Overview:
Chinese name: oxygen
1. Physical properties
①Properties: color, taste, state: colorless and odorless gas (standard condition)
②Melting point: -218.4 ° C (into a blue snowflake solid) Boiling point: -182.9 ° C (into a light blue liquid)
③Density: 1.429 g / l (gas), 1.419 g / cm (gas), 1.419 g / cm (liquid). Becomes light blue liquid)
③Density:1.429 g/L (gas), 1.419 g/cm3 (liquid), 1.426 g/cm3 (solid)
④Water solubility: not easily soluble in water, under standard conditions, 1L of water can be dissolved in about 30mL of oxygen
⑤Storage: sky-blue cylinders
2.Chemical properties
Overall, oxygen is chemically active.
(1), Oxygen reacts with metals:
Reaction with potassium:
4K+O2=2K2O, the surface of potassium darkens
2K+O2=K2O2; K+O2=KO2 (superoxide of potassium), (conditions: ignition or heating, both reactions take place at the same time)
Reaction with sodium:
4Na+O2=2Na2O, the surface of sodium darkens
2Na+O2=Na2O2 (conditions: ignition or heating), a yellow flame is produced, a lot of heat is released, and a light yellow powder is produced.
Reaction with magnesium; 2Mg + O2 = 2MgO (condition: ignition), burns violently emitting a dazzling bright light, gives off a lot of heat, produces a white solid.
Reaction with aluminum; 4Al + 3O2 = 2Al2O3 (condition: ignition), emits a bright light, emits heat and produces a white solid.
Reaction with iron;
4Fe + 3O2 + 2xH2O = 2Fe2O3-H2O, (rust formation)
3Fe + 2O2 = Fe3O4 (condition: ignition), red-hot wire burns violently with sparks, gives off a lot of heat and produces a black solid.
Reaction with zinc: 2Zn + O2 = 2ZnO (condition: ignition),
Reaction with copper; 2Cu + O2 = 2CuO (condition: heating), after heating the bright red copper wire surface to produce a layer of black material.
(2), oxygen and non-metal reactions:
Reaction with hydrogen: 2H2 + O2 = 2H2O (conditions: ignition), producing a light blue flame, giving off a lot of heat, and water formation.
Reaction with carbon: CO2 (carbon dioxide)
(Carbon + Oxygen → Carbon Dioxide) C + O2 = CO2 (condition: ignition), burns violently, emits a white light, gives off heat, and produces a gas that makes lime water cloudy.
Incomplete oxygen then produces carbon monoxide: 2C + O2 = 2CO (condition: ignition).
Reaction with sulfur: S + O2 = SO2 (condition: ignition), a bright blue-violet flame, the emission of heat, the production of a gas with an irritating odor, the gas can also make into clear lime water turbid, and can make the acidic potassium permanganate solution or magenta solution discoloration.
Reaction with red phosphorus: 4P + 5O2 = P4O10 (conditions: ignition), burning violently, luminous exothermic, generating white smoke. (P4O10 is the molecular formula of phosphorus pentoxide, P2O5 can also be written here)
Reaction with white phosphorus: P4 + 5O2 = P4O10, white phosphorus spontaneous combustion in the air, luminous heat, white smoke.
Reaction with nitrogen: N2 + O2 = 2NO (conditions: discharge)
Reaction with oxygen: 3O2 = 2O3 (conditions: discharge)
(3), oxygen reacts with some organic matter, such as methane, acetylene, alcohol, paraffin, etc. can be burned in oxygen to produce water and carbon dioxide.
The combustion of gaseous hydrocarbons usually emits a bright blue flame, releases a large amount of heat, and produces water and a gas that can make clarified lime water cloudy.
