Slide 1
Chemistry 8th grade 05/12/2008 * Chemistry teacher of secondary school No. 33 “Norilsk secondary secondary school» Zavalishina Elena NikolaevaSlide 2
1. The element oxygen is in group VI, main subgroup, period II, serial number No. 8, Ar = 16. 2. Atomic structure: P11 = 8; n01 = 8; ē = 8 valency II, oxidation state -2 (rarely +2; +1; -1). 3. Part of oxides, bases, salts, acids, organic substances, including living organisms - up to 65% by weight. * *
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4. In the earth's crust it is 49% by mass, in the hydrosphere - 89% by mass. 5. Composed of air (in the form of a simple substance) – 20-21% by volume. Air composition: O2 – 20-21%; N2 – 78%; CO2 – 0.03%, the rest comes from inert gases, water vapor, and impurities. * * Oxygen is the most common element on our planet. By weight, it accounts for approximately half of the total mass of all elements of the earth's crust.
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Gas - colorless, tasteless and odorless; 3V O2 (n.s.) dissolves in 100V H2O; t boil= -183 C; t pl = -219 C; d by air = 1.1. At a pressure of 760 mm. Hg and a temperature of –183 C, oxygen liquefies * *
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With non-metals C + O2 CO2 S + O2 SO2 2H2 + O2 2H2O * 5 With complex substances 4FeS2 + 11O2 2Fe2O3 + 8SO2 2H2S + 3O2 2SO2 + 2H2O CH4 + 2O2 CO2 + 2H2O With metals 2Mg + O2 2MgO 2Cu + O2 –t Interaction substances with oxygen is called oxidation. All elements react with oxygen except Au, Pt, He, Ne and Ar; in all reactions (except for the interaction with fluorine), oxygen is an oxidizing agent. 1. Unstable: O3 O2 + O 2. Strong oxidizing agent: 2KI + O3 + H2O 2KOH + I2 + O2 Discolors dyes, reflects UV rays, destroys microorganisms.
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Industrial method (distillation of liquid air). Laboratory method (decomposition of some oxygen-containing substances) 2KClO3 –t ;MnO2 2KCl + 3O2 2H2O2 –MnO2 2H2O + O2 Obtaining 3O2 2O3 During a thunderstorm (in nature), (in the laboratory) in an ozonizer * 6
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potassium permanganate when heated: 2KMnO4 –t K2MnO4 + MnO2 + O2 The decomposition of this salt occurs when it is heated above 2000 C. Heating 2KMnO4 Checking the collected oxygen * *
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Oxygen is an element of the main subgroup of group VI, the second period of D.I. Mendeleev’s periodic system of chemical elements, with atomic number 8. It is designated by the symbol O (lat. Oxygenium). Oxygen is a chemically active non-metal and is the lightest element from the group of chalcogens. The simple substance oxygen under normal conditions is a colorless, tasteless and odorless gas, the molecule of which consists of two oxygen atoms (formula O2), for which reason it is also called dioxygen. Liquid oxygen is light blue in color, while solid oxygen is light blue crystals.
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There are other allotropic forms of oxygen, for example, ozone - under normal conditions a gas blue color with a specific odor, the molecule of which consists of three oxygen atoms (formula O3).
Slide 4
It is officially believed that oxygen was discovered by the English chemist Joseph Priestley on August 1, 1774 by decomposing mercuric oxide in a hermetically sealed vessel (Priestley directed sunlight at this compound using a powerful lens). However, Priestley initially did not realize that he had discovered a new simple substance; he believed that he had isolated one of components air (and called this gas “dephlogisticated air”). Priestley reported his discovery to the outstanding French chemist Antoine Lavoisier. In 1775, A. Lavoisier established that oxygen is integral part air, acids and is found in many substances. A few years earlier (in 1771), oxygen was obtained by the Swedish chemist Karl Scheele. He calcined saltpeter with sulfuric acid and then decomposed the resulting nitric oxide. Scheele called this gas “fire air” and described his discovery in a book published in 1777 (precisely because the book was published later than Priestley announced his discovery, the latter is considered the discoverer of oxygen). Scheele also reported his experience to Lavoisier.
