Oxygen in solid form. What is oxygen

Perhaps, among all the known chemical elements, it is oxygen that occupies the leading importance, because without it the emergence of life on our planet would simply be impossible. Oxygen is the most common chemical element on Earth, it accounts for 49% of total mass earth's crust. It is also part of the earth's atmosphere, the composition of water and the composition of more than 1,400 different minerals, such as basalt, marble, silicate, silica, etc. Approximately 50-80% of the total mass of tissues, both animals and plants, consists of oxygen. And, of course, its role in the respiration of all living things is well known.

History of the discovery of oxygen

People did not immediately understand the nature of oxygen, although the first guesses that air was based on a certain chemical element appeared back in the 8th century. However, at that distant time there were neither suitable technical tools for studying it, nor the ability to prove the existence of oxygen as a gas, which is also responsible for combustion processes.

The discovery of oxygen took place only a millennium later, in the 18th century, thanks to working together several scientists.

In 1771, the Swedish chemist Karl Scheele experimentally studied the composition of air and determined that air consists of two main gases: one of these gases was nitrogen, and the second was oxygen itself, although at that time the very name “oxygen” had not yet appeared in science .
In 1775, the French scientist A. Louvasier gave the name to the gas discovered by Scheele - oxygen, also known as oxygen in Latin, the word “oxygen” itself means “producing acids.”
A year before the official “birthday of oxygen,” in 1774, the English chemist Priestley obtained pure oxygen for the first time through the decomposition of mercury oxide. His experiments supported Scheele's discovery. By the way, Scheele himself also tried to get oxygen in pure form by heating saltpeter, but he did not succeed.
More than centuries later, in 1898, English physicist Joseph Thompson first made the public think that oxygen supplies could run out due to intense emissions. carbon dioxide into the atmosphere.
In the same year, Russian biologist Kliment Timiryazev, a researcher, discovered the ability of plants to release oxygen.

Although plants release oxygen into the atmosphere, the problem posed by Thompson about a possible lack of oxygen in the future remains relevant in our time, especially in connection with intensive deforestation (oxygen suppliers), pollution environment, waste incineration, etc. We wrote more about this in our previous article. environmental problems modernity.

The importance of oxygen in nature

It was the presence of oxygen, in combination with water, that led to the emergence of life on our planet. As we noted above, the main suppliers of this unique gas are various plants, including greatest number of the oxygen released comes from underwater algae. Some types of bacteria also produce oxygen. Oxygen in upper layers The atmosphere forms an ozone ball, which protects all inhabitants of the Earth from harmful ultraviolet radiation from the sun.

The structure of the oxygen molecule

The oxygen molecule consists of two atoms, chemical formula has the form O 2. How is an oxygen molecule formed? The mechanism of its formation is non-polar, in other words, due to the sharing of an electron in each atom. The bond between oxygen molecules is also covalent and non-polar, while it is double, because each of the oxygen atoms has two unpaired electrons at the outer level.

This is what an oxygen molecule looks like; due to its characteristics, it is very stable. For many, its participation requires special conditions: heating, high blood pressure, the use of catalysts.

Physical properties of oxygen

First of all, oxygen is a gas that makes up 21% of air.
Oxygen has no color, no taste, no smell.
Can dissolve in organic matter ah, absorbed by coal and powders.
- The boiling point of oxygen is -183 C.
The oxygen density is 0.0014 g/cm3

Chemical properties of oxygen

Main chemical property oxygen is, of course, its combustion support. That is, in a vacuum, where there is no oxygen, fire is not possible. If you lower a smoldering splinter into pure oxygen, it will light up with renewed vigor. Combustion different substances This is a redox chemical process in which the role of the oxidizing agent is oxygen. Oxidizing agents are substances that “take away” electrons from reducing substances. The excellent oxidizing properties of oxygen are due to its outer electron shell.

The valence shell of oxygen is located close to the nucleus and, as a result, the nucleus attracts electrons to itself. Oxygen also ranks second after fluorine on the Pauling electronegativity scale, for this reason, entering into chemical reactions with all other elements (except fluorine), oxygen acts as a negative oxidizing agent. And only by reacting with fluorine does oxygen have a positive oxidative effect.

And since oxygen is the second most powerful oxidizing agent among all the chemical elements of the periodic table, this also determines its chemical properties.