Methane: CH4 + 2O2 → CO2 + 2H2O (condition: ignition)
Ethylene: C2H4 + 3O2 → 2CO2 + 2H2O (condition: ignition)
Ethyne: 2C2H2 + 5O2 → 4CO2 + 2H2O (condition: ignition)
Benzene: 2CH6 + 15O2 → 12CO2 + 6H2O (condition: ignition). 6H2O (conditions: ignition)
Methanol: 2CH3OH + 3O2 → 2CO2 + 4H2O (conditions: ignition)
Ethanol: CH3CH2OH + 3O2 → 2CO2 + 3H2O (conditions: ignition)
Carbon-hydrogen-oxygen compounds and oxygen combustion of the general formula: 4CxHyOz + (4x + y - 2z)O2 →4xCO2+2yH2O (condition: ignition) (The general formula should be completed with attention to simplification! (The same below)
Hydrocarbon combustion formula: 4CxHy + (4x + y)O2 → 4xCO2 + 2yH2O (conditions: ignition)
Ethanol oxidized by oxygen: 2CH3CH2OH + O2 → 2CH3CHO + 2H2O (conditions: Cu, heating)
This reaction consists of two steps: (1)2Cu + O2= 2CuO (heating) (2) CH3CH2OH + CuO → CH3CHO + Cu + H2O (heating)
Chloroform reaction with oxygen: 2CHCl3 + O2 → 2COCl2 (phosgene) + 2HCl
(4), the reaction between oxygen and other compounds:
Hydrogen sulfide combustion: (complete) 2H2S + 3O2=2H2O+2SO2; (incomplete) 2H2S+O2=2H2O+2S (condition: ignition)
Calcination of pyrite: 4FeS2+11O2=2Fe2O3+8SO2 (condition: high temperature)
Catalytic oxidation of sulfur dioxide: 2SO2+O2=2SO3 (condition: V2O5, heating)
Formation of sulfuric acid rain in air: 2SO2+O2+2H2O=2H2SO4
Combustion of ammonia in pure oxygen: 4NH3+3O2(pure)=2N2+6H2O (condition: ignition)
Catalytic oxidation of ammonia: 4NH3+5O2=4NO+6H2O (condition: Pt, heating)
Nitrogen monoxide vs. Reaction of nitric oxide with oxygen: 2NO + O2 = 2NO2
Two, some of the uses and negative effects of oxygen
1. Smelting process
Blowing in the steelmaking process with high purity oxygen, oxygen and carbon and phosphorus, sulfur, silicon and other oxidation reaction, which not only reduces the carbon content of steel, but also conducive to the removal of phosphorus, sulfur, silicon and other impurities. And the heat generated in the oxidation process is enough to maintain the temperature required for the steelmaking process, therefore, oxygen blowing not only shortens the smelting time, while improving the quality of steel. In blast furnace ironmaking, increasing the oxygen concentration in the blast air can reduce the coke ratio and increase the output. In non-ferrous metal smelting, the use of oxygen-enriched can also shorten the smelting time to improve production.
2. Chemical industry
In the production of ammonia, oxygen is mainly used for the oxidation of raw gas, for example, the high temperature cracking of heavy oil, as well as the gasification of pulverized coal, etc., in order to strengthen the process and improve the yield of fertilizer.
3. Defense industry
Liquid oxygen is the best modern rocket accelerant, in the supersonic aircraft also need liquid oxygen as an oxidizing agent, combustible substances impregnated with liquid oxygen has a strong explosive, can make liquid oxygen explosives.
4. Health care
Supply of respiration: used for hypoxia, low oxygen or no
oxygen environment, such as: diving operations, mountaineering, high-altitude flights, cosmic voyage, medical rescue and so on.
I. Oxygen is the heart of the "power source"
Oxygen is the body's metabolism of the key substances, is the body's first need for life activities. Respiratory oxygen is converted into oxygen available in the body, known as blood oxygen. The blood carries blood oxygen to the whole body energy input, the amount of blood oxygen delivery and the heart, the brain's working condition is closely related. The stronger the heart's ability to pump blood, the higher the content of blood oxygen; the stronger the heart's coronary artery blood transfusion ability, the higher the concentration of blood oxygen delivered to the heart and brain and the whole body, the more important organs of the human body's operational status.
