Four “chalcogen” elements (i.e., “giving birth to copper”) lead the main subgroup of group VI (according to the new classification - 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 enters chemical composition 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.
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.
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. The nitrogen that is obtained during separation 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 progress economic activity human oxygen is consumed in large quantities- for example, when burning various types 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 sunlight. As a result of this process, glucose is formed, which the plant then uses to build its tissues.
Oxygen is a chemical element of group VI of the periodic table of Mendeleev and the most common element in 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, air enriched with oxygen 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 chemical industry oxygen is used as a reactant.
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 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, diseases gastrointestinal tract. For these purposes, oxygen cocktails are used.
Also great importance have oxygen cushions - a rubberized container filled with oxygen. It is used for individual use of medical oxygen.
Rice. 3. Oxygen cushion
What have we learned?
This message, which covers the topic “Oxygen” in grade 9 chemistry, briefly provides general information about the properties and applications of this gas. Oxygen is extremely important for mechanical engineering, medicine, metallurgy, etc.
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Oxygen O has atomic number 8, located in the main subgroup (subgroup a) VI group, in the second period. In oxygen atoms, valence electrons are located on the 2nd energy level, which has only s- And p-orbitals. This excludes the possibility of transition of O atoms to an excited state, therefore oxygen in all compounds exhibits a constant valency equal to II. Having high electronegativity, oxygen atoms in compounds are always negatively charged (c.d. = -2 or -1). An exception is the fluorides OF 2 and O 2 F 2 .
For oxygen, the oxidation states are known -2, -1, +1, +2
General characteristics of the element
Oxygen is the most abundant element on Earth, accounting for slightly less than half, 49%, of the total mass of the earth’s crust. Natural oxygen consists of 3 stable isotopes 16 O, 17 O and 18 O (16 O predominates). Oxygen is part of the atmosphere (20.9% by volume, 23.2 by mass), in the composition of water and more than 1,400 minerals: silica, silicates and aluminosilicates, marbles, basalts, hematite and other minerals and rocks. Oxygen makes up 50-85% of the mass of tissues of plants and animals, as it is contained in proteins, fats and carbohydrates that make up living organisms. The role of oxygen for respiration and oxidation processes is well known.
Oxygen is relatively slightly soluble in water - 5 volumes in 100 volumes of water. However, if all the oxygen dissolved in water passed into the atmosphere, it would occupy a huge volume - 10 million km 3 (n.s.). This is equal to approximately 1% of all oxygen in the atmosphere. The formation of an oxygen atmosphere on earth is due to the processes of photosynthesis.
It was discovered by the Swede K. Scheele (1771 – 1772) and the Englishman J. Priestley (1774). The first used heating of nitrate, the second – mercury oxide (+2). The name was given by A. Lavoisier (“oxygenium” - “giving birth to acids”).
In its free form, it exists in two allotropic modifications - “ordinary” oxygen O 2 and ozone O 3 .
The structure of the ozone molecule
3O 2 = 2O 3 – 285 kJ
Ozone in the stratosphere forms a thin layer that absorbs most of the biologically harmful ultraviolet radiation.
During storage, ozone spontaneously turns into oxygen. Chemically, oxygen O2 is less active than ozone. The electronegativity of oxygen is 3.5.
Physical properties of oxygen
O 2 – colorless, odorless and tasteless gas, m.p. –218.7 °C, bp. –182.96 °C, paramagnetic.
Liquid O 2 blue, solid – of blue color. O 2 is soluble in water (better than nitrogen and hydrogen).
Obtaining oxygen
1. Industrial method - distillation of liquid air and electrolysis of water:
2H 2 O → 2H 2 + O 2 
2. In the laboratory oxygen is obtained:
1. Electrolysis of alkaline aqueous solutions or aqueous solutions of oxygen-containing salts (Na 2 SO 4, etc.)
2. Thermal decomposition of potassium permanganate KMnO 4:
2KMnO 4 = K 2 MnO4 + MnO 2 + O 2,
Berthollet salt KClO 3:
2KClO 3 = 2KCl + 3O 2 (MnO 2 catalyst)
Manganese oxide (+4) MnO 2:
4MnO 2 = 2Mn 2 O 3 + O 2 (700 o C),
3MnO 2 = 2Mn 3 O 4 + O 2 (1000 o C),
Barium peroxide BaO 2:
2BaO2 = 2BaO + O2
3. Decomposition of hydrogen peroxide:
2H 2 O 2 = H 2 O + O 2 (MnO 2 catalyst)
4. Decomposition of nitrates:
2KNO 3 → 2KNO 2 + O 2
On spaceships and submarines, oxygen is obtained from a mixture of K 2 O 2 and K 2 O 4:
2K 2 O 4 + 2H 2 O = 4KOH +3O 2
4KOH + 2CO 2 = 2K 2 CO 3 + 2H 2 O
Total:
2K 2 O 4 + 2CO 2 = 2K 2 CO 3 + 3O 2
When K 2 O 2 is used, the overall reaction looks like this:
2K 2 O 2 + 2CO 2 = 2K 2 CO 3 + O 2
If you mix K 2 O 2 and K 2 O 4 in equal (i.e., equimolar) quantities, then one mole of O 2 will be released per 1 mole of absorbed CO 2.
