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>> Obtaining oxygen
Obtaining oxygen
This paragraph is about:
> about the discovery of oxygen;
> on the production of oxygen in industry and laboratories;
> about decomposition reactions.
Discovery of oxygen.
J. Priestley obtained this gas from a compound whose name is mercury (II) oxide. The scientist used a glass lens to focus sunlight on matter.
In the modern version, this experience is shown in Figure 54. When heated, mercury (||) oxide (powder yellow color) is converted into mercury and oxygen. Mercury is released in a gaseous state and condenses on the walls of the test tube in the form of silvery droplets. Oxygen is collected over water in the second test tube.
Now the Priestley method is not used because mercury vapor is toxic. Oxygen is produced by other reactions similar to the one discussed. They usually occur when heated.
Reactions in which several other substances are formed from one substance are called decomposition reactions.
To obtain oxygen in the laboratory, the following oxygen-containing compounds are used:
Potassium permanganate KMnO 4 (common name potassium permanganate; substance is a common disinfectant)
Potassium chlorate KClO 3 (the trivial name is Bertolet's salt, in honor of the French chemist of the late XVIII - early XIX in. K.-L. Berthollet)
A small amount of catalyst - manganese (IV) oxide MnO 2 - is added to potassium chlorate so that the decomposition of the compound occurs with the release of oxygen 1 .
Laboratory experiment No. 8
Obtaining oxygen by decomposition of hydrogen peroxide H 2 O 2
Pour 2 ml of a hydrogen peroxide solution (the traditional name for this substance is hydrogen peroxide) into a test tube. Light a long splinter and extinguish it (as you do with a match), so that it barely smolders.
Pour a little catalyst - black powder of manganese (IV) oxide into a test tube with a hydrogen oxide solution. Observe vigorous evolution of gas. Use a smoldering splinter to verify that this gas is oxygen.
Write an equation for the decomposition of hydrogen peroxide, the product of which is water.
In the laboratory, oxygen can also be obtained by decomposition of sodium nitrate NaNO 3 or potassium nitrate KNO 3 2 . When heated, compounds first melt and then decompose:
1 When the compound is heated without a catalyst, another reaction occurs
2 These substances are used as fertilizers. Them common name- saltpeter.
Scheme 7. Laboratory methods getting oxygen
Turn reaction schemes into chemical equations.
Information on how oxygen is obtained in the laboratory is collected in Scheme 7.
Oxygen together with hydrogen are products of the decomposition of water under the action of an electric current:
In nature, oxygen is produced by photosynthesis in the green leaves of plants. A simplified diagram of this process is as follows:
findings
Oxygen was discovered in late XVIII in. several scientists .
Oxygen is obtained in industry from the air, and in the laboratory - with the help of decomposition reactions of certain oxygen-containing compounds. During a decomposition reaction, two or more substances are formed from one substance.
129. How is oxygen obtained in industry? Why is potassium permanganate or hydrogen peroxide not used for this?
130. What reactions are called decomposition reactions?
131. Turn the following reaction schemes into chemical equations:
132. What is a catalyst? How can it affect the course of chemical reactions? (Also refer to § 15 for your answer.)
133. Figure 55 shows the moment of decomposition of white solid, which has the formula Cd(NO3)2. Look at the picture carefully and describe everything that happens during the reaction. Why does a smoldering splinter flare up? Write the appropriate chemical equation.
134. The mass fraction of Oxygen in the residue after heating potassium nitrate KNO 3 was 40%. Has this compound completely decomposed?
Rice. 55. Decomposition of a substance when heated
Popel P. P., Kriklya L. S., Chemistry: Pdruch. for 7 cells. zahalnosvit. navch. zakl. - K .: Exhibition Center "Academy", 2008. - 136 p.: il.
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Oxygen O 2 is the most abundant element on earth. He is in in large numbers as chemical compounds with various substances earth's crust(up to 50% wt.), in combination with hydrogen in water (about 86% wt.) and in a free state in atmospheric air in a mixture mainly with nitrogen in an amount of 20.93% vol. (23.15% by weight).
