What is the air? Chemical composition of air. What is air? What it consists of - chemical composition. Air on the planet. What pollutes the atmosphere
It can not be touched and can not be seen, but the main thing is what we owe him - life. Of course, this is the air that occupied not the last place in the folklore of every nation. As his people's antiquity presented, and that he actually represents - I will write about it below.
Gases from which air consists
Natural mixture of gases called air. Its necessity and significance for living hard to underestimate - he plays an important role in oxidative processeswhich are accompanied by the allocation necessary for all living energy. By experiments, scientists were able to determine the exact composition, but the main thing is that it is necessary to understand - this is not a homogeneous substance, but a gas mixture. About 99% of the composition - a mixture of oxygen and nitrogen, and in general air forms an atmosphere Our planet. So, the mixture consists of the following gases:
- methane;
- krypton;
- helium;
- xenon;
- hydrogen;
- neon;
- carbon dioxide;
- oxygen;
- nitrogen;
- argon.
It should be noted that the composition is not constant And it can be significantly different in different sections. For example, large cities are distinguished by a large content of carbon dioxide. In the mountains will be observed low oxygen levelSince this gas is heavier than nitrogen, and as the density of it will fall. Science claims that the composition may differ in different parts of the planet from 1% to 4% for each of the gases.
In addition to the percentage of gases, the air is characterized by the following parameters:
- humidity;
- temperature;
- pressure.
Air is constantly in motion, forming vertical streams. Horizontal - winds depend on certain natural conditions, so they can have different characteristics of speed, strength and directions.
Air in folklore
Legends of each nation make air some "alive" qualities. As a rule, spirits of this element were elusive and invisible creatures. According to legends, they inhabited peaks of mountains or clouds, and differed in predisposition to a person. They were, as it was thought worked snowflakes and collected clouds In clouds, flying across the sky in the winds.
The Egyptians considered air symbol of lifeand the Indians believed that overtake Brahma - Life, and inhale, respectively, death. As for Slavs, the air (wind) occupied almost a central place in the legends of this nation. He could hear, and sometimes even to fulfill small requests. However, he was not always kind, sometimes speaking on the side of the power of evil in the form of an evil and unpredictable wanderer.
The composition of the Earth. Air
Air is a mechanical mixture of various gases that make up the Earth's atmosphere. The air is necessary for breathing living organisms, is widely used in industry.
The fact that air is the mixture is precisely a mixture, and not a homogeneous substance, it was proven during the experiments of the Scottish scientist Joseph Blake. During one of them, the scientist found that when heated by white magnesia (carbon dioxide), "bound air" is distinguished, that is, carbon dioxide, and marginal magnesia (magnesium oxide) is formed. When firing limestone, on the contrary, the removal of "related air" occurs. Based on these experiments, the scientist concluded that the difference between carbon dioxide and caustic alkalis lies in the fact that carbon dioxide contains carbon dioxide, which is one of the components of air. Today we know that besides carbon dioxide, the composition of the earth's air includes:
The gasein ratio in the earth's atmosphere specified in the table is characteristic of its lower layers, up to a height of 120 km. In these areas, there is a well mixed, homogeneous area, called homosfer. Above the homosphere is a heterosphere, which is characterized by the decomposition of gases on atoms and ions. Areas are separated from each other by turboauze.
Chemical reaction at which under the influence of solar and cosmic radiation there is a decomposition of molecules to atoms, is called photodissociation. During the decay of molecular oxygen, atomic oxygen is formed, which is the main gas of the atmosphere at the heights of over 200 km. At altitudes from 1200 km, hydrogen and helium begin to prevail, which are the easiest of the gases.
Since the bulk of air is concentrated in 3 lower atmospheric layers, changes in the composition of air at heights of more than 100 km do not have a noticeable effect on the total atmosphere.
Nitrogen is the most common gas, which accounts for more than three quarters of the volume of terrestrial air. Modern nitrogen was formed during the oxidation of the early ammonary-hydrogen atmosphere with molecular oxygen, which is formed during photosynthesis. Currently, a small amount of nitrogen into the atmosphere flows as a result of denitrification - the process of restoring nitrates to nitrites, followed by the formation of gaseous oxides and molecular nitrogen, which is performed by anaerobic prokaryotes. Part of the nitrogen into the atmosphere comes with volcanic eruptions.