Chemical properties of oxygen
Oxygen supports combustion. Combustion - b
a rapid process of oxidation of a substance, accompanied by the release of a large amount of heat and light.
To prove that the flask contains oxygen and not some other gas, you need to lower a smoldering splinter into the flask. In oxygen, a smoldering splinter flashes brightly. The combustion of various substances in air is a redox process in which oxygen is the oxidizing agent. Oxidizing agents are substances that “take away” electrons from reducing substances. The good oxidizing properties of oxygen can be easily explained by the structure of its outer electron shell.
The valence shell of oxygen is located at the 2nd level - relatively close to the core. Therefore, the nucleus strongly attracts electrons to itself. On the valence shell of oxygen 2s 2 2p 4 there are 6 electrons. Consequently, the octet lacks two electrons, which oxygen tends to accept from the electron shells of other elements, reacting with them as an oxidizing agent.
Oxygen has the second (after fluorine) electronegativity on the Pauling scale. Therefore, in the vast majority of its compounds with other elements, oxygen has negative degree of oxidation. The only stronger oxidizing agent than oxygen is its neighbor in the period, fluorine. Therefore, compounds of oxygen with fluorine are the only ones where oxygen has a positive oxidation state.
So, oxygen is the second most powerful oxidizing agent among all the elements of the Periodic Table. Most of its most important chemical properties are associated with this.
All elements react with oxygen except Au, Pt, He, Ne and Ar; in all reactions (except for the interaction with fluorine), oxygen is an oxidizing agent.
Oxygen easily reacts with alkali and alkaline earth metals:
4Li + O 2 → 2Li 2 O,
2K + O 2 → K 2 O 2,
2Ca + O 2 → 2CaO,
2Na + O 2 → Na 2 O 2,
2K + 2O 2 → K 2 O 4
Fine iron powder (the so-called pyrophoric iron) spontaneously ignites in air, forming Fe 2 O 3, and steel wire burns in oxygen if it is heated in advance:
3 Fe + 2O 2 → Fe 3 O 4
2Mg + O 2 → 2MgO
2Cu + O 2 → 2CuO
Oxygen reacts with non-metals (sulfur, graphite, hydrogen, phosphorus, etc.) when heated:
S + O 2 → SO 2,
C + O 2 → CO 2,
2H 2 + O 2 → H 2 O,
4P + 5O 2 → 2P 2 O 5,
Si + O 2 → SiO 2, etc.
Almost all reactions involving oxygen O2 are exothermic, with rare exceptions, for example:
N2+O2 → 2NO–Q
This reaction occurs at temperatures above 1200 o C or in an electrical discharge.
Oxygen is capable of oxidizing complex substances, for example:
2H 2 S + 3O 2 → 2SO 2 + 2H 2 O (excess oxygen),
2H 2 S + O 2 → 2S + 2H 2 O (lack of oxygen),
4NH 3 + 3O 2 → 2N 2 + 6H 2 O (without catalyst),
4NH 3 + 5O 2 → 4NO + 6H 2 O (in the presence of a Pt catalyst),
CH 4 (methane) + 2O 2 → CO 2 + 2H 2 O,
4FeS 2 (pyrite) + 11O 2 → 2Fe 2 O 3 + 8SO 2.
Compounds containing the dioxygenyl cation O 2 + are known, for example, O 2 + - (the successful synthesis of this compound prompted N. Bartlett to try to obtain compounds of inert gases).
Ozone
Ozone is chemically more active than oxygen O2. Thus, ozone oxidizes iodide - I ions - in a Kl solution:
O 3 + 2Kl + H 2 O = I 2 + O 2 + 2KOH
Ozone is highly toxic and poisonous properties stronger than, for example, hydrogen sulfide. However, in nature, ozone contained in high layers of the atmosphere acts as a protector of all life on Earth from the harmful ultraviolet radiation of the sun. The thin ozone layer absorbs this radiation and it does not reach the Earth's surface. There are significant fluctuations in the thickness and extent of this layer over time (the so-called ozone hole); the reasons for such fluctuations have not yet been clarified.
Application of Oxygen O 2: to intensify the processes of producing cast iron and steel, in the smelting of non-ferrous metals, as an oxidizer in various chemical industries, for life support on submarines, as an oxidizer for rocket fuel (liquid oxygen), in medicine, in welding and cutting metals.
Application of ozone O 3: for disinfection drinking water, wastewater, air, for bleaching fabrics. 
Lecture “Oxygen – a chemical element and a simple substance »
Lecture outline:
1. Oxygen is a chemical element:
c) The prevalence of a chemical element in nature
2. Oxygen is a simple substance
a) Obtaining oxygen
b) Chemical properties of oxygen
c) The oxygen cycle in nature
d) Use of oxygen
"Dum spiro spero
"(While I breathe, I hope...), says the Latin
Breathing is synonymous with life, and the source of life on Earth is oxygen.
Emphasizing the importance of oxygen for earthly processes, Jacob Berzelius said: “Oxygen is the substance around which earthly chemistry revolves.”The material in this lecture summarizes previously acquired knowledge on the topic “Oxygen”.
