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Ozone Ozone (from other Greek ὄζω - smell) is an allotropic modification of oxygen consisting of triatomic O3 molecules. At normal conditions- blue gas. When liquefied, it turns into an indigo-colored liquid. IN solid form It is a dark blue, almost black crystal.

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Structure of ozone Both O-O connections in the ozone molecule have the same length 1.272 Å. The angle between the bonds is 116.78°. The central oxygen atom is sp²-hybridized and has one lone pair of electrons. The order of each bond is 1.5, resonance structures are with a localized single bond with one atom and a double bond with another and vice versa. The molecule is polar, dipole moment 0.5337 D.

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History of discovery Ozone was first discovered in 1785 by the Dutch physicist M. van Marum from the characteristic odor and oxidizing properties that air acquires after passing electric sparks through it. However, it was not described as a new substance; van Marum believed that a special “electric matter” was being formed. The term ozone was proposed by the German chemist X.F. Schönbein in 1840, entered the dictionaries in late XIX century. Many sources give priority to the discovery of ozone in 1839.

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Physical properties Molecular weight - 48 a.u.m. The gas density under normal conditions is 2.1445 µg/m³. Relative gas density for oxygen 1.5; by air - 1.62 (1.658). Liquid density at −183 °C - 1.71 g/cm³ Boiling point - −111.9 °C. Liquid ozone is dark purple in color. Melting point - −197.2 ± 0.2 °C (the melting point usually given as −251.4 °C is erroneous, since its determination did not take into account the great ability of ozone to supercool). In the solid state, it is black in color with a purple sheen. Solubility in water at 0 °C is 0.394 kg/m³ (0.494 l/kg), it is 10 times higher than oxygen. In the gaseous state, ozone is diamagnetic; in the liquid state, it is weakly paramagnetic. The smell is sharp, specific “metallic” (according to Mendeleev - “the smell of crayfish”). At high concentrations it smells like chlorine. The smell is noticeable even when diluted 1: 100,000.

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Ozone production Ozone is formed in many processes accompanied by the release of atomic oxygen, for example, during the decomposition of peroxides, oxidation of phosphorus, etc. In industry, it is obtained from air or oxygen in ozonizers by the action of an electric discharge. O3 liquefies more easily than O2, and therefore it is easy to separate them. Ozone for ozone therapy in medicine is obtained only from pure oxygen. When air is irradiated with hard ultraviolet radiation, ozone is formed. The same process occurs in the upper layers of the atmosphere, where the ozone layer is formed and maintained by solar radiation. In the laboratory, ozone can be obtained by reacting bismuth pentafluoride and some strong oxidizing agents with water. Ozone is obtained using an ozonator device.

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Biological properties The high oxidizing ability of ozone and the formation of free oxygen radicals in many reactions with its participation determine its high toxicity. Exposure of the body to ozone can lead to premature death. The most dangerous effect: on the respiratory organs by direct irritation and tissue damage on cholesterol in the human blood with the formation of insoluble forms, leading to atherosclerosis on the reproductive organs in males of all species of animals, including humans (inhalation of this gas kills male reproductive cells and prevents them education). If exposed to high concentrations for a long time, this gas can cause male infertility. Ozone in Russian Federation attributed to the first, most high class dangers harmful substances. Ozone standards: maximum single maximum permissible concentration (MAC m.r.) in the atmospheric air of populated areas 0.16 mg/m³ average daily maximum permissible concentration (MAC s.s.) in the atmospheric air of populated areas 0.03 mg/m³ maximum permissible concentration (MPC) in the air of the working area is 0.1 mg/m³. At the same time, the threshold of human smell is approximately equal to 0.01 mg/m³. Ozone effectively kills mold and bacteria.

