Report on the topic oxygen. Chemical and physical properties, application and production of oxygen

Oxygen is a chemical element of group VI of the periodic table of Mendeleev and the most common element in the earth’s crust (47% of its mass). Oxygen is a vital element in almost all living organisms. Read more about the functions and uses of oxygen in this article.

General information

Oxygen is a colorless, tasteless and odorless gas that is poorly soluble in water. It is part of water, minerals, and rocks. Free oxygen is formed through the processes of photosynthesis. Oxygen plays the most important role in human life. First of all, oxygen is necessary for the respiration of living organisms. It also takes part in the decomposition processes of dead animals and plants.

Air contains about 20.95% oxygen by volume. The hydrosphere contains almost 86% oxygen by mass.

Oxygen was obtained simultaneously by two scientists, but they did it independently of each other. The Swede K. Scheele obtained oxygen by calcining saltpeter and other substances, and the Englishman J. Priestley obtained oxygen by heating mercury oxide.

Rice. 1. Obtaining oxygen from mercury oxide

Use of oxygen in industry

The areas of application of oxygen are vast.

In metallurgy, it is necessary for the production of steel, which is obtained from scrap metal and cast iron. In many metallurgical units, oxygen-enriched air is used for better combustion of fuel.

In aviation, oxygen is used as a fuel oxidizer in rocket engines. It is also necessary for flights into space and in conditions where there is no atmosphere.

In the field of mechanical engineering, oxygen is very important for cutting and welding metals. To melt metal you need a special burner consisting of metal pipes. These two pipes are inserted into each other. The free space between them is filled with acetylene and ignited. At this time, oxygen is released through the inner tube. Both oxygen and acetylene are supplied from a pressurized cylinder. A flame is formed, the temperature of which reaches 2000 degrees. Almost any metal melts at this temperature.

Rice. 2. Acetylene torch

The use of oxygen in the pulp and paper industry is very important. It is used for bleaching paper, for alcoholization, and for washing out excess components from cellulose (delignification).

In the chemical industry, oxygen is used as a reagent.

Liquid oxygen is needed to create explosives. Liquid oxygen is produced by liquefying air and then separating the oxygen from the nitrogen.

The use of oxygen in nature and human life

Oxygen plays the most important role in the life of humans and animals. Free oxygen exists on our planet thanks to photosynthesis. Photosynthesis is the process of formation of organic matter in light with the help of carbon dioxide and water. As a result of this process, oxygen is produced, which is necessary for the life of animals and humans. Animals and humans constantly consume oxygen, but plants consume oxygen only at night and produce it during the day.

Use of oxygen in medicine

Oxygen is also used in medicine. Its use is especially important for difficulty breathing during certain diseases. It is used to enrich the airways in pulmonary tuberculosis, and is also used in anesthesia equipment. Oxygen in medicine is used to treat bronchial asthma and diseases of the gastrointestinal tract. For these purposes, oxygen cocktails are used.

Also of great importance are oxygen cushions - a rubberized container filled with oxygen. It is used for individual use of medical oxygen.

Four “chalcogen” elements (i.e., “giving birth to copper”) lead the main subgroup of group VI (according to the new classification - the 16th group) of the periodic system. In addition to sulfur, tellurium and selenium, these also include oxygen. Let's take a closer look at the properties of this element, the most common on Earth, as well as the use and production of oxygen.

Element prevalence

In bound form, oxygen is included in the chemical composition of water - its percentage is about 89%, as well as in the composition of the cells of all living beings - plants and animals.

In the air, oxygen is in a free state in the form of O2, occupying a fifth of its composition, and in the form of ozone - O3.

Physical properties

Oxygen O2 is a gas that is colorless, tasteless and odorless. Slightly soluble in water. The boiling point is 183 degrees below zero Celsius. In liquid form, oxygen is blue, and in solid form it forms blue crystals. The melting point of oxygen crystals is 218.7 degrees below zero Celsius.

