Oxygen formsperoxides with oxidation state −1.
— For example, peroxides are produced by the combustion of alkali metals in oxygen:
2Na + O 2 → Na 2 O 2

— Some oxides absorb oxygen:
2BaO + O 2 → 2BaO 2

— According to the principles of combustion 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:
H 2 + O 2 → H 2 O 2

Superoxides have an oxidation state of −1/2, that is, one electron per two oxygen atoms (O 2 - ion). Obtained by reacting peroxides with oxygen at elevated pressures and temperatures:
Na 2 O 2 + O 2 → 2NaO 2

Ozonides contain the O 3 - ion with an oxidation state of −1/3. Obtained by the action of ozone on alkali metal hydroxides:
KOH(tv) + O 3 → KO 3 + KOH + O 2

Ion dioxygenyl O 2 + has an oxidation state of +1/2. Obtained by the reaction:
PtF 6 + O 2 → O 2 PtF 6

Oxygen fluorides
Oxygen difluoride, OF 2 oxidation state +2, is obtained by passing fluorine through an alkali solution:
2F 2 + 2NaOH → OF 2 + 2NaF + H 2 O

Oxygen monofluoride (Dioxydifluoride), O 2 F 2, unstable, oxidation state +1. It is 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.
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).

Application of oxygen

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.

In metallurgy

The converter method of steel production involves the use of oxygen.

Welding and cutting of metals

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

Propellant

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).

In medicine

Oxygen is used to enrich respiratory gas mixtures for breathing problems, for the treatment of asthma, in the form of oxygen cocktails, oxygen pillows, etc.

In the food industry

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

Biological role of oxygen

Living things 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 isotope of oxygen 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 of oxygen

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. And such nuclei, as follows from the theory of the structure of the atomic nucleus, are particularly stable.

There are radioactive isotopes 11 O, 13 O, 14 O (half-life 74 sec), 15 O (T 1/2 = 2.1 min), 19 O (T 1/2 = 29.4 sec), 20 O (contradictory half-life data from 10 minutes to 150 years).

Additional information

Oxygen compounds
Liquid oxygen
Ozone

Oxygen, Oxygenium, O (8)
The discovery of oxygen (Oxygen, French Oxygene, German Sauerstoff) marked the beginning of the modern period in the 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, but this completely rational hypothesis was not developed at that time, since the idea of ​​combustion as a process of combining a burning body with a certain component of the air seemed at that time contradicting such an obvious act as the fact that during combustion the decomposition of the burning body into elementary components takes place. It was on this basis that at the turn of the 17th century. The phlogiston theory arose, created by Becher and Stahl. With the advent of the chemical-analytical period in the development of chemistry (the second half of the 18th century) and the emergence of “pneumatic chemistry” - one of the main branches of the chemical-analytical direction - combustion, as well as respiration, again attracted the attention of researchers. The discovery of various gases and the establishment of their important role in chemical processes was one of the main incentives for the systematic studies of combustion processes undertaken by Lavoisier. Oxygen was discovered in the early 70s of the 18th century.

The first report of this discovery was made by Priestley at a meeting of the Royal Society of England in 1775. Priestley, by heating red mercury oxide with a large burning glass, obtained a gas in which the candle burned more brightly than in ordinary air, and the smoldering splinter flared up. Priestley determined some of the properties of the new gas and called it daphlogisticated air. However, two years earlier than Priestley (1772), Scheele also obtained oxygen by the decomposition of mercuric oxide and other methods. Scheele called this gas fire air (Feuerluft). Scheele was able to report his discovery only in 1777.

In 1775, Lavoisier spoke before the Paris Academy of Sciences with the message that he had succeeded in obtaining “the purest part of the air that surrounds us,” and described the properties of this part of the air. At first, Lavoisier called this “air” empyrean, vital (Air empireal, Air vital) the basis of vital air (Base de l'air vital). The almost simultaneous discovery of oxygen by several scientists in different countries gave rise to disputes about priority. Priestley was especially persistent in achieving recognition as a discoverer In essence, these disputes have not yet ended. 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, in accordance with this conclusion. introduced a new name for oxygen - the acid-forming principle (principe acidifiant ou principe oxygine). Lavoisier derived the word oxygine appearing in this complex name from the Greek - acid and “I produce”.