Oxygen has great importance in national economy. It is widely used in metallurgy; chemical industry; for flame treatment of metals, fire drilling of solid rocks, underground coal gasification; in medicine and various breathing apparatus, for example for high-altitude flights, and in other areas.
Under normal conditions, oxygen is a colorless, odorless and tasteless gas, non-flammable, but actively supports combustion. At very low temperatures, oxygen turns into a liquid and even a solid.
The most important physical constants of oxygen are as follows:
| Molecular weight | 32 |
| Weight 1 m 3 at 0 ° C and 760 mm Hg. Art. in kg | 1,43 |
| The same at 20 ° C and 760 mm Hg. Art. in kg | 1,33 |
| Critical temperature in °C | -118 |
| Critical pressure in kgf / m 3 | 51,35 |
| Boiling point at 760 mm Hg. Art. in °С | -182,97 |
| Weight of 1 liter of liquid oxygen at -182, 97 °C and 760 mm Hg. Art. in kg. |
1,13 |
| The amount of gaseous oxygen obtained from 1 liter of liquid at 20 ° C and 760 mm Hg. Art. in l |
850 |
| Solidification temperature at 760 mm Hg. Art. in °С | -218,4 |
Oxygen has a high chemical activity and forms compounds with all chemical elements, except for rare gases. Reactions of oxygen with organic substances have a pronounced exothermic character. So, when compressed oxygen interacts with fatty or finely dispersed solid combustible substances, they are instantly oxidized and the heat released contributes to spontaneous combustion of these substances, which can cause a fire or explosion. This property must be especially taken into account when handling oxygen equipment.
One of important properties oxygen is its ability to form explosive mixtures with combustible gases and vapors of liquid combustibles over a wide range, which can also lead to explosions in the presence of open fire or even sparks. Explosives are also mixtures of air with gaseous or vaporous combustibles.
Oxygen can be obtained: 1) by chemical means; 2) water electrolysis; 3) in a physical way from the air.
Chemical methods, which consist in obtaining oxygen from various substances, are inefficient and currently have only laboratory significance.
The electrolysis of water, i.e., its decomposition into components - hydrogen and oxygen, is carried out in apparatuses called electrolyzers. Through water, to which caustic soda NaOH is added to increase the electrical conductivity, D.C.; oxygen is collected at the anode and hydrogen is collected at the cathode. The disadvantage of this method is the high power consumption: 12-15 kW is consumed per 1 m 3 0 2 (in addition, 2 m 3 H 2 is obtained). h. This method is rational in the presence of cheap electricity, as well as in the production of electrolytic hydrogen, when oxygen is a waste product.
The physical method consists in the separation of air into components by deep cooling. This method makes it possible to obtain oxygen in practically unlimited quantities and is of major industrial importance. Electricity consumption per 1 m 3 O 2 is 0.4-1.6 kW. h, depending on the type of installation.
OBTAINING OXYGEN FROM AIR
atmospheric air basically it is a mechanical mixture of three gases with the following volumetric content: nitrogen - 78.09%, oxygen - 20.93%, argon - 0.93%. In addition, it contains about 0.03% carbon dioxide and small amounts of rare gases, hydrogen, nitrous oxide, etc.
The main task in obtaining oxygen from air is to separate the air into oxygen and nitrogen. Along the way, argon is separated, the use of which in special welding methods is constantly increasing, as well as rare gases, which play an important role in a number of industries. Nitrogen has some uses in welding as a shielding gas, in medicine and other fields.
The essence of the method lies in the deep cooling of air with its conversion to a liquid state, which at normal atmospheric pressure can be achieved in the temperature range from -191.8 ° C (the beginning of liquefaction) to -193.7 ° C (the end of liquefaction).