Chemical properties

When heated, this element reacts with many simple substances, both metals and non-metals, forming so-called oxides - compounds of elements with oxygen. in which elements enter with oxygen is called oxidation.

For example,

4Na + O2= 2Na2O

2. Through the decomposition of hydrogen peroxide when it is heated in the presence of manganese oxide, which acts as a catalyst.

3. Through the decomposition of potassium permanganate.

Oxygen is produced in industry in the following ways:

1. For technical purposes, oxygen is obtained from air, in which its usual content is about 20%, i.e. fifth part. To do this, the air is first burned, producing a mixture containing about 54% liquid oxygen, 44% liquid nitrogen and 2% liquid argon. These gases are then separated using a distillation process, using the relatively small range between the boiling points of liquid oxygen and liquid nitrogen - minus 183 and minus 198.5 degrees, respectively. It turns out that nitrogen evaporates earlier than oxygen.

Modern equipment ensures the production of oxygen of any degree of purity. Nitrogen, which is obtained by separating liquid air, is used as a raw material in the synthesis of its derivatives.

2. Also produces very pure oxygen. This method has become widespread in countries with rich resources and cheap electricity.

Application of oxygen

Oxygen is the most important element in the life of our entire planet. This gas, which is contained in the atmosphere, is consumed in the process by animals and people.

Obtaining oxygen is very important for such areas of human activity as medicine, welding and cutting of metals, blasting, aviation (for human breathing and for engine operation), and metallurgy.

In the process of human economic activity, oxygen is consumed in large quantities - for example, when burning various types of fuel: natural gas, methane, coal, wood. In all these processes, it is formed. At the same time, nature has provided for the process of natural binding of this compound using photosynthesis, which takes place in green plants under the influence of sunlight. As a result of this process, glucose is formed, which the plant then uses to build its tissues.

The widespread industrial use of oxygen began in the mid-twentieth century, after the invention of turboexpanders - devices for liquefaction and separation.
The use of oxygen is very diverse and is based on its chemical properties.
Chemical and petrochemical industry.
Oxygen is used to oxidize the starting reactants, producing nitric acid, ethylene oxide, propylene oxide, vinyl chloride and other basic compounds. In addition, it can be used to increase the productivity of waste incinerators.
Oil and gas industry.
Increasing the productivity of oil cracking processes, processing high-octane compounds, injection into the reservoir to increase displacement energy.
Metallurgy and mining industry.
Oxygen is used in converter steel production, oxygen blasting in blast furnaces, extraction of gold from ores, production of ferroalloys, smelting of nickel, zinc, lead, zirconium and other non-ferrous metals, direct reduction of iron, fire stripping of slabs in foundries, fire drilling of hard rocks.
Welding and cutting of metals.
Oxygen in cylinders is widely used for flame cutting and welding of metals, for plasma high-precision cutting of metals.
Military equipment.
In hyperbaric chambers, for operating diesel engines under water, fuel for rocket engines.
Glass industry.
Glass melting furnaces use oxygen to improve combustion. In addition, it is used to reduce nitrogen oxide emissions to safe levels.
Pulp and paper industry.
Oxygen is used in delignification, alcoholization and other processes.
Medicine.
In oxygen chambers, refilling oxygen generators (oxygen masks, pillows, etc.), in rooms with a special microclimate, making oxygen cocktails,
when growing microorganisms on petroleum paraffins.

Safety

It is prohibited to smoke or use open flames near oxygen work. Unauthorized persons should not enter areas with high oxygen concentrations in the air. After working in a room with a high concentration of oxygen in the air, it is necessary to ventilate clothing well.
Tools and clothing must be free of oil and grease. No component used with oxygen should come into contact with oil or grease.
When working with liquid oxygen Use proper gloves, safety glasses, safety shoes and body protection.
Fire fighting. Since oxygen strongly promotes combustion, quickly closing the oxygen source valve can reduce the severity of the fire. If possible, remove cylinders to a safe place. To avoid explosions, protect cylinders from heat.

