Oxygen is a gas without taste, smell or color. In terms of content in the atmosphere, it ranks second after nitrogen. Oxygen is a strong oxidizing agent and a reactive non-metal. This gas was discovered simultaneously by several scientists in the 18th century. The Swedish chemist Scheele was the first to extract oxygen in 1772. The study of oxygen was carried out by the French chemist Lavoisier, who gave it the name “oxygène”. A smoldering splinter helps identify oxygen: upon contact with gas, it flashes brightly.
Oxygen value
This gas is involved in combustion processes. Oxygen is produced by green plants, in the leaves of which the process of photosynthesis occurs, which enriches the atmosphere with this vital gas.
How to get oxygen? Gas is extracted from the air industrially, and the air is purified and liquefied. Our planet has huge reserves of water, the component of which is oxygen. This means that gas can be produced by decomposing water. This can be done at home.
How to get oxygen from water
To conduct the experiment you will need the following tools and materials:
Power supply;
Plastic glasses (2 pieces);
Electrodes (2 pieces);
Galvanic bath.
Let's look at the process itself. Pour water into the galvanic bath to more than half the volume, then add 2 ml of caustic soda or dilute sulfuric acid - this will increase the electrical conductivity of the water.
We make holes in the bottom of plastic glasses and stretch electrodes - carbon plates - through them. It is necessary to insulate the air gap between the glass and the plate. We place the glasses in the bath so that the electrodes are in the water and the glasses are upside down. There should be very little air between the surface of the water and the bottom of the glass.
We solder a metal wire to each electrode and connect it to a power source. The electrode connected to the negative pole is called the cathode, and the electrode connected to the positive pole is called the anode.
Passes through the water electricity- electrolysis of water is carried out.
Electrolysis of water
A chemical reaction occurs during which two gases are formed. Hydrogen collects inside the glass with the cathode, and oxygen collects in the glass with the anode. The formation of gases in glasses with electrodes is determined by air bubbles rising from the water. Through the tube we remove oxygen from the glass into another container.
Safety regulations
Carrying out chemical experience It is possible to obtain oxygen from water only if safety regulations are observed. Gases obtained during the electrolysis of water must not be mixed. The resulting hydrogen is explosive, so it should not come into contact with air. You can find out what experiments with gases are safe to conduct at home.
How to produce oxygen in a laboratory way
Method one: pour potassium permanganate into a test tube, put the test tube on the fire. Potassium permanganate heats up and oxygen is released. We catch gas with a pneumatic bath. Result: 1 liter of oxygen is released from 10 g of potassium permanganate.
Stephen Hales Pneumatic Bath
Method two: pour 5 g of nitrate into a test tube, close the test tube with a fireproof stopper with a glass tube. We fix the test tube on the table using a tripod, and place a bath of sand under it to avoid excessive heating. Turn on the gas burner and direct the fire to the test tube with saltpeter. The substance melts and oxygen is released. We collect gas through a glass tube into a balloon placed on it.
Method three: pour potassium chlorate into a test tube and place the test tube on the fire of a gas burner, having previously closed it with a fireproof stopper with a glass tube. Berthollet salt releases oxygen when heated. We collect gas through a tube by placing a balloon on it.
Method four: We fix the glass test tube on the table using a tripod, pour hydrogen peroxide into the test tube. On contact with air, the unstable compound decomposes into oxygen and water. To speed up the oxygen release reaction, add activated carbon to the test tube. We close the test tube with a fireproof stopper with a glass tube, put a balloon on the tube and collect oxygen.
Hello. You have already read my articles on the Tutoronline.ru blog. Today I will tell you about oxygen and how to obtain it. Let me remind you that 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 on 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 percentages on Earth - 99.76%, 0.048%, 0.192%, respectively.
In the free state, oxygen exists in the form of three allotropic modifications : atomic oxygen - O o, dioxygen - O 2 and ozone - O 3. Moreover, atomic oxygen can be obtained as follows:
KClO 3 = KCl + 3O 0
KNO 3 = KNO 2 + O 0
Oxygen is found in more than 1,400 different minerals and organic matter, in the atmosphere its content is 21% by volume. And 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 o C).
In the laboratory, oxygen is obtained by moderately heating 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 decomposing perchlorates:
2KClO 4 → KClO 2 + KCl + 3O 2
perchlorate
potassium
3) During the decomposition of berthollet salt (potassium chlorate).
In this case, atomic oxygen is formed:
2KClO 3 → 2 KCl + 6O 0
chlorate
potassium
4) During the decomposition of hypochlorous acid salts in the light- hypochlorites:
2NaClO → 2NaCl + O 2
Ca(ClO) 2 → CaCl 2 + O 2
5) When heating nitrates.