The separation of liquid into oxygen and nitrogen is carried out by using the difference in their boiling points, namely: T kip. o2 \u003d -182.97 ° C; Boiling point N2 = -195.8 ° C (at 760 mm Hg).
With the gradual evaporation of the liquid, nitrogen, which has a lower boiling point, will first pass into the gaseous phase, and as it is released, the liquid will be enriched with oxygen. Repeating this process many times makes it possible to obtain oxygen and nitrogen of the required purity. This method of separating liquids into their component parts is called rectification.
For the production of oxygen from the air, there are specialized enterprises equipped with high-performance plants. In addition, large metalworking enterprises have their own oxygen stations.
The low temperatures required to liquefy the air are obtained by means of so-called refrigeration cycles. The main refrigeration cycles used in modern installations are briefly discussed below.
The refrigeration cycle with air throttling is based on the Joule-Thomson effect, i.e., a sharp decrease in the temperature of the gas during its free expansion. The cycle diagram is shown in fig. 2.
The air is compressed in a multi-stage compressor 1 to 200 kgf / cm 2 and then passes through the refrigerator 2 with running water. Deep air cooling takes place in the heat exchanger 3 by a reverse flow of cold gas from the liquid collector (liquefier) 4. As a result of air expansion in the throttle valve 5, it is additionally cooled and partially liquefied.
The pressure in the collection 4 is regulated within 1-2 kgf/cm 2 . The liquid is periodically drained from the collector into special containers through valve 6. The unliquefied part of the air is removed through the heat exchanger, cooling new portions of the incoming air.
Air is cooled down to the liquefaction temperature gradually; when the unit is turned on, there is a start-up period during which no air liquefaction is observed, but only the unit cools down. This period takes several hours.
The advantage of the cycle is its simplicity, and the disadvantage is relatively high flow electricity - up to 4.1 kW. h per 1 kg of liquefied air at a compressor pressure of 200 kgf/cm 2 ; at lower pressure, the specific power consumption increases sharply. This cycle is used in installations of small and medium capacity to produce gaseous oxygen.
Somewhat more complex is the throttling cycle with ammonia pre-cooling.
The medium-pressure refrigeration cycle with expansion in an expander is based on a decrease in gas temperature during recoil expansion external work. In addition, the Joule-Thomson effect is also used. The cycle diagram is shown in fig. 3.
The air is compressed in the compressor 1 to 20-40 kgf / cm 2, passes through the refrigerator 2 and then through the heat exchangers 3 and 4. After the heat exchanger 3 most of air (70-80%) is sent to the piston expansion machine-expander 6, and a smaller part of the air (20-30%) goes to free expansion into the throttle valve 5 and then the collector 7, which has a valve 8 for draining the liquid. In expander 6
the air, already cooled in the first heat exchanger, does work - it pushes the piston of the machine, its pressure drops to 1 kgf / cm 2, due to which the temperature drops sharply. From the expander cold air, having a temperature of about -100 ° C, is brought out through heat exchangers 4 and 3, cooling the incoming air. Thus, the expander provides a very efficient cooling of the plant at a relatively low pressure in the compressor. The work of the expander is used usefully and this partially compensates for the energy spent on compressing the air in the compressor.
The advantages of the cycle are: a relatively low compression pressure, which simplifies the design of the compressor and increased cooling capacity (thanks to the expander), which ensures stable operation of the unit when oxygen is taken in liquid form.
Refrigeration cycle low pressure with expansion in a turboexpander, developed by Acad. P. L. Kapitsa, is based on the use of low-pressure air with cold production only due to the expansion of this air in an air turbine (turbo expander) with the production of external work. The cycle diagram is shown in fig. 4.
