Carbon oxides

In recent years, preference has been given to personality-oriented learning in pedagogical science. The formation of individual personality traits occurs in the process of activity: study, play, work. Therefore, an important factor in learning is the organization of the learning process, the nature of the relationship between the teacher and students and students among themselves. Based on these ideas, I try to build the educational process in a special way. At the same time, each student chooses his own pace of studying the material, has the opportunity to work at a level accessible to him, in a situation of success. In the lesson, it is possible to master and improve not only subject-specific, but also such general educational skills as setting an educational goal, choosing means and ways to achieve it, monitoring one’s achievements, and correcting errors. Students learn to work with literature, make notes, diagrams, drawings, work in a group, in pairs, individually, conduct a constructive exchange of opinions, reason logically and draw conclusions.

Conducting such lessons is not easy, but if you succeed, you feel satisfaction. I offer a script for one of my lessons. It was attended by colleagues, administration and a psychologist.

Lesson type. Learning new material.

Goals. Based on motivation and updating the basic knowledge and skills of students, consider the structure, physical and chemical properties, production and use of carbon dioxide and carbon dioxide.

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Equipment and reagents.“Programmed survey” cards, poster diagram, devices for producing gases, glasses, test tubes, fire extinguisher, matches; lime water, sodium oxide, chalk, hydrochloric acid, indicator solutions, H 2 SO 4 (conc.), HCOOH, Fe 2 O 3.

Poster diagram
“Structure of the molecule of carbon monoxide (carbon monoxide (II)) CO”

DURING THE CLASSES

The desks for students in the office are arranged in a circle. The teacher and students have the opportunity to freely move to laboratory tables (1, 2, 3). During the lesson, children sit at study tables (4, 5, 6, 7, ...) with each other as desired (free groups of 4 people).

Teacher. Wise Chinese proverb(written beautifully on the board) reads:

“I hear - I forget,
I see - I remember
I do - I understand.”

Do you agree with the conclusions of the Chinese sages?

What Russian proverbs reflect Chinese wisdom?

Children give examples.

Teacher. Indeed, only by creating can one obtain a valuable product: new substances, devices, machines, as well as intangible values ​​- conclusions, generalizations, conclusions. I invite you today to take part in a study of the properties of two substances. It is known that when undergoing a technical inspection of a car, the driver provides a certificate about the condition of the car’s exhaust gases. What gas concentration is indicated in the certificate?

(O t v e t. SO.)

Student. This gas is poisonous. Once in the blood, it causes poisoning of the body (“burning”, hence the name of the oxide - carbon monoxide). It is found in car exhaust gases in quantities dangerous to life.(reads a report from a newspaper about a driver who fell asleep in a garage while the engine was running and died of death). The antidote to carbon monoxide poisoning is breathing fresh air and pure oxygen. Another carbon monoxide is carbon dioxide.

Teacher. There is a “Programmed Survey” card on your desks. Familiarize yourself with its contents and, on a blank piece of paper, mark the numbers of those tasks for which you know the answers based on your life experience. Opposite the number of the task-statement, write the formula of carbon monoxide to which this statement relates.

Student consultants (2 people) collect answer sheets and, based on the results of the answers, form new groups for subsequent work.

Programmed survey “Carbon oxides”

1. The molecule of this oxide consists of one carbon atom and one oxygen atom.

2. The bond between atoms in a molecule is polar covalent.

3. A gas that is practically insoluble in water.

4. The molecule of this oxide contains one carbon atom and two oxygen atoms.

5. It has no smell or color.

6. Gas soluble in water.

7. Does not liquefy even at –190 °C ( t kip = –191.5 °C).

8. Acidic oxide.

9. It is easily compressed, at 20 °C under a pressure of 58.5 atm it becomes liquid and hardens into “dry ice”.

10. Not poisonous.

11. Non-salt-forming.

12. Flammable

13. Interacts with water.

14. Interacts with basic oxides.

15. Reacts with metal oxides, reducing free metals from them.

16. Obtained by reacting acids with carbonic acid salts.

17. I.

18. Interacts with alkalis.

19. The source of carbon absorbed by plants in greenhouses and greenhouses leads to increased yield.

20. Used for carbonating water and drinks.

Teacher. Review the contents of the card again. Group the information into 4 blocks:

structure,

physical properties,

Chemical properties,

receiving.