DEFINITION

Oxygen- the eighth element of the Periodic Table. Designation - O from the Latin “oxygenium”. Located in the second period, group VIA. Refers to non-metals. The nuclear charge is 8.

Oxygen is the most common element in the earth's crust. In a free state, it is found in the atmospheric air; in a bound form, it is part of water, minerals, rocks and all substances from which the organisms of plants and animals are built. The mass fraction of oxygen in the earth's crust is about 47%.

In its simple form, oxygen is a colorless, odorless gas. It is slightly heavier than air: the mass of 1 liter of oxygen under normal conditions is 1.43 g, and 1 liter of air is 1.293 g. Oxygen dissolves in water, although in small quantities: 100 volumes of water at 0 o C dissolve 4.9, and at 20 o C - 3.1 volumes of oxygen.

Atomic and molecular mass of oxygen

DEFINITION

Relative atomic mass A r is the molar mass of an atom of a substance divided by 1/12 of the molar mass of a carbon-12 atom (12 C).

The relative atomic mass of atomic oxygen is 15.999 amu.

DEFINITION

Relative molecular weight M r is the molar mass of a molecule divided by 1/12 the molar mass of a carbon-12 atom (12 C).

This is a dimensionless quantity. It is known that the oxygen molecule is diatomic - O 2. The relative molecular mass of an oxygen molecule will be equal to:

M r (O 2) = 15.999 × 2 ≈32.

Allotropy and allotropic modifications of oxygen

Oxygen can exist in the form of two allotropic modifications - oxygen O 2 and ozone O 3 (the physical properties of oxygen are described above).

Under normal conditions, ozone is a gas. It can be separated from oxygen by strong cooling; ozone condenses into a blue liquid, boiling at (-111.9 o C).

The solubility of ozone in water is much greater than that of oxygen: 100 volumes of water at 0 o C dissolve 49 volumes of ozone.

The formation of ozone from oxygen can be expressed by the equation:

3O 2 = 2O 3 - 285 kJ.

Isotopes of oxygen

It is known that in nature oxygen can be found in the form of three isotopes 16 O (99.76%), 17 O (0.04%) and 18 O (0.2%). Their mass numbers are 16, 17 and 18, respectively. The nucleus of an atom of the oxygen isotope 16 O contains eight protons and eight neutrons, and the isotopes 17 O and 18 O contain the same number of protons, nine and ten neutrons, respectively.

There are twelve radioactive isotopes of oxygen with mass numbers from 12 to 24, of which the most stable isotope 15 O with a half-life of 120 s.

Oxygen ions

The outer energy level of the oxygen atom has six electrons, which are valence electrons:

1s 2 2s 2 2p 4 .

The structure of the oxygen atom is shown below:

As a result of chemical interaction, oxygen can lose its valence electrons, i.e. be their donor, and turn into positively charged ions or accept electrons from another atom, i.e. be their acceptor and turn into negatively charged ions:

O 0 +2e → O 2- ;

O 0 -1e → O 1+ .

Oxygen molecule and atom

The oxygen molecule consists of two atoms - O 2. Here are some properties that characterize the oxygen atom and molecule:

Examples of problem solving

EXAMPLE 1

Elements located in the main subgroup of group VI of the periodic system of elements of D. I. Mendeleev.

An examination of the atomic structures of the elements of the main subgroup of group VI shows that they all have a six-electron structure of the outer layer (Table 13) and, therefore, have relatively high electronegativity values. , has the greatest electronegativity, and the least, which is explained by the change in the atomic radius. The special place of oxygen in this group is emphasized by the fact that, and tellurium can directly combine with oxygen, but cannot combine with each other.

Elements of the oxygen group also belong to the group r-elements, since they are being completed r-shell. For all elements of the family, except oxygen itself, 6 electrons in the outer layer are valence electrons.
In redox reactions, elements of the oxygen group often exhibit oxidizing properties. The most strongly oxidizing properties are expressed in oxygen.
All elements of the main subgroup of group VI are characterized by a negative oxidation state of -2. However, for sulfur, selenium and tellurium, positive oxidation states are also possible (maximum +6).
The oxygen molecule, like any simple gas, is diatomic, built like a covalent bond formed through two electron pairs. Therefore, oxygen is divalent when forming a simple oxygen.
Sulfur is a solid substance. The molecule contains 8 sulfur atoms (S8), but they are connected in a kind of ring, in which each sulfur atom is connected to only two neighboring atoms by a covalent bond

Thus, each sulfur atom, having one common electron pair with two neighboring atoms, is itself divalent. Similar molecules form selenium (Se8) and tellurium (Te8).