The air is compressed by the turbocharger 1 to 6-7 kgf/cm 2 , cooled with water in the cooler 2 and enters the regenerators 3 (heat exchangers), where it is cooled by a reverse flow of cold air. Up to 95% of the air after the regenerators is sent to the turbo expander 4, expands to an absolute pressure of 1 kgf/cm 2 with the performance of external work and at the same time cools rapidly, after which it is fed into the tube space of the condenser 5 and condenses the rest compressed air(5%) entering the annulus. From the condenser 5, the main air flow is directed to the regenerators and cools the incoming air, and the liquid air is passed through the throttle valve 6 to the collector 7, from which it drains through the valve 8. The diagram shows one regenerator, but in reality they are installed several and switched on in turn.
The advantages of a low-pressure cycle with a turbo-expander are: higher efficiency of turbomachines compared to piston-type machines, simplification of the technological scheme, and increased reliability and explosion safety of the plant. The cycle is used in installations of high productivity.
The separation of liquid air into components is carried out by means of a rectification process, the essence of which is that the vaporous mixture of nitrogen and oxygen formed during the evaporation of liquid air is passed through a liquid with a lower oxygen content. Since there is less oxygen in the liquid and more nitrogen, it has a lower temperature than the vapor passing through it, and this causes the condensation of oxygen from the vapor and the enrichment of the liquid with simultaneous evaporation of nitrogen from the liquid, i.e., the enrichment of the vapor above the liquid .
An idea of the essence of the rectification process can be given by the one shown in Fig. 5 is a simplified diagram of the process of multiple evaporation and condensation of liquid air.
We assume that air consists only of nitrogen and oxygen. Imagine that there are several vessels connected to each other (I-V), in the upper one there is liquid air with a content of 21% oxygen. Due to the stepped arrangement of the vessels, the liquid will flow down and, at the same time, will gradually be enriched with oxygen, and its temperature will increase.
Let us assume that in vessel II there is a liquid containing 30% 0 2 , in vessel III - 40%, in vessel IV - 50%, and in vessel V - 60% oxygen.
To determine the oxygen content in the vapor phase, we use a special graph - fig. 6, whose curves indicate the oxygen content in liquid and vapor at various pressures.
Let's start to evaporate the liquid in the vessel V at an absolute pressure of 1 kgf/cm 2 . As can be seen from fig. 6, above the liquid in this vessel, consisting of 60% 0 2 and 40% N 2, there can be an equilibrium vapor in composition, containing 26.5% 0 2 and 73.5% N 2, having the same temperature as the liquid . We feed this vapor into vessel IV, where the liquid contains only 50% 0 2 and 50% N 2 and therefore will be colder. From fig. 6 it can be seen that the vapor above this liquid can contain only 19% 0 2 and 81% N 2, and only in this case its temperature will be equal to the temperature of the liquid in this vessel.
Therefore, the steam supplied to vessel IV from vessel V, containing 26.5% O 2 , has a higher temperature than the liquid in vessel IV; therefore, the oxygen of the vapor condenses in the liquid of vessel IV, and part of the nitrogen from it will evaporate. As a result, the liquid in vessel IV will be enriched with oxygen, and the vapor above it with nitrogen.
Similarly, the process will take place in other vessels and, thus, when draining from the upper vessels into the lower ones, the liquid is enriched with oxygen, condensing it from the rising vapors and giving them its nitrogen.
Continuing the process up, you can get a vapor consisting of almost pure nitrogen, and in the lower part - pure liquid oxygen. In fact, the rectification process that takes place in distillation columns oxygen plants, much more complicated than described, but its fundamental content is the same.
Regardless of the technological scheme of the installation and the type of refrigeration cycle, the process of producing oxygen from air includes the following stages:
1) air purification from dust, water vapor and carbon dioxide. The binding of CO 2 is achieved by passing air through water solution NaOH;
2) air compression in the compressor with subsequent cooling in refrigerators;
3) cooling of compressed air in heat exchangers;
4) expansion of compressed air in a throttle valve or expander for its cooling and liquefaction;
5) liquefaction and rectification of air to obtain oxygen and nitrogen;
6) discharge of liquid oxygen into stationary tanks and removal of gaseous oxygen into gas holders;
7) quality control of the resulting oxygen;
8) filling transport tanks with liquid oxygen and filling cylinders with gaseous oxygen.