Obtaining oxygen

To obtain oxygen in laboratory conditions, the method is used heat treatment or peroxides or salts of acidic acids. When exposed to high temperatures, they decompose releasing pure oxygen. Oxygen can also be obtained using hydrogen peroxide; even a 3% solution of peroxide instantly decomposes under the action of the catalyst, releasing oxygen.

2KC l O 3 = 2KC l + 3O 2 - this is what the chemical reaction for producing oxygen looks like.

Also in industry, as another method of producing oxygen, electrolysis of water is used, during which water molecules are decomposed, and again pure oxygen is released.

Use of oxygen in industry

In industry, oxygen is actively used in such areas as:

Metallurgy (for welding and cutting metals).
Medicine.
Agriculture.
How propellant.
For purification and disinfection of water.
Synthesis of certain chemical compounds, including explosives.

Oxygen, video

And finally, an educational video about oxygen.

Omnipresent, omnipotent and invisible - that's all about him. It also has no taste or smell. It seems that the conversation is about something that does not exist at all. However, this substance exists, and what’s more: without it, humanity would simply suffocate. That’s probably why Lavoisier immediately called this gas “life gas.”

Oxygen almighty

According to religious people, only God can be omnipresent, omnipotent and at the same time invisible. In fact, all three of these epithets can be attributed to the chemical element with atomic number 8 - oxygen. If plants, during the process of photosynthesis, did not convert water and carbon dioxide into organic compounds, and this process was not accompanied by the release of bound oxygen, then, having exhausted the reserves quite quickly atmospheric oxygen, all fauna, including humanity, would soon suffocate.

Oxygen is omnipresent: not only air, water and earth are largely composed of it, but also you and me, our food, drink, clothing; The vast majority of substances around us contain oxygen. The power of oxygen is already manifested in the fact that we breathe it, and breathing is synonymous with life. And oxygen can also be considered omnipotent because the mighty element of fire, as a rule, strongly depends on our candidate for omnipresence and omnipotence.

As for the third epithet - “invisible”, there is probably no need for proof. Under normal conditions, elemental oxygen is not only colorless and therefore invisible, but also not perceivable or perceptible by any sense organs. True, we would immediately feel the lack, and especially the absence of oxygen...

Discovery: 18th century

The fact that oxygen is invisible, tasteless, odorless, and gaseous under normal conditions delayed its discovery for a long time. Many scientists in the past guessed that there was a substance with properties that we now know are inherent in oxygen.

Opening oxygen (English oxygen, French oxygen, German Sauerstoff) marked the beginning modern period development of chemistry. It has been known since ancient times that combustion requires air, but for many centuries the combustion process remained unclear. Only in the 17th century. Mayow and Boyle independently expressed the idea that the air contains some substance that supports combustion.

Oxygen was discovered almost simultaneously and independently of each other by two outstanding chemists of the second half of the 18th century - the Swede Karl Wilhelm Scheele and the Englishman Joseph Priestley. Scheele received oxygen earlier, but his treatise “On Air and Fire,” which contained information about oxygen, was published later than the message about Priestley’s discovery.

Joseph
Priestley

“On August 1, 1774, I tried to extract air from mercury scale and found that the air could easily be expelled from it by means of a lens. This air was not absorbed by the water. Imagine my amazement when I discovered that the candle was burning in this air with an unusually bright flame. I tried in vain to find an explanation for this phenomenon.”

And yet the main figure in the history of the discovery of oxygen is not Scheele or Priestley. They discovered a new gas - and that’s all. Later, Friedrich Engels would write about this: “Both of them never knew what was in their hands. The element that was destined to revolutionize chemistry disappeared without a trace in their hands... Therefore, it is Lavoisier who actually discovered oxygen, and not the two who only described oxygen, without even knowing what they were describing.”

A detailed study of the properties of oxygen and its role in the processes of combustion and the formation of oxides led Lavoisier to the incorrect conclusion that this gas is an acid-forming principle. In 1779 Lavoisier introduced the name for oxygen Oxygenium(from Greek“oxide” - “sour” and “gennao” - giving birth) - “giving birth to acids”.

"Oxidizing" element

Oxygen is a colorless (blue in a thick layer) gas without taste or smell. It is slightly heavier than air and slightly soluble in water. When cooled to -183°C, oxygen turns into a mobile liquid blue color, and at -219°C it freezes.