In the upper layers of the atmosphere, when exposed to electrical discharges, with the participation of ozone, molecular nitrogen is oxidized to nitrogen monoxide:
N 2 + O 2 → 2NO
Under normal conditions, monoxide immediately reacts with oxygen to form nitrogen oxides:
2NO + O 2 → 2N 2 O
Nitrogen is an essential chemical element of the earth's atmosphere. Nitrogen is part of proteins, provides mineral nutrition of plants. It determines the rate of biochemical reactions, plays the role of oxygen diluent.
The second largest gas atmosphere is oxygen. The formation of this gas is associated with photosynthetic activities of plants and bacteria. And the more diverse and numerous photosynthesising organisms became numerous, the more significant was the process of oxygen content in the atmosphere. A small amount of heavy oxygen is distinguished in the degassing of the mantle.
In the upper layers of the troposphere and stratosphere under the influence of ultraviolet solar radiation (we denote it as hν) Ozone is formed:
O 2 + Hν → 2O
As a result of the action of the same ultraviolet radiation, the disintegration of ozone occurs:
O 3 + Hν → O 2 + O
O 3 + O → 2O 2
As a result of the first reaction, atomic oxygen is formed, as a result of the second - molecular oxygen. All 4 reactions are called "Cepmen mechanism", named British scientist Sydney Chepman who discovered them in 1930.
Oxygen serves to breathe living organisms. With it, the processes of oxidation and burning occur.
Ozone serves to protect the living organisms from ultraviolet radiation, which causes irreversible mutations. The greatest ozone concentration is observed in the lower stratosphere within the same name. The ozone layer or ozone screen lying on the heights of 22-25 km. Ozone content is small: under normal pressure, all ozone of the earth's atmosphere would occupy a layer of only 2.91 mm thick.
The formation of the third prevalence in the argon gas atmosphere, as well as neon, helium, crypton and xenon bind to volcanic eruptions and the decay of radioactive elements.
In particular, helium is a product of radioactive decay of uranium, thorium and radium: 238 U → 234 TH + α, 230 TH → 226 RA + 4 HE, 226 RA → 222 RN + α (in these α-particle reaction is the helium core, which in The process of energy loss captures electrons and becomes 4 He).
The argon is formed in the process of decay of radioactive potassium isotope: 40 K → 40 AR + γ.
Neon disappears from the erupted rocks.
Crypton is formed as a final product of uranium decay (235 U and 238 U) and Thorium TH.
The bulk of atmospheric crypton was formed in the early stages of the Earth's evolution as a result of the decay of transuran elements with a phenomenally small half-life or came from space, the crypton content in which is ten million times higher than on Earth.
Xenon is the result of uranium division, but the bulk of this gas remained from the early stages of the Earth's formation, from the primary atmosphere.
Carbon dioxide enters the atmosphere as a result of volcanic eruptions and in the process of decomposition of organic matter. Its content in the average latitudes of land is very different depending on the seasons of the year: in winter, the amount of CO 2 increases, and in the summer it is reduced. This oscillation is connected with plant activity that use carbon dioxide during photosynthesis.
Hydrogen is formed as a result of water decomposition by solar radiation. But, being the easiest of the gases, which are part of the atmosphere, constantly disappears into outer space, and therefore its content in the atmosphere is very small.
Water steam is the result of evaporation of water from the surface of lakes, rivers, seas and sushi.
The concentration of basic gases in the lower layers of the atmosphere, with the exception of water vapor and carbon dioxide, is constant. In small quantities in the atmosphere, sulfur sulfur SO 2, ammonia NH 3, CO carbon monoxide, ozone O 3, HCl chloride, fluoroporod HF, nitrogen monooxide NO, hydrocarbons, mercury Hg, iodine i 2 and many others. In the lower atmospheric layer, the troposphere constantly contains a large amount of suspended solid and liquid particles.
Sources of solid particles in the Earth's atmosphere are volcanic eruptions, pollen of plants, microorganisms, and recently both human activity, such as burning fossil fuels in the production process. The smallest dust particles that are condensation cores serve as the causes of the formation of fogs and clouds. Without solid particles that are constantly present in the atmosphere, there would be no precipitation on the ground.
The gas composition of atmospheric air is one of the most important indicators of the state of the natural environment. The main gas content near the surface of the Earth in percent is:
· Nitrogen - 78.09%,
· Oxygen - 20.95%,
· Water vapor - 1.6%,
· Argon - 0.93%,
· Carbon dioxide - 0.04% (data is given in terms of normal conditions Tº \u003d 25 ºC, p \u003d 760 mm Hg).
Nitrogen - Gas, which is the main component of the air. In conventional atmospheric pressure and low nitrogen temperatures inert. The dissociation of nitrogen molecules and their disintegration on atomic nitrogen occurs at the heights of more than 200 km.