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Application of liquid ozone The use of ozone as a high-energy and at the same time environmentally friendly oxidizer in rocketry. The total chemical energy released during the combustion reaction involving ozone is approximately one quarter greater than for simple oxygen (719 kcal/kg). Accordingly, the specific impulse will be greater. Liquid ozone has a larger specific gravity, than that of liquid oxygen (1.35 and 1.14, respectively), and its boiling point is higher (minus 112° and minus 183°C, respectively), so in this regard, liquid ozone has a greater advantage as an oxidizing agent in rocket technology. However, an obstacle to this is the chemical instability and explosiveness of liquid ozone. When an explosion occurs, a detonation wave moves at enormous speed - according to some data, more than 200 km/sec - and a destructive detonation pressure of more than 4000 atm develops, which makes the use of liquid ozone impossible with the current level of technology

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The presentation on the topic "Ozone" can be downloaded absolutely free on our website. Project subject: Chemistry. Colorful slides and illustrations will help you engage your classmates or audience. To view the content, use the player, or if you want to download the report, click on the corresponding text under the player. The presentation contains 15 slide(s).

Presentation slides

Slide 1

Topic: “Ozone” Purpose: Repeat the topic “Oxygen”, develop knowledge on the topic “Ozone” Learning objectives: Review the chemical properties, physical properties, production, use of O2, develop knowledge about the physical and chemical properties of ozone, its production and use. Development objectives: Develop the ability to compare and draw conclusions using the example of gases O2 and O3. Develop the ability to achieve a goal - completing multi-level tasks to achieve a score of “5” points. Educational objectives: to form an idea of ​​ozone as a chemical substance that plays one of the most important roles in human life. Consider the problem of “ozone holes”: causes, consequences and ways to solve this problem. Develop a caring attitude towards planet Earth and your health. Equipment: In test tubes on desks a) colored cards with multi-level Fe2O3 tasks; СuO; CaO. b) on the interactive board pictures “ozone, ozone holes”. Teachers: geographer, biologist.

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During the classes

Organizational stage. Test of knowledge a) we studied the topic “O2” Task: a) There are 2 gases in two flasks - O2 and CO2 Question: with the help of what chemical experiment do you recognize these gases? Answer: (interactive whiteboard - 2 test tubes of O2 and CO2) - give an explanation Question: List the physical properties of O2 (orally) On the board: 1 student write down the equation for the interaction of O2 with Al, arrange the coefficients. Multi-level tasks: colored cards with tasks different levels Task for “3” - blue color for “4” - red color for “5” - green color

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Blue - write down the equation for the combustion reaction of substances, arrange the coefficients. “3” P+O2= P(V) S+O2= S(VI) Red - write down the equations of chemical reactions based on the reaction products and assign the coefficients “4”…. +…. = СuO Cu(II)…. +…. = CaO…. +…. = Fe2O3 Fe(III) Green – write down the equations for the combustion reactions of complex substance “5” CuS + O2 = …. +…. Cu(II), S(VI) All students complete the blue task - compulsory level. Next, students complete the reverse task in red (distribute samples of substances in rows, pass them to each other, write down the reaction equations for the production of these oxides in notebooks - independently) At the blackboard: analyze the equation for the combustion of methane CH4 + 2O2 = CO2+ 2H2O; Students independently complete the task with a grade of “5.” Mutual testing—correct solutions on the board give each other grades

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And so, guys, we got acquainted with the properties of O3, its application. And what is the importance of the ozone layer for the Earth, the appearance of “ozone holes” in our century and the problems associated with this environmental problem - we will be introduced to geography teacher A. Khusainova. and biologist Bayraktarova R.B. Geographer - There is a protective layer of ozone in the atmosphere above the earth. At an altitude of 25 km, it says to the UV rays - “stop!” Biologist - Excessive doses of UV radiation can cause skin cancer and various eye diseases. Too high a level has a detrimental effect on plants and the smallest aquatic organisms that form marine plankton - the basis of all food chains in the ocean. As a result economic activity As humans, various pollutants enter the atmosphere, including those that destroy the ozone layer.

Teacher: A great danger to the ozone layer is represented by a) nuclear explosions in the atmosphere b) the release of freons into the atmosphere.