■ 1. Write a story about the oxygen group according to the following plan: a) position in the periodic table; b) charges of nuclei and. number of neutrons in the nucleus; c) electronic configurations; d) crystal lattice structure; e) possible oxidation states of oxygen and all other elements of this group.
2. What are the similarities and differences between the atomic structures and electronic configurations of the atoms of the elements of the main subgroups of groups VI and VII?
3. How many valence electrons do elements of the main subgroup of group VI have?
4. How should the elements of the main subgroup of group VI behave in redox reactions?
5. Which of the elements of the main subgroup of group VI is the most electronegative?

When considering the elements of the main subgroup of group VI, we first encounter the phenomenon of allotropy. The same element in a free state can form two or more simple substances. This phenomenon is called allotropy, and they themselves are called allotropic modifications.

Write this wording in your notebook.

For example, the element oxygen is capable of forming two simple elements - oxygen and ozone.
Formula of simple oxygen O2, formula of simple substance ozone O3. Their molecules are built differently:

Oxygen and ozone are allotropic modifications of the element oxygen.
Sulfur can also form several allotropes (modifications). Orthorhombic (octahedral), plastic and monoclinic sulfur is known. Selenium and tellurium also form several allotropes. It should be noted that the phenomenon of allotropy is characteristic of many elements. We will consider the differences in the properties of different allotropic modifications when studying elements.

■ 6. What is the difference between the structure of an oxygen molecule and the structure of an ozone molecule?

7. What type of bond is in the molecules of oxygen and ozone?

Oxygen. Physical properties, physiological effects, the importance of oxygen in nature

Oxygen is the lightest element of the main subgroup of group VI. The atomic weight of oxygen is 15.994. 31,988. The oxygen atom has the smallest radius of the elements of this subgroup (0.6 Å). Electronic configuration of the oxygen atom: ls 2 2s 2 2p 4.

The distribution of electrons over the orbitals of the second layer indicates that oxygen has two unpaired electrons in its p-orbitals, which can easily be used to form a chemical bond between atoms. Characteristic oxidation state of oxygen.
Oxygen is a colorless and odorless gas. It is heavier than air, at a temperature of -183° it turns into a blue liquid, and at a temperature of -219° it solidifies.

The oxygen density is 1.43 g/l. Oxygen is poorly soluble in water: 3 volumes of oxygen dissolve in 100 volumes of water at 0°C. Therefore, oxygen can be kept in a gasometer (Fig. 34) - a device for storing gases that are insoluble and slightly soluble in water. Most often, oxygen is stored in a gasometer.
The gasometer consists of two main parts: vessel 1, which serves to store gas, and a large funnel 2 with a tap and a long tube that reaches almost to the bottom of vessel 1 and serves to supply water to the device. Vessel 1 has three tubes: a funnel 2 with a stopcock is inserted into tube 3 with a ground-in inner surface; a gas outlet tube equipped with a stopcock is inserted into tube 4; tube 5 at the bottom serves to release water from the device when charging and discharging it. In a charged gasometer, vessel 1 is filled with oxygen. At the bottom of the vessel is located, into which the end of the funnel tube 2 is lowered.

Rice. 34.
1 - gas storage vessel; 2 - funnel for water supply; 3 - tube with a ground surface; 4 - tube for removing gas; 5 - tube for releasing water when charging the device.

If you need to get oxygen from a gasometer, first open the funnel tap and slightly compress the oxygen in the gasometer. Then open the valve on the gas outlet pipe, through which oxygen comes out, displaced by water.

In industry, oxygen is stored in steel cylinders in a compressed state (Fig. 35, a), or in liquid form in oxygen “tanks” (Fig. 36).