1. Oxygen is a chemical element
a) Characteristics of the chemical element - oxygen according to its position in the PSCE
Oxygen - an element of the main subgroup of the sixth group, the second period of the periodic system of chemical elements of D. I. Mendeleev, with atomic atomic number 8. Denoted by the symbol O(lat.Oxygenium). The relative atomic mass of the chemical element oxygen is 16, i.e. Ar(O)=16.
b) Valence possibilities of the oxygen atom
In compounds, oxygen is usually divalent (in oxides), valence VI does not exist. In free form, it is found in the form of two simple substances: O 2 (“ordinary” oxygen) and O 3 (ozone). O 2 is a colorless and odorless gas with a relative molecular weight = 32. O 3 is a colorless gas with a pungent odor, with a relative molecular weight = 48.
Attention! H2O2( hydrogen peroxide) - O (valence II)
CO (carbon monoxide) – O (valency III)
c) The prevalence of the chemical element oxygen in nature
Oxygen is the most common element on Earth; its share (in various compounds, mainly silicates) accounts for about 49% of the mass of the solid earth's crust. Sea and fresh waters contain a huge amount of bound oxygen - 85.5% (by mass), in the atmosphere the content of free oxygen is 21% by volume and 23% 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 20%, and in terms of mass fraction - about 65%.
2. Oxygen is a simple substance
a) Obtaining oxygen
Obtained in the laboratory
1) Decomposition of potassium permanganate (potassium permanganate):
2KMnO 4 t˚C =K 2 MnO 4 +MnO 2 +O 2
2) Decomposition of hydrogen peroxide:
2H 2 O 2 MnO2 = 2H 2 O + O 2
3) Decomposition of Berthollet salt:
2KClO 3 t˚C, MnO2 = 2KCl + 3O 2
Receipt in industry
1) Electrolysis of water
2 H 2 O el. current =2 H 2 + O 2
2) From thin air
AIR pressure, -183˚ C = O 2 (blue liquid)
Currently, in industry, oxygen is obtained from the air. In laboratories, small amounts of oxygen can be obtained by heating potassium permanganate (potassium permanganate) KMnO 4 . Oxygen is slightly soluble in water and is heavier than air, so it can be obtained in two ways:
1. The concept of circulation
There is a constant exchange of chemical elements between the lithosphere, hydrosphere, atmosphere and living organisms of the Earth. This process is cyclical: having moved from one sphere to another, the elements return to their original state. The cycle of elements has taken place throughout the history of the Earth, which spans 4.5 billion years.
The cycle of substances is a repeatedly repeated process of joint, interconnected transformation and movement of substances in nature, which is more or less cyclical. The general circulation of substances is characteristic of all geospheres and consists of individual processes of the circulation of chemical elements, water, gases and other substances. The circulation processes are not completely reversible due to the dispersion of substances, changes in its composition, local concentration and deconcentration.
To substantiate and explain the very concept of a cycle, it is useful to refer to the four most important principles of geochemistry, which are of paramount applied importance and confirmed by indisputable experimental data:
a) widespread distribution of chemical elements in all geospheres;
b) continuous migration (movement) of elements in time and space;
c) the variety of types and forms of existence of elements in nature;
d) the predominance of the dispersed state of elements over the concentrated state, especially for ore-forming elements.
Most of all, in my opinion, it is worth focusing on the process of moving chemical elements.
The migration of chemical elements is reflected in the gigantic tectonic-magamtic processes that transform the earth's crust, and in the finest chemical reactions occurring in living matter, in the continuous progressive development of the surrounding world, characterizing movement as a form of existence of matter. The migration of chemical elements is determined by numerous external factors, in particular, the energy of solar radiation, the internal energy of the Earth, the action of gravity and internal factors depending on the properties of the elements themselves.
Cycles can occur in a limited space and over short periods of time, or they can cover the entire outer part of the planet and huge periods. At the same time, small cycles are included in larger ones, which together form colossal biogeochemical cycles. They are closely related to the environment.
Gigantic masses chemical substances transported by the waters of the World Ocean. This primarily applies to dissolved gases - carbon dioxide, oxygen, nitrogen. Cold water high latitudes dissolves atmospheric gases. Acting with ocean currents in the tropical zone, it releases them, since the solubility of gases decreases when heated. The absorption and release of gases also occurs during the change of warm and cold seasons of the year.
The emergence of life on the planet had a huge impact on the natural cycles of some elements. This, first of all, refers to the circulation of the main elements of organic matter - carbon, hydrogen and oxygen, as well as such vital elements as nitrogen, sulfur and phosphorus. Living organisms also influence the cycle of many metal elements. Despite the fact that the total mass of living organisms on Earth is millions of times less than the mass of the earth's crust, plants and animals play a vital role in the movement of chemical elements. There is a law of global closure of the biogeochemical cycle in the biosphere, which operates at all stages of its development, as well as the rule of increasing closure of the biogeochemical cycle during succession (succession (from the Latin succesio - continuity) - a sequential change of ecosystems that successively arise on a certain area of the earth's surface. Usually succession occurs under the influence of processes of internal development of communities, their interaction with the environment. The duration of succession ranges from tens to millions of years). In the process of biosphere evolution, the role of the biological component in closing the biogeochemical cycle increases.