II. Oxygen fountain
With people's desire for fresh oxygen demand is increasing day by day, in the United States, such as Los Angeles and other major cities, a kind of oxygen fountain bar set up. In the oxygen fountain bar, people holding a transparent oxygen canister, which is inserted on the delicate external absorption device, gently sucked, the canister of pure oxygen is gushing out. Oxygen with lemon or other flavors can be delivered continuously for 20 minutes. In addition, other oxygen-related products continue to emerge in the United States, such as a variety of oxygenated water, oxygenated sodas, oxygenated pills and so on. The emerging consumption of oxygen has formed a new trend.
Three. Increase the amount of oxygen can reduce postoperative infection and antiemetic
The United States of America's New England Journal of Medicine published a new research results. Anesthesiologists in Austria, the United States and Australia reported that by increasing oxygen intake to patients during and after surgery, the risk of postoperative infection in patients will be reduced by half. This is because increased oxygen improves the immune system's ability to provide more "ammunition" for the patient's "immune army" to kill bacteria at the wound site.
The study was conducted on 500 patients in hospitals in Vienna, Austria, and Hamburg, Germany. The procedure involved administering anesthesia with 30 percent oxygen to a first group of 250 patients throughout surgery and for two hours afterward, and another group of 250 patients received anesthesia with 80 percent oxygen at the same time. As a result, 28 people became infected after surgery in the first group, while only 13 became infected after surgery in the second group.
Nausea or vomiting after surgery is quite common in anesthetized patients and can be very unpleasant for them. The anesthesiologists who conducted the study said that increased oxygen intake was more effective than all antiemetic medications used up to 2009, and that it was non-hazardous and inexpensive. The mechanism by which oxygen prevents vomiting may be to prevent localized ischemia in the gut, which prevents the release of emetic factors. However, the use of oxygen exclusively without nitric oxide is not desirable because of the risk of awakening the patient during the procedure.
IV. Hyperbaric oxygen treatment of sudden deafness
According to a hospital director of hyperbaric oxygen, hyperbaric oxygen not only improves the hypoxia of the inner ear hearing organs, but also improves the inner ear blood circulation that is tissue metabolism, and promotes the restoration of auditory function. Once suffering from sudden deafness, should immediately go to the hospital hyperbaric oxygen section, because the efficacy of hyperbaric oxygen on sudden deafness often depends on the initial treatment time, generally within three days after the onset of the disease (should not be more than a week at the latest) the treatment effect is best.
V. Hyperbaric oxygen treatment of periodontal disease effect
Periodontal disease refers to the gums, periodontal membrane and alveolar bone inflammation, deformation, atrophy, and finally lead to tooth loosening, loss of a chronic progressive disease. With periodontal disease there will be gum congestion, redness, swelling, bleeding, deepening of the gingival sulcus, the formation of periodontitis, periodontal pockets overflowing with pus, bad breath, loose teeth, and often accompanied by recession of the gums.
The conventional treatment of periodontal disease is not ideal. In recent years, medical workers with hyperbaric oxygen treatment of periodontal disease, achieved good results. Hyperbaric oxygen treatment of periodontal disease can improve the oxygen content of the local tissues of periodontal disease and oxygen diffusion distance, promote the reconstruction of collateral circulation, improve local circulation. The vasoconstriction effect can relieve local swelling. In addition, hyperbaric oxygen can effectively inhibit the growth and reproduction of bacteria, especially anaerobic bacteria, improve the blood supply and oxygen supply of periodontal tissues, and promote metabolism to facilitate the repair of local tissues to achieve the purpose of anti-inflammation, swelling, hemostasis and deodorization.
Six, middle-aged and elderly need to supplement oxygen
Oxygen deficiency is generally divided into two kinds: one is the lack of oxygen outside the body, one is the lack of oxygen in the body:
Oxygen deficiency outside the body: mainly because of the lack of oxygen caused by external reasons. People in a lack of oxygen in the environment, such as cloudy weather pressure, plateau areas, environmental pollution areas and office buildings, shopping malls, basements, etc. are prone to external hypoxia.