In this case, atomic oxygen is formed. Depending on the position of the nitrate metal in the activity series, various reaction products are formed:
2NaNO 3 → 2NaNO 2 + O 2
Ca(NO 3) 2 → CaO + 2NO 2 + O 2
2AgNO3 → 2Ag + 2NO2 + O2
6) During the decomposition of peroxides:
2H 2 O 2 ↔ 2H 2 O + O 2
7) When heating oxides of inactive metals:
2Аg 2 O ↔ 4Аg + O 2
This process is relevant in everyday life. The fact is that dishes made of copper or silver, having a natural layer of 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 highest degree oxidation:
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 carbon dioxide with peroxides:
CO 2 + K 2 O 2 →K 2 CO 3 + O 2
This method is an indispensable technical solution to the problem of breathing 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 during the process of photosynthesis. occurring in plants. All life on Earth fundamentally depends on this process. Photosynthesis is a complex multi-step process. Light gives it its beginning. Photosynthesis itself consists of two phases: light and dark. During the light phase, the chlorophyll pigment contained in plant leaves forms a so-called “light-absorbing” complex,” which takes electrons from water, and thereby splits it into hydrogen ions and oxygen:
2H 2 O = 4e + 4H + O 2
Accumulated protons contribute to the synthesis of ATP:
ADP + P = ATP
During the dark phase, carbon dioxide and water are converted into glucose. And oxygen is released as a by-product:
6CO 2 + 6H 2 O = C 6 H 12 O 6 + O 2
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Hello.. Today I will tell you about oxygen and how to obtain it. Let me remind you that if you have questions for me, you can write them in the comments to the article. If you need any help in chemistry, . 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 percentages on Earth - 99.76%, 0.048%, 0.192%, respectively.
In the free state, oxygen exists in the form of three allotropic modifications : atomic oxygen - O o, dioxygen - O 2 and ozone - O 3. Moreover, atomic oxygen can be obtained as follows:
KClO 3 = KCl + 3O 0
KNO 3 = KNO 2 + O 0
Oxygen is part of more than 1,400 different minerals and organic substances; in the atmosphere its content is 21% by volume. And 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 o C).
In the laboratory, oxygen is obtained by moderately heating 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 decomposing perchlorates:
2KClO 4 → KClO 2 + KCl + 3O 2
perchlorate
potassium
3) During the decomposition of berthollet salt (potassium chlorate).
In this case, atomic oxygen is formed:
2KClO 3 → 2 KCl + 6O 0
chlorate
potassium
4) During the decomposition of hypochlorous acid salts in the light- hypochlorites:
2NaClO → 2NaCl + O 2
Ca(ClO) 2 → CaCl 2 + O 2
5) When heating nitrates.
In this case, atomic oxygen is formed. Depending on the position of the nitrate metal in the activity series, various reaction products are formed:
2NaNO 3 → 2NaNO 2 + O 2
Ca(NO 3) 2 → CaO + 2NO 2 + O 2
2AgNO3 → 2Ag + 2NO2 + O2
6) During the decomposition of peroxides:
2H 2 O 2 ↔ 2H 2 O + O 2
7) When heating oxides of inactive metals:
2Аg 2 O ↔ 4Аg + O 2
This process is relevant in everyday life. The fact is that dishes made of copper or silver, having a natural layer of 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 an indispensable technical solution to the problem of breathing 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 during the process of photosynthesis. occurring in plants. All life on Earth fundamentally depends on this process. Photosynthesis is a complex multi-step process. Light gives it its beginning. Photosynthesis itself consists of two phases: light and dark. During the light phase, the chlorophyll pigment contained in plant leaves forms a so-called “light-absorbing” complex,” which takes electrons from water, and thereby splits it into hydrogen ions and oxygen:
2H 2 O = 4e + 4H + O 2
Accumulated protons contribute to the synthesis of ATP:
ADP + P = ATP
During the dark phase, carbon dioxide and water are converted into glucose. And oxygen is released as a by-product:
6CO 2 + 6H 2 O = C 6 H 12 O 6 + O 2
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The purpose of the lesson:
- contribute to the formation of student knowledge about methods of obtaining oxygen in nature, industry and laboratories, evidence of the presence and methods of collecting it;
- promote the formation of skills to identify general and essential features; the ability to see a problem and find ways to solve it; skills to apply acquired knowledge in practice and evaluate the results of completed actions;
- continue to develop memory, attention, creative activity;
- continue to develop independence and the ability to work in groups;
- continue to form the team.
Organizing time.
Introductory part
– Which chapter are we studying? (Simple substances.)
– What substances are called simple? (Substances whose molecules consist of atoms of the same type.)
– What groups are they divided into? simple substances? (For metals and non-metals.)
Learning new material.
We continue to get acquainted with simple substances. Today we will learn more about the substance that Berzelius said that earthly chemistry revolves around. You will find out what this substance is by completing the following task. Instead of ... insert the word that corresponds to the element of the substance and write the word in your notebook. (Appendix 2.)