The teacher gives each group of students the opportunity to speak and summarizes the presentations. Then students of different groups choose their work plan - the order of studying oxides. For this purpose, they number the blocks of information and justify their choice. The learning order can be as written above, or with any other combination of the four blocks marked.

The teacher draws students' attention to the key points of the topic. Since carbon oxides are gaseous substances, they must be handled with care (safety instructions). The teacher approves the plan for each group and assigns consultants (pre-prepared students).

Demonstration experiments

1. Pouring carbon dioxide from glass to glass.

2. Extinguishing candles in a glass as CO 2 accumulates.

3. Place several small pieces of dry ice into a glass of water. The water will boil and thick white smoke will pour out of it.

CO 2 gas is liquefied already at room temperature under a pressure of 6 MPa. In a liquid state, it is stored and transported in steel cylinders. If you open the valve of such a cylinder, the liquid CO 2 will begin to evaporate, due to which strong cooling occurs and part of the gas turns into a snow-like mass - “dry ice”, which is pressed and used to store ice cream.

4. Demonstration of a chemical foam fire extinguisher (CFO) and explanation of the principle of its operation using a model - a test tube with a stopper and a gas outlet tube.

Information on structure at table No. 1 (instruction cards 1 and 2, structure of CO and CO 2 molecules).

Information about physical properties– at table No. 2 (working with the textbook – Gabrielyan O.S. Chemistry-9. M.: Bustard, 2002, p. 134–135).

Data about preparation and chemical properties– on tables No. 3 and 4 (instruction cards 3 and 4, instructions for practical work, pp. 149–150 of the textbook).

Homework

The teacher suggests taking the “Programmed Survey” card home and, in preparation for the next lesson, thinking about ways to obtain information. (How did you know that the gas you are studying liquefies, reacts with acid, is poisonous, etc.?)

Independent work of students

Groups of children perform practical work at different speeds. Therefore, games are offered to those who complete the work faster.

Fifth wheel

Four substances can have something in common, but the fifth substance stands out from the series, is superfluous.

1. Carbon, diamond, graphite, carbide, carbine. (Carbide.)

2. Anthracite, peat, coke, oil, glass. (Glass.)

3. Limestone, chalk, marble, malachite, calcite. (Malachite.)

4. Crystalline soda, marble, potash, caustic, malachite. (Caustic.)

5. Phosgene, phosphine, hydrocyanic acid, potassium cyanide, carbon disulfide. (Phosphine.)

6. Sea water, mineral water, distilled water, ground water, hard water. (Distilled water.)

7. Lime milk, fluff, slaked lime, limestone, lime water. (Limestone.)

8. Li 2 CO 3; (NH 4) 2 CO 3; CaCO 3; K 2 CO 3 , Na 2 CO 3 . (CaCO3.)

Synonyms

Write the chemical formulas of the substances or their names.

1. Halogen -... (Chlorine or bromine.)

2. Magnesite – ... (MgCO 3.)

3. Urea –... ( Urea H 2 NC(O)NH 2 .)

4. Potash - ... (K 2 CO 3.)

5. Dry ice - ... (CO 2.)

6. Hydrogen oxide –... ( Water.)

7. Ammonia -... ( 10% aqueous ammonia solution.)

8. Salts of nitric acid –... ( Nitrates– KNO 3, Ca(NO 3) 2, NaNO 3.)

9. Natural gas – ... ( Methane CH 4.)

Antonyms

Write chemical terms that are opposite in meaning to those proposed.

1. Oxidizing agent –... ( Reducing agent.)

2. Electron donor –… ( Electron acceptor.)

3. Acid properties – ... ( Basic properties.)

4. Dissociation –… ( Association.)

5. Adsorption – ... ( Desorption.)

6. Anode –... ( Cathode.)

7. Anion –… ( Cation.)

8. Metal –... ( Non-metal.)

9. Starting substances –... ( Reaction products.)

Search for patterns

Establish a sign that combines the specified substances and phenomena.

1. Diamond, carbine, graphite – ... ( Allotropic modifications of carbon.)

2. Glass, cement, brick - ... ( Construction Materials.)

3. Breathing, rotting, volcanic eruption - ... ( Processes accompanied by the release of carbon dioxide.)

4. CO, CO 2, CH 4, SiH 4 – ... ( Compounds of group IV elements.)

5. NaHCO 3, CaCO 3, CO 2, H 2 CO 3 – ... ( Oxygen compounds of carbon.)

Physical properties.