As befits an element occupying a place in the upper right corner of the periodic table, oxygen is one of the most active non-metal elements and has pronounced oxidizing properties. So to speak, there is only one element more oxidizing than oxygen, fluorine. That is why tanks with liquid oxygen are a necessary accessory for most liquid rocket engines. A combination of oxygen has been obtained even with such a chemically passive gas as xenon.

For the development of an active reaction of oxygen with most simple and complex substances heat is needed to overcome the potential barrier to the chemical process. With the help of catalysts that reduce the activation energy, processes can proceed without heating, in particular, the combination of oxygen with hydrogen.

The high oxidizing power of oxygen underlies the combustion of all types of fuel, including gunpowder, for which combustion does not require atmospheric oxygen: during the combustion of such substances, oxygen is released from them.

Slow oxidation processes various substances at ordinary temperatures are no less important for life than combustion is for energy.

The slow oxidation of food substances in our body is the “energy base” of life. Let us note in passing that our body does not use inhaled oxygen very economically: exhaled air contains approximately 16% oxygen. The heat of rotting hay is the result of the slow oxidation of organic matter. plant origin. The slow oxidation of manure and humus warms the greenhouses.

Application: “sea of energy”

Oxygen is used in medical practice, and not only for pulmonary and heart diseases, when breathing is difficult. Subcutaneous administration of oxygen has proven to be an effective treatment for such serious diseases as gangrene, thrombophlebitis, elephantiasis, and trophic ulcers.

It is no less important for industry. Enriching the air with oxygen makes many more efficient, faster, and more economical technological processes, which are based on oxidation. And so far almost everything is based on such processes thermal energy. Turning iron into steel is also impossible without oxygen. It is oxygen that “removes” excess carbon from cast iron. At the same time, the quality of the steel improves. Need oxygen and non-ferrous metallurgy. Liquid oxygen serves rocket fuel oxidizer.

When hydrogen is burned in a stream of oxygen, a very ordinary substance is formed - H 2 O. Of course, in order to obtain this substance one should not burn hydrogen (which, by the way, is often obtained from water). The purpose of this process is different; it will be clear if the same reaction is written down in full, taking into account not only the chemical products, but also the energy released during the reaction: H 2 +0.5O 2 = H 2 O + 68317 calories.

Almost seventy large calories per gram molecule! This way you can get not only a “sea of water”, but also a “sea of energy”. This is why they get water from jet engines, operating on hydrogen and oxygen.

The same reaction is used for welding and cutting metals. True, in this area hydrogen can be replaced with acetylene. By the way, acetylene is produced on a large scale precisely with the help of oxygen, in the processes of thermal oxidative cracking: 6CH 4 + 4O 2 = C 2 H 2 + 8H 2 + 3SO + CO 2 + 3H 2 O.

This is just one example use of oxygen in chemical industry. Oxygen is needed for the production of many substances (just remember nitric acid), for gasification of coal, oil, fuel oil...

Any porous flammable substance, for example, sawdust, when saturated with a bluish cold liquid - liquid oxygen, becomes an explosive. Such substances are called oxyliquits and, if necessary, can replace dynamite when developing ore deposits.

Annual global production (and consumption) of oxygen is measured in millions of tons. Not counting the oxygen we breathe.

Oxygen production

Attempts to create a more or less powerful oxygen industry were made back in the last century in many countries. But from the idea to the technical implementation there is often a “huge distance”...

Particularly rapid development of the oxygen industry began after the invention of a turboexpander by Academician P.L. Kapitsa and the creation of powerful air separation plants.

The easiest way to get oxygen is from air, since air is not a compound and it is not that difficult to separate air. The boiling points of nitrogen and oxygen differ (at atmospheric pressure) by 12.8°C. Consequently, liquid air can be divided into components in distillation columns in the same way as, for example, oil is divided. But to turn air into liquid, it must be cooled to minus 196°C. We can say that the problem of obtaining oxygen is the problem of obtaining cold.

To obtain cold using ordinary air, the latter must be compressed, and then allowed to expand and at the same time forced to produce mechanical work. Then, in accordance with the laws of physics, the air must cool. The machines in which this occurs are called expanders.