Plan:

History of discovery

Origin of name

Being in nature

Receipt

Physical properties

Chemical properties

Application

10. Isotopes

Oxygen

Oxygen- element of the 16th group (according to the outdated classification - the main subgroup of group VI), the second period of the periodic system of chemical elements of D.I. Mendeleev, with atomic number 8. Denoted by the symbol O (lat. Oxygenium). Oxygen is a chemically active non-metal and is the lightest element from the group of chalcogens. Simple substance oxygen(CAS number: 7782-44-7) under normal conditions is a colorless, tasteless and odorless gas, the molecule of which consists of two oxygen atoms (formula O 2), and therefore it is also called dioxygen. Liquid oxygen has a light blue color, and solid crystals are light blue in color.

There are other allotropic forms of oxygen, for example, ozone (CAS number: 10028-15-6) - under normal conditions, a blue gas with a specific odor, the molecule of which consists of three oxygen atoms (formula O 3).

History of discovery

It is officially believed that oxygen was discovered by the English chemist Joseph Priestley on August 1, 1774 by decomposing mercuric oxide in a hermetically sealed vessel (Priestley directed sunlight at this compound using a powerful lens).

However, Priestley initially did not realize that he had discovered a new simple substance; he believed that he had isolated one of the constituent parts of air (and called this gas “dephlogisticated air”). Priestley reported his discovery to the outstanding French chemist Antoine Lavoisier. In 1775, A. Lavoisier established that oxygen is a component of air, acids and is found in many substances.

A few years earlier (in 1771), oxygen was obtained by the Swedish chemist Karl Scheele. He calcined saltpeter with sulfuric acid and then decomposed the resulting nitric oxide. Scheele called this gas “fire air” and described his discovery in a book published in 1777 (precisely because the book was published later than Priestley announced his discovery, the latter is considered the discoverer of oxygen). Scheele also reported his experience to Lavoisier.

An important step that contributed to the discovery of oxygen was the work of the French chemist Pierre Bayen, who published works on the oxidation of mercury and the subsequent decomposition of its oxide.

Finally, A. Lavoisier finally figured out the nature of the resulting gas, using information from Priestley and Scheele. His work was of enormous importance because thanks to it, the phlogiston theory, which was dominant at that time and hampered the development of chemistry, was overthrown. Lavoisier conducted experiments on the combustion of various substances and disproved the theory of phlogiston, publishing results on the weight of the burned elements. The weight of the ash exceeded the original weight of the element, which gave Lavoisier the right to claim that during combustion a chemical reaction (oxidation) of the substance occurs, and therefore the mass of the original substance increases, which refutes the theory of phlogiston.

Thus, the credit for the discovery of oxygen is actually shared between Priestley, Scheele and Lavoisier.

Origin of name

The word oxygen (also called “acid solution” at the beginning of the 19th century) owes its appearance in the Russian language to some extent to M.V. Lomonosov, who introduced the word “acid”, along with other neologisms; Thus, the word “oxygen”, in turn, was a tracing of the term “oxygen” (French oxygène), proposed by A. Lavoisier (from ancient Greek ὀξύς - “sour” and γεννάω - “giving birth”), which is translated as “generating acid”, which is associated with its original meaning - “acid”, which previously meant substances called oxides according to modern international nomenclature.

Being in nature

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. Sea 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%, and in terms of mass fraction - about 65%.

Receipt

Currently, in industry, oxygen is obtained from the air. The main industrial method for producing oxygen is cryogenic rectification. Oxygen plants operating on the basis of membrane technology are also well known and successfully used in industry.

Laboratories use industrially produced oxygen, supplied in steel cylinders under a pressure of about 15 MPa.