Carbon monoxide is a colorless and odorless gas that is slightly soluble in water.

t pl. 205 °C,

t kip. 191 °C

critical temperature =140°C

critical pressure = 35 atm.

The solubility of CO in water is about 1:40 by volume.

Chemical properties.

Under normal conditions, CO is inert; when heated - a reducing agent; non-salt-forming oxide.

1) with oxygen

2C +2 O + O 2 = 2C +4 O 2

2) with metal oxides

C +2 O + CuO = Cu + C +4 O 2

3) with chlorine (in the light)

CO + Cl 2 --hn-> COCl 2 (phosgene)

4) reacts with alkali melts (under pressure)

CO + NaOH = HCOONa (sodium formic acid (sodium formate))

5) forms carbonyls with transition metals

Ni + 4CO =t°= Ni(CO) 4

Fe + 5CO =t°= Fe(CO) 5

Carbon monoxide does not react chemically with water. CO also does not react with alkalis and acids. It is extremely poisonous.

From the chemical side, carbon monoxide is characterized mainly by its tendency to undergo addition reactions and its reducing properties. However, both of these trends usually appear only at elevated temperatures. Under these conditions, CO combines with oxygen, chlorine, sulfur, some metals, etc. At the same time, carbon monoxide, when heated, reduces many oxides to metals, which is very important for metallurgy. Along with heating, an increase in the chemical activity of CO is often caused by its dissolution. Thus, in solution it is capable of reducing salts of Au, Pt and some other elements to free metals already at ordinary temperatures.

At elevated temperatures and high pressures, CO interacts with water and caustic alkalis: in the first case, HCOOH is formed, and in the second, sodium formic acid. The latter reaction occurs at 120 °C, a pressure of 5 atm and is used technically.

The reduction of palladium chloride in solution is easy according to the general scheme:

PdCl 2 + H 2 O + CO = CO 2 + 2 HCl + Pd

serves as the most commonly used reaction for the discovery of carbon monoxide in a mixture of gases. Even very small amounts of CO are easily detected by the slight coloring of the solution due to the release of finely crushed palladium metal. Quantitative determination of CO is based on the reaction:

5 CO + I 2 O 5 = 5 CO 2 + I 2.

The oxidation of CO in solution often occurs at a noticeable rate only in the presence of a catalyst. When selecting the latter, the main role is played by the nature of the oxidizing agent. Thus, KMnO 4 oxidizes CO most quickly in the presence of finely crushed silver, K 2 Cr 2 O 7 - in the presence of mercury salts, KClO 3 - in the presence of OsO 4. In general, in its reducing properties, CO is similar to molecular hydrogen, and its activity under normal conditions is higher than that of the latter. Interestingly, there are bacteria that, through the oxidation of CO, obtain the energy they need for life.

The comparative activity of CO and H2 as reducing agents can be assessed by studying the reversible reaction:

H 2 O + CO = CO 2 + H 2 + 42 kJ,

the equilibrium state of which at high temperatures is established quite quickly (especially in the presence of Fe 2 O 3). At 830 °C, the equilibrium mixture contains equal amounts of CO and H 2, i.e., the affinity of both gases for oxygen is the same. Below 830 °C, the stronger reducing agent is CO, above - H2.

The binding of one of the products of the reaction discussed above, in accordance with the law of mass action, shifts its equilibrium. Therefore, by passing a mixture of carbon monoxide and water vapor over calcium oxide, hydrogen can be obtained according to the scheme:

H 2 O + CO + CaO = CaCO 3 + H 2 + 217 kJ.

This reaction occurs already at 500 °C.

In air, CO ignites at about 700 °C and burns with a blue flame to CO 2:

2 CO + O 2 = 2 CO 2 + 564 kJ.

The significant release of heat that accompanies this reaction makes carbon monoxide a valuable gaseous fuel. However, it is most widely used as a starting product for the synthesis of various organic substances.

The combustion of thick layers of coal in furnaces occurs in three stages:

1) C + O 2 = CO 2; 2) CO 2 + C = 2 CO; 3) 2 CO + O 2 = 2 CO 2.

If the pipe is closed prematurely, a lack of oxygen is created in the furnace, which can cause CO to spread throughout the heated room and lead to poisoning (fumes). It should be noted that the smell of “carbon monoxide” is not caused by CO, but by impurities of some organic substances.

