Is oxygen an oxidizing agent? "Oxygen: meaning, production, physical and chemical properties, application"

• Designation - O (Oxygen);
• Latin name - Oxigenium;
• Period - II;
• Group - 16 (VIa);
• Atomic mass - 15.9994;
• Atomic number - 8;
• Radius of an atom = 60 pm;
• Covalent radius = 73 pm;
• Electron distribution - 1s 2 2s 2 2p 4 ;
• t melting = -218.4°C;
• boiling point = -182.96°C;
• Electronegativity (according to Pauling / according to Alpred and Rochov) = 3.44 / 3.50;
• Oxidation state: +2; +1; 12 ; 0; - 13 ; - 12 ; -1; -2;
• Density (n.a.) \u003d 1.42897 g / cm 3;
• Molar volume = 14.0 cm 3 / mol.

Oxygen ("generating acids") was discovered in 1774 by J. Priestley. This is the most common chemical element on Earth - the mass fraction of oxygen in the earth's crust is 47.2%. In the atmospheric air, the proportion of oxygen is 21%, which is associated with the activity of green plants.

Oxygen is a constituent of many, both inorganic and organic compounds. Oxygen is necessary for the life of all highly organized living organisms: humans, animals, birds, fish. Oxygen makes up from 50 to 85% of the mass of animal and plant tissues.

Three stable isotopes of oxygen are known: 16 O, 17 O, 18 O.

In the free state, oxygen exists in two allotropic modifications: O 2 - oxygen; O 3 - ozone.

Rice. The structure of the oxygen atom.

The oxygen atom contains 8 electrons: 2 electrons are in the inner s-orbital and 6 more in the outer energy level - 2 (paired) in the s-sublevel and 4 (two paired and two unpaired) in the p-sublevel (see Electronic structure of atoms) .

Due to the two unpaired p-electrons of the outer level, oxygen forms two covalent bonds, accepting two electrons and showing the oxidation state -2 (H 2 O, CaO, H 2 SO 4).

In compounds with an O-O oxygen bond, the oxygen atom exhibits an oxidation state of -1 (H 2 O 2).

With the more electronegative fluorine, oxygen donates its valence electrons, exhibiting an oxidation state of +2 (OF 2).

O2

A diatomic oxygen molecule is formed by a double bond of two oxygen atoms. For this reason, molecular oxygen under normal conditions is a stable compound.

The dissociation energy of an oxygen molecule is about 2 times lower than in a nitrogen molecule (see Covalent bond multiplicity), therefore, oxygen has a higher reactivity than nitrogen (but much less than, for example, fluorine).

The reactivity of oxygen increases as it is heated. Oxygen reacts with all elements except inert gases. Due to its high electronegativity (see What is electronegativity) in chemical compounds (with the exception of fluorine), oxygen acts as an oxidizing agent with a degree of -2 (only fluorine oxidizes oxygen to form oxygen difluoride OF 2).

Properties of oxygen gas:

• colorless, odorless and tasteless gas;
• in liquid or solid form, oxygen has a blue color;
• sparingly soluble in water: the mass fraction of oxygen at 20°C is 0.004%.

Chemical properties of oxygen

In all reactions, oxygen plays the role of an oxidizing agent, combining with all elements (with the exception of helium, argon and neon) by direct interaction (except for fluorine, chlorine, gold and platinum metals).

With metals and non-metals (simple substances), oxygen forms oxides:

2Cu + O 2 = 2CuO 4Li + O 2 = 2Li 2 O 2Ca + O 2 = 2CaO S + O 2 = SO 2 C + O 2 = CO 2

When the alkali metals sodium and potassium are oxidized, peroxides are formed:

2Na + O 2 \u003d Na 2 O 2

Almost all reactions involving oxygen are exothermic, but there are exceptions:

N 2 + O 2 ↔ 2NO-Q

Many substances react with oxygen to release heat and light, a process called burning.