Human activities also influence the cycle of elements. It has become especially noticeable in the last century. When considering the chemical aspects of global changes in chemical cycles, one must consider not only changes in natural cycles due to the addition or removal of chemicals present in them as a result of normal cycling and/or human-induced impacts, but also inputs into environment chemicals that previously did not exist in nature.
The cycles of elements and substances are carried out due to self-regulating processes in which all components of ecosystems participate. These processes are waste-free. There is nothing useless or harmful in nature; even volcanic eruptions have benefits, since the necessary elements, for example, nitrogen and sulfur, are released into the air with volcanic gases.
There are two main cycles: large (geological) and small (biotic).
The great cycle, which continues for millions of years, consists in the fact that rocks are destroyed, and weathering products (including water-soluble nutrients) are carried by water flows into the World Ocean, where they form marine strata and only partially return to land with precipitation . Geotectonic changes, the processes of continental subsidence and seabed rise, the movement of seas and oceans over a long period of time lead to the fact that these strata return to land and the process begins again.
The small cycle, being part of the large one, occurs at the ecosystem level and consists in the fact that nutrients, water and carbon accumulate in the substance of plants, are spent on building the body and on the life processes of both the plants themselves and other organisms (usually animals) who eat them. The decay products of organic matter under the influence of decomposers and microorganisms (bacteria, fungi, worms) again decompose into mineral components that are accessible to plants and are drawn into the flow of matter by them.
Thus, the circulation of chemicals from the inorganic environment through plant and animal organisms back into the inorganic environment using solar energy and the energy of chemical reactions is called the biogeochemical cycle. Almost all chemical elements are involved in such cycles, and primarily those that participate in the construction of a living cell.
2. Oxygen cycle in nature
2.1 General information about oxygen element
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):
2HgO(t)→ 2Hg + O2
However, Priestley initially did not realize that he had discovered a new simple substance. He believed that he had isolated one of the constituents of air (and called this gas “dephlogisticated air”). Priestley reported his discovery to the outstanding French chemist Antoine Lavoisier.
A few years earlier (possibly in 1770), 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 stage that contributed to the discovery of oxygen was the work of the French chemist Peter Bayen, who published works on the oxidation of mercury and the subsequent decomposition of its oxide.
Finally, Antoine 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 that was dominant at that time and hampered the development of chemistry was overthrown (phlogiston (from the Greek phlogistos - combustible, flammable) - a hypothetical “fiery substance” that supposedly fills all combustible substances and is released from them when burning). Lavoisier conducted experiments on the combustion of various substances and disproved the theory of phlogiston, publishing results on the weight of the elements burned. The weight of the ash exceeded the original weight of the element, which gave Lavoisier the right to claim that during combustion chemical reaction(oxidation) of the substance, in connection with this the mass of the original substance increases, which refutes the theories of phlogiston.
Thus, the credit for the discovery of oxygen is actually shared between Priestley, Scheele and Lavoisier.
Origin of name. The name oxygenium (“oxygen”) comes from Greek words, meaning “acid-generating”; this is due to the original meaning of the term "acid". Previously, this term was used to refer to oxides.
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). The element oxygen is part of more than 1,500 compounds in the earth's crust.
Physical properties. Under normal conditions, the density of oxygen gas is 1.42897 g/l. The boiling point of liquid oxygen (the liquid is blue) is -182.9 °C. In the solid state, oxygen exists in at least three crystalline modifications. At 20°C, the solubility of O2 gas is: 3.1 ml per 100 ml of water, 22 ml per 100 ml of ethanol, 23.1 ml per 100 ml of acetone. There are organic fluorine-containing liquids (for example, perfluorobutyltetrahydrofuran), in which the solubility of oxygen is much higher.
Chemical properties element are determined by its electronic configuration: 2s22p4. The high strength of the chemical bond between the atoms in the O2 molecule leads to the fact that at room temperature oxygen gas is chemically quite inactive. In nature, it slowly undergoes transformation during decay processes. In addition, oxygen at room temperature is able to react with hemoglobin in the blood (more precisely with iron (II) heme (heme is a derivative of porphyrin containing a divalent iron atom in the center of the molecule), which ensures the transfer of oxygen from the respiratory organs to other organs.
Oxygen reacts with many substances without heating, for example, with alkali and alkaline earth substances, causing the formation of rust on the surface of steel products. Without heating, oxygen reacts with white phosphorus, with some aldehydes and other organic substances.
When heated, even slightly, the chemical activity of oxygen increases sharply. When ignited, it reacts explosively with hydrogen, methane, other flammable gases, a large number simple and complex substances. It is known that when heated in an oxygen atmosphere or in air, many simple and complex substances burn, and various oxides, peroxides and superoxides are formed, such as SO2, Fe2O3, H2O2, BaO2, KO2.
If a mixture of oxygen and hydrogen is stored in a glass vessel at room temperature, then the exothermic reaction to form water
2H2 + O2 = 2H2 O + 571 kJ
proceeds extremely slowly; According to calculations, the first drops of water should appear in the vessel in about a million years. But when platinum or palladium (playing the role of a catalyst) is introduced into a vessel with a mixture of these gases, as well as when ignited, the reaction proceeds with an explosion.