1. ... is the most common element of the earth’s crust.
2. The molecule of the simple substance ozone is formed by the element ...
3. The air contains 21%...
4. Oxides are complex substances consisting of two elements, one of which is...
5. Water contains two hydrogen atoms and one atom...
-Have you written down one word?
– Who wrote down a few words?
-What word is this? (Oxygen.)
So, let's start studying the simple substance oxygen!
– Why are we studying this topic? Why is oxygen important? (Oxygen, an essential substance for respiration, is the most common element in the earth’s crust and is part of water.)
– In the section on simple substances there is a vital task that is related to oxygen. Read it.
Life task.
To travel through the cave you need a supply of oxygen. How can you get it while traveling?
– Based on your life task, tell me what you should study today? (How do you get oxygen?)
Lesson topic: “Getting oxygen.”
While studying this topic:
- you will learn
To solve the life task that faces us, work in groups.
The class is divided into five groups of 4 people. Each group has its own task. (Annex 1.)
– Carefully study the information, answer the questions, write down the reaction equations.
Work in groups.
Then presenting the completed task. One representative from the group answers the questions orally, and the second writes the reaction equations on the board.
– Be careful when listening to each other. As your presentations progress, we will draw up a scheme for obtaining oxygen.
Using air oxygen for breathing, we reduce its amount. But the content in the air remains constant - 21%. How is the constant oxygen content we need maintained? How is oxygen produced in nature?
Speech by group 1 about obtaining oxygen in nature.
Reaction equation
General conclusion: oxygen in nature is obtained through the process of photosynthesis in plants in the light.
Part of the scheme is being drawn up
– Is this method suitable for solving a life problem? (No, photosynthesis requires light.)
Oxygen is necessary not only in nature. In industry it is used to obtain metals and other necessary substances. For this, oxygen is needed in large quantities. The production methods that are used in this case are called industrial.
Speech by group 2 on the production of oxygen in industry.
Reaction equation 
General conclusion: oxygen in industry is obtained from air and water.
– Why do they use air and water to produce large quantities of oxygen? (the most common substances in nature containing oxygen)
The next part of the scheme “Oxygen production” is being drawn up
– Is this method suitable for solving a life problem? (no, expensive equipment, such processes take a lot of time)
In England, on one of the squares in Leeds there is a monument to the scientist. In his right hand he holds a lens to collect the beam sun rays, and on the left is a crucible with mercury oxide. The young man is focused and attentive, awaiting the results of the experience. This is Joseph Priestley, English. scientist captured at the moment of obtaining oxygen in his laboratory.
We consider laboratory methods for producing oxygen.
Speech by group 3 about some methods of producing oxygen in the laboratory.
Reaction equations
Conclusion: these methods are not suitable for solving a life problem, because... mercury compounds are poisonous, and potassium nitrate may not be available in camp conditions.
– These laboratory methods do not limit the production of oxygen. There are several other ways to produce oxygen in the laboratory.
Speech by group 4 about the most common methods of producing oxygen in the laboratory.
Reaction equations
MnO 2 is a catalyst that accelerates a chemical reaction, but is not consumed.
All chemical decomposition reactions.
General conclusion: in the laboratory, oxygen is produced by the decomposition reactions of oxygen-containing substances when heated or exposed to a catalyst.
The rest of the diagram is drawn up.
Students make guesses.
For example, to obtain oxygen in camping conditions, you can use the decomposition reaction of potassium permanganate, which is always in your first aid kit. You can also use the decomposition of hydrogen peroxide; for this reaction, you can use blood and saliva, which contain natural catalysts, as a catalyst.
– Having received oxygen, it is also necessary to collect it in a certain way and prove its presence.
Presentation by group 5 about methods of collecting oxygen and proving its presence.
General conclusion: oxygen is collected by displacing air and water; the presence of oxygen is proven using a smoldering splinter.
Performance laboratory work“Production of oxygen by decomposition of potassium permanganate and proof of its presence” in vapor.
Before work, repeat the safety rules when working with an alcohol lamp and when heating.
Conclusion.
– Have you achieved the objectives of the lesson?
– How do you get oxygen?
Lesson conclusion: oxygen can be obtained in nature, industry and the laboratory. To obtain oxygen, decomposition reactions of oxygen-containing substances are used. Reactions occur when heated or in the presence of a catalyst.
Homework.
Choose the task that you like best.
Task No. 1.
Tell your friend who was absent from the “Getting Oxygen” lesson using the knowledge about speaking styles you learned in Russian lessons.
Task No. 2.
Prepare a speech for a school conference - Lomonosov readings on the topic “The History of the Discovery of Oxygen”, using knowledge about speech styles acquired in Russian language lessons.
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