Combustion reactions:

• combustion of ammonia in air with the formation of water and nitrogen: 4NH 3 + 3O 2 \u003d 2N 2 + 6H 2 O
• catalytic oxidation of ammonia: 4NH 3 + 5O 2 \u003d 2NO + 6H 2 O
• combustion of hydrogen sulfide in excess oxygen: 2H 2 S + 3O 2 \u003d 2SO 2 + 2H 2 O
• with a lack of oxygen, hydrogen sulfide is slowly oxidized to free sulfur: 2H 2 S + O 2 \u003d 2S + 2H 2 O
• combustion of organic substances in oxygen with the formation of water and carbon dioxide: CH 4 + 2O 2 → CO 2 + 2H 2 O C 2 H 5 OH + 3O 2 → 2CO 2 + 3H 2 O
• during the combustion of nitrogen-containing organic substances, in addition to carbon dioxide and water, free nitrogen is released: 4CH 3 NH 5 + 9O 2 → 4CO 2 + 2N 2 + 10H 2 O

Many substances (alcohols, aldehydes, acids) are obtained by the reaction of controlled oxidation of organic substances. Also, many natural processes, such as respiration or decay, are inherently oxidative reactions of organic substances.

An even stronger oxidizing agent than oxygen is ozone, which can oxidize potassium iodide to a free ion - this reaction is used for the qualitative and quantitative determination of ozone: O 3 + 2KI + H 2 O \u003d I 2 ↓ + 2KOH + O 2

Obtaining and using oxygen

Oxygen is widely used in industry and medicine:

• in metallurgy, oxygen is used in the smelting of steel (cast iron);
• in the chemical industry, oxygen is needed for the production of acids (sulfuric and nitric), methanol, acetylene, aldehydes;
• in the space industry, oxygen is used as an oxidizer for rocket fuel;
• in medicine, oxygen is used in breathing apparatus;
• in nature, oxygen plays an extremely important role - in the process of oxidation of carbohydrates, fats and proteins, the energy necessary for living organisms is released.

How to get oxygen:

• industrial ways:
  • liquefaction of air with subsequent separation of the liquid mixture of gases into components;
  • water electrolysis:
    2H 2 O \u003d 2H 2 + O 2.
• laboratory methods (decomposition of salts when heated):
  • potassium permanganate:
    2KMnO 4 \u003d K 2 MnO 4 + MnO 2 + O 2;
  • Berthollet salt:
    2KClO 3 \u003d 2KCl + 3O 2.
• thermal decomposition of alkali metal nitrates:
  2NaNO 3 \u003d 2NaNO 2 + O 2
• catalytic decomposition of hydrogen peroxide (MnO 2 catalyst):
  2H 2 O 2 \u003d 2H 2 O + O 2;
• interaction of carbon dioxide peroxides with alkali metal peroxides:
  2CO 2 + 2Na 2 O 2 \u003d 2Na 2 CO 3 + O 2.

>>

Chemical properties of oxygen. oxides

This paragraph is about:

> about the reactions of oxygen with simple and complex substances;
> about compound reactions;
> about compounds that are 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. Ho 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 the occurrence of a chemical reaction of the substance with oxygen. The heat that is released in this case 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 \u003d CO 2.

Carbon forms simple substances - graphite and diamond. They have a common name - carbon - and interact 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 is carried out by everyone when he strikes 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 melts, then ignites as a result of interaction with atmospheric oxygen and burns with a barely noticeable blue flame (Fig. 56, b). There is a sharp smell of the reaction product - sulfur dioxide (we feel this smell at the moment the match is lit). The chemical formula of sulfur dioxide is SO 2, and the reaction equation is
t
S + O 2 \u003d SO 2.

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

1 In case of insufficient amount of oxygen, another compound of Carbon is formed with Oxygen- carbon monoxide
t
CO: 2C + O 2 \u003d 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 reaction product is a white solid - phosphorus (\/) oxide (its small particles form smoke):
t
P + O 2 -> P 2 0 5 .

Turn the reaction scheme into a chemical equation.

reaction with magnesium.

Previously, this reaction was used photographers to create bright lighting ("magnesium flash") when taking pictures. In the chemical laboratory, the corresponding experience is carried out as follows. Magnesium tape is taken with metal tweezers and set on fire in air. Magnesium burns with a dazzling white flame (Fig. 58, b); you can't look at it! 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 \u003d 2C0 2.

We carry out many reactions of oxygen with complex substances in everyday life by burning natural gas (methane), alcohol, wood, paper, kerosene, etc. When they are burned, carbon dioxide and water vapor are formed:
t
CH 4 + 20 2 \u003d CO 2 + 2H 2 O;
methane
t
C 2 H 5 OH + 30 2 \u003d 2C0 2 + 3H 2 O.
alcohol

Oxides.

The products of all reactions considered 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 for 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, then it can form several oxides. Their names must be different. To do this, after the name of the element, indicate (without indentation) with a Roman numeral in brackets the value of its valence in the oxide. An example of such a name for a compound is cuprum(II) oxide (read "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 with 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. What is the difference between the reactions of combination and decomposition?