Small amounts of oxygen can be obtained by heating potassium permanganate KMnO 4:

The reaction of catalytic decomposition of hydrogen peroxide H2O2 in the presence of manganese(IV) oxide is also used:

Oxygen can be obtained by the catalytic decomposition of potassium chlorate (Berthollet salt) KClO 3:

Laboratory methods for producing oxygen include the method of electrolysis of aqueous solutions of alkalis, as well as the decomposition of mercury(II) oxide (at t = 100 °C):

In submarines it is usually obtained by the reaction of sodium peroxide and carbon dioxide exhaled by humans:

Physical properties

In the world's oceans, the content of dissolved O2 is greater in cold water and less in warm water.

Under normal conditions, oxygen is a gas without color, taste or smell.

1 liter of it has a mass of 1.429 g. Slightly heavier than air. Slightly soluble in water (4.9 ml/100 g at 0 °C, 2.09 ml/100 g at 50 °C) and alcohol (2.78 ml/100 g at 25 °C). It dissolves well in molten silver (22 volumes of O 2 in 1 volume of Ag at 961 ° C). Interatomic distance - 0.12074 nm. Is paramagnetic.

When gaseous oxygen is heated, its reversible dissociation into atoms occurs: at 2000 °C - 0.03%, at 2600 °C - 1%, 4000 °C - 59%, 6000 °C - 99.5%.

Liquid oxygen (boiling point −182.98 °C) is a pale blue liquid.

O2 phase diagram

Solid oxygen (melting point −218.35°C) - blue crystals. There are 6 known crystalline phases, three of which exist at a pressure of 1 atm:

α-O 2 - exists at temperatures below 23.65 K; bright blue crystals belong to the monoclinic system, cell parameters a=5.403 Å, b=3.429 Å, c=5.086 Å; β=132.53°.

β-O 2 - exists in the temperature range from 23.65 to 43.65 K; pale blue crystals (with increasing pressure the color turns pink) have a rhombohedral lattice, cell parameters a=4.21 Å, α=46.25°.

γ-O 2 - exists at temperatures from 43.65 to 54.21 K; pale blue crystals have cubic symmetry, lattice parameter a=6.83 Å.

Three more phases form at high pressures:

δ-O 2 temperature range 20-240 K and pressure 6-8 GPa, orange crystals;

ε-O 4 pressure from 10 to 96 GPa, crystal color from dark red to black, monoclinic system;

ζ-O n pressure more than 96 GPa, a metallic state with a characteristic metallic luster, at low temperatures it transforms into a superconducting state.

Chemical properties

A strong oxidizing agent, it interacts with almost all elements, forming oxides. Oxidation state −2. As a rule, the oxidation reaction proceeds with the release of heat and accelerates with increasing temperature (see Combustion). Example of reactions occurring at room temperature:

Oxidizes compounds that contain elements with less than the maximum oxidation state:

Oxidizes most organic compounds:

Under certain conditions, it is possible to carry out mild oxidation of an organic compound:

Oxygen reacts directly (under normal conditions, with heating and/or in the presence of catalysts) with all simple substances except Au and inert gases (He, Ne, Ar, Kr, Xe, Rn); reactions with halogens occur under the influence of an electrical discharge or ultraviolet radiation. Oxides of gold and heavy inert gases (Xe, Rn) were obtained indirectly. In all two-element compounds of oxygen with other elements, oxygen plays the role of an oxidizing agent, except for compounds with fluorine

Oxygen forms peroxides with the oxidation state of the oxygen atom formally equal to −1.

For example, peroxides are produced by the combustion of alkali metals in oxygen:

Some oxides absorb oxygen:

According to the combustion theory developed by A. N. Bach and K. O. Engler, oxidation occurs in two stages with the formation of an intermediate peroxide compound. This intermediate compound can be isolated, for example, when a flame of burning hydrogen is cooled with ice, hydrogen peroxide is formed along with water:

In superoxides, oxygen formally has an oxidation state of −½, that is, one electron per two oxygen atoms (O − 2 ion). Obtained by reacting peroxides with oxygen at elevated pressure and temperature:

Potassium K, rubidium Rb and cesium Cs react with oxygen to form superoxides:

In the dioxygenyl ion O 2 +, oxygen formally has an oxidation state of +½. Obtained by the reaction:

Oxygen fluorides

Oxygen difluoride, OF 2 oxidation state of oxygen +2, is prepared by passing fluorine through an alkali solution:

Oxygen monofluoride (dioxydifluoride), O 2 F 2, is unstable, the oxidation state of oxygen is +1. Obtained from a mixture of fluorine and oxygen in a glow discharge at a temperature of −196 °C:

By passing a glow discharge through a mixture of fluorine and oxygen at a certain pressure and temperature, mixtures of higher oxygen fluorides O 3 F 2, O 4 F 2, O 5 F 2 and O 6 F 2 are obtained.

Quantum mechanical calculations predict the stable existence of the trifluorohydroxonium ion OF 3 +. If this ion really exists, then the oxidation state of oxygen in it will be equal to +4.

Oxygen supports the processes of respiration, combustion, and decay.

In its free form, the element exists in two allotropic modifications: O 2 and O 3 (ozone). As Pierre Curie and Marie Skłodowska-Curie established in 1899, under the influence of ionizing radiation O 2 turns into O 3 .

Application

The widespread industrial use of oxygen began in the middle of the 20th century, after the invention of turboexpanders - devices for liquefying and separating liquid air.

INmetallurgy

The converter method of steel production or matte processing involves the use of oxygen. In many metallurgical units, for more efficient combustion of fuel, an oxygen-air mixture is used instead of air in the burners.

Welding and cutting of metals

Oxygen in blue cylinders is widely used for flame cutting and welding of metals.

Rocket fuel

Liquid oxygen, hydrogen peroxide, nitric acid and other oxygen-rich compounds are used as oxidizers for rocket fuel. A mixture of liquid oxygen and liquid ozone is one of the most powerful oxidizers of rocket fuel (the specific impulse of the hydrogen-ozone mixture exceeds the specific impulse for the hydrogen-fluorine and hydrogen-oxygen fluoride pairs).

INmedicine

Medical oxygen is stored in high-pressure metal gas cylinders (for compressed or liquefied gases) of blue color of various capacities from 1.2 to 10.0 liters under pressure up to 15 MPa (150 atm) and is used to enrich respiratory gas mixtures in anesthesia equipment, when breathing disorders, to relieve an attack of bronchial asthma, to eliminate hypoxia of any origin, for decompression sickness, to treat pathologies of the gastrointestinal tract in the form of oxygen cocktails. For individual use, special rubberized containers - oxygen cushions - are filled from cylinders with medical oxygen. Oxygen inhalers of various models and modifications are used to supply oxygen or an oxygen-air mixture simultaneously to one or two victims in the field or in a hospital setting. The advantage of an oxygen inhaler is the presence of a condenser-humidifier of the gas mixture, which uses the moisture of the exhaled air. To calculate the amount of oxygen remaining in the cylinder in liters, the pressure in the cylinder in atmospheres (according to the pressure gauge of the reducer) is usually multiplied by the cylinder capacity in liters. For example, in a cylinder with a capacity of 2 liters, the pressure gauge shows an oxygen pressure of 100 atm. The volume of oxygen in this case is 100 × 2 = 200 liters.

INFood Industry

In the food industry, oxygen is registered as a food additive E948, as a propellant and packaging gas.

INchemical industry

In the chemical industry, oxygen is used as an oxidizing agent in numerous syntheses, for example, the oxidation of hydrocarbons into oxygen-containing compounds (alcohols, aldehydes, acids), ammonia into nitrogen oxides in the production of nitric acid. Due to the high temperatures developing during oxidation, the latter are often carried out in combustion mode.

INagriculture

In greenhouse farming, for making oxygen cocktails, for weight gain in animals, for enriching the aquatic environment with oxygen in fish farming.