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An important step, which contributed to the discovery of oxygen was the work of the French chemist Pierre Bayen, who published work on the oxidation of mercury and the subsequent decomposition of its oxide. Finally, A. Lavoisier finally figured out the nature of the resulting gas, using information from Priestley and Scheele. His work was of enormous importance because thanks to it, the phlogiston theory, which was dominant at that time and hampered the development of chemistry, was overthrown. Lavoisier conducted a combustion experiment various substances and disproved the phlogiston theory by publishing results on the weight of elements burned. The weight of the ash exceeded the original weight of the element, which gave Lavoisier the right to claim that during combustion a chemical reaction (oxidation) of the substance occurs, and therefore the mass of the original substance increases, which refutes the theory of phlogiston. Phlogiston (from Greek - combustible, flammable) - in the history of chemistry - a hypothetical “superfine matter” - a “fiery substance” that supposedly fills all flammable substances and is released from them during combustion. Thus, the credit for the discovery of oxygen is actually shared between Priestley, Scheele and Lavoisier.
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Joseph Priestley Antoine Laurent Lavoisier Carl Wilhelm Scheele
Slide 7
The word oxygen owes its appearance in the Russian language to some extent to M.V. Lomonosov, who introduced the word “acid”, along with other neologisms; Thus, the word “oxygen”, in turn, was a tracing of the term “oxygen” proposed by A. Lavoisier, which is translated as “generating acid”, which is associated with its original meaning - “acid”, which previously meant oxides, called according to modern international oxide nomenclature.
Slide 8
Oxygen is the most common element on Earth; its share (in various compounds, mainly silicates) accounts for about 47% of the mass of the solid earth's crust. Marine and fresh waters contain huge amount bound oxygen - 85.82% (by weight). More than 1,500 compounds in the earth's crust contain oxygen. Oxygen is part of many organic substances and is present in all living cells. By the number of atoms in living cells it is about 25%, by mass fraction - about 65%.
Slide 9
Currently, in industry, oxygen is obtained from the air. The main industrial method for producing oxygen is cryogenic rectification. Oxygen plants operating on the basis of membrane technology are also well known and successfully used in industry. Laboratories use industrially produced oxygen, supplied in steel cylinders under a pressure of about 15 MPa. Small amounts of oxygen can be obtained by heating potassium permanganate KMnO4:
Slide 10
The reaction of catalytic decomposition of hydrogen peroxide H2O2 in the presence of manganese(IV) oxide is also used: Oxygen can be obtained by the catalytic decomposition of potassium chlorate (Berthollet salt) KClO3: K laboratory methods oxygen production is a method of electrolysis aqueous solutions alkalis, as well as the decomposition of mercury(II) oxide (at t = 100 °C): On submarines it is usually obtained by the reaction of sodium peroxide and carbon dioxide exhaled by humans:
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Under normal conditions, oxygen is a gas without color, taste or smell. 1 liter of it has a mass of 1.429 g. Slightly heavier than air. Slightly soluble in water (4.9 ml/100 g at 0 °C, 2.09 ml/100 g at 50 °C) and alcohol (2.78 ml/100 g at 25 °C). Dissolves well in molten silver. When gaseous oxygen is heated, its reversible dissociation into atoms occurs: at 2000 °C - 0.03%, at 2600 °C - 1%, 4000 °C - 59%, 6000 °C - 99.5%. Liquid oxygen (boiling point −182.98 °C) is a pale blue liquid. Solid oxygen (melting point −218.35°C) - blue crystals.
Slide 12
A strong oxidizing agent, it interacts with almost all elements, forming oxides. Oxidation state −2. As a rule, the oxidation reaction proceeds with the release of heat and accelerates with increasing temperature. Example of reactions occurring at room temperature: Oxidizes compounds that contain elements with less than the maximum oxidation state: Oxidizes most organic compounds: Under certain conditions, mild oxidation of an organic compound can be carried out:
Slide 13
Oxygen reacts directly (under normal conditions, with heat and/or in the presence of catalysts) with all simple substances, except Au and inert gases (He, Ne, Ar, Kr, Xe, Rn); reactions with halogens occur under the influence of an electrical discharge or ultraviolet radiation. Oxides of gold and heavy inert gases (Xe, Rn) were obtained indirectly. In all two-element compounds of oxygen with other elements, oxygen plays the role of an oxidizing agent, except for compounds with fluorine. Oxygen forms peroxides with the oxidation state of the oxygen atom formally equal to −1. For example, peroxides are produced by the combustion of alkali metals in oxygen: Some oxides absorb oxygen:
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Oxygen supports the processes of respiration, combustion, and decay. Combustion of steel wire in oxygen.