136. Turn reaction schemes into chemical equations:

a) Li + O 2 -> Li 2 O;
N2 + O2 -> NO;

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

137. Choose among 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 .

Take into account that the elements that form these oxides are of 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. Add formulas of simple substances in reaction schemes and make chemical equations:

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

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

141. Write the reaction equations with which you can carry out such "chains" of transformations, i.e. get the second from the first substance, and the 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.. Make the equations of the reactions that occur during the combustion of acetone (CH 3) 2 CO and ether (C 2 H 5) 2 O in air. The products of each reaction are carbon dioxide and water.

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

144. Two flasks are filled with oxygen. After their sealing, excess magnesium was burned in one flask, and excess sulfur was burned in the other. Which flask has a vacuum? Explain the answer.

Popel P. P., Kriklya L. S., Chemistry: Pdruch. for 7 cells. zahalnosvit. navch. zakl. - K .: Exhibition Center "Academy", 2008. - 136 p.: il.

Oxygen is the most abundant chemical element on the planet. Its mass fraction in the earth's crust is 47.3%, its volume fraction in the atmosphere is 20.95%, and its mass fraction in living organisms is about 65%. What is this gas, and what physical and chemical properties does oxygen have?

Oxygen: general information

Oxygen is a non-metal that under normal conditions has no color, taste or smell.

Rice. 1. Formula of oxygen.

In almost all compounds, except for compounds with fluorine and peroxides, it exhibits a constant valency II and an oxidation state of -2. The oxygen atom does not have excited states, since there are no free orbitals on the second outer level. As a simple substance, oxygen exists in the form of two allotropic modifications - oxygen gases O 2 and ozone O 3.

under certain conditions, oxygen can be in a liquid or solid state. they, unlike gases, have a color: liquid - light blue, and solid oxygen has a light blue tint.

Rice. 2. Solid oxygen.

Oxygen in industry is obtained by liquefying air, followed by the separation of nitrogen due to its evaporation (there is a difference in boiling points: -183 degrees for liquid oxygen and -196 degrees for liquid nitrogen).

Chemical properties of oxygen interaction

Oxygen is an active non-metal. Oxygen is able to react with all elements except neon, helium and argon. usually the reactions of this gas with other substances are exothermic. The process of oxidation, which takes place with the simultaneous release of energy in the form of heat and light, is called combustion. It is very important to use organic compounds, in particular, alkanes, as a fuel, since a large amount of heat is released during the free-radical combustion reaction:

CH 4 + 2O 2 \u003d CO 2 + 2H 2 O + 880 kJ.

With non-metals, oxygen usually reacts when heated, forming an oxide. So, the reaction with nitrogen begins only at temperatures above 1200 degrees or in an electric discharge:

Oxygen also reacts with metals:

3Fe + 2O 2 \u003d Fe 3 O 4 (as a result of the reaction, a compound is formed - iron oxide)

In nature, there is an even stronger oxidizing agent than oxygen, this is ozone. It is able to oxidize gold and platinum. Under natural conditions, ozone is formed from atmospheric oxygen during lightning discharges, and in the laboratory - by passing an electric discharge through oxygen: 3O 2 \u003d 2O 3 - 285 kJ (endothermic reaction)

Rice. 3. Ozone.

The most significant compound of oxygen is water. About 71% of the earth's surface is occupied by a water shell. The corner water molecules are polar, each of them forms four hydrogen bonds: two as a proton donor and two as a proton acceptor. (H 2 O)x associates are formed, where x varies from 2 to 5. Water vapor contains (H 2 O) 2 dimers, and in condensed phases, a water molecule can be in a tetrahedral environment of four other molecules. if water molecules were not associated, then its boiling point would not be 100 degrees, but about 80 degrees.

What have we learned?

Oxygen is a strong oxidizing agent and an active non-metal, so its study begins as early as grade 8. It is a colorless, odorless gas, but under certain conditions it can also be in liquid and solid states. It interacts with metals and non-metals, forming oxides, and also reacts with most simple substances.