The CO flame can have a temperature of up to 2100 °C. The CO combustion reaction is interesting in that when heated to 700-1000 °C, it proceeds at a noticeable speed only in the presence of traces of water vapor or other hydrogen-containing gases (NH 3, H 2 S, etc.). This is due to the chain nature of the reaction under consideration, which occurs through the intermediate formation of OH radicals according to the following schemes:

H + O 2 = HO + O, then O + CO = CO 2, HO + CO = CO 2 + H, etc.

At very high temperatures, the CO combustion reaction becomes noticeably reversible. The CO 2 content in an equilibrium mixture (under a pressure of 1 atm) above 4000 °C can only be negligibly small. The CO molecule itself is so thermally stable that it does not decompose even at 6000 °C. CO molecules have been discovered in the interstellar medium. When CO acts on metal K at 80 °C, a colorless crystalline, highly explosive compound of the composition K 6 C 6 O 6 is formed. With the elimination of potassium, this substance easily turns into carbon monoxide C 6 O 6 (“triquinone”), which can be considered as a product of CO polymerization. Its structure corresponds to a six-membered ring formed by carbon atoms, each of which is connected by a double bond to oxygen atoms.

Interaction of CO with sulfur according to the reaction:

CO + S = COS + 29 kJ

It goes fast only at high temperatures. The resulting carbon thioxide (O=C=S) is a colorless and odorless gas (mp -139, bp -50 °C). Carbon (II) monoxide is capable of combining directly with certain metals. As a result, metal carbonyls are formed, which should be considered as complex compounds.

Carbon(II) monoxide also forms complex compounds with some salts. Some of them (OsCl 2 ·3CO, PtCl 2 ·CO, etc.) are stable only in solution. The formation of the latter substance is associated with the absorption of carbon monoxide (II) by a solution of CuCl in strong HCl. Similar compounds are apparently formed in an ammonia solution of CuCl, which is often used to absorb CO in the analysis of gases.

Receipt.

Carbon monoxide is formed when carbon burns in the absence of oxygen. Most often it is obtained as a result of the interaction of carbon dioxide with hot coal:

CO 2 + C + 171 kJ = 2 CO.

This reaction is reversible, and its equilibrium below 400 °C is almost completely shifted to the left, and above 1000 °C - to the right (Fig. 7). However, it is established with noticeable speed only at high temperatures. Therefore, under normal conditions, CO is quite stable.

Rice. 7. Equilibrium CO 2 + C = 2 CO.

The formation of CO from elements follows the equation:

2 C + O 2 = 2 CO + 222 kJ.

It is convenient to obtain small amounts of CO by the decomposition of formic acid: HCOOH = H 2 O + CO

This reaction occurs easily when HCOOH reacts with hot, strong sulfuric acid. In practice, this preparation is carried out either by the action of conc. sulfuric acid into liquid HCOOH (when heated), or by passing the vapors of the latter over phosphorus hemipentaoxide. The interaction of HCOOH with chlorosulfonic acid according to the scheme:

HCOOH + CISO 3 H = H 2 SO 4 + HCI + CO

It already works at normal temperatures.

A convenient method for laboratory production of CO can be heating with conc. sulfuric acid, oxalic acid or potassium iron sulfide. In the first case, the reaction proceeds according to the following scheme: H 2 C 2 O 4 = CO + CO 2 + H 2 O.

Along with CO, carbon dioxide is also released, which can be retained by passing the gas mixture through a solution of barium hydroxide. In the second case, the only gaseous product is carbon monoxide:

K 4 + 6 H 2 SO 4 + 6 H 2 O = 2 K 2 SO 4 + FeSO 4 + 3 (NH 4) 2 SO 4 + 6 CO.

Large quantities of CO can be obtained by incomplete combustion of coal in special furnaces - gas generators. Conventional (“air”) generator gas contains on average (volume %): CO-25, N2-70, CO 2 -4 and small impurities of other gases. When burned, it produces 3300-4200 kJ per m3. Replacing ordinary air with oxygen leads to a significant increase in CO content (and an increase in the calorific value of the gas).

Even more CO is contained in water gas, which consists (in an ideal case) of a mixture of equal volumes of CO and H 2 and produces 11,700 kJ/m 3 upon combustion. This gas is obtained by blowing water vapor through a layer of hot coal, and at about 1000 °C the interaction takes place according to the equation:

H 2 O + C + 130 kJ = CO + H 2.

