Message on the topic carbon dioxide (CO2). Physical and chemical properties of carbon dioxide Presentation history of the discovery of carbon dioxide

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Carbon dioxide

Carbon dioxide is colorless and odorless. It is almost 1.5 times heavier than air. Under normal conditions, one volume of carbon dioxide dissolves in one volume of water.

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The air always contains about 0.3% carbon dioxide. Its content in the air is not constant. The air in cities, especially near factories, contains slightly more carbon dioxide than the air in rural areas.

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Carbon dioxide is formed during respiration and combustion of fuel, as well as during smoldering and rotting of various organic matter.

The water of many mineral springs contains a significant amount of dissolved carbon dioxide. One of these mineral water sources is located in Kislovodsk. Every day this source discharges about two and a half million liters of mineral water containing up to 5 g of free carbon dioxide.

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The waters of the seas and oceans contain a lot of dissolved carbon dioxide, tens of times more than in the air.

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When the pressure increases to 60 atm, it turns into a colorless liquid. When liquid carbon dioxide evaporates, some of it can turn into a solid snow-like mass. It is pressed and the so-called “dry ice” is obtained, which sublimes at normal pressure without melting, and its temperature drops to -78.5 ° C. Therefore, dry ice is mainly used for storage food products and especially ice cream.

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Carbon dioxide

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Molecule structure
The CO2 molecule is linear, the length of the C=O double bond is 0.116 nm. Within the framework of the theory of hybridization atomic orbitals two σ-bonds are formed by sp-hybrid orbitals of the carbon atom and 2p-orbitals of the oxygen atom. Carbon p-orbitals that do not participate in hybridization form p-bonds with similar oxygen orbitals. The molecule is non-polar.

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Physical properties
Carbon monoxide (IV) is carbon dioxide, a colorless and odorless gas, heavier than air, soluble in water, and upon strong cooling it crystallizes in the form of a white snow-like mass - “dry ice”. At atmospheric pressure it does not melt, but evaporates, the sublimation temperature is -78 ° C. Carbon dioxide is formed when organic matter rots and burns. Contained in the air and mineral springs, released during the respiration of animals and plants. Slightly soluble in water (1 volume of carbon dioxide in one volume of water at 15 ° C).

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Chemical properties
Chemically, carbon monoxide is inert. 1. Oxidizing properties With strong reducing agents at high temperatures it exhibits oxidizing properties. Coal is reduced to carbon monoxide: C + CO2 = 2CO. Magnesium ignited in air continues to burn in an atmosphere of carbon dioxide: 2Mg + CO2 = 2MgO + C.

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Chemical properties
2. Properties of acid oxide Typical acid oxide. Reacts with basic oxides and bases, forming carbonic acid salts: Na2O + CO2 = Na2CO3, 2NaOH + CO2 = Na2CO3 + H2O, NaOH + CO2 = NaHCO3.

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Chemical properties
3. Qualitative reaction A qualitative reaction for detecting carbon dioxide is the turbidity of lime water: Ca(OH)2 + CO2 = CaCO3↓ + H2O. At the beginning of the reaction, a white precipitate is formed, which disappears when CO2 is passed through lime water for a long time, because insoluble calcium carbonate turns into soluble bicarbonate: CaCO3 + H2O + CO2 = Ca(HCO3)2.

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In industry, it is a by-product of lime production. In the laboratory when acids interact with chalk or marble. During combustion of carbon-containing substances. With slow oxidation in biochemical processes (respiration, rotting, fermentation).
Receipt

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Getting sugar. Fire extinguishing. Production of fruit waters. "Dry ice". Obtaining cleaning supplies. Receiving medications. Preparation of soda, which is used to make glass.
Applications of carbon monoxide (IV)

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Combustion is associated with the appearance of smoke. The smoke can be white, black, and sometimes invisible. An “invisible” smoke called carbon dioxide rises above a hot candle or alcohol lamp. Hold a clean test tube over the candles and catch a little of the “invisible” smoke. To prevent it from flying away, quickly close the test tube with a stopper without a hole. Carbon dioxide will be invisible in a test tube. Save this test tube with carbon dioxide for further experiments.
We're catching smoke

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"Muddy Story"
Pour a little lime water (to cover the bottom) into the test tube in which you captured the carbon dioxide from the candle flame. Close the test tube with your finger and shake it. The clear lime water became completely cloudy. Only carbon dioxide is to blame for this. If you take lime water into a test tube that does not contain carbon dioxide, and shake the test tube, the water will remain clear. This means that the turbidity of the limewater is evidence that there was carbon dioxide in the test tube.