To obtain liquid air using piston expanders, pressures of about 200 atmospheres were needed. The efficiency of the installation was slightly higher than that of a steam engine. The installation turned out to be complex, cumbersome, and expensive. At the end of the thirties, the Soviet physicist Academician P.L. Kapitsa proposed using a turbine as an expander. Main feature Kapitsa turboexpander is that the air in it expands not only in the nozzle apparatus, but also on the impeller blades. In this case, the gas moves from the periphery of the wheel to the center, working against centrifugal forces.

A turboexpander “makes” cold using air compressed to just a few atmospheres. The energy given off by the expanding air is not wasted; it is used to rotate the generator rotor electric current.

Modern air separation plants, in which cold is produced using turboexpanders, provide industry, primarily metallurgy and chemistry, with hundreds of thousands of cubic meters of oxygen gas.

Among all the substances on Earth special place occupies what provides life - oxygen gas. It is its presence that makes our planet unique among all others, special. Thanks to this substance, so many beautiful creatures live in the world: plants, animals, people. Oxygen is an absolutely irreplaceable, unique and extremely important compound. Therefore, we will try to find out what it is, what characteristics it has.

The first method is especially often used. After all, a lot of this gas can be released from the air. However, it will not be completely clean. If a product is needed more high quality, then electrolysis processes are put into action. The raw material for this is either water or alkali. Sodium or potassium hydroxide is used to increase the electrical conductivity of the solution. In general, the essence of the process comes down to the decomposition of water.

Obtained in the laboratory

Among laboratory methods, the heat treatment method has become widespread:

peroxides;
salts of oxygen-containing acids.

At high temperatures they decompose releasing oxygen gas. The process is most often catalyzed by manganese (IV) oxide. Oxygen is collected by displacing water, and discovered by a smoldering splinter. As you know, in an oxygen atmosphere, a flame burns very brightly.

Another substance used to produce oxygen in school lessons chemistry - hydrogen peroxide. Even a 3% solution under the influence of a catalyst instantly decomposes, releasing pure gas. You just need to have time to collect it. The catalyst is the same - manganese oxide MnO 2.

The most commonly used salts are:

Berthollet's salt, or potassium chlorate;
potassium permanganate, or potassium permanganate.

An equation can be used to describe the process. Enough oxygen is released for laboratory and research needs:

2KClO 3 = 2KCl + 3O 2.

Allotropic modifications of oxygen

There is one allotropic modification that oxygen has. The formula of this compound is O 3, it is called ozone. This is a gas that is formed in natural conditions when exposed to ultraviolet radiation and lightning discharges on air oxygen. Unlike O2 itself, ozone has a pleasant smell of freshness, which is felt in the air after rain with lightning and thunder.

The difference between oxygen and ozone lies not only in the number of atoms in the molecule, but also in the structure of the crystal lattice. Chemically, ozone is an even stronger oxidizing agent.

Oxygen is a component of air

The distribution of oxygen in nature is very wide. Oxygen is found in:

rocks and minerals;
salt and fresh water;
soil;
plant and animal organisms;
air, including the upper layers of the atmosphere.

It is obvious that all the shells of the Earth are occupied by it - the lithosphere, hydrosphere, atmosphere and biosphere. Its content in the air is especially important. After all, it is this factor that allows us to exist on our planet. life forms, including humans.

The composition of the air we breathe is extremely heterogeneous. It includes both constant components and variables. The unchanging and always present include:

carbon dioxide;
oxygen;
nitrogen;
noble gases.

Variables include water vapor, dust particles, foreign gases (exhaust, combustion products, rotting and others), plant pollen, bacteria, fungi and others.

The importance of oxygen in nature

It is very important how much oxygen is found in nature. After all, it is known that on some satellites major planets(Jupiter, Saturn) trace amounts of this gas have been discovered, but there is no obvious life there. Our Earth has a sufficient amount of it, which, in combination with water, makes it possible for all living organisms to exist.

In addition to being an active participant in respiration, oxygen also carries out countless oxidation reactions, which release energy for life.

The main suppliers of this unique gas in nature are green plants and some types of bacteria. Thanks to them, a constant balance of oxygen and carbon dioxide is maintained. In addition, ozone builds a protective screen over the entire Earth, which does not allow penetration a large number destructive ultraviolet radiation.