Rice. 35. Oxygen cylinder

Write down from the text the names of devices intended for storing oxygen.
Oxygen is the most common element. It makes up almost 50% of the weight of the entire earth's crust (Fig. 37). The human body contains 65% oxygen, which is part of various organic substances from which tissues and organs are built. Water contains about 89% oxygen. In the atmosphere, oxygen accounts for 23% by weight and 21% by volume. Oxygen is part of a wide variety of rocks (for example, limestone, chalk, marble CaCO3, sand SiO2), ores of various metals (magnetic iron ore Fe3O4, brown iron ore 2Fe2O3 nH2O, red iron ore Fe2O3, bauxite Al2O3 nH2O, etc.) . Oxygen is part of most organic substances.

The physiological significance of oxygen is enormous. It is the only gas that living organisms can use to breathe. Lack of oxygen causes life processes to stop and the body to die. Without oxygen, a person can live only a few minutes. When breathing, oxygen is absorbed, which takes part in the redox processes occurring in the body, and oxidation products of organic substances are released - carbon dioxide and other substances. Both terrestrial and aquatic living organisms breathe oxygen: terrestrial ones - with free atmospheric oxygen, and aquatic ones - with oxygen dissolved in water.
In nature, a kind of oxygen cycle occurs. Oxygen from the atmosphere is absorbed by animals, plants, humans, and is spent on fuel combustion processes, decay and other oxidative processes. Carbon dioxide and water formed during the oxidation process are consumed by green plants, in which, with the help of leaf chlorophyll and solar energy, the process of photosynthesis is carried out, i.e., the synthesis of organic substances from carbon dioxide and water, accompanied by the release of oxygen.
To provide oxygen to one person, the crowns of two large trees are needed. Green plants maintain a constant composition of the atmosphere.

■ 8. What is the importance of oxygen in the life of living organisms?
9. How is the supply of oxygen in the atmosphere replenished?

Chemical properties of oxygen

Free oxygen, when reacting with simple and complex substances, usually behaves like.

Rice. 37.

The oxidation state it acquires in this case is always -2. Many elements interact directly with oxygen, with the exception of noble metals, elements with electronegativity values ​​close to oxygen () and inert elements.
As a result, oxygen compounds with simple and complex substances are formed. Many burn in oxygen, although in air they either do not burn or burn very weakly. burns in oxygen with a bright yellow flame; this produces sodium peroxide (Fig. 38):
2Na + O2 =Na2O2,
Sulfur burns in oxygen with a bright blue flame to form sulfur dioxide:
S + O2 = SO2
Charcoal barely smolders in air, but in oxygen it becomes very hot and burns to form carbon dioxide (Fig. 39):
C + O2 = CO2

Rice. 36.

It burns in oxygen with a white, dazzlingly bright flame, and solid white phosphorus pentoxide is formed:
4P + 5O2 = 2P2O5
burns in oxygen, scattering sparks and forming iron scale (Fig. 40).
Organic substances also burn in oxygen, for example methane CH4, the constituent composition of natural gas: CH4 + 2O2 = CO2 + 2H2O
Combustion in pure oxygen occurs much more intensely than in air, and allows one to obtain significantly higher temperatures. This phenomenon is used to intensify a number of chemical processes and more efficient combustion of fuel.
In the process of breathing, oxygen, combining with hemoglobin in the blood, forms oxyhemoglobin, which, being a very unstable compound, easily decomposes in tissues with the formation of free oxygen that goes into oxidation. Rotting is also an oxidative process involving oxygen.
They recognize pure oxygen by introducing a smoldering splinter into the vessel where it is supposed to be present. It flashes brightly - this is a high-quality test for oxygen.

■ 10. How, having a splinter at your disposal, can you recognize oxygen and carbon dioxide in different vessels? 11. What volume of oxygen will be used to burn 2 kg of coal containing 70% carbon, 5% hydrogen, 7% oxygen, and the rest - non-combustible components?

Rice. 38. Sodium combustion Rice. 39. Coal burning Rice. 40. Combustion of iron in oxygen.

12. Is 10 liters of oxygen enough to burn 5 g of phosphorus?
13. 1 m3 of a gas mixture containing 40% carbon monoxide, 20% nitrogen, 30% hydrogen and 10% carbon dioxide was burned in oxygen. How much oxygen was consumed?
14. Is it possible to dry oxygen by passing it through: a) sulfuric acid, b) calcium chloride, c) phosphoric anhydride, d) metal?
15. How to free carbon dioxide from oxygen impurities and vice versa, how to free oxygen from carbon dioxide impurities?
16. 20 liters of oxygen containing an admixture of carbon dioxide were passed through 200 ml of 0.1 N. barium solution. As a result, the Ba 2+ cation was completely precipitated. How much carbon dioxide (in percent) did the original oxygen contain?