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Carbon dioxide is released from soda
Take some soda powder and heat it in a horizontal reinforced test tube. Connect this test tube with an elbow tube to another test tube containing water. Bubbles will begin to appear from the tube. Consequently, some kind of gas comes from the soda into the water. The glass tube should not be allowed to be lowered into the water after heating has finished, otherwise the water will rise up the tube and fall into the hot test tube with soda. This may cause the test tube to burst. After you see that gas is released from the soda when heated, try replacing the plain water in the test tube with lime water. It will become cloudy. Carbon dioxide is released from soda.

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Lemonade gas is also carbon dioxide
If you open a bottle of lemonade or start shaking it, a lot of gas bubbles will appear in it. Close the lemonade bottle with a stopper containing a glass tube, and place the long end of the tube in a test tube containing lime water. Soon the water will become cloudy. So lemon gas is carbon dioxide. It is formed from carbonic acid contained in lemonade.

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Vinegar removes carbon dioxide from baking soda
Carbon dioxide is found in a number of substances, but it is impossible to detect it by sight. If you pour vinegar on a piece of soda, the vinegar will hiss strongly and some kind of gas will be released from the soda. If you put a piece of soda in a test tube, pour a little vinegar into it, close it with a stopper with an elbow tube and dip the long end of the tube into lime water, you will be convinced that carbon dioxide is also released from the soda.

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Lemonade Factory
Even a weak acid expels carbon dioxide from soda. Cover the bottom of the test tube with citric acid and pour the same amount of soda on top of it. Mix these two substances. They both get along, but not for long. Pour this mixture into an ordinary glass and quickly fill it with fresh water. How much it hisses and foams! Like real lemonade. You can safely sip it. It is absolutely harmless, even tasty. You just need to add sugar at the very beginning, just to make it tastier.

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Lemonade in your pocket
Carbon dioxide in drinks increases their refreshing effect. You can make foaming lemon anytime. To do this, mix 2 cubic centimeters of citric acid powder, 2 cubic centimeters of soda and 6 cubic centimeters of powdered sugar in a test tube. These three substances must be thoroughly mixed by shaking and pouring onto a large sheet of paper. This amount must be divided into equal portions. Each portion should be large enough to cover the round bottom of the test tube. Wrap each portion in a separate piece of paper, just like they wrap powders in a pharmacy. From one such bag you can get a glass of refreshing lemonade.

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Limestone releases carbon dioxide
If foam appears when a substance is wetted with acid, it is almost always due to the release of carbon dioxide. It is he who forms this foam. The wetted limestone hisses and foams, and carbon dioxide is released from it. If you are not sure about this, do an experiment: put a piece of limestone in a test tube and add acid, then close the test tube with a stopper with a glass tube and dip the long end of this tube into lime water. The water will become cloudy. There are several types of lime. Limestone is calcium carbonate.

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Sinking flame
Warmed carbon dioxide, or smoke, is light and freely rises into the air, cold carbon dioxide is heavy, settles to the bottom of the vessel and gradually fills it to the brim. Combustion is impossible in carbon dioxide, since it itself is a combustion product. If you place a candle at the bottom of a vessel and watch it for a while, you will see that the flame will soon go out. Carbon dioxide, transformed when the candle burns, gradually fills the vessel to the brim, and the flame “drowns” in carbon dioxide.

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Carbon oxides Chemistry teacher of Municipal Educational Institution “KSOSH No. 7” Gareeva O. I.

