Carbon(II) monoxide – CO
(carbon monoxide, carbon monoxide, carbon monoxide)
Physical properties: 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 burns in internal combustion engines at insufficient temperatures or poor adjustment of the air supply system (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 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 metals high purity during 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 =
CO + Al 2 O 3 =No. 2. Calculate the amount of energy required to produce 448 liters of carbon monoxide according to thermochemical equation
Everything that surrounds us consists of compounds of various chemical elements. We breathe not just air, but a complex organic compound containing oxygen, nitrogen, hydrogen, carbon dioxide and other necessary components. The influence of many of these elements on the human body in particular and on life on Earth in general has not yet been fully studied. In order to understand the processes of interaction of elements, gases, salts and other formations with each other, in school course and the subject “Chemistry” was introduced. 8th grade is the start of chemistry lessons according to the approved general education program.
One of the most common compounds found in both earth's crust, and in the atmosphere, is an oxide. An oxide is a compound of any chemical element with an oxygen atom. Even the source of all life on Earth - water, is hydrogen oxide. But in this article we will not talk about oxides in general, but about one of the most common compounds - carbon monoxide. These compounds are obtained by merging oxygen and carbon atoms. These compounds may contain various quantities carbon and oxygen atoms, however, two main compounds of carbon and oxygen should be distinguished: carbon monoxide and carbon dioxide.
Chemical formula and method of producing carbon monoxide
What is its formula? Carbon monoxide is quite easy to remember - CO. The carbon monoxide molecule is formed by a triple bond, and therefore has a fairly high bond strength and has a very small internuclear distance (0.1128 nm). The rupture energy of this chemical compound is 1076 kJ/mol. A triple bond occurs due to the fact that the element carbon has a p-orbital in its atomic structure that is not occupied by electrons. This circumstance creates the opportunity for the carbon atom to become an acceptor electron pair. The oxygen atom, on the contrary, has an unshared pair of electrons in one of the p-orbitals, which means it has electron-donating capabilities. When these two atoms are combined, in addition to two valence bonds a third one also appears - a donor-acceptor covalent bond.
There are various ways obtaining CO One of the simplest is passing carbon dioxide over hot coal. IN laboratory conditions Carbon monoxide is produced by the following reaction: formic acid is heated with sulfuric acid, which separates the formic acid into water and carbon monoxide.
CO is also released when oxalic and sulfuric acid are heated.
Physical properties of CO
Carbon monoxide (2) has the following physical properties It is a colorless gas with no distinct odor. All foreign odors that appear during a carbon monoxide leak are products of the breakdown of organic impurities. It is much lighter than air, extremely toxic, very poorly soluble in water and different high degree flammability.
The most important property of CO is its negative effect on the human body. Carbon monoxide poisoning can be fatal. The effects of carbon monoxide on the human body will be discussed in more detail below.
Chemical properties of CO
Basic chemical reactions, in which carbon oxides (2) can be used - this is a redox reaction, as well as an addition reaction. The redox reaction is expressed in the ability of CO to reduce metal from oxides by mixing them with further heating.
When interacting with oxygen, carbon dioxide is formed and released significant amount warmth. Carbon monoxide burns with a bluish flame. Very important function carbon monoxide - its interaction with metals. As a result of such reactions, metal carbonyls are formed, the vast majority of which are crystalline substances. They are used for the production of ultra-pure metals, as well as for applying metal coating. By the way, carbonyls have proven themselves well as catalysts for chemical reactions.
Chemical formula and method of producing carbon dioxide
Carbon dioxide, or carbon dioxide, has the chemical formula CO 2 . The structure of the molecule is slightly different from that of CO. IN this education carbon has an oxidation state of +4. The structure of the molecule is linear, which means it is non-polar. The CO 2 molecule is not as strong as CO. IN earth's atmosphere contains about 0.03% carbon dioxide by total volume. An increase in this indicator destroys ozone layer Earth. In science, this phenomenon is called the greenhouse effect.