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

Consideration 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 highest electronegativity, the smallest -, which is explained by a change in the value of 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 number R-elements, since they are being completed R-shell. For all elements of the family, except for oxygen itself, 6 electrons of the outer layer are valence.
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, along with this, positive oxidation states are also possible (maximum +6).
The oxygen molecule, like any simple gas, is diatomic, built according to the type of covalent bond formed by two electron pairs. Therefore, oxygen is divalent when a simple is formed.
Sulfur is a solid. The molecule contains 8 sulfur atoms (S8), but they are connected in a kind of ring, in which each sulfur atom is connected only with 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. Make a story about the oxygen group according to the following plan: a) position in the periodic system; b) nuclear charges and. the number of neutrons in the nucleus; c) electronic configurations; d) the structure of the crystal lattice; e) possible oxidation states of oxygen and all other elements of this group.
2. What are the similarities and differences in 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 the 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 the 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 able to form two simple ones - oxygen and ozone.
The formula of simple oxygen is O2, the formula of the simple substance of ozone is O3. Their molecules are built differently:

Oxygen and ozone are allotropic modifications of the element oxygen.
Sulfur can also form several allotropic modifications (modifications). Known rhombic (octahedral), plastic and monoclinic sulfur. Selenium and tellurium also form several allotropic modifications. 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 the 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 oxygen and ozone molecules?

Oxygen. Physical properties, physiological action, 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 on the p-orbitals, which can be easily 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 density of oxygen 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, reaching almost to the bottom of vessel 1 and serving to supply water to the device. Vessel 1 has three tubes: tube 3 with a ground inner surface is inserted, a funnel 2 with a tap, a gas outlet tube equipped with a tap is inserted into tube 4; tube 5 at the bottom serves to release water from the device when it is charging and discharging. In a charged gasometer vessel 1 is filled with oxygen. At the bottom of the vessel is located, into which the end of the tube of funnel 2 is lowered.

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

If you need to get oxygen from the gasometer, first open the funnel valve and slightly compress the oxygen in the gasometer. Then the valve on the gas outlet tube is opened, through which oxygen displaced by water escapes.

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 balloon

Write out from the text the names of devices designed to store 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 included in 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 a constituent of most organic substances.

The physiological significance of oxygen is enormous. It is the only gas that living organisms can use for respiration. The lack of oxygen causes the cessation of vital processes and the death of the organism. 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, carbon dioxide and other substances, are released. Both terrestrial and aquatic living organisms breathe oxygen: terrestrial - free oxygen of the atmosphere, and aquatic - oxygen dissolved in water.
In nature, a kind of oxygen cycle occurs. Oxygen from the atmosphere is absorbed by animals, plants, humans, is spent on the processes of fuel combustion, 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, that is, 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, reacting with simple and complex substances, usually behaves like.

Rice. 37.

The oxidation state that it acquires in this case is always -2. Many elements enter into direct interaction 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 they either do not burn or burn very weakly in air. burns in oxygen with a bright yellow flame; in this case, sodium peroxide is formed (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 out with the formation of 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, which is part of natural gas: CH4 + 2O2 = CO2 + 2H2O
Combustion in pure oxygen is much more intense than in air, and makes it possible to obtain significantly higher temperatures. This phenomenon is used to intensify a number of chemical processes and more efficient fuel combustion.
In the process of respiration, oxygen, combining with blood hemoglobin, forms oxyhemoglobin, which, being a very unstable compound, easily decomposes in tissues with the formation of free oxygen, which is used for oxidation. Rotting is also an oxidative process involving oxygen.
They recognize pure oxygen by introducing a smoldering splinter into the vessel, where its presence is expected. It flashes brightly - this is a qualitative 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 are non-combustible components?

Rice. 38. burning sodium Rice. 39. burning coal Rice. 40. Combustion of iron in oxygen.

12. Will 10 liters of oxygen be 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) metallic?
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 Bertolet salt KClO3:
2KMnO4 = K2MnO4 + MnO2 + O2

2KSlO3 = 2KSl + O2
When obtaining oxygen from Bertolet salt, a catalyst, manganese dioxide, must be present to accelerate the reaction. The catalyst accelerates decomposition and makes it more uniform. Without a catalyst

Rice. 41. A device for obtaining oxygen in a laboratory way from potassium permanganate. 1 - potassium permanganate; 2 - oxygen; 3 - cotton wool; 4 - cylinder - collection.

an explosion occurs if Bertolet 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 over water. Reflect this in the device diagram.
19. Sometimes, in the absence of manganese dioxide in the laboratory, a little residue is added to Bertolet's salt instead of it after calcination of potassium permanganate. Why is such a change possible?
20. What volume of oxygen will be released during the decomposition of 5 moles of Bertolet salt?