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The widespread industrial use of oxygen began in the middle of the 20th century, after the invention of turboexpanders - devices for liquefying and separating liquid air. 1. In metallurgy, the converter method of steel production or matte processing involves the use of oxygen. In many metallurgical units, for more efficient combustion of fuel, an oxygen-air mixture is used instead of air in the burners. 2. Welding and cutting of metals Oxygen in cylinders is widely used for flame cutting and welding of metals.
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3. Rocket fuel Liquid oxygen, hydrogen peroxide, nitric acid and other oxygen-rich compounds are used as an oxidizer for rocket fuel. A mixture of liquid oxygen and liquid ozone is one of the most powerful oxidizers of rocket fuel (the specific impulse of the hydrogen-ozone mixture exceeds the specific impulse for the hydrogen-fluorine and hydrogen-oxygen fluoride pairs). 4. In medicine, oxygen is used to enrich respiratory gas mixtures in case of breathing problems, to treat asthma, to prevent hypoxia in the form of oxygen cocktails, oxygen pillows. 5.B food industry In the food industry, oxygen is registered as food additives E948 as propellant and packaging gas.
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6. In agriculture: In greenhouse farming, for making oxygen cocktails, for weight gain in animals, for enriching the aquatic environment with oxygen in fish farming
Slide 19
Some oxygen derivatives (reactive oxygen species), such as singlet oxygen, hydrogen peroxide, superoxide, ozone and hydroxyl radical, are highly toxic. They are formed during the activation process or partial recovery oxygen. Superoxide (superoxide radical), hydrogen peroxide and hydroxyl radical can be formed in cells and tissues of the human and animal body and cause oxidative stress.
Slide 20
Thank you for your attention
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Oxygen
journey
Lavoisier Antoine Laurent
French chemist. One of the founders of classical chemistry. Introduced strict quantitative research methods into chemistry. He laid the foundation for the refutation of the phlogiston theory. Got oxygen. Proven complex composition atmospheric air containing oxygen and “suffocating air” (nitrogen). He proved the complex composition of water, establishing that it consists of oxygen and hydrogen.
“Oxygen is the substance around which all earthly chemistry revolves.”
(J. Berzelius)
« Living organisms drink air in order to
to get oxygen."
(D.I. Mendeleev)
« The first duty of someone who wants to become healthy is to cleanse the air around him.”
(R.Roland)
What do you know about oxygen?
And what do you want to know about him?
Objective of the lesson:
What scientists
worked
with oxygen?
Oxygen
What is it
catalyst?
History of discovery
Methods of obtaining
oxygen
Finding
in nature
Physical properties
Objective of the lesson:
oxygen as a chemical element and
like a simple substance
"Historical and informational"
General characteristics
Chemical sign - O
Serial number - 8
Chemical formula - O 2
Molar mass M (O 2) = 32 g/mol
Valence - II
Group - 6 A
Period - 2
2 KMnO 4 = K 2 MnO 4 +MnO 2 +O 2
Catalysts are substances
which speed up chemical reactions, but at the same time
are not spent.
Oxygen production in industry
Oxygen
Option 1.
c) does not support combustion.
4. The name “Oxygenium” was suggested by:
5. What substances does the chemical element oxygen form? a) only simple substances;
b) simple and complex substances;
c) only complex substances.
Answers: Option 1 – b, b, b, b, b.
Oxygen
Option 2.
c) does not dissolve at all.
5. In 1774, one scientist after an experiment
wrote: “But what struck me most was that
the candle burned in this air amazingly brilliant
flame..." It was: a) Priestley b) Lavoisier c) Scheele.
Answers: Option 2 – a, a, a, a, a.
Homework
§18, 19, 20 (physical properties),
exercises 1 - 3 (page 59).
Lesson #2
Oxygen
journey
in "The World of Amazing Substance".
Chemical properties oxygen.
I. Interaction with non-metals:
sulfur burns in oxygen.
II. Interaction with metals.
Combustion of iron in oxygen.
Calcium combustion in oxygen.
3Fe + 2O 2 = Fe 3 ABOUT 4
2Ca+O 2 = 2CaO
There are different oxides Solid, liquid, gaseous. Called differently And the properties differ. But they are united in one thing They are collectively called oxides.
SO 2
Na 2 O
N 2 O 5
Fe 2 O 3
"The third wheel."
Identify the excess substance. Motivate your answer.
“Find a match.”
Did you do the right thing?
Homework
§ 20 - 21, No. 4 - 12, rear. No. 1 - 3 (p. 60);
prepare for practical
work No. 3, p. 70.