Oxygen - It is produced by plants in the process of photosynthesis (approximately 100 billion tons annually). During the chemical evolution, one of the earliest major changes was the transition from the rehabilitation atmosphere to the oxidative, in which biological systems began to develop, characterizing today's life on Earth. It has been established that with a decrease in the proportion of oxygen in the composition of the air to 16%, the main natural processes will stop - breathing, burning, rotting.
Carbon dioxide (carbon dioxide) enters the air as a result of fuel combustion processes, respiration, rotting and decomposition of organic substances. The essential accumulation of carbon dioxide in the atmosphere does not occur, as it is absorbed by plants in the process of photosynthesis.
In addition, in the air always contains: neon, helium, methane, crypton, nitrogen oxides, xenon, hydrogen. But these components are contained in quantities that do not exceed the thousands of percent. This composition of atmospheric air can be considered inherent in modern absolutely clean air. However, so it never happens.
Many impurities falling into atmospheric air from various natural and artificial sources in different parts of the Earth with time-changing intensity make up its non-permanent impurities that can be called conditionally pollution .
Among the natural pollution factors allocate :
but) extraterrestrial air pollution with cosmic dust and cosmic radiation;
b) Earthly pollution of the atmosphere when eruption of volcanoes, weathered rocks, dusty storms, forest fires arising from lightning strikes, removal of sea salts.
Conditionally divide the natural contamination of the atmosphere on continental and sea, as well as inorganic and organic.
One of the most constant impurities present in the atmospheric air is suspended particles. They can be both mineral and organic, a significant part of which are pollen and spores of plants, spores of mushrooms, microorganisms. Often, dust is formed by the smallest particles of the soil and, in addition to mineral, contains some organic substances.
With the smoke of forest fires in the air, particles of soot fall, that is, carbon, and non-combustion products of wood, that is, various organic substances, including many phenolic compounds with mutagenic and carcinogenic properties.
Volcanic dust and ash contain a certain amount of soluble potassium salts, calcium, magnesium and other substances important for mineral nutrition of plants. Oxides of sulfur, nitrogen, carbon, as well as chlorine, fall into the atmosphere with volcanic gases. Carbon dioxide enters the atmospheric carbon stock, nitrogen and sulfur oxides are quickly washed with rains and fall on the soil in the form of weak solutions of acids.
The atmospheric air is in constant interaction and metabolism with a stone shell of the Earth - a lithosphere and aqueous shell - hydrosphere. The role of the atmosphere in the cycle of substances causing life on our planet is very high. Whole through the atmosphere passes the cycle of water. The volcanic ashes carrying by the wind enriches the soil by elements of plants mineral nutrition. The carbon dioxide discharged by volcanoes, falling into the atmosphere, is included in the carbon cycle and is absorbed by plants.
Natural sources of atmospheric impurities have always existed. The removal paths for different impurities can be different: dust loss, leaning with precipitations, absorbing by plants or water surface and others. There is a natural equilibrium between the admission of impurities into the atmosphere and its self-cleaning, as a result of which for any substance part of the impurities, you can specify the natural limits of its content in the air, which is called background.
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The atmosphere is an air environment that surrounds the globe and one of the most important reasons for the appearance of life on Earth. It is the atmospheric air, its unique composition gave living beings the opportunity to oxidize organic substances with oxygen and get energy for existence. Without it, the existence of a person will be impossible, as well as all representatives of the kingdom of animals, most plants, fungi and bacteria.
Meaning for man
Air environment is not only an oxygen source. It allows a person to see, perceive spatial signals, use the senses. Rumor, vision, smell - all of them depend on the state of the air.
The second important point is to protect against solar radiation. The atmosphere envelops the planet with a shell, which delays a part of the spectrum of sunlight. As a result, about 30% of solar radiation reaches the Earth.
The air environment is a shell in which precipitates are formed and evaporation rises. It is she who meets half the cycle of moisture exchange. The precipitate formed in the atmosphere affect the work of the World Ocean, contribute to the accumulation of moisture on continents, determine the destruction of open rocks. She takes part in the formation of climate. Air mass circulation is the most important factor in the formation of specific climatic belts and natural zones. Winds arising above the ground determine the temperature, humidity, precipitation level, pressure, weather stability in the region.
Currently, chemicals are produced from the air: oxygen, helium, argon, nitrogen. The technology is still at the testing stage, but in the future this can be considered a promising direction of the chemical industry.