Oxygen reacts with nitrogen N2 either at high temperature (about 1500-2000 °C), or by passing an electric discharge through a mixture of nitrogen and oxygen. Under these conditions, nitric oxide (II) is reversibly formed:
The resulting NO then reacts with oxygen to form brown gas (nitrogen dioxide):
2NO + O2 = 2NO2
Of non-metals, oxygen does not directly interact with halogens under any circumstances, and of metals - with silver, gold, platinum and platinum group metals.
With the most active nonmetal fluorine, oxygen forms compounds in positive oxidation states. Thus, in the O2 F2 compound the oxidation state of oxygen is +1, and in the O2 F compound it is +2. These compounds do not belong to oxides, but to fluorides. Oxygen fluorides can be synthesized only indirectly, for example, by the action of fluorine F2 on dilute aqueous solutions of KOH.
Application. The uses of oxygen are very diverse. The main quantities of oxygen obtained from the air are used in metallurgy. Oxygen (rather than air) blast in blast furnaces can significantly increase the speed of the blast furnace process, save coke and produce cast iron best quality. Oxygen blast is used in oxygen converters when converting cast iron into steel. Pure oxygen or air enriched with oxygen is used in the production of many other metals (copper, nickel, lead, etc.). Oxygen is used in cutting and welding metals. In this case, compressed gaseous oxygen is used, stored under a pressure of 15 MPa in special steel cylinders. Oxygen cylinders are painted blue to distinguish them from cylinders with other gases.
Liquid oxygen is a powerful oxidizing agent and is used as a component of rocket fuel. A mixture of liquid oxygen and liquid ozone is one of the most powerful oxidizers of rocket fuel. Easily oxidizing materials such as sawdust, cotton wool, coal powder, etc., impregnated with liquid oxygen (these mixtures are called oxyliquits), are used as explosives, used, for example, in laying roads in the mountains.
oxygen cycle chemical element
2.2 Oxygen cycle
Oxygen is the most abundant element on Earth. IN sea water contains 88.8% oxygen, in atmospheric air 23.15% by weight or 20.95% by volume, and in the earth's crust 47.4% by weight.
The indicated oxygen concentration in the atmosphere is maintained constant due to the process of photosynthesis (Fig. 1). In this process, green plants, when exposed to sunlight, convert carbon dioxide and water into carbohydrates and oxygen:
6CO2 + 6H2 O + light energy = C6 H12 O6 + 6O2
Above is the summary equation for photosynthesis; in fact, oxygen is released into the atmosphere at its first stage - during the process of photolysis of water.
Along with the, powerful source oxygen is apparently the photochemical decomposition of water vapor in the upper layers of the atmosphere under the influence of ultraviolet rays of the sun.
Fig.1. Conditional diagram of photosynthesis.
Oxygen is the main biogenic element that is part of the molecules of all the most important substances that provide the structure and function of cells - proteins, nucleic acids, carbohydrates, lipids, as well as many low-molecular compounds. Every plant or animal contains much more oxygen than any other element (on average about 70%). Human muscle tissue contains 16% oxygen, bone tissue - 28.5%; In total, the body of an average person (body weight 70 kg) contains 43 kg of oxygen. Oxygen enters the body of animals and humans mainly through the respiratory organs (free oxygen) and with water ( bound oxygen). The body's need for oxygen is determined by the level (intensity) of metabolism, which depends on the mass and surface of the body, age, gender, nature of nutrition, external conditions, etc. In ecology, the ratio of total respiration (that is, total oxidative processes) of a community is determined as an important energy characteristic organisms to its total biomass.
In natural life, oxygen is of exceptional importance. Oxygen and its compounds are indispensable for maintaining life. They play a vital role in metabolic processes and respiration. Most organisms obtain the energy necessary to perform their vital functions through the oxidation of certain substances with the help of oxygen. The loss of oxygen in the atmosphere as a result of the processes of respiration, decay and combustion is compensated by oxygen released during photosynthesis.
A small amount of atmospheric oxygen participates in the cycle of formation and destruction of ozone under strong ultraviolet radiation:
O2 * + O2 → O3 + O
Most of the oxygen produced during geological epochs did not remain in the atmosphere, but was fixed by the lithosphere in the form of carbonates, sulfates, iron oxides, etc.
The geochemical oxygen cycle connects the gas and liquid shells with the earth's crust. Its main points: the release of free oxygen during photosynthesis, the oxidation of chemical elements, the entry of extremely oxidized compounds into the deep zones of the earth's crust and their partial reduction, including due to carbon compounds, the removal of carbon monoxide and water to the surface of the earth's crust and their involvement in the reaction photosynthesis. A diagram of the oxygen cycle in unbound form is presented below.
Fig.2. Diagram of the oxygen cycle in nature.
In addition to the oxygen cycle described above in an unbound form, this element also completes the most important cycle, entering the composition of water (Fig. 3). During the cycle, water evaporates from the surface of the ocean, water vapor moves along with air currents, condenses, and water returns in the form of precipitation to the surface of land and sea. There is a large water cycle, in which water that falls as precipitation on land returns to the seas through surface and underground runoff; and the small water cycle, which deposits precipitation on the ocean surface.