In vivo hypoxia: refers to the body's own reasons, resulting in insufficient oxygen inhalation, with some of the old age, fast-paced work and other reasons. Such as respiratory diseases (bronchitis, asthma, emphysema, pulmonary heart disease, lung infections, etc.); poor blood circulation (various heart diseases, insufficient cerebral blood supply, cerebral infarction, vasculitis, varicose veins, etc.). Prolonged hypoxia in the body, insufficient oxygen supply to all tissues of the human body, accelerating the body's exhaustion, and even triggering accidents such as stroke, which directly threatens the safety of life.
Symptoms of hypoxia in middle-aged and old people
1) Mild hypoxia: yawning, cold hands and feet, shortness of breath in the big shopping malls, underground facilities, panic, shortness of breath.
2) moderate hypoxia: shortness of breath, shortness of breath after climbing two or more flights of stairs; bad breath, excess stomach acid, constipation, dry skin, lack of sleep, dreamy and easy to wake up, poor concentration, pale, dandruff after stress, sweating, vision loss, high blood pressure, blood lipids, blood glucose, weakening of the resistance to colds and flu.
VII. Negative effects of excessive oxygen inhalation
As early as the mid-19th century, British scientists Paul Burt first found that if the animals breathe pure oxygen will cause poisoning, humans are the same. If a person is greater than 0.05 MPa (half an atmosphere) of pure oxygen in the environment, all the cells have a toxic effect, inhalation time is too long, it may occur "oxygen poisoning". The capillary barrier of the lungs is destroyed, resulting in pulmonary edema, pulmonary bruising and hemorrhage, seriously affecting respiratory function, and then the distensible organs are damaged by hypoxia. In a pure oxygen environment of 0.1 MPa (1 atmosphere), a person can only survive for 24 hours before pneumonia occurs, which ultimately leads to respiratory failure, asphyxia and death. In 0.2 MPa (2 atmospheres) high-pressure oxygen environment, people can stay up to 1.5 hours ~ 2 hours, more than that will cause brain poisoning, life rhythm disorders, mental disorganization, memory loss. If you add 0.3 MPa (3 atmospheres) or even higher oxygen, you will experience brain cell degeneration and necrosis within minutes, convulsions and coma, leading to death.
In addition, excessive oxygen intake also promotes the aging of life. Oxygen into the human body and cell oxidizing enzyme reaction, can generate hydrogen peroxide, and then into lipofuscin. This lipofuscin is to accelerate cellular aging of harmful substances, it accumulates in the myocardium, so that the cardiomyocyte aging, cardiac function decline; accumulates in the wall of blood vessels, resulting in aging and hardening of blood vessels; accumulates in the liver, weakening the function of the liver; accumulates in the brain, resulting in intellectual decline, memory loss, people become demented; accumulates in the skin, the formation of age spots.
[edit]Third, the manufacture of oxygen
General laboratory manufacture of oxygen using the following methods:
Experimental setup
1. Heating of potassium permanganate, the chemical formula: 2KMnO4===(△) K2MnO4 + MnO2 + O2↑
2. With the catalyst MnO2 and heating of potassium chlorate, the chemical formula is 2KClO3===(△,MnO2) 2KCl+3O2↑
3. Hydrogen peroxide (hydrogen peroxide) in the catalyst MnO2 (or red brick powder, potatoes, cement, etc.), to produce O2 and H2O, the chemical formula: 2H2O2===(MnO2) 2H2O+O2↑
Industrial production of oxygen methods:
1. Compressed cooling air
2. molecular sieve
Nuclear submarines in the method of making oxygen: 2Na2O2 + 2CO2 === 2Na2CO3 + O2 ↑ The advantages of this method: 1, room temperature 2, so that the formation of oxygen and carbon dioxide cycle (people consume oxygen, exhaling carbon dioxide, and this reaction consumes carbon dioxide, generating oxygen)
[Edit This Paragraph] 4, the discovery of oxygen
The world's first discovery of oxygen is China's Tang Dynasty alchemist Ma He. Ma and carefully observed a variety of combustibles, such as charcoal, sulfur and other combustion in the air, the proposed conclusion is: the air composition is complex, mainly by the yang gas (nitrogen) and the yin gas (oxygen), of which the yang gas than the yin gas is much more than the yin gas, the yin gas can be combined with combustibles to remove it from the air, while the yang gas can still be safe and sound to remain in the air. Ma and further pointed out that yin qi exists in substances such as lapis lazuli (oxides) and fire nitrate (nitrates). If they are heated by fire, they will be released, and he also believed that there is a large amount of yin in the water, but it is often difficult to take it out. Mahe's discovery predates Europe by 1,000 years.