Obtaining oxygen

Oxygen is obtained in several ways. In the laboratory, oxygen is obtained from oxygen-containing substances that can easily split it off, for example from potassium permanganate KMnO4 (Fig. 41) or from berthollet salt KClO3:
2КМnО4 = K2MnO4 + МnО2 + O2

2КlO3 = 2Кl + O2
When producing oxygen from bertholite salt, a catalyst must be present to speed up the reaction - manganese dioxide. The catalyst speeds up decomposition and makes it more uniform. Without a catalyst it can

Rice. 41. A device for producing oxygen using a laboratory method from potassium permanganate. 1 - potassium permanganate; 2 - oxygen; 3 - cotton wool; 4 - cylinder - collection.

an explosion may occur if Bertholet salt is taken in large quantities and especially if it is contaminated with organic substances.
Oxygen is also obtained from hydrogen peroxide in the presence of a catalyst - manganese dioxide MnO2 according to the equation:
2H2O2[MnO2] = 2H2O + O2

■ 17. Why is MnO2 added during the decomposition of Berthollet salt?
18. Oxygen formed during the decomposition of KMnO4 can be collected above water. Reflect this in the device diagram.
19. Sometimes, if manganese dioxide is not available in the laboratory, a little residue after calcination of potassium permanganate is added to the bertholtol salt instead. Why is such a replacement possible?
20. What volume of oxygen will be released during the decomposition of 5 moles of Berthollet salt?

Oxygen can also be obtained by the decomposition of Nitrates when heated above the melting point:
2KNO3 = 2KNO2 + O2
In industry, oxygen is obtained mainly from liquid air. The air, converted into a liquid state, is subjected to evaporation. First, it evaporates (its boiling point is 195.8°), and oxygen remains (its boiling point is -183°). In this way, oxygen is obtained in almost pure form.
Sometimes, if cheap electricity is available, oxygen is obtained by electrolysis of water:
H2O ⇄ H + + OH —
N + + e— → Н 0
at the cathode
2OH — — e— → H2O + O; 2O = O2
at the anode

■ 21. List the laboratory and industrial methods for producing oxygen known to you. Write them down in your notebook, accompanying each method with a reaction equation.
22. Are the reactions used to produce oxygen redox? Give a reasoned answer.
23. 10 g of the following substances were taken; potassium permanganate, bertholet salt, potassium nitrate. In which case will it be possible to obtain the largest volume of oxygen?
24. 1 g of coal was burned in oxygen obtained by heating 20 g of potassium permanganate. What percentage of the permanganate was decomposed?

Oxygen is the most abundant element in nature. It is widely used in medicine, chemistry, industry, etc. (Fig. 42).

Rice. 42. Use of oxygen.

Pilots at high altitudes, people working in an atmosphere of harmful gases, and those engaged in underground and underwater work use oxygen devices (Fig. 43).

In cases where it is difficult due to a particular disease, the person is given pure oxygen to breathe from an oxygen bag or placed in an oxygen tent.
Currently, oxygen-enriched air or pure oxygen is widely used to intensify metallurgical processes. Oxygen-hydrogen and oxy-acetylene torches are used for welding and cutting metals. By impregnating flammable substances with liquid oxygen: sawdust, coal powder, etc., explosive mixtures called oxyliquits are obtained.

■ 25. Draw a table in your notebook and fill it out.

Ozone O3

As already mentioned, the element oxygen can form another allotropic modification - ozone O3. Ozone boils at -111° and solidifies at -250°. In the gaseous state it is blue, in the liquid state it is blue. ozone in water is much higher than oxygen: 45 volumes of ozone dissolve in 100 volumes of water.