Only some types of anaerobic organisms (bacteria, fungi) are able to live outside of an oxygen atmosphere. However, there are far fewer of them than those who really need it.

Use of oxygen and ozone in industry

The main areas of use of allotropic modifications of oxygen in industry are as follows.

Metallurgy (for welding and cutting metals).
Medicine.
Agriculture.
As rocket fuel.
Synthesis of many chemical compounds, including explosives.
Water purification and disinfection.

It is difficult to name at least one process in which this great gas, a unique substance - oxygen, does not take part.

Lump in throat is oxygen. It was found that in a state of stress, the glottis widens. It is located in the middle of the larynx, limited by 2 muscle folds.

They put pressure on nearby tissues, creating the sensation of a lump in the throat. The widening of the gap is a consequence of increased oxygen consumption. It helps cope with stress. So, the notorious lump in the throat can be called oxygen.

The 8th element of the table is familiar in the form. But it can also be liquid oxygen. Element In this state it is magnetic. However, we’ll talk about the properties of oxygen and the advantages that can be extracted from them in the main part.

Properties of oxygen

Due to magnetic properties oxygen is moved using powerful. If we talk about an element in its usual state, it itself is capable of moving, in particular, electrons.

Actually, the respiratory system is built on the redox potential of a substance. Oxygen in it is the final acceptor, that is, the receiving agent.

Enzymes act as donors. Substances oxidized by oxygen are released into external environment. This is carbon dioxide. It produces from 5 to 18 liters per hour.

Another 50 grams of water comes out. So drinking plenty of fluids is a reasonable recommendation from doctors. Plus, about 400 substances are by-products of respiration. Among them is acetone. Its secretion increases in a number of diseases, for example, diabetes.

The breathing process involves the usual modification of oxygen – O 2 . This is a diatomic molecule. It has 2 unpaired electrons. Both are in antibonding orbitals.

They have a greater energy charge than the binders. Therefore, the oxygen molecule easily breaks down into atoms. The dissociation energy reaches almost 500 kilojoules per mole.

In natural conditions oxygen – gas with almost inert molecules. They have a strong interatomic bond. Oxidation processes occur barely noticeably. Catalysts are needed to speed up reactions. In the body they are enzymes. They provoke the formation of radicals, which initiate the chain process.

Catalyst chemical reactions with oxygen the temperature may rise. The 8th element reacts even to slight heating. Heat reacts with hydrogen, methane and other flammable gases.

Interactions occur with explosions. It’s not for nothing that one of the first airships in human history exploded. It was filled with hydrogen. The aircraft was called the Hindenburg and crashed in 1937.

Heating allows oxygen to form bonds with all elements of the periodic table except the noble gases, that is, argon, neon and helium. By the way, helium has become a replacement for filling airships.

The gas does not react, but it is expensive. But, let's return to the hero of the article. Oxygen is a chemical element, interacting with metals already at room temperature.

It is also sufficient for contact with some complex compounds. The latter include nitrogen oxides. But with simple nitrogen chemical element oxygen reacts only at 1,200 degrees Celsius.

For reactions of the hero of the article with non-metals, heating is required to at least 60 degrees Celsius. This is enough, for example, for contact with phosphorus. The hero of the article interacts with sulfur already at 250 degrees. By the way, sulfur is included in oxygen subgroup elements. She is the main one in the 6th group of the periodic table.

Oxygen interacts with carbon at 700-800 degrees Celsius. This refers to the oxidation of graphite. This mineral is one of the crystalline forms of carbon.

By the way, oxidation is the role of oxygen in any reaction. Most of them occur with the release of light and heat. Simply put, the interaction of substances leads to combustion.

The biological activity of oxygen is due to its solubility in water. At room temperature, 3 milliliters of the 8th substance dissociate in it. The calculation is based on 100 milliliters of water.

The element shows high levels in ethanol and acetone. 22 grams of oxygen dissolve in them. The maximum dissociation is observed in liquids containing fluorine, for example, perfluorobutytetrahydrofuran. Almost 50 grams of the 8th element are dissolved per 100 milliliters of it.

Speaking about dissolved oxygen, let's mention its isotopes. Atmospheric is number 160. There is 99.7% of it in the air. 0.3% are isotopes 170 and 180. Their molecules are heavier.