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Freons are synthetic chemicals that are widely used as coolants, aerosols and foam reagents. Freons practically do not enter into chemical reactions and therefore are not toxic to living organisms. However, when they enter the stratosphere and are exposed to UV radiation there, they disintegrate, releasing atomic chlorine. Biologist. To save the decreasing ozone from destruction, a law was signed between the countries in Montreal: Reduce the production of all substances and objects using freons and later, after a while, replace all freons. On September 16, 1987, 36 countries signed the Montreal Protocol. In 1994, the UN General Assembly proclaimed September 16 as International Day for the Preservation of the Ozone Layer. The Earth's ozone layer is no longer declining. The production of freons has decreased by more than 2 times, but their production is still ongoing and, according to scientists, it will take at least another 50 years for the ozone layer to stabilize. 4. Consolidation (TPO p. 39) Problem: How many moles of O3 can be obtained from Given: 18 moles of O2? How much energy will V(O2)-18 be consumed in the reaction Q KJ -? 1) 3O2 →2O3 -288.5 KJ. V 3 2 18 x

"Question answer"

Lesson topic:

"Ozone. Allotropy of oxygen"

oxygen

Allotropy - This is the ability of atoms of one chemical element to form several simple substances.

Different simple substances formed by the same chemical element, are called allotropic modifications (modifications)

oxygen

O 2 is a colorless and odorless gas.

O 3 is a bluish gas with a fresh smell and has bactericidal properties.

COMPARATIVE CHARACTERISTICS OXYGEN AND OZONE

• Chemical formula

• Simple substance

• Simple substance

• Classification

• Oxygen atoms

• Oxygen atoms

• Qualitative composition of the molecule

• Quantitative composition of the molecule

• Two oxygen atoms

• Three oxygen atoms

• Relative molecular weight

• Being in nature

• In the atmosphere, in the hydrosphere

• Ozone layer of the stratosphere

• Physical properties

• Gas, no color, no taste, no smell, heavier than air

• Gas, blue, smells fresh, heavier than air

• Oxidation reactions (stronger oxidizing agent)

• Chemical properties

• Oxidation reactions

PRODUCTION OF OZONE:

• 1) Ozone is formed under the influence of solar radiation. During this reaction, that part of solar radiation is absorbed, which is destructive for all life on Earth.
• Ultraviolet rays (a component of solar radiation), invading the stratosphere, break oxygen molecules (O 2) into two atoms (O), which react with oxygen molecules (O 2), forming ozone (O 3).
• 2) Ozone is also formed due to electrical discharges (during a thunderstorm).
• 3) Ozone is also formed during the oxidation of resin from coniferous trees or seaweed.

CHEMICAL PROPERTIES OF OZONE

• 1) The ozone molecule is very fragile O 3 - O 2 + O, 2O- O 2, 2O 3 - 3O 2
• 2) The resulting atomic oxygen reacts more vigorously with substances than molecular oxygen, therefore ozone is more chemically active than oxygen.
• Really,
• it quickly destroys rubber, which changes very slowly in the air;
• interacts at room temperature with silver, forming silver oxide Ag + O 3 -AgO + O 2 (and silver does not react with oxygen).

The ozone layer protects the Earth from ultraviolet radiation.

The ozone hole is an area of ​​low ozone content in the atmosphere.

Fastening:

Give names to the oxides:

N 2 O 5 , CaO,SO 2 , Al 2 O 3 , BaO,

Cl 2 O 7 , ZnO, V 2 O 5 , Cr 2 O 3 ,

CuO,SO 3 , MoO 3

Fastening:

The solution of the problem:

Determine the mass of the oxide that is formed during the oxidation of 65 g of zinc.

Goals:

1) develop the idea of ​​oxygen as a chemical element, forming the concepts of “ozone”, “allotropy”, “allotropic modifications”;

2) promote the development of skills to characterize substances according to plan and compare them, establish cause-and-effect relationships, and formulate conclusions;

3) contribute to the formation of a worldview idea about the relationship between quantitative and qualitative changes.

During the classes

I. Preparation for studying new material.

In previous lessons we studied oxygen. Oxygen - as a chemical element and oxygen - as a simple substance formed by the atoms of this chemical element.

Let's remember what you know about oxygen as a chemical element. Using the plan, characterize the chemical element oxygen. (Slide)

Thus, atoms of the chemical element oxygen participate in the formation of the following substances: O 2, CO 2, O 3, H 2 O, CaCO 3, SiO 2, including oxygen as a substance.