The quality of gaseous and liquid oxygen is regulated by the relevant GOSTs.
According to GOST 5583-58, gaseous technical oxygen of three grades is produced: the highest - with a content of at least 99.5% O 2, the 1st - at least 99.2% O 2 and the 2nd - at least 98.5% O 2 , the rest is argon and nitrogen (0.5-1.5%). The moisture content should not exceed 0.07 g/l 3 . Oxygen obtained by electrolysis of water must not contain more than 0.7% hydrogen by volume.
According to GOST 6331-52, liquid oxygen of two grades is produced: grade A with a content of at least 99.2% O 2 and grade B with a content of at least 98.5% O 2. The content of acetylene in liquid oxygen should not exceed 0.3 cm 3 /l.
Used for the intensification of various processes at the enterprises of the metallurgical, chemical and other industries, technological oxygen contains 90-98% O 2 .
Quality control of gaseous, as well as liquid oxygen is carried out directly in the production process using special instruments.
Administration Overall rating of the article: Published: 2012.06.01
Hello. You have already read my articles on the Tutoronline.ru blog. Today I will tell you about oxygen and how to get it. I remind you, if you have questions for me, you can write them in the comments to the article. If you need any help in chemistry, sign up for my classes in the schedule. I will be glad to help you.
Oxygen is distributed in nature in the form of isotopes 16 O, 17 O, 18 O, which have the following percentage on Earth - 99.76%, 0.048%, 0.192%, respectively.
In the free state, oxygen is in three allotropic modifications : atomic oxygen - O o, dioxygen - O 2 and ozone - O 3. Moreover, atomic oxygen can be obtained as follows:
KClO 3 \u003d KCl + 3O 0
KNO 3 = KNO 2 + O 0
Oxygen is found in over 1400 different minerals and organic matter, in the atmosphere its content is 21% by volume. The human body contains up to 65% oxygen. Oxygen is a colorless and odorless gas, slightly soluble in water (3 volumes of oxygen dissolve in 100 volumes of water at 20 ° C).
In the laboratory, oxygen is obtained by moderate heating of certain substances:
1) When decomposing manganese compounds (+7) and (+4):
2KMnO 4 → K 2 MnO 4 + MnO 2 + O 2
permanganate manganate
potassium potassium
2MnO 2 → 2MnO + O 2
2) When perchlorates are decomposed:
2KClO 4 → KClO 2 + KCl + 3O 2
perchlorate
potassium
3) When decomposing berthollet salt (potassium chlorate).
In this case, atomic oxygen is formed:
2KClO 3 → 2KCl + 6O 0
chlorate
potassium
4) When the salts of hypochlorous acid decompose in the light- hypochlorites:
2NaClO → 2NaCl + O 2
Ca(ClO) 2 → CaCl 2 + O 2
5) When heating nitrates.
This produces atomic oxygen. Depending on what position the nitrate metal occupies in the activity series, various reaction products are formed:
2NaNO 3 → 2NaNO 2 + O 2
Ca(NO 3) 2 → CaO + 2NO 2 + O 2
2AgNO 3 → 2 Ag + 2NO 2 + O 2
6) When decomposing peroxides:
2H 2 O 2 ↔ 2H 2 O + O 2
7) When heating oxides of inactive metals:
2Ag 2 O ↔ 4Ag + O 2
This process is relevant in everyday life. The fact is that dishes made of copper or silver, having a natural layer of an oxide film, form active oxygen when heated, which is an antibacterial effect. The dissolution of salts of inactive metals, especially nitrates, also leads to the formation of oxygen. For example, the overall process of dissolving silver nitrate can be represented in stages:
AgNO 3 + H 2 O → AgOH + HNO 3
2AgOH → Ag 2 O + O 2
2Ag 2 O → 4Ag + O 2
or in summary form:
4AgNO 3 + 2H 2 O → 4Ag + 4HNO 3 + 7O 2
8) When heating chromium salts of the highest oxidation state:
4K 2 Cr 2 O 7 → 4K 2 CrO 4 + 2Cr 2 O 3 + 3 O 2
dichromate chromate
potassium potassium
In industry, oxygen is obtained:
1) Electrolytic decomposition of water:
2H 2 O → 2H 2 + O 2
2) Interaction of carbon dioxide with peroxides:
CO 2 + K 2 O 2 → K 2 CO 3 + O 2
This method is indispensable technical solution breathing problems in isolated systems: submarines, mines, spacecraft.