The reaction of the formation of water gas occurs with the absorption of heat, the coal gradually cools and to maintain it in a hot state, it is necessary to alternate the passage of water vapor with the passage of air (or oxygen) into the gas generator. In this regard, water gas contains approximately CO-44, H 2 -45, CO 2 -5 and N 2 -6%. It is widely used for the synthesis of various organic compounds.

Mixed gas is often obtained. The process of obtaining it boils down to simultaneously blowing air and water vapor through a layer of hot coal, i.e. a combination of both methods described above - Therefore, the composition of the mixed gas is intermediate between generator and water. On average it contains: CO-30, H 2 -15, CO 2 -5 and N 2 -50%. A cubic meter of it produces about 5400 kJ when burned.

Carbon(II) monoxide – CO

(carbon monoxide, carbon monoxide, carbon monoxide)

Physical properties: a colorless, poisonous gas, tasteless and odorless, burns with a bluish flame, lighter than air, poorly soluble in water. The concentration of carbon monoxide in the air is 12.5-74% explosive.

Molecule structure:

The formal oxidation state of carbon +2 does not reflect the structure of the CO molecule, in which, in addition to the double bond formed by the sharing of electrons C and O, there is an additional one formed by the donor-acceptor mechanism due to the lone pair of oxygen electrons (depicted by an arrow):

In this regard, the CO molecule is very strong and is capable of entering into oxidation-reduction reactions only at high temperatures. Under normal conditions, CO does not react with water, alkalis or acids.

Receipt:

The main anthropogenic source of carbon monoxide CO is currently the exhaust gases of internal combustion engines. Carbon monoxide is formed when fuel is burned in internal combustion engines at insufficient temperatures or the air supply system is poorly tuned (insufficient oxygen is supplied to oxidize carbon monoxide CO into carbon dioxide CO2). Under natural conditions, on the surface of the Earth, carbon monoxide CO is formed during incomplete anaerobic decomposition of organic compounds and during the combustion of biomass, mainly during forest and steppe fires.

1) In industry (in gas generators):

Video - experiment "Generating carbon monoxide"

C + O 2 = CO 2 + 402 kJ

CO 2 + C = 2CO – 175 kJ

In gas generators, water vapor is sometimes blown through hot coal:

C + H 2 O = CO + H 2 – Q,

a mixture of CO + H 2 is called synthesis gas .

2) In the laboratory- thermal decomposition of formic or oxalic acid in the presence of H 2 SO 4 (conc.):

HCOOH t˚C, H2SO4 → H2O+CO

H2C2O4 t˚C,H2SO4 → CO + CO 2 + H 2 O

Chemical properties:

Under normal conditions, CO is inert; when heated - reducing agent;

CO - non-salt-forming oxide .

1) with oxygen

2 C +2 O + O 2 t ˚ C →2 C +4 O 2

2) with metal oxides CO + Me x O y = CO 2 + Me

C +2 O + CuO t ˚ C →Сu + C +4 O 2

3) with chlorine (in the light)

CO + Cl 2 light → COCl 2 (phosgene - poisonous gas)

4)* reacts with alkali melts (under pressure)

CO+NaOHP → HCOONa (sodium formate)

The effect of carbon monoxide on living organisms:

Carbon monoxide is dangerous because it prevents the blood from carrying oxygen to vital organs such as the heart and brain. Carbon monoxide combines with hemoglobin, which carries oxygen to the body's cells, making the body unsuitable for oxygen transport. Depending on the amount inhaled, carbon monoxide impairs coordination, aggravates cardiovascular diseases and causes fatigue, headaches, and weakness. The effect of carbon monoxide on human health depends on its concentration and the time of exposure to the body. A concentration of carbon monoxide in the air of more than 0.1% leads to death within one hour, and a concentration of more than 1.2% within three minutes.

Applications of carbon monoxide :

Carbon monoxide is mainly used as a flammable gas mixed with nitrogen, the so-called generator or air gas, or water gas mixed with hydrogen. In metallurgy for the recovery of metals from their ores. To obtain high purity metals from the decomposition of carbonyls.

