these flashes create exceptional heat.

NITROGEN IN AIR

Despite the translation of the meaning of the word nitrogen (and it means “azoos” in Greek. - lifeless), this element is very important in the life of a person and the world around him. The chemical element nitrogen, the sign - N, with the seventh ordinal number, belongs to the V group of the periodic table. It has a relative atomic mass. Nitrogen in the air  is a gas without color, odorless and tasteless.

Nitrogen in the air and nature

Nitrogen gas is very common among other elements on Earth, its main mass - approximately 4 x 1015 tons is in the free composition of the atmosphere. In the form of N2 molecules, nitrogen in air is by volume 78.09%, by mass - 75.6% without taking into account the impurity in the form of oxides and ammonia. Natural compounds are various nitrates and ammonium chloride. The dry desert climate is characterized by large accumulations of nitrate. A considerable amount of time saltpeter was the main producer of industrial nitrogen. Today, the main importance in the binding of nitrogen accounts for the synthesis of ammonia in industrial conditions from hydrogen and air. In the seas, oceans, rivers contain a very small amount of fixed nitrogen. It contains a little oil (content of about 0.02 - 1.5%) and coal (1 - 2.5%). The accumulation of nitrogen occurs in the soil and in living organisms.

Nitrogen in the airabsolutely necessary element, as included in its composition. Due to its inertia, nitrogen reacts with oxygen and prevents oxidation. For these properties, nitrogen is popular in the use of the fields of the metallurgical chemical and petrochemical industry, medicine, fire fighting.

When it is required to provide large enterprises with gaseous nitrogen in the quantity that is required, for you a modular nitrogen station.

The chemical composition of air is of important hygienic importance, since it plays a crucial role in the implementation of the respiratory function of the body. Atmospheric air is a mixture of oxygen, carbon dioxide, argon and other gases in the ratios given in table. one.

Oxygen (O 2) - the most important component of air for a person. At rest, a person usually absorbs an average of 0.3 liters of oxygen per minute.

During physical activity, oxygen consumption increases dramatically and can reach 4.5 / 5 liters or more per minute. Oxygen fluctuations in atmospheric air are small and do not exceed, as a rule, 0.5%.

In residential, public and sports facilities significant changes in the oxygen content is not observed, because they penetrate the outside air. Under the most unfavorable hygienic conditions in the room, a decrease in the oxygen content by 1% was noted. Such fluctuations do not have a noticeable effect on the body.

Usually, physiological changes are observed when the oxygen content decreases to 16-17%. If its content is reduced to 11 -13% (when climbing to a height), there is a pronounced oxygen deficiency, a sharp deterioration in health and a decrease in efficiency. An oxygen content of up to 7-8% can be fatal.

In sports practice in order to improve the efficiency and intensity of recovery processes, inhalation of oxygen is used.

Carbon dioxide (CO 2), or carbon dioxide, is a colorless, odorless gas formed during the breathing of people and animals, decay and decomposition of organic substances, fuel combustion, etc. In atmospheric air outside human settlements, carbon dioxide is on average 0.04% and in industrial centers, its concentration rises to 0.05-0.06%. In residential and public buildings, when there is a large number of people in them, the carbon dioxide content can increase to 0.6-0.8%. Under the worst hygienic conditions in the room (large crowds of people, poor ventilation, etc.), its concentration usually does not exceed 1% due to the penetration of outside air. Such concentrations do not cause negative effects in the body.

With prolonged inhalation of air with a content of 1 - 1.5% carbon dioxide, the state of health is worsened, and at 2-2.5%, pathological changes are detected. Significant dysfunctions of the body and decreased performance occur when the carbon dioxide content is 4-5%. With the content of 8-10% loss of consciousness and death occurs. A significant increase in carbon dioxide in the air can occur in emergency situations in confined spaces (mines, mines, submarines, bomb shelters, etc.) or in those places where intensive decomposition of organic substances occurs.

Determination of carbon dioxide content in residential, public and sports facilities can serve as an indirect indicator of air pollution from waste products of people. As already noted, carbon dioxide in itself does not harm the body in these cases, but along with an increase in its content, there is a deterioration in the physical and chemical properties of air (temperature and humidity increase, disturbed, ionic composition, foul-smelling gases appear). Indoor air is considered to be of poor quality if the content of carbon dioxide in it exceeds 0.1%. This value is taken as a calculation for the design and ventilation of the premises.