3) When ozone interacts with reducing agents:
O 3 + 2KJ + H 2 O → J 2 + 2KOH + O 2
Of particular importance is the production of oxygen in the process of photosynthesis. occurring in plants. All life on Earth depends fundamentally on this process. Photosynthesis is a complex multi-step process. The beginning gives him light. Photosynthesis itself consists of two phases: light and dark. In the light phase, the pigment chlorophyll contained in the leaves of plants forms the so-called “light-absorbing” complex, which takes electrons from water, and thereby splits it into hydrogen ions and oxygen:
2H 2 O \u003d 4e + 4H + O 2
The accumulated protons contribute to the synthesis of ATP:
ADP + F = ATP
In the dark phase, carbon dioxide and water are converted into glucose. And oxygen is released as a by-product:
6CO 2 + 6H 2 O \u003d C 6 H 12 O 6 + O 2
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Page 1
Industrial production of oxygen is currently carried out according to three schemes: high pressure, two pressures and one low pressure. In installations with low productivity (up to 300 m3 / h of technical oxygen), it is usually used refrigeration cycle high or medium pressure. In these units, the air is compressed by reciprocating compressors. Air purification from carbon dioxide is carried out in calciners or scrubbers. To obtain cold in these installations, throttling or expansion of air in a piston expander is used.
In the industrial production of oxygen by the method of air separation by the method of deep cooling and rectification, it is theoretically necessary to consume 0,056 kW h / m3 of oxygen.
The main source of industrial production of oxygen is liquid air. The oxygen released from it usually contains only minor impurities of nitrogen and heavy inert gases. To obtain especially pure oxygen, sometimes the decomposition of water by electric current is used.
The main source of industrial oxygen production is air, which is liquefied and then fractionated.
The main source of industrial production of oxygen is liquid air. To obtain especially pure oxygen, sometimes the decomposition of water by electric current is used.
The main source of industrial production of oxygen is liquid air. The oxygen released from it usually contains only minor impurities of nitrogen and heavy inert gases. To obtain special pure oxygen, sometimes the decomposition of water by electric current is used.
What is the basis for the industrial production of oxygen and nitrogen from the air.
This is the basis for the industrial production of oxygen and nitrogen from the air.
However, both of these methods are unsuitable for the industrial production of oxygen because they are uneconomical.
Atmospheric air is an inexhaustible source of raw materials for the industrial production of oxygen, nitrogen and rare (inert) gases by deep cooling. In addition to oxygen and nitrogen, air contains the following gases in small quantities: argon, neon, helium, krypton, xenon, and various impurities.
The presence of acetylene in liquid oxygen in an amount exceeding the permissible limits can cause explosions in air separation apparatus during the industrial production of oxygen. Therefore, the control of the content of acetylene in liquid oxygen is very important. Below are methods for the determination of acetylene in liquid oxygen.
We have already pointed out that the production of oxygen by liquefaction of air and the subsequent separation of nitrogen is not applicable under laboratory conditions, because this requires a complex and cumbersome plant, suitable only for the industrial production of oxygen.