FIXING

No. 1. Complete the reaction equations, draw up an electronic balance for each reaction, indicate the processes of oxidation and reduction; oxidizing agent and reducing agent:

CO2+C=

C+H2O=

C O + O 2 =

No. 2. Calculate the amount of energy required to produce 448 liters of carbon monoxide according to the thermochemical equation

CARBON OXIDE (CARBON MONOXIDE). Carbon(II) oxide (carbon monoxide) CO, non-salt-forming carbon monoxide. This means that there is no acid corresponding to this oxide. Carbon monoxide (II) is a colorless and odorless gas that liquefies at atmospheric pressure at a temperature of –191.5°C and solidifies at –205°C. The CO molecule is similar in structure to the N2 molecule: both contain an equal number of electrons (such molecules are called isoelectronic) , the atoms in them are connected by a triple bond (two bonds in the CO molecule are formed due to the 2p electrons of carbon and oxygen atoms, and the third is formed by a donor-acceptor mechanism with the participation of a lone electron pair of oxygen and a free 2p orbital of carbon). As a result, the physical properties of CO and N2 (melting and boiling points, solubility in water, etc.) are very similar.

Carbon oxide (II) is formed during the combustion of carbon-containing compounds with insufficient access to oxygen, as well as when hot coal comes into contact with the product of complete combustion - carbon dioxide: C + CO2 → 2CO. In the laboratory, CO is obtained by dehydration of formic acid by the action of concentrated sulfuric acid on liquid formic acid when heated, or by passing formic acid vapor over P2O5: HCOOH → CO + H2O. CO is obtained by the decomposition of oxalic acid: H2C2O4 → CO + CO2 + H2O. CO can be easily separated from other gases by passing it through an alkali solution.
Under normal conditions, CO, like nitrogen, is chemically quite inert. Only at elevated temperatures does the tendency of CO to undergo oxidation, addition and reduction reactions appear. Thus, at elevated temperatures it reacts with alkalis: CO + NaOH → HCOONa, CO + Ca(OH)2 → CaCO3 + H2. These reactions are used to remove CO from industrial gases.

Carbon monoxide (II) is a high-calorie fuel: combustion is accompanied by the release of a significant amount of heat (283 kJ per 1 mole of CO). Mixtures of CO with air explode when its content ranges from 12 to 74%; Fortunately, in practice such mixtures are extremely rare. In industry, to obtain CO, gasification of solid fuel is carried out. For example, blowing water vapor through a layer of coal heated to 1000oC leads to the formation of water gas: C + H2O → CO + H2, which has a very high calorific value. However, combustion is far from the most profitable use of water gas. From it, for example, it is possible to obtain (in the presence of various catalysts under pressure) a mixture of solid, liquid and gaseous hydrocarbons - a valuable raw material for the chemical industry (Fischer-Tropsch reaction). From the same mixture, enriching it with hydrogen and using the necessary catalysts, you can obtain alcohols, aldehydes, and acids. Of particular importance is the synthesis of methanol: CO + 2H2 → CH3OH - the most important raw material for organic synthesis, therefore this reaction is carried out industrially on a large scale.

Reactions in which CO is a reducing agent can be demonstrated by the example of the reduction of iron from ore during the blast furnace process: Fe3O4 + 4CO → 3Fe + 4CO2. The reduction of metal oxides with carbon(II) oxide is of great importance in metallurgical processes.

CO molecules are characterized by addition reactions to transition metals and their compounds with the formation of complex compounds - carbonyls. Examples include liquid or solid metal carbonyls Fe(CO)4, Fe(CO)5, Fe2(CO)9, Ni(CO)4, Cr(CO)6, etc. These are very toxic substances that, when heated, decompose again into metal and CO. This way you can obtain powdered metals of high purity. Sometimes metal “smudges” are visible on the burner of a gas stove; this is a consequence of the formation and decay of iron carbonyl. Currently, thousands of different metal carbonyls have been synthesized, containing, in addition to CO, inorganic and organic ligands, for example, PtCl2(CO), K3, Cr(C6H5Cl)(CO)3.

CO is also characterized by a reaction of the compound with chlorine, which occurs in the light already at room temperature with the formation of exclusively toxic phosgene: CO + Cl2 → COCl2. This reaction is a chain reaction, it follows a radical mechanism with the participation of chlorine atoms and free radicals COCl. Despite its toxicity, phosgene is widely used for the synthesis of many organic compounds.