By contacting them, water hardly turns into a vapor state. So only the 160th modification of the 8th element rises into the air. Heavy isotopes remain in the seas and oceans.

Interestingly, in addition to gaseous and liquid states, oxygen can be solid. It, like the liquid version, is formed at sub-zero temperatures. Watery oxygen requires -182 degrees, and rock oxygen requires a minimum of -223.

The latter temperature produces a cubic crystal lattice. From -229 to -249 degrees Celsius, the crystal structure of oxygen is already hexagonal. Other modifications have also been obtained artificially. But, in addition to lower temperatures, they require increased pressure.

In a normal state oxygen belongs to the elements with 2 atoms, colorless and odorless. However, there is a 3-atomic variety of the hero of the article. This is ozone.

It has a distinctly fresh aroma. It's pleasant, but toxic. The difference from ordinary oxygen is also the large mass of molecules. Atoms come together during lightning discharges.

Therefore, the smell of ozone is felt after rainstorms. The aroma is also felt at high altitudes of 10-30 kilometers. There, the formation of ozone is provoked by ultraviolet radiation. Oxygen atoms capture radiation from the sun, combining into large molecules. This, in fact, protects humanity from radiation.

Oxygen production

Industrialists extract the hero of the article out of thin air. It is cleaned of water vapor, carbon monoxide and dust. Then, the air is liquefied. After cleaning, only nitrogen and oxygen remain. The first evaporates at -192 degrees.

Oxygen remains. But, Russian scientists discovered a storehouse of an already liquefied element. It is located in the Earth's mantle. It is also called the geosphere. The layer is located under the solid crust of the planet and above its core.

Install there oxygen element sign The laser press helped. We worked with him at the DESY synchrotron center. It is located in Germany. The research was carried out jointly with German scientists. Together, they calculated that the oxygen content in the supposed layer of mania is 8-10 times higher than in the atmosphere.

Let us clarify the practice of calculating deep oxygen rivers. Physicists worked with iron oxide. By squeezing and heating it, scientists obtained new metal oxides, previously unknown.

When it came to thousand-degree temperatures and pressure 670,000 times higher than atmospheric pressure, the compound Fe 25 O 32 was obtained. The conditions of the middle layers of the geosphere are described.

The oxide transformation reaction occurs with a global release of oxygen. It should be assumed that this is also happening inside the planet. Iron is a typical element for the mantle.

Combination of element with oxygen also typical. An atypical version is that atmospheric gas leaked from underground over millions of years and accumulated at its surface.

To put it bluntly, scientists have questioned the dominant role of plants in the production of oxygen. Greens may only provide some of the gas. In this case, you need to be afraid not only of the destruction of flora, but also of the cooling of the planet’s core.

A decrease in mantle temperature can block the formation process oxygen. Mass fraction its presence in the atmosphere will also decline, and at the same time life on the planet.

The question of how to extract oxygen from mania is not worth it. It is impossible to drill into the earth to a depth of more than 7,000-8,000 kilometers. All we have to do is wait until the hero of the article reaches the surface himself and extracts him from the atmosphere.

Application of oxygen

The active use of oxygen in industry began with the invention of turboexpanders. They appeared in the middle of the last century. The devices liquefy the air and separate it. Actually, these are production installations oxygen.

What elements is it formed by? the “social circle” of the hero of the article? Firstly, these are metals. It's not about direct interaction, but about the melting of elements. Oxygen is added to burners to burn fuel as efficiently as possible.

As a result, metals soften faster, mixing into alloys. For example, the convection method of steel production cannot do without oxygen. Ordinary air is ineffective as ignition. Metal cutting cannot do without liquefied gas in cylinders.

Oxygen as a chemical element was discovered and farmers. In liquefied form, the substance ends up in cocktails for animals. They are actively gaining weight. The connection between oxygen and the mass of animals can be traced in Carboniferous period development of the Earth.

The era is marked by a hot climate, an abundance of plants, and therefore the 8th gas. As a result, centipedes 3 meters long crawled around the planet. Insect fossils have been found. The scheme also works in modern times. Give the animal a constant supplement to the usual portion of oxygen, and you will get an increase in biological mass.

Doctors stock oxygen in cylinders to relieve, that is, stop asthma attacks. Gas is also needed to eliminate hypoxia. This is what is called oxygen starvation. The 8th element also helps with ailments of the gastrointestinal tract.