In our country, new stations and workshops for oxygen production are annually put into operation and existing stations and workshops are expanded. Industrial production of oxygen is currently carried out by the method of low-temperature distillation of liquefied air. Air-separating (oxygen) installations are a complex of machines and devices associated with a certain technological scheme. The operation of air distribution units is characterized by the fact that explosions sometimes occur in the units, leading to their destruction or, at best, to a decrease in the quality of production products.
The lump in the throat is oxygen. It was found that in a state of stress, the glottis expands. It is located in the middle of the larynx, limited by 2 muscle folds.
It is they who put pressure on nearby tissues, creating a sensation of a lump in the throat. The expansion of the gap is a consequence of increased oxygen consumption. It helps to 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 sometimes liquid oxygen. Element magnetized in this state. However, we will talk about the properties of oxygen and the advantages that can be extracted from them in the main part.
Properties of oxygen
Due to the magnetic properties, oxygen is moved with the help of powerful ones. If we talk about an element in its usual state, it itself is able to move, 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 with oxygen are released into external environment. It's carbon dioxide. It produces from 5 to 18 liters per hour.
Another 50 grams of water comes out. So drinking plenty of water is a reasonable recommendation from doctors. Plus, the by-products of breathing are about 400 substances. Among them is acetone. Its release is enhanced in a number of diseases, for example, diabetes.
The usual modification of oxygen, O 2, is involved in the process of respiration. This is a diatomic molecule. It has 2 unpaired electrons. Both are in antibonding orbitals.
They have a greater energy charge than binders. Therefore, the oxygen molecule easily breaks up into atoms. The dissociation energy reaches almost 500 kilojoules per mole.
AT vivo oxygen - gas with almost inert molecules. They have a strong interatomic bond. Oxidation processes are barely noticeable. Catalysts are needed to speed up reactions. In the body they are enzymes. They provoke the formation of radicals, which excite the chain process.
Catalyst chemical reactions temperature can become with oxygen. The 8th element reacts even to a slight heating. Heat gives reactions with hydrogen, methane and other combustible gases.
Interactions proceed with explosions. No wonder that one of the first airships in the history of mankind 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 inert gases, i.e. argon, neon and helium. By the way, helium has become a substitute for filling airships.
The gas does not enter into the reaction, only it is expensive. But, back to the hero of the article. Oxygen - chemical element interacting with metals even 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 1200 degrees Celsius.
For the reactions of the hero of the article with non-metals, heating is required at least up to 60 degrees Celsius. This is sufficient, for example, for contact with phosphorus. The hero of the article interacts with gray 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 reactions. Most of them proceed 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 performance in ethanol and acetone. They dissolve 22 grams of oxygen. The maximum dissociation is observed in liquids containing fluorine, for example, perfluorobutitetrahydrofuran. Almost 50 grams of the 8th element are dissolved per 100 milliliters of it.
Speaking of dissolved oxygen, let's mention its isotopes. Atmospheric ranked 160th number. Its in the air 99.7%. 0.3% are isotopes 170 and 180. Their molecules are heavier.
Contacting with them, the water hardly passes into a vapor state. Only the 160th modification of the 8th element rises into the air. Heavy isotopes remain in the seas and oceans.
Interestingly, in addition to the gaseous and liquid states, oxygen is solid. It, like the liquid version, is formed when sub-zero temperatures. For watery oxygen, -182 degrees are needed, and for stone, at least -223.
The latter temperature gives the cubic lattice of crystals. From -229 to -249 degrees Celsius, the crystal structure of oxygen is already hexagonal. Artificially obtained and other modifications. But, for them, in addition to low temperatures, increased pressure is required.
In the usual state oxygen belongs to the elements with 2 atoms, it is colorless and odorless. However, there is a 3-atomic version of the hero of the article. This is ozone.
It has a pronounced fresh aroma. It's pleasant, but toxic. The difference from ordinary oxygen is also a large mass of molecules. Atoms come together in lightning discharges.