Production of carbon monoxide (II) Industrial method 1. Formed during the combustion of carbon or compounds based on it (for example, gasoline) in conditions of lack of oxygen: 2C + O 2 = 2CO 2. When carbon monoxide (IV) is reduced with hot coal: CO 2 + C = 2CO This reaction often occurs in stove fires.

Production of carbon monoxide (IV) 1. In industry, it is obtained by roasting natural carbonates (limestone, dolomite). CaCO 3 = CaO + CO 2 2. B laboratory conditions obtained by reacting carbonates and bicarbonates with acids, for example marble, chalk or soda with hydrochloric acid: CaCO 3 + 2HCI = CaCI 2 + H 2 O + CO 2 To prepare drinks, the reaction of baking soda with citric acid or with sour lemon juice can be used.

Physical properties CO - carbon monoxide (II), carbon monoxide, carbon monoxide Gas, colorless, odorless, lighter than air, slightly soluble in water, much more soluble in alcohol, T. pl. -205.02 0 C, bp. -191.5 density 1.25 g/l (0 0 C) Very poisonous! CO 2 - carbon monoxide (IV), carbon dioxide, carbon dioxide. Gas, colorless, odorless, 1.5 times heavier than air, soluble in water, density 1.98 g/l M.P. −57 °C), T, boiling −78 °C, sublimes. The solid oxide is called "dry ice"

Chemical properties of carbon monoxide (II) At room temperature, CO is inactive, its chemical activity increases significantly when heated and in solutions CO is a non-salt-forming oxide 1. When heated, it reduces metals from oxides: CO + CuO → Cu + CO 2 2. Burns blue in air flame (start of reaction temperature 700 °C): 2 CO + O 2 → 2CO 2 + Q The combustion temperature of CO can reach 2100 °C.

Chemical properties of carbon monoxide (IV) CO 2 - acidic oxide 1. Reacts with water, forming unstable carbonic acid (reversible reaction) CO 2 + H 2 O H 2 CO 3 2. Reacts with alkalis, resulting in the formation of carbonates and bicarbonates CO 2 + Ca (OH) 2 = CaCO 3 ↓ + H 2 O CaCO 3 + CO 2 + H 2 O = Ca (HCO 3) 2 3. Interacts with basic oxides CO 2 + CaO = CaCO 3

Application of carbon monoxide (II) As a reducing agent, CO is used in metallurgy in the smelting of cast iron.

Water gas is used as fuel, and is also used in chemical synthesis - to produce ammonia, higher alcohols, etc.

Carbon monoxide (II) is used to process animal and fish meat, giving them a bright red color and a fresh appearance without changing the taste. The permissible CO concentration is 200 mg/kg of meat.

Applications of carbon monoxide (IV) Carbon dioxide is used to carbonate fruit and mineral waters, for sugar production, in medicine for carbon dioxide baths.

IN Food Industry carbon monoxide (IV) is used as a preservative and is indicated on the packaging under the code E290, and also as a leavening agent.

Cylinders with liquid carbon dioxide are widely used as fire extinguishers 1) in portable fire extinguishers; 2) in fire extinguishing systems of aircraft and ships, carbon dioxide fire engines. Such widespread use in fire extinguishing is due to the fact that in some cases water is not suitable for extinguishing.

Technologies for cleaning various surfaces with dry ice granules. Cleaning injection molds with dry ice

Solid carbon dioxide - dry ice - is used in glaciers. Liquid carbon dioxide is used as a refrigerant and working fluid in refrigerators, freezers, and solar power generators.

Scientists have found a way to use carbon dioxide: it can be used to make polycarbonate, which is used to make compact discs. The first DVDs and plastic bottles made from CO 2 may appear on sale in just a couple of years.

Biological significance of carbon dioxide Carbon monoxide (IV) plays one of the main roles in living nature, participating in many metabolic processes of a living cell. Atmospheric carbon dioxide is the main source of carbon for plants. Plants absorb carbon dioxide during photosynthesis,

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