From the given examples of cycles and migration of an element, it is clear that the global system of cyclic migration of chemical elements has a high ability for self-regulation, while the biosphere plays a huge role in the cycle of chemical elements.
Oxygen is the most abundant element in the earth's crust. In the atmosphere it is about 23% (mass), in water - about 89%, in the human body - about 65%, in sand there is 53% oxygen, in clay - 56%, etc. If we calculate its amount in the air (atmosphere), water (hydrosphere) and the part of the solid earth’s crust accessible to direct chemical research (lithosphere), it turns out that oxygen accounts for approximately 50% of their total mass.
Oxygen cycle in nature. The use of oxygen, its biological role
Free oxygen is found almost exclusively in the atmosphere, and its quantity is estimated in tons. Despite the enormity of this value, it does not exceed 0.0001 of the total oxygen content in the earth's crust.
In a bound state, oxygen is part of almost all substances around us.
For example, water, sand, many rocks and minerals found in the earth's crust contain oxygen. Oxygen is integral part many organic compounds, such as proteins, fats and carbohydrates, which are extremely important in the life of plants, animals and humans.
The oxygen cycle in nature is the process of oxygen exchange that occurs between the atmosphere, hydrosphere and lithosphere. The main source of oxygen renewal on Earth is photosynthesis, a process that occurs in plants due to their absorption of carbon dioxide.
Dissolved oxygen in water is absorbed by aquatic life forms through respiration.
Oxygen cycle– a planetary process that connects the atmosphere, hydro- and lithosphere through the combined activity of living organisms.
Main stages of the cycle˸
1) production of oxygen during photosynthesis by photoautotrophs of land and ocean;
2) production of oxygen during the dissociation of H2O and O3 in the upper layers of the atmosphere under the influence of ionizing and ultraviolet radiation (insignificant amount);
3) consumption of O2 during the respiration of living organisms;
4) oxygen consumption during soil respiration (oxidation of organic matter by soil microorganisms);
5) consumption of O2 during combustion and other forms of oxidation (volcanic eruptions);
6) oxygen consumption for O3 production in the stratosphere;
7) participation in oceanic transformations of hydrocarbonates in the composition of CO2 and H2O˸
All O2 completely passes through living organisms in 2,000 years.
The annual production of oxygen by the Earth's photosynthetics is approximately 240 billion tons. In the ocean, there is much more oxygen in dissolved form, just like CO2, than in the atmosphere (from 2 to 8 g/l). Some of the organic matter is buried, so some of the oxygen is removed from the cycle.
There are several biosphere problems associated with the circulation of oxygen in the atmosphere.
1) burning fossil fuels wastes a huge amount of oxygen.
The total annual consumption of oxygen on Earth is 230 billion tons, 2.6 billion tons are used for the respiration of plants and animals, soil oxidation is 50 billion tons, and the rest is combustion processes. Taking into account the rapid deforestation on the planet and the increasing pace of industrialization, it is natural that in the future there will be a further increase in consumption and a decrease in O2 production.
2) as a result of human activity, hundreds of substances enter the atmosphere, many of which are greenhouse gases and destroyers of the ozone layer of the stratosphere. For example, the ozone layer is destroyed when chlorine and nitrogen enter the atmosphere.
In the stratosphere, under the influence of hard ionizing radiation (less than 242 nm), O2 molecules disintegrate into atoms, which combine with O2 molecules and form ozone (O3).
As a result, a layer is formed that is impenetrable to ultraviolet A (< 280 нм), В (280 < <315 нм) и задерживающий большую часть ультрафиолета С (315 < 400 нм).
When ozone absorbs UV radiation quanta, thermal energy is released, due to which the stratosphere heats up.
The thickness of the ozone layer is measured in Dobson units (100 DU = 0.1 cm at normal atmospheric pressure).
There is more ozone at the poles (301.6 DU) than at the equator, but the thickness of the troposphere is greater at the equator. Ozone concentration and life expectancy are different at different altitudes and vary depending on the time of day and season. Each altitude has its own sources of ozone and its own sinks, and the exchange of ozone masses also occurs between different latitudes. In general, estimating atmospheric ozone circulation is a very labor-intensive process with only approximate actual results.
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Unlike carbon, the reservoirs of oxygen available to biota are enormous compared to its flows.
Therefore, the problem of global O2 deficiency and the closedness of its cycle disappears. The biotic oxygen cycle is 270 Gt/year. Oxygen on Earth is the first in… [read more].
26). Besides,…
Describe in DETAIL the oxygen cycle in nature.
It was not always part of the earth's atmosphere. It appeared as a result of the vital activity of photosynthetic organisms and, under the influence of ultraviolet rays, was converted into ozone.
As ozone accumulated, an ozone layer formed in the upper atmosphere. … [read more].
Atmospheric oxygen is of biogenic origin and its circulation of oxygen in the biosphere is carried out by replenishing reserves in the atmosphere as a result of photosynthesis of plants and absorption during the respiration of organisms and the combustion of fuel in the human economy (Fig.
Oxygen is the most common element, without which life on Earth is not possible. It makes up 47.2% of the mass of the earth's crust in the form of metal and non-metal oxides.