In this case, oxygen cocktails become the medicine. In other cases, the substance is given to patients in rubberized cushions, or through special tubes and masks.

In the chemical industry, the hero of the article is an oxidizing agent. Reactions in which the 8th element may participate have already been discussed. Characteristics of oxygen positively considered, for example, in rocket science.

The hero of the article was chosen as the oxidizer of ship fuel. The most powerful oxidizing mixture is the combination of both modifications of the 8th element. That is, rocket fuel interacts with ordinary oxygen and ozone.

Oxygen price

The hero of the article is sold in cylinders. They provide element connection. With oxygen You can purchase cylinders of 5, 10, 20, 40, 50 liters. In general, the standard step between container volumes is 5-10 liters. The price range for the 40-liter version, for example, is from 3,000 to 8,500 rubles.

Next to high price tags, as a rule, there is an indication of the compliance with GOST. His number is “949-73”. In advertisements with the budget cost of cylinders, GOST is rarely stated, which is alarming.

Transportation of oxygen in cylinders

Philosophically speaking, oxygen is priceless. The element is the basis of life. Iron transports oxygen throughout the human body. A bunch of elements is called hemoglobin. Its deficiency is anemia.

The disease has serious consequences. The first of them is a decrease in immunity. Interestingly, in some animals, oxygen in the blood is not carried by iron. In horseshoe crabs, for example, copper delivers the 8th element to the organs.

The processes of combustion and respiration have long attracted the attention of scientists. The first indications that not all the air, but only the “active” part of it supports combustion, were found in Chinese manuscripts of the 8th century. Much later, Leonardo da Vinci considered air as a mixture of two gases, only one of which is consumed during combustion and respiration. The final discovery of the two main components air - nitrogen and oxygen, which made an era in science, occurred only at the end of the 18th century. Oxygen was obtained almost simultaneously by K. Scheele (1769-70) by calcining saltpeter (KNO3, NaNO3), manganese dioxide MnO2 and other substances and J. Priestley (1774) by heating red lead Pb3O4 and mercuric oxide HgO. In 1772, D. Rutherford discovered nitrogen. In 1775, A. Lavoisier, having produced quantitative analysis air, found that it “consists of two gases of different and, so to speak, opposite nature,” that is, oxygen and nitrogen. Based on extensive experimental research, Lavoisier correctly explained combustion and respiration as processes of interaction of substances with oxygen. Since oxygen is part of acids, Lavoisier called it oxygene, that is, “acid-forming” (from the Greek oxys - sour and gennao - I give birth; hence Russian name"oxygen").

Oxygen is a chemically active non-metal and is the lightest element from the group of chalcogens. The simple substance oxygen normal conditions- a colorless, tasteless and odorless gas, the molecule of which consists of two oxygen atoms (formula O2), for which reason it is also called dioxygen. Liquid oxygen is light blue in color, while solid oxygen is light blue crystals. There are other allotropic forms of oxygen, for example, ozone - under normal conditions, a blue gas with a specific odor, the molecule of which consists of three oxygen atoms (formula O3).

Atomic number 8

Atomic mass 15.999

Density, kg/m³ 1.429

Melting point, °C -218.8

Boiling point, °C -183

Heat capacity, kJ/(kg °C) 0.913

Electronegativity 3.5

Oxygen is the most common element on Earth; its share (in various compounds, mainly silicates) accounts for about 47.4% of the mass of the solid earth's crust. Marine and fresh waters contain a huge amount of bound oxygen - 88.8% (by mass), in the atmosphere the content of free oxygen is 20.95% by volume and 23.12% by mass. More than 1,500 compounds in the earth's crust contain oxygen. Oxygen is part of many organic substances and is present in all living cells. In terms of the number of atoms in living cells, it is about 25%, according to mass fraction- about 65%.

The role of free oxygen in biochemical and physiological processes, especially in respiration, is extremely important. With the exception of some anaerobic microorganisms, all animals and plants obtain the energy necessary for life through the biological oxidation of various substances with the help of oxygen. The entire mass of free oxygen on the Earth arose and is preserved thanks to the vital activity of green plants on land and the world's oceans, which release oxygen during the process of photosynthesis. On earth's surface where photosynthesis occurs and free oxygen predominates, sharply oxidizing conditions are formed. On the contrary, in magma, as well as deep horizons groundwater, in the silts of seas and lakes, in swamps, where there is no free oxygen, a reducing environment is formed. Redox processes involving oxygen determine the concentration of many elements and the formation of mineral deposits - coal, oil, sulfur, iron ores, copper, etc.