Oxygen can also be obtained by decomposition of nitrates when heated above the melting point:
2KNO3 = 2KNO2 + O2
In industry, oxygen is obtained mainly from liquid air. Translated into a liquid state, the air 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 almost in pure form.
Sometimes, in the presence of cheap electricity, oxygen is obtained by electrolysis of water:
H2O ⇄ H + + OH -
H++ e— → H 0
at the cathode
2OH — — e— → H2O + O; 2O = O2
at the anode

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

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

Rice. 42. The use of oxygen.

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

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

■ 25. Draw a table in your notebook and complete it.

Ozone O3

As already mentioned, the element oxygen can form another allotropic modification - ozone O3. Ozone boils at -111° and solidifies at -250°. It is blue in the gaseous state and blue in the liquid state. 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. In this regard, 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 the decay of ozone makes it a much stronger oxidizing agent than oxygen. Ozone has a fresh smell (“ozone” in translation means “odorous”). In nature, it is formed under the action of a quiet electric 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, bleeding from the nose. In chronic poisoning, heart disease can occur.
In the laboratory, ozone is obtained from oxygen in ozonizers (Fig. 44). Oxygen is passed into the glass tube 1, wound on the outside with wire 2. Wire 3 passes inside the tube. Both of these wires are connected to the poles of a current source that creates a high voltage on these electrodes. A quiet electrical discharge occurs between the electrodes, due to which ozone is formed from oxygen.

Figure 44; Ozonator. 1 - glass bottle; 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 is much more energetic than oxygen, enters into reactions and is generally much more active than oxygen. For example, unlike oxygen, it can displace from hydrogen iodide or iodine 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 the absorption of ultraviolet sunlight, so they fall on the ground in smaller quantities and do not have a detrimental 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 starch iodine paper turn blue when exposed to ozone? Give a reasoned answer.
28. Why is the oxygen molecule much more stable than the ozone molecule? Justify your answer in terms of intramolecular structure.
29. How to explain why ozone exhibits a stronger oxidizing effect than oxygen?

Article on the topic Oxygen physical properties

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The structure of the outer shell: 1 s 2 2s 2 2p 4, which suggests that it is easier for oxygen to attach 2 electrons to itself before filling the outer level than to give it away. Therefore, oxygen is an oxidizing agent.

Isotopes of oxygen.

There are 3 stable forms oxygen: 16 Oh, 17 Oh and 18 Oh, the average content of which is respectively 99.759%, 0.037% and 0.204% of the total number of atoms.

The most frequently occurring 16 ABOUT, since it is the lightest (consists of 8 protons and 8 electrons), which makes it very stable.

Physical properties of oxygen.

Methods for obtaining oxygen.

There are 4 ways to get oxygen:

1. Water electrolysis.

2. Industrial method: distillation of the air mixture (oxygen, as a heavier element, remains in the mixture, and nitrogen evaporates)

3. Laboratory methods for the decomposition of oxides, peroxides, salts:

2KMnO 4 \u003d K 2 MnO 4 + MnO 2 + O 2,

2BaO 2 \u003d 2BaO + O 2,

2KNO 3 \u003d 2KNO 2 + O 2.

4. From peroxides (used in space for regeneration O2 from carbon dioxide)

2 K2O 2 + 2CO2 = 2K2CO3+O 2.

Chemical properties of oxygen.

Reacts with metals already at room temperature:

2Ca + O 2 \u003d 2CaO,

2Mg + O 2 \u003d 2MgO,

With non-metals (when heated):

S + O 2 \u003d SO 2 (T=250°C),

C + O 2 = CO 2 (T=700°C),

O2 interacts with complex compounds:

2NO + O 2 \u003d 2NO 2,

2H 2 S + O 2 \u003d 2S + 2H 2 O,

Finding oxygen in nature.

Oxygen is the most common chemical element. Bound oxygen makes up about 6/7 of the mass of the Earth's water shell - the hydrosphere (85.82% by mass), almost half of the lithosphere (47% by mass), and only in the atmosphere, where oxygen is in a free state, does it take second place (23 .15% by weight) after nitrogen.

Oxygen forms a large number of minerals: silicates, quartz, iron oxides, carbonates, sulfates, nitrates. It is part of the cells of living organisms, participates in the processes of respiration, diffusion, blood flow, in the reaction of oxidation and reduction.

Oxygen is the main component of photosynthesis.