Oxygen cycle: Oxygen plays a vital role in the lives of most living organisms on our planet. Everyone needs it to breathe. Oxygen was not always part of the earth's atmosphere. It appeared as a result of the vital activity of photosynthetic organisms.
About a quarter of the atoms of all living matter are oxygen. Since the total number of oxygen atoms in nature is constant, as oxygen is removed from the air due to respiration and other processes, it must be replenished. The most important sources of oxygen in inanimate nature are carbon dioxide and water. Oxygen enters the atmosphere mainly through the process of photosynthesis, which involves CO2.
An important source of oxygen is the Earth's atmosphere.
Some of the oxygen is formed in the upper parts of the atmosphere due to the dissociation of water under the influence of solar radiation. Some of the oxygen is released by green plants during photosynthesis with H2O and CO2.
In turn, atmospheric CO2 is formed as a result of combustion reactions and respiration of animals. Atmospheric O2 is spent on the formation of ozone in the upper parts of the atmosphere, the oxidative processes of rock weathering, during the respiration of animals and in combustion reactions.
The conversion of V2 to CO2 leads to the release of energy; accordingly, energy must be spent on the conversion of CO2 to O2.
Features of the circulation of water and some substances in the biosphere
This energy turns out to be the Sun. Thus, life on Earth depends on cyclic chemical processes made possible by solar energy.
The use of oxygen is due to its chemical properties. Oxygen is widely used as an oxidizing agent. It is used for welding and cutting metals, in the chemical industry - to obtain various compounds and intensify some production processes.
In space technology, oxygen is used to burn hydrogen and other types of fuel, in aviation - when flying at high altitudes, in surgery - to support patients with difficulty breathing.
The biological role of oxygen is determined by its ability to support respiration.
When breathing for one minute, a person consumes on average 0.5 dm3 of oxygen, during a day - 720 dm3, and during a year - 262.8 m3 of oxygen.
Oxygen cycle in nature
Tasks “C” Unified State Examination_ 2007 – C 4
What is the adaptation of flowering plants to living together in a forest community? Provide at least 3 examples.
1) tiered arrangement, ensuring the use of light by plants;
2) non-simultaneous flowering of wind-pollinated and insect-pollinated plants;
Name at least 3 differences in the structure of prokaryotic and eukaryotic cells.
1) the nuclear substance is not separated from the cytoplasm by a membrane;
2) one circular DNA molecule – nucleoid;
3) most organelles are missing, except ribosomes.
What changes in the meadow ecosystem could a decrease in the number of pollinating insects lead to?
1) reduction in the number of insect-pollinated plants, changes in the species composition of plants;
2) reduction in the number and change in the species composition of herbivorous animals;
3) reduction in the number of insectivorous animals.
What consequences can various types of anthropogenic impact on the environment lead to?
Give at least 4 consequences.
1) burning fuel leads to the accumulation of CO 2 in the atmosphere and the greenhouse effect;
2) the work of industrial enterprises contributes to environmental pollution with solid waste (dust particles), gaseous products (nitrogen oxides, etc.), which causes acid rain;
3) the use of freons leads to the formation of ozone holes and the penetration of ultraviolet rays, which have a detrimental effect on all living things;
4) deforestation, drainage of swamps, plowing of virgin lands lead to desertification.
In recent years, thanks to advances in biotechnology, a new food source has become available: protein derived from microorganisms.
What are the advantages of using microorganisms to produce protein compared to the traditional use of crops and animals for this purpose?
1) large areas for crops and housing for livestock are not required, which reduces energy costs;
2) microorganisms are grown on cheap or by-products of agriculture or industry;
3) with the help of microorganisms it is possible to obtain proteins with specified properties (for example, feed proteins).
Modern lobe-finned fish are in a state of biological regression.
Provide data confirming this phenomenon.
1) low abundance of the species: currently only one species of these fish is known - coelacanth;
2) small area of distribution: coelacanth has a limited distribution in the Indian Ocean;
3) coelacanth is adapted to life only at a certain depth, i.e.
she is a highly specialized species.
Give at least 3 changes in a mixed forest ecosystem that could result from a reduction in the number of insectivorous birds.
1) increase in the number of insects;
2) reducing the number of plants eaten and damaged by insects;
3) reduction in the number of predatory animals that feed on insectivorous birds.
The biological progress of mammals was accompanied by the appearance of many particular adaptations – idioadaptations.
Give at least 3 idioadaptations in the external structure that allow moles to successfully lead an underground burrowing lifestyle. Explain your answer.
1) shovel-shaped forelimbs adapted for digging; 2) absence of ears;
3) short coat does not interfere with movement in the soil.
Explain what features of the forelimbs of primates contributed to the development of the hand for tool activity during anthropogenesis.
1) forelimb of the grasping type, opposable thumb;
2) the presence of nails: the fingertips are open and have greater tactile sensitivity;
3) the presence of a clavicle, which provides a variety of movements of the forelimb.
What aromorphoses allowed mammals to spread widely on Earth?
1) warm-bloodedness due to a 4-chambered heart, alveolar lungs, and hair;
2) intrauterine development, feeding the young with milk;
3) a high level of organization of the central nervous system, complex forms of behavior.