Therefore, the smell of ozone is felt after showers. The aroma is also felt at high altitudes of 10-30 kilometers. There, the formation of ozone provokes ultraviolet radiation. Oxygen atoms capture the radiation of the sun, combining into large molecules. This, in fact, saves humanity from radiation.
Oxygen extraction
Industrialists get the hero of the article out of thin air. It is purified from water vapor, carbon monoxide and dust. Then, the air is liquefied. After purification, only nitrogen and oxygen remain. The first one evaporates at -192 degrees.
The oxygen remains. But, Russian scientists have discovered a storehouse of the already liquefied element. It is located in the mantle of the Earth. It is also called the geosphere. There is a layer under the solid crust of the planet and above its core.
Install there oxygen element sign helped laser press. 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 alleged layer of mania is 8-10 times greater than in the atmosphere.
Let us clarify the practice of calculating deep oxygen rivers. Physicists have worked with iron oxide. Squeezing and heating it, scientists received all new metal oxides, previously unknown.
When it came to temperatures of 1,000 degrees and pressures 670,000 times atmospheric, the compound Fe 25 O 32 was obtained. The conditions of the middle layers of the geosphere are described.
The oxide conversion reaction goes with a global release of oxygen. It should be assumed that this also happens inside the planet. Iron is a typical element for the mantle.
Combination of an element with oxygen also typical. The version that atmospheric gas has seeped out of the ground over millions of years and accumulated near its surface is not typical.
Roughly speaking, scientists questioned the dominant role of plants in the formation of oxygen. Greens can give only part of the gas. In this case, you need to be afraid not only of the destruction of the flora, but also of the cooling of the core of the planet.
A decrease in mantle temperature can block the formation of oxygen. Mass fraction it 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 the earth to a depth of more than 7,000-8,000 kilometers. It remains to wait until the hero of the article seeps to 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. Devices liquefy the air and separate it. Actually, these are installations for mining oxygen.
What elements are formed the circle of "communication" of the hero of the article? First, they are metals. This is not about direct interaction, but about the melting of elements. Oxygen is added to the burners to burn the fuel as efficiently as possible.
As a result, metals soften faster, mixing into alloys. Without oxygen, for example, the convector method of steel production is indispensable. Ordinary air as an ignition is ineffective. Not without liquefied gas in cylinders and metal cutting.
Oxygen as a chemical element was discovered and farmers. In liquefied form, the substance enters 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, consequently, of the 8th gas. As a result, centipedes under 3 meters long crawled around the planet. Insect fossils have been found. The scheme still works today. Give the animal a constant supplement to the usual portion of oxygen, you will get an increase in biological mass.
Doctors stock up on oxygen in cylinders for stopping, that is, stopping asthma attacks. Gas is also needed when eliminating 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 medicine. In other cases, the substance is given to patients in rubberized pillows, or through special tubes and masks.
In the chemical industry, the hero of the article is an oxidizing agent. The reactions in which the 8th element can participate have already been mentioned. Characterization of oxygen positively considered, for example, in rocket science.
The hero of the article was chosen as a fuel oxidizer for ships. The combination of both modifications of the 8th element is recognized as the most powerful oxidizing mixture. That is, rocket fuel interacts with ordinary oxygen and ozone.
The price of oxygen
The hero of the article is sold in balloons. They provide element link. With oxygen you can buy cylinders in 5, 10, 20, 40, 50 liters. In general, the standard step between tare 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 the high price tags, as a rule, there is an indication of the observed GOST. His number is "949-73". In advertisements with the budget cost of cylinders, GOST is rarely registered, which is alarming.
Transportation of oxygen in cylinders
Philosophically speaking, oxygen is priceless. The element is the basis of life. Oxygen transports iron throughout the human body. A bunch of elements is called hemoglobin. Its deficiency is anemia.
The disease has serious consequences. The first of these is a decrease in immunity. Interestingly, in some animals, blood oxygen is not carried by iron. In horseshoe crabs, for example, copper delivers the 8th element to the organs.