Listed above are obvious things. But the air environment is also important for industry and human economic activities:
- It is an essential chemical agent for the flow of combustion reactions, oxidation.
- Carry heat.
Thus, atmospheric air is a unique air environment that allows living exist, and man is to develop industry. Ground interaction has been established between the human body and the air medium. If you break it - serious consequences will not make yourself wait.
Pollution of the atmosphere is a serious ecological problem of this century. Toxic chemical compounds, organic substances, pathogenic microorganisms - any major emissions into the atmosphere change its composition. She, like any other part of the geographical shell of the Earth, is capable of self-cleaning and self-regulation. The question is when self-cleaning resources are completely depleted.
Gas composition
What gases are part of the atmosphere? The chemical composition of atmospheric air is relatively constant, this is the most important indicator that reflects the state of the environment.
The composition of the atmospheric air includes the following gases:
- Nitrogen - 78%.
- 21% oxygen.
- Water steam - about 1.5%, the indicator strongly depends on the climatic belt and air temperature.
- Just less than 1% of argon.
- 0.04% carbon dioxide
- Ozone.
As well as other gases that are an integral and constant component of atmospheric air. The gas composition of atmospheric air is preserved due to the natural cycle of substances. For human vital activity, oxygen is extremely important, which is formed by plants. So, scientists managed to calculate that the loss of only 3% oxygen could lead to a complete stop of all biological processes on Earth. Ozone is required for dilution of oxygen, as well as it is concentrated in the upper stratospheres, creating an ozone layer that protects the ground from solar radiation.
The atmospheric air also contains carbon dioxide gas (carbon dioxide), which is formed by different paths - with decomposition of organic substances, if the fuel is heated or burns, in the process of respiration of animals and plants. It is absorbed in the main plant - therefore support for sufficient vegetation cover is extremely important for stable atmospheric work.
Constancy
The air environment is capable of self-regulation, that is, to maintaining the constancy of the composition. If her chemical composition had changed - only bacteria remained on Earth. But, fortunately for a person, it can eliminate local pollution.
Self-regulation is due to:
- The precipitation, which falls out in the form of rainwater, make contaminants into the soil.
- Chemical reactions that proceed directly in the air involving oxygen and ozone. These reactions are oxidative.
- Plants that are saturated with oxygen air and absorb carbon dioxide.
However, no self-regulation can eliminate the damage that affixes the industry. Therefore, recently, the sanitary protection of atmospheric air is particularly important.
Hygienic air characteristics
Pollution is the process of entering the atmospheric air of impurities, which should not be normal. Pollution is natural and artificial. Impurities that fall from natural sources are neutralized in the planetary cycle of substances. It is more complicated with artificial pollution.
Natural pollution belongs:
- Cosmic dust.
- Impurities formed by eruption of volcanoes, weathered, fires.
Artificial pollution is anthropogenic. Allocate global pollution and local. Global is all emissions that may affect the composition or structure of the atmosphere. Local is a change in the indicators on a specific territory or used to accommodate, work or public events of the room.
Atmospheric air hygiene is an important section of hygiene, which is evaluating and controlling indoor air indicators. This section appeared in connection with the need for sanitary protection. The hygienic value of atmospheric air is difficult to overestimate - all impurities and particles contained in the air fall into the human body.
Hygienic estimate includes such indicators:
- Physical properties of atmospheric air. This includes temperature (the most frequent violation of Sanpina in the workplace is that the air is too much heated), pressure, wind speed (in open areas), radioactivity, humidity and other indicators.
- The presence of impurities and deviation from the standard chemical composition. Characterize the atmospheric air based on breathing.
- The presence of solid impurities - dust, other microparticles.
- The presence of bacterial contamination is pathogenic and conditionally pathogenic microorganisms.
To compile hygienic characteristics compare the readings obtained in four items with established standards.
Environmental protection
Recently, the condition of atmospheric air is concerned about the ecologists. Along with the development of the industry, environmental risks are growing. Plants and industries not only destroy the ozone layer, heating the atmosphere and saturated with its carbon impurities, but also reduce the hygienic quality of air. Therefore, in developed countries, integrated air protection measures are taken.
The main directions of security:
- Legislative regulation.
- Development of recommendations for the placement of industrial zones, taking into account climatic and geographical factors.
- Conduct activities to reduce the number of emissions.
- Sanitary and hygienic control in enterprises.
- Regular monitoring of the composition.
The protection of green plantings, the creation of artificial reservoirs, the creation of barrier zones between industrial and residential quarters. Recommendations for the conduct of security activities are developed in such organizations such as WHO and UNESCO. State and regional recommendations are developed on the basis of international.