Oxygen forms chemical compounds with all elements except light inert gases. Being the most active (after fluorine) non-metal, oxygen reacts directly with most elements; exceptions are heavy inert gases, halogens, gold and platinum; their connections with oxygen are obtained indirectly. Almost all reactions of oxygen with other substances - oxidation reactions - are exothermic, that is, they are accompanied by the release of energy.

There are 3 main ways of producing oxygen: chemical, electrolysis (electrolysis of water) and physical (separation of air).

The chemical method was invented earlier than others. Oxygen can be obtained, for example, from berthollet salt KClO3, which decomposes when heated, releasing O2 in the amount of 0.27 m3 per 1 kg of salt. Barium oxide BaO, when heated to 540°C, first absorbs oxygen from the air, forming BaO2 peroxide, and upon subsequent heating to 870°C, BaO2 decomposes, releasing pure oxygen. It can also be obtained from KMnO4, Ca2PbO4, K2Cr2O7 and other substances by heating and adding catalysts. The chemical method of producing oxygen is low-productivity and expensive, has no industrial significance and is used only in laboratory practice.

The electrolysis method consists of passing a direct electric current through water, to which a NaOH solution has been added to increase its electrical conductivity. In this case, water decomposes into oxygen and hydrogen. Oxygen collects near the positive electrode of the electrolyzer, and hydrogen collects near the negative electrode. In this way, oxygen is produced as a by-product of hydrogen production.

Air separation is the main way to obtain oxygen in modern technology. It is very difficult to separate air in its normal gaseous state, so the air is first liquefied and then separated into its component parts. This method of producing oxygen is called air separation using the deep cooling method. First, the air is compressed by a compressor, then, after passing through heat exchangers, it expands in an expander machine or throttle valve, as a result of which it is cooled to a temperature of 93 K (-180 ° C) and turns into liquid air. Further separation of liquid air, consisting mainly of liquid nitrogen and liquid oxygen, is based on the difference in boiling point of its components. With the gradual evaporation of liquid air, mainly nitrogen is evaporated first, and the remaining liquid is increasingly enriched with oxygen. By repeating a similar process many times on the distillation trays of air separation columns, liquid oxygen of the required purity (concentration) is obtained.

Gaseous oxygen is stored and transported in steel cylinders and receivers at a pressure of 15 and 42 Mn/m2 (150 and 420 bar, respectively, or 150 and 420 atm), liquid oxygen - in metal Dewar vessels or in special tank tanks. Special pipelines are also used to transport liquid and gaseous oxygen. Oxygen cylinders are painted blue and have the word “oxygen” written in black.

Technical oxygen is used in the processes of gas-flame processing of metals, in welding, oxygen cutting, surface hardening, metallization and others, as well as in aviation, on submarines, etc. Technological oxygen is used in the chemical industry to produce artificial liquid fuel, lubricating oils, nitric and sulfuric acids, methanol, ammonia and ammonia fertilizers, metal peroxides and other chemical products. Liquid oxygen is used in blasting operations, in jet engines and in laboratory practice as a coolant.

Pure oxygen contained in cylinders is used for breathing at high altitudes, at space flights, when diving, etc. In medicine, oxygen is given for inhalation to seriously ill patients, used for preparing oxygen, water and air (in oxygen tents) baths, for intramuscular administration, etc.

Oxygen is widely used in metallurgy to intensify a number of pyrometallurgical processes. The complete or partial replacement of air entering metallurgical units with oxygen changed the chemistry of the processes, their thermal parameters and technical and economic indicators. Oxygen blast made it possible to reduce heat losses with exhaust gases, a significant part of which was nitrogen during air blast. Without taking a significant part in chemical processes, nitrogen slowed down the course of reactions, reducing the concentration of active reagents in the redox environment. When blowing with oxygen, fuel consumption is reduced, the quality of the metal is improved, in metallurgical units it is possible to obtain new types of products (for example, slags and gases of an unusual composition for a given process, which find special technical applications), etc.