Mahe recorded the results of his lifelong research in a 68-page book called Pinglongxiang, published on March 9 of the first year of the Tang Dynasty (756), which was passed down until the Qing Dynasty, when it was seized by German invaders in the chaos.
In 1774, the British chemist J. Priestley and his companions used a large convex lens to focus the sun's rays and then heated the mercuric oxide to produce pure oxygen, and found that it fuels combustion and helps breathing, called "deflagration of vegetative air". In Sweden, C.W. Scheele produced oxygen by heating mercuric oxide and other oxygenated acid salts a year earlier than Priestley, but his paper, "Essay on the Chemistry of Air and Fire", was not published until 1777, but the two of them did produce oxygen independently of each other. 1774, Priestley visited France, and told the method of oxygen production to A.L. Lavoisier, who repeated the experiment in 1775, and found that the oxygen in the air that could aid respiration and help breathing was pure oxygen. The latter repeated the experiment in 1775, and called the gas in the air, which aids respiration and combustion, oxygene, a word derived from the Greek oxygenēs, meaning "acid-former". Thus, all three scholars were recognized as the discoverers of oxygen.
[edit]V. Determination of the volume fraction of oxygen in the air
Name: red phosphorus combustion experiment
Principle: red phosphorus combustion in a closed container to determine the volume fraction of oxygen in the air
Red phosphorus + oxygen = (ignition of) phosphorus pentoxide
4P+5O2=(ignition of) 2P2O5
Equation: 4P + 5O2 = ignition = 2P2O5
Phenomenon: red phosphorus: yellow flame, white smoke, heat release
Water along the conduit into the cylinder to about one-fifth of the stop
Conclusion: 1. Oxygen accounts for about one-fifth of the volume of the air (Principle) (1. Oxygen is difficult to dissolve in water, 2. Nitrogen is not flammable and does not contribute to the flammability)
Note: red phosphorus can be replaced by other substances. Substances can be replaced, but the product must not be a gas and react only with oxygen
Key to success: good airtightness Otherwise the result is small
Red phosphorus should be enough Otherwise the result is small
Wait until the device is completely cooled and then open the stopcock Otherwise the result is small
Plus the stopcock before the start of the experiment Otherwise the result is large
[edit this paragraph]VI. Oxygen Element
A chemical element. Chemical symbol O , atomic number 8 , atomic weight 15.9994, belongs to the periodic system VI A group. )
Oxygen discovery In 1774, the British chemist J. Priestley and his companions with a large convex lens will focus the sun's rays after heating mercuric oxide, the production of pure oxygen, and found that it helps to ignite and help breathing, called the "deflammatory element air". In Sweden, C.W. Scheele produced oxygen by heating mercuric oxide and other oxygenated acid salts a year earlier than Priestley, but his paper, "Essay on the Chemistry of Air and Fire", was not published until 1777, but the two of them did produce oxygen independently of each other. 1774, Priestley visited France, and told the method of oxygen production to A.L. Lavoisier, who repeated the experiment in 1775, and found that the oxygen in the air that could aid respiration and help breathing was pure oxygen. The latter repeated the experiment in 1775, and called the gas in the air, which aids respiration and combustion, oxygene, a word derived from the Greek oxygenēs, meaning "acid-former". Thus, all three scholars were recognized by later generations as the discoverers of oxygen.