Carbon monoxide (II) is a strong poison, as it forms strong complexes with metal-containing biologically active molecules; this disrupts tissue respiration. The cells of the central nervous system are especially affected. The binding of CO to Fe(II) atoms in blood hemoglobin prevents the formation of oxyhemogloblin, which carries oxygen from the lungs to the tissues. Even when the air contains 0.1% CO, this gas displaces half of the oxygen from oxyhemoglobin. In the presence of CO, death from asphyxiation can occur even in the presence of large amounts of oxygen. Therefore, CO is called carbon monoxide. In a “distressed” person, the brain and nervous system are primarily affected. For salvation, you first need clean air that does not contain CO (or, even better, pure oxygen), while CO bound to hemoglobin is gradually replaced by O2 molecules and suffocation goes away. The maximum permissible average daily concentration of CO in atmospheric air is 3 mg/m3 (about 3.10–5%), in the air of the work area – 20 mg/m3.

Typically, the CO content in the atmosphere does not exceed 10–5%. This gas enters the air as part of volcanic and swamp gases, with secretions of plankton and other microorganisms. Thus, 220 million tons of CO are released into the atmosphere annually from the surface layers of the ocean. The concentration of CO in coal mines is high. A lot of carbon monoxide is produced during forest fires. The smelting of every million tons of steel is accompanied by the formation of 300–400 tons of CO. In total, the technogenic release of CO into the air reaches 600 million tons per year, more than half of which comes from motor vehicles. If the carburetor is not adjusted, the exhaust gases can contain up to 12% CO! Therefore, most countries have introduced strict standards for the CO content in car exhaust.

The formation of CO always occurs during the combustion of carbon-containing compounds, including wood, with insufficient access to oxygen, as well as when hot coal comes into contact with carbon dioxide: C + CO2 → 2CO. Such processes also occur in village ovens. Therefore, prematurely closing the stove chimney to conserve heat often leads to carbon monoxide poisoning. One should not think that city dwellers who do not heat their stoves are insured against CO poisoning; For example, it is easy for them to get poisoned in a poorly ventilated garage where a car is parked with the engine running. CO is also found in natural gas combustion products in the kitchen. Many aviation accidents in the past were caused by engine wear or poor adjustments, allowing CO to enter the cockpit and poison the crew. The danger is compounded by the fact that CO cannot be detected by smell; in this regard, carbon monoxide is more dangerous than chlorine!

Carbon monoxide (II) is practically not sorbed by active carbon and therefore an ordinary gas mask does not protect against this gas; To absorb it, an additional hopcalite cartridge is required containing a catalyst that “afterburns” CO to CO2 with the help of atmospheric oxygen. More and more passenger cars are now equipped with afterburning catalysts, despite the high cost of these catalysts based on platinum metals.

The physical properties of carbon monoxide (carbon monoxide CO) at normal atmospheric pressure are considered depending on temperature at negative and positive values.

In tables The following physical properties of CO are presented: carbon monoxide density ρ , specific heat capacity at constant pressure C p, thermal conductivity coefficients λ and dynamic viscosity μ .

The first table shows the density and specific heat capacity of carbon monoxide CO in the temperature range from -73 to 2727°C.

The second table gives the values ​​of such physical properties of carbon monoxide as thermal conductivity and its dynamic viscosity in the temperature range from minus 200 to 1000°C.

The density of carbon monoxide, like , depends significantly on temperature - when carbon monoxide CO is heated, its density decreases. For example, at room temperature the density of carbon monoxide is 1.129 kg/m3, but in the process of heating to a temperature of 1000°C, the density of this gas decreases by 4.2 times - to a value of 0.268 kg/m 3.

Under normal conditions (temperature 0°C), carbon monoxide has a density of 1.25 kg/m3. If we compare its density with other common gases, then the density of carbon monoxide relative to air is less important - carbon monoxide is lighter than air. It is also lighter than argon, but heavier than nitrogen, hydrogen, helium and other light gases.

The specific heat of carbon monoxide under normal conditions is 1040 J/(kg deg). As the temperature of this gas increases, its specific heat capacity increases. For example, at 2727°C its value is 1329 J/(kg deg).

The thermal conductivity of carbon monoxide under normal conditions is 0.02326 W/(m deg). It increases with increasing temperature and at 1000°C it becomes equal to 0.0806 W/(m deg). It should be noted that the thermal conductivity of carbon monoxide is slightly less than this value y.

The dynamic viscosity of carbon monoxide at room temperature is 0.0246·10 -7 Pa·s. When carbon monoxide is heated, its viscosity increases. This type of dependence of dynamic viscosity on temperature is observed in . It should be noted that carbon monoxide is more viscous than water vapor and carbon dioxide CO 2, but has a lower viscosity compared to nitrogen oxide NO and air.