Ozone differs from oxygen in that its molecule consists of three rather than two atoms. Due to this, the oxygen molecule is much more stable than the ozone molecule. Ozone breaks down easily according to the equation:
O3 = O2 + [O]

The release of atomic oxygen during ozone decomposition makes it a much stronger oxidizing agent than oxygen. Ozone has a fresh smell (“ozone” in translation means “smelling”). In nature, it is formed under the influence of a quiet electrical discharge and in pine forests. Patients with lung disease are advised to spend more time in pine forests. However, prolonged exposure to an atmosphere highly enriched with ozone can have a toxic effect on the body. Poisoning is accompanied by dizziness, nausea, and nosebleeds. With chronic poisoning, heart disease can occur.
In the laboratory, ozone is obtained from oxygen in ozonizers (Fig. 44). Oxygen is passed into glass tube 1, wrapped on the outside with wire 2. Wire 3 runs inside the tube. Both of these wires are connected to the poles of a current source that creates a high voltage at the indicated electrodes. A quiet electrical discharge occurs between the electrodes, due to which ozone is formed from oxygen.

Fig 44; Ozonizer. 1 - glass container; 2 - outer winding; 3 - wire inside the tube; 4 - solution of potassium iodide with starch

3O2 = 2O3
Ozone is a very strong oxidizing agent. It reacts much more energetically than oxygen, and is generally much more active than oxygen. For example, unlike oxygen, it can displace hydrogen iodide or iodide salts:
2KI + O3 + H2O = 2KOH + I2 + O2

There is very little ozone in the atmosphere (about one millionth of a percent), but it plays a significant role in absorbing ultraviolet rays from the sun, which is why they reach the earth in smaller quantities and do not have a harmful effect on living organisms.
Ozone is used in small quantities mainly for air conditioning and also in chemistry.

■ 26. What are allotropic modifications?
27. Why does iodine-starch paper turn blue under the influence of ozone? Give a reasoned answer.
28. Why is an oxygen molecule much more stable than an ozone molecule? Justify your answer in terms of intramolecular structure.

>>

Chemical properties of oxygen. Oxides

This paragraph talks about:

> about the reactions of oxygen with simple and complex substances;
> about compound reactions;
> about compounds called oxides.

The chemical properties of each substance are manifested in chemical reactions with his participation.

Oxygen is one of the most active non-metals. But under normal conditions it reacts with few substances. Its reactivity increases significantly with increasing temperature.

Reactions of oxygen with simple substances.

Oxygen reacts, as a rule, when heated, with most non-metals and almost all metals.

Reaction with coal (carbon). It is known that coal heated in air to a high temperature ignites. This indicates a chemical reaction of the substance with oxygen. The heat released during this process is used, for example, to heat houses in rural areas.

The main product of coal combustion is carbon dioxide. His chemical formula- CO 2 . Coal is a mixture of many substances. The mass fraction of carbon in it exceeds 80%. Assuming that coal consists only of carbon atoms, we write the corresponding chemical equation:

t
C + O 2 = CO 2.

Carbon forms simple substances - graphite and diamond. They have a common name - carbon - and react with oxygen when heated according to the given chemical equation 1.

Reactions in which one substance is formed from several substances are called compound reactions.

Reaction with sulfur.

This chemical transformation occurs when everyone lights a match; sulfur is part of its head. In the laboratory, the reaction of sulfur with oxygen is carried out in a fume hood. A small amount of sulfur (light yellow powder or crystals) is heated in an iron spoon. Substance first it melts, then it ignites as a result of interaction with oxygen in the air and burns with a barely noticeable blue flame (Fig. 56, b). A pungent odor of the reaction product appears - sulfur dioxide (we smell this odor at the moment a match lights up). The chemical formula of sulfur dioxide is SO 2, and the reaction equation is
t
S + O 2 = SO 2.

Rice. 56. Sulfur (a) and its combustion in air (b) and in oxygen (c)

1 In case of insufficient oxygen, another Carbon compound is formed with Oxygen- carbon monoxide
t
CO: 2C + O 2 = 2CO.

Rice. 57. Red phosphorus (a) and its combustion in air (b) and in oxygen (c)

If a spoon with burning sulfur is placed in a vessel with oxygen, then the sulfur will burn with a brighter flame than in air (Fig. 56, c). This can be explained by the fact that there are more O 2 molecules in pure oxygen than in air.

Reaction with phosphorus. Phosphorus, like sulfur, burns more intensely in oxygen than in air (Fig. 57). The product of the reaction is a white solid - phosphorus(\/) oxide (its small particles form smoke):
t
P + O 2 -> P 2 0 5 .

Convert the reaction diagram into a chemical equation.

Reaction with magnesium.