What do you know about the substance oxygen? Describe the substance oxygen using the plan presented on the screen. (Slide)

Indeed, oxygen easily enters into chemical reactions. Wherein, chemical interaction of substances with oxygen called oxidation reaction. The substances formed in this case are called oxides. The equation of a chemical reaction reflects the material balance of the process. This allows such equations to be used for quantitative calculations.

Let's solve the problem. Open your notebooks, sign today's date... (Slide)

II. The purpose of today's lesson: to continue studying the topic “Oxygen” and get acquainted with another substance, also formed by atoms of only this chemical element, which is called ozone.(Slide)

III. Learning new material.

Write down the topic of today’s lesson “Ozone” in your notebook.

Before characterizing the substance ozone according to the plan you know (slide), remember: What do you know about this substance? What have you heard or read about ozone?(Conversation with students)

Being in nature. (Slide)

Receipt

1) Ozone is formed under the influence of solar radiation (its ultraviolet part) from oxygen (slide hyperlink), which explains the accumulation of this substance in the upper layers of the atmosphere (in the stratosphere). During this reaction, that part of solar radiation is absorbed, which is destructive for all life on Earth.

Ultraviolet rays (a component of solar radiation), invading the stratosphere, break oxygen molecules (O 2) into two atoms (O), which react with oxygen molecules (O 2), forming ozone (O 3).

2) Ozone is also formed due to electrical discharges (for example, during a thunderstorm).

3) Ozone is also formed during the oxidation of resin from coniferous trees or seaweed.

For further acquaintance with ozone, you can watch the video material (Disk - physical properties, chemical properties, application)

So what do you know about ozone now?

Characterize the substance ozone according to the plan presented on the screen. (Slide)

It should be noted. (Teacher's comments as he fills out the table)

Being in nature

The thickness of the ozone layer above the Earth's surface is not constant.

1) Seasonal changes in the thickness of the ozone layer are a natural phenomenon.

Besides,

2) Man-made chemicals, in particular freons (substances used as refrigerants in refrigeration units), react with ozone, destroying it, thereby reducing the thickness of the ozone layer (forming the so-called “ozone hole”).

To date, scientists have found a significant decrease in the thickness of the ozone layer over Antarctica, which allows more ultraviolet rays to reach the Earth's surface.

In this image taken from space, the hole in the ozone layer above Antarctica appears as a blue blob.

Physical properties

1) Ozone has a smell that you can clearly smell after a thunderstorm or in a coniferous forest. “Ozone” (Greek) – “smelling”.

2) Ozone is heavier than air: M r (O 3) = 48.

1) The ozone molecule is very fragile O 3 -> O 2 + O, 2O -> O 2, 2O 3 -> 3O 2

2) The resulting atomic oxygen reacts more vigorously with substances than molecular oxygen, therefore ozone is more chemically active than oxygen.

Really,

• it quickly destroys rubber, which changes very slowly in the air;
• interacts at room temperature with silver, forming silver oxide Ag + O 3 -> AgO + O 2 (and silver does not react with oxygen);
• ozone has a bactericidal effect (the atmosphere of a pine forest or sea coast is healing).

Having characterized each of the substances formed by atoms of the chemical element oxygen, you can now compare them.

Give a comparative description of oxygen and ozone, note the similarities and differences. (Slide)

Oxygen and ozone are simple substances formed by atoms of the same chemical element oxygen.

However, an oxygen molecule contains 2 oxygen atoms, an ozone molecule contains 3 oxygen atoms.

At the same time, we note their different properties (somewhat similar).

Differences in the number of atoms lead to differences in properties. Quantitative changes turn into qualitative ones (one of the basic laws of philosophy).

1) The phenomenon when the same chemical element forms several simple substances is called allotropy.(Slide)

2) Different simple substances formed by the same chemical element are called allotropic modifications(modifications).

IV. Lesson summary.

So, today in class it was necessary. (Slide)

Formulate a conclusion (by purpose).

V. Homework.

At home, after reading the text of § 4.5:

• answer questions after §4.5 (p. 79 of the textbook) - orally;
• learn the definitions of “allotropy” and “allotropic modifications”.

For the next lesson you need to be able to:

• characterize the simple substance ozone;
• compare it with the substance oxygen;
• explain the phenomenon of “allotropy” and the concept of “allotropic modifications”.