Existence of Oxygen Oxygen has three stable isotopes, namely, Oxygen 16, Oxygen 17, and Oxygen 18, of which Oxygen 16 accounts for 99.759%. Oxygen in the crust of the earth's content of 48.6%, in the first place, oxygen on the earth's distribution is extremely wide, the oxygen in the atmosphere accounted for 20.95% of the oceans and rivers and lakes are full of oxygen compounds water, oxygen in the water accounted for 88.8%. There are also many oxygen-containing acid salts on the earth, such as aluminum silicates contained in the soil, and minerals of silicates, oxides, and carbonates. Oxygen in the atmosphere is constantly used in the metabolism of animals, and oxygen accounts for 65% in the human body. Photosynthesis in plants converts carbon dioxide into oxygen, allowing oxygen to be constantly recycled. Although the earth is full of oxygen, oxygen is mainly extracted from the air, there is an inexhaustible resource.
Oxygen is a chemically active element, in addition to noble gases, halogens in chlorine, bromine, iodine, and some inactive metals (such as gold, platinum), the vast majority of non-metallic and metal can be directly with the oxidation of the combination, but the oxygen can be indirectly with the noble gas xenon to generate oxides:
XeF6 + 3H2O = XeO3 + 6HF
Similarly , oxides of chlorine can also be made by indirect methods:
2Cl2 + 2HgO = HgO?HgCl2 + Cl2O
Oxygen can also oxidize other compounds at room temperature:
2NO + O2 = 2NO2
Oxygen can oxidize glucose, an action that constitutes the main reaction of respiration in living organisms:
C6H12O6+6O2=6CO2+6H2O
The oxidation states of oxygen are -2 , - 1, + 2 . Oxygen is second only to fluorine in oxidizability , so when oxygen and fluorine react, they exhibit a +2 valence, forming oxygen fluoride (F2O). The binary compounds formed by oxygen with metallic elements are oxides, peroxides, and superoxides. Oxygen molecules can lose an electron to form a dioxygen positive ion (), forming compounds such as O2PtF6.
Oxygen laboratory methods are: ① thermal decomposition of potassium chlorate:
② electrolysis of water:
③ thermal decomposition of oxides:
④ manganese dioxide as a catalyst, so that the decomposition of hydrogen peroxide:
⑤ the thermal decomposition of potassium permanganate
in the spaceship, can use the astronauts exhale of carbon dioxide gas and potassium peroxide to produce oxygen for the astronauts to breathe.
Production and application of large-scale production of oxygen is the method of fractionation of liquid air, first of all, air compression, to be its expansion of oxygen expansion and then frozen as liquid air, due to rare gases and nitrogen boiling point is lower than that of oxygen, after the fractional distillation, the rest is liquid oxygen, which can be stored in high-pressure cylinders. All oxidation reactions and combustion processes require oxygen, such as steelmaking in addition to sulfur, phosphorus and other impurities, oxygen and acetylene mixture combustion temperature of up to 3500 ℃, used for steel welding and cutting. Oxygen is required for glass manufacturing, cement production, mineral roasting, and hydrocarbon processing. Liquid oxygen is also used as rocket fuel, which is cheaper than other fuels. In the low-oxygen or oxygen-deficient environment work, such as divers, astronauts, oxygen is more indispensable to maintain life. However, the active state of oxygen, such as , OH and H2O2, etc. on the organization of living beings have serious damage, ultraviolet radiation on the skin and eye damage is mostly related to this effect. Oxygen is one of the components of air, colorless, odorless and tasteless. Oxygen density than air, in standard conditions (0 ℃ and atmospheric pressure 101325 Pa) density of 1.429 g / liter, can be dissolved in water, but the solubility is very small, 1L of water about 30mL oxygen. At a pressure of 101kPa, oxygen turns into a light blue liquid at about -180 degrees Celsius and a snowy light blue solid at about -218 degrees Celsius.
1. Oxygen can combine directly with many elements to form oxides.
2. Oxygen is a gas necessary for combustion and for the respiration of plants and animals. Oxygen-enriched air is used for medical treatment and high-altitude flights, pure oxygen is used for steelmaking and for cutting and welding metals, and liquid oxygen is used as an oxidizing agent in rocket engines.
3. Oxygen used in production is obtained by fractionation of liquid air.
4. An oxygen molecule is composed of two oxygen atoms atomic radius of 0.074 nanometers
5. The chemical reaction between a substance and oxygen belongs to the oxidation reaction (combination reaction)