Various methods are used to control agricultural and forestry pests.
Give at least 3 advantages of using biological methods over chemical ones.
1) biological methods are harmless and environmentally friendly, as they are based on attracting natural enemies of pests;
2) chemicals also poison beneficial insects, pollute the soil, are absorbed by plants growing on it, and, consequently, contaminate possible human food products; 3) the use of biological methods of pest control contributes to the conservation of biological diversity of nature or the regulation of one type of pest.
In nature, the oxygen cycle occurs.
What role do living organisms play in this process?
1) oxygen is formed in plants during photosynthesis and released into the atmosphere;
2) in the process of respiration, oxygen is used by living organisms; 3) in the cells of living organisms, oxygen participates in redox processes of energy metabolism with the formation of water and carbon dioxide.
1) living in the host’s body, protection from adverse conditions, food supply, and absence of enemies contributed to the reduction of some organ systems and the formation of a highly developed reproductive system;
2) dense integument of the body prevents its digestion, and the organs of attachment are retained in the host’s body;
3) self-fertilization, high fertility, and a complex development cycle allow it to disperse widely.
What features in body structure are common only to humans and apes?
1) the presence of nails instead of claws;
2) the presence of a coccyx and the absence of a tail;
3) the same dental system;
4) similar shape of ears, face without continuous hair.
The impact of motor transport on humans and the environment
1.3.1 Concept of noise
Noise is any sound that is unwanted by humans. Under normal atmospheric conditions, the speed of sound in air is 344 m/s. A sound field is a region of space in which sound waves travel...
Air envelope of the Earth
9.
Concept of climate
Climate is the long-term weather pattern characteristic of a given area. Climate influences the regime of rivers, the formation of various types of soils, vegetation and fauna. So, in areas where the earth's surface receives a lot of heat and moisture...
Genetically modified organisms and genetically modified products
1.
A genetically modified organism (GMO) is an organism whose genotype has been artificially changed using genetic engineering methods. This definition can be applied to plants, animals and microorganisms. Genetic changes...
Patterns of self-purification of water in water bodies
1.1 Concept of EIA
So far, the only current Russian regulatory document regulating environmental impact assessment (EIA) is the Regulation “On Environmental Impact Assessment in the Russian Federation” (approved.
Oxygen cycle
by order of the Russian Ministry of Natural Resources dated 18...
Cycle of matter and energy in nature
1.1 Circles of the cycle of substances
Solar energy on Earth causes two cycles of substances: · large (geological), most clearly manifested in the water cycle and atmospheric circulation. · small, biological (biotic)…
Phosphorus cycle
2. Make a diagram of the cycle and show the movement of phosphorus-containing compounds
Write an explanatory text for the diagram and answer the questions: 1.
Which phase does not exist in the phosphorus cycle? 2. Where can phosphorus accumulate? 3…
Lapland State Nature Reserve: ecological condition and health improvement measures
7. Mechanisms of substance circulation
The circulation of substances in biogeocenosis is a necessary condition for the existence of life.
It arose in the process of the formation of life and became more complex during the evolution of living nature. On the other hand, in order for the circulation of substances to be possible in the biogeocenosis...
Relationships of organisms in agricultural systems
4. Features of the cycle of substances in agroecosystems
Mass and energy exchange on the planet includes various processes of material and energy transformations and movements in the lithosphere, hydrosphere, and atmosphere.
With the advent of life, these cycles and flows intensified...
Legal protection of waters
2.1.1. The concept of “water use”
In relation to the numerous and varied specific social relations that arise in the process of using natural water reserves, the concept of “water use” acts as one collective, generalizing concept.
It should be noted...
Legal basis for licensing in the field of environmental protection
1.1 Concept of licensing
Licensing is a procedure for issuing a permit to a particular entity for the right to engage in a certain activity, which reflects the terms and conditions for the implementation of such activity. Vinokurov A.Yu...
Air pollution problem
1.1 The concept of geospheres
The biosphere is the living shell of the planet Earth. The biosphere is the totality of those layers of the Earth that, throughout its geological history, have been exposed to the influence of organisms.
Studying the biosphere as a special shell of the globe...
Solving the problem of carbon sequestration at the state and interstate levels
Chapter 2. Impact of the carbon cycle on global climate
The current level of violations of environmental conditions and balances on Earth
The concept of environmental management
At present, when a person, at a high level of development of science and productive forces, through his activities radically changes the components of nature, the problem of coexistence of man (human society) and nature arises...
Man as a biological and social organism of nature
2.
Participation of organisms in the cycle of matter and energy. The problem of disruption of the cycle of substances in the biosphere
The main function of the biosphere is to ensure the cycle of chemical elements, which is expressed in the circulation of substances between the atmosphere, soil, hydrosphere and living organisms...
Ecological system
3.
Draw and discuss a model of the biotic (biological) cycle of biogenic substances with the participation of producers, consumers, and decomposers. Explain the names of organisms and their role in the cycle
Rice. Model of the biotic (biological) cycle of biogenic substances with the participation of producers, consumers, and decomposers. The biotic cycle is ensured by the interaction of three main groups of organisms: 1) producers - green plants...