Previously this reaction was used photographers to create bright lighting (“magnesium flash”) when taking photographs. In a chemical laboratory, the corresponding experiment is carried out as follows. Using metal tweezers, take the magnesium strip and set it on fire in air. Magnesium burns with a dazzling white flame (Fig. 58, b); You can't look at him! The reaction produces a white solid. This is a compound of Magnesium with Oxygen; its name is magnesium oxide.

Rice. 58. Magnesium (a) and its combustion in air (b)

Write an equation for the reaction of magnesium with oxygen.

Reactions of oxygen with complex substances. Oxygen can interact with some oxygen-containing compounds. For example, carbon monoxide CO burns in air to form carbon dioxide:

t
2CO + O 2 = 2C0 2.

We carry out many reactions of oxygen with complex substances in everyday life, burning natural gas (methane), alcohol, wood, paper, kerosene, etc. When they burn, carbon dioxide and water vapor are formed:
t
CH 4 + 20 2 = CO 2 + 2H 2 O;
methane
t
C 2 H 5 OH + 30 2 = 2C0 2 + 3H 2 O.
alcohol

Oxides.

The products of all reactions discussed in the paragraph are binary compounds of elements with Oxygen.

A compound formed by two elements, one of which is Oxygen, is called an oxide.

The general formula of the oxides is EnOm.

Each oxide has a chemical name, and some also have traditional, or trivial 1 names (Table 4). The chemical name of the oxide consists of two words. The first word is the name of the corresponding element, and the second is the word “oxide”. If an element has a variable valency, it can form several oxides. Their names should be different. To do this, after the name of the element, indicate (without indentation) in Roman numerals in brackets the value of its valence in the oxide. An example of such a compound name is cuprum(II) oxide (pronounced cuprum-two-oxide).

Table 4

1 The term comes from the Latin word trivialis - ordinary.

Conclusions

Oxygen is a chemically active substance. It interacts with most simple substances as well as complex substances. The products of such reactions are compounds of elements with Oxygen - oxides.

Reactions in which one substance is formed from several substances are called compound reactions.

?
135. How do compound and decomposition reactions differ?

136. Convert reaction schemes into chemical equations:

a) Li + O 2 -> Li 2 O;
N2 + O 2 -> NO;

b) SO 2 + O 2 -> SO 3;
CrO + O 2 -> Cr 2 O 3.

137. Select from the given formulas those that correspond to oxides:

O 2, NaOH, H 2 O, HCI, I 2 O 5, FeO.

138. Give chemical names to oxides with the following formulas:

NO, Ti 2 O 3, Cu 2 O, MnO 2, CI 2 O 7, V 2 O 5, CrO 3.

Please note that the elements that form these oxides have variable valence.

139. Write down the formulas: a) plumbum(I\/) oxide; b) chromium(III) oxide;
c) chlorine(I) oxide; d) nitrogen(I\/) oxide; e) osmium(\/III) oxide.

140. Complete the formulas of simple substances in the reaction schemes and make up chemical equations:

a) ... + ... -> CaO;

b) NO + ... -> NO 2; ... + ... -> As 2 O 3 ; Mn 2 O 3 + ... -> MnO 2.

141. Write the reaction equations with the help of which you can carry out such “chains” of transformations, i.e., get a second from the first substance, and a third from the second:

a) C -> CO -> CO 2;
b) P -> P 2 0 3 -> P 2 0 5 ;
c) Cu -> Cu 2 O -> CuO.

142.. Write down equations for the reactions that occur when acetone (CH 3) 2 CO and ether (C 2 H 5) 2 O burn in air. The products of each reaction are carbon dioxide and water.

143. The mass fraction of Oxygen in EO 2 oxide is 26%. Identify element E.

144. Two flasks are filled with oxygen. After they were sealed, excess magnesium was burned in one flask, and excess sulfur in the other. In which flask was a vacuum formed? Explain your answer.

Popel P. P., Kryklya L. S., Chemistry: Pidruch. for 7th grade zagalnosvit. navch. closing - K.: VC "Academy", 2008. - 136 p.: ill.

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 its magnetic properties, oxygen is moved using powerful ones. 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 the 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 respiration 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.

Temperature can be a catalyst for chemical reactions with oxygen. 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 create bonds with all elements of the periodic table, except for 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. This is 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 the Carboniferous period of the Earth's development.

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.