Biological role of oxygen

Emergency oxygen supply in a bomb shelter

Most living beings (aerobes) breathe oxygen from the air. Oxygen is widely used in medicine. In case of cardiovascular diseases, to improve metabolic processes, oxygen foam (“oxygen cocktail”) is injected into the stomach. Subcutaneous administration of oxygen is used for trophic ulcers, elephantiasis, gangrene and other serious diseases. Artificial ozone enrichment is used to disinfect and deodorize air and purify drinking water. The radioactive oxygen isotope 15 O is used to study blood flow speed and pulmonary ventilation.

Toxic oxygen derivatives

Some oxygen derivatives (so-called reactive oxygen species), such as singlet oxygen, hydrogen peroxide, superoxide, ozone and hydroxyl radical, are highly toxic. They are formed during the process of activation or partial reduction of oxygen. Superoxide (superoxide radical), hydrogen peroxide and hydroxyl radical can form in cells and tissues of humans and animals and cause oxidative stress.

Isotopes

Oxygen has three stable isotopes: 16 O, 17 O and 18 O, the average content of which is, respectively, 99.759%, 0.037% and 0.204% of the total number of oxygen atoms on Earth. The sharp predominance of the lightest of them, 16 O, in the mixture of isotopes is due to the fact that the nucleus of the 16 O atom consists of 8 protons and 8 neutrons (a double magic nucleus with filled neutron and proton shells). And such nuclei, as follows from the theory of the structure of the atomic nucleus, are particularly stable.

Radioactive isotopes of oxygen with mass numbers from 12 O to 24 O are also known. All radioactive isotopes of oxygen have a short half-life, the longest-lived of them is 15 O with a half-life of ~120 s. The shortest-lived isotope 12 O has a half-life of 5.8·10−22 s.

The report on the topic “Uses of Oxygen”, summarized in this article, will tell you about the areas of industry in which this invisible substance brings incredible benefits.

Message about oxygen use

Oxygen is an integral part of the life of all living organisms and chemical processes on the planet. In this article we will look at the most common uses of oxygen:

Use of oxygen in medicine

In this area, it is extremely important: the chemical element is used to support the life of people suffering from difficulty breathing and to treat certain ailments. It is noteworthy that at normal pressure you cannot breathe pure oxygen for a long time. This is not safe for health.

Application of oxygen in the glass industry

This chemical element is used in glass melting furnaces as a component that improves combustion in them. Also, thanks to oxygen, the industry reduces nitrogen oxide emissions to a level that is safe for life.

Use of oxygen in the pulp and paper industry

This chemical element is used in alcoholization, delignification and other processes, such as:

1. Whitening paper
2. Cleaning of drains
3. Preparation of drinking water
4. Intensification of combustion of waste incinerators
5. Tire recycling

Application of oxygen in aviation

Since a person cannot breathe outside the atmosphere without oxygen, he needs to take a supply of this useful element with him. Artificially produced oxygen is used by people for breathing in an alien environment: in aviation during flights, in spacecraft.

Use of oxygen in nature

In nature, there is an oxygen cycle: during the process of photosynthesis, plants convert carbon dioxide and water into organic compounds in the light. This process is characterized by the release of oxygen. Like humans and animals, plants consume oxygen from the atmosphere at night. The oxygen cycle in nature is determined by the fact that humans and animals consume oxygen, and plants produce it during the day and consume it at night.

Application of oxygen in metallurgy

The chemical and metallurgical industries require pure oxygen, not atmospheric oxygen. Every year, enterprises around the world receive more than 80 million tons of this chemical element. It is used up in the process of producing steel from scrap metal and cast iron.

What is the use of oxygen in mechanical engineering?

In construction and mechanical engineering it is used for cutting and welding metals. These processes are carried out at high temperatures.

Use of oxygen in life

In life, a person uses oxygen in various areas, such as:

1. Growing fish in pond farms (the water is saturated with oxygen).
2. Water treatment during food production.
3. Disinfection of storage facilities and production premises with oxygen.
4. Development of oxygen cocktails for animals so that they gain weight.

Human use of oxygen in electricity

Thermal and power plants that run on oil, natural gas or coal use oxygen to burn the fuel. Without it, all industrial production plants simply would not work.