Currently, the problem of air hygiene is paying more attention. Unfortunately, at the moment the measures taken is not enough to completely minimize anthropogenic harm. But it can be hoped that in the future, together with the development of more environmentally friendly industries, it will be possible to reduce the load on the atmosphere.
Children often ask their parents about what the air is usually consisting of. But not every adult can answer correctly. Of course, everyone studied the building of the air in the school in the lessons of environmental education, but over the years these knowledge could forget. We will try to fill them up.
Air is a unique "substance". It can not be seen, touch, he is tasteless. That is why it is so difficult to give a clear definition that it is. Usually just say - air, this is what we breathe. He is around us, although we do not notice it at all. It is possible to feel it only when it blows a strong wind or an unpleasant smell appears.
What will happen if the air disappears? Without a single living organism, no living organism cannot live without it, and therefore all people and animals will die. It does not go around for the respiratory process. It is important how clean and the air is useful to which everything is breathing.
The most useful air is:
- In the forests, especially pine.
- In the mountains.
- Near the sea.
Air in these places is distinguished by a pleasant aroma and has properties useful for the body. This explains why children's wellness camps and various sanatoriums are located near forests, in the mountains or on the sea coast.
Enjoy the fresh air you can only away from the city. For this reason, many people buy summer cottages outside the settlement. Some move to temporary or permanent residence in the village, build there at home. Especially often make families with young children. People are leaving, because the air in the city is strongly polluted.
In the modern world, the problem of environmental pollution is particularly relevant. The work of modern factories, enterprises, nuclear power plants, cars negatively affects nature. They throw out harmful substances that pollute the atmosphere. Therefore, very often people in urban settlements experience a shortage of fresh air, which is very dangerous.
Heavy air inside the poorly ventilated room carries a serious problem, especially if it contains computers and other techniques. Attending in such a place, a person can begin to fall from a lack of air, he has pain in his head, weakness arises.
If you believe the statistics compiled by the World Health Organization, about 7 million human deaths per year are associated with the absorption of polluted air on the street and in closed rooms.
Harmful air is considered one of the main reasons for the occurrence of such a terrible disease as cancer. So argue organizations involved in the study of cancer.
Therefore, it is necessary to take prevention measures.
How to get fresh air?
The person will be healthy if the fresh air can breathe daily. If there is no opportunity to move for the city due to important work, lack of money or for other reasons, then you need to look for a way out of the situation. In order for the body to receive the necessary rate of fresh air, the following rules should be followed:
- It is more likely to be on the street, for example, walking in the evenings in the parks, gardens.
- Leave on weekends for a walk in the forest.
- Constantly air residential and work premises.
- Plant more green plants, especially in working offices, where there are computers.
- It is desirable to visit the resorts located on the sea or in the mountains once a year.
What gas consists of air?
Every day, every second people are inhaling and exhale, absolutely not thinking about the air. People do not react to him, despite the fact that he surrounds them everywhere. Contrary to its weightlessness and invisibility for the human eye, the air has a rather complicated structure. It includes the relationship of several gases:
- Nitrogen.
- Oxygen.
- Argon.
- Carbon dioxide.
- Neon.
- Methane.
- Helium.
- Krypton.
- Hydrogen.
- Xenon.
The main share of air occupies nitrogen , the mass fraction of which is 78 percent. 21 percent of the total number falls on oxygen - the most indispensable gas for human life. The remaining interest occupy other gases and water vapor from which the clouds are formed.
A question may arise why so little oxygen, just a little more than 20%? This gas is reactive. Therefore, with an increase in its share in the atmosphere, the likelihood of fires in the world will increase significantly.
What makes the air that we breathe?
Two main gas that make up the basis of the air that we breathe every day:
- Oxygen.
- Carbon dioxide.
Inhale oxygen, exhaling carbon dioxide. This information knows every schoolboy. But where does oxygen come from? The main source of oxygen production is green plants. They are consumers of carbon dioxide.
It is interesting to the world. In all life processes, the balance of the balance is observed. If somewhere left something, then something came somewhere. So with air. Green plantings produce oxygen necessary to humanity for breathing. People consume oxygen and distinguish carbon dioxide, which, in turn, feed on plants. Thanks to this system of interaction, there is life on the planet Earth.
Knowing, which consists of air, which we breathe, and how strong it is polluted in modern times, you need to take care of the plant world of the planet and do everything possible to increase the representatives of green plants.