You can get carbon dioxide in various ways. In industry, it is formed as a result of combustion of flue gases. May be a by-product of the alcohol production process. It can be obtained through the process of decomposing air into its main components, such as nitrogen, oxygen, argon and others. In laboratory conditions, carbon monoxide (4) can be obtained by burning limestone, and at home, carbon dioxide can be produced using the reaction of citric acid and baking soda. By the way, this is exactly how carbonated drinks were made at the very beginning of their production.
Physical properties of CO 2
Carbon dioxide is a colorless gaseous substance without a characteristic pungent odor. Because of high number Oxidation causes this gas to have a slightly sour taste. This product does not support the combustion process, since it is itself the result of combustion. At increased concentration carbon dioxide, a person loses the ability to breathe, which leads to death. The effects of carbon dioxide on the human body will be discussed in more detail below. CO 2 is much heavier than air and is highly soluble in water even at room temperature.
One of the most interesting properties carbon dioxide is that it does not have a liquid state of aggregation under normal conditions atmospheric pressure. However, if the structure of carbon dioxide is exposed to a temperature of -56.6 °C and a pressure of about 519 kPa, it transforms into a colorless liquid.
When the temperature drops significantly, the gas is in the state of so-called “dry ice” and evaporates at a temperature higher than -78 o C.
Chemical properties of CO 2
According to their own chemical properties Carbon monoxide (4), whose formula is CO 2, is a typical acidic oxide and has all its properties.
1. When interacting with water, carbonic acid is formed, which has weak acidity and low stability in solutions.
2. When interacting with alkalis, carbon dioxide forms appropriate salt and water.
3. During interaction with active metal oxides, it promotes the formation of salts.
4. Does not support the combustion process. Activate this process only some can active metals, such as lithium, potassium, sodium.
The effect of carbon monoxide on the human body
Let's return to the main problem of all gases - the effect on the human body. Carbon monoxide belongs to the group of extremely life-threatening gases. For humans and animals, it is an extremely strong toxic substance, which, when entering the body, seriously affects the blood, nervous system body and muscles (including the heart).
Carbon monoxide in the air cannot be recognized, since this gas does not have any distinct odor. This is precisely why he is dangerous. Entering the human body through the lungs, carbon monoxide activates its destructive activity in the blood and begins to interact with hemoglobin hundreds of times faster than oxygen. As a result, a very stable compound called carboxyhemoglobin appears. It interferes with the delivery of oxygen from the lungs to the muscles, which leads to muscle tissue starvation. The brain is especially seriously affected by this.
Due to the inability to recognize carbon monoxide poisoning through the sense of smell, you should be aware of some basic signs that appear in the early stages:
- dizziness accompanied by headache;
- ringing in the ears and flickering before the eyes;
- palpitations and shortness of breath;
- facial redness.
Subsequently, the victim of poisoning develops severe weakness, sometimes vomiting. In severe cases of poisoning, involuntary convulsions are possible, accompanied by further loss of consciousness and coma. If the patient is not provided with appropriate medical care in a timely manner, death is possible.
The effect of carbon dioxide on the human body
Carbon oxides with acidity +4 belong to the category of asphyxiating gases. In other words, carbon dioxide is not a toxic substance, but it can significantly affect the flow of oxygen to the body. When the level of carbon dioxide increases to 3-4%, a person becomes seriously weak and begins to feel drowsy. When the level increases to 10%, severe headaches, dizziness, hearing loss begin to develop, and sometimes loss of consciousness occurs. If the concentration of carbon dioxide rises to a level of 20%, then death occurs from oxygen starvation.
Treatment for carbon dioxide poisoning is very simple - give the victim access to clean air, if necessary, perform artificial respiration. IN as a last resort you need to connect the victim to a ventilator.
From the descriptions of the influence of these two carbon oxides on the body, we can conclude that carbon monoxide still poses a great danger to humans with its high toxicity and targeted effect on the body from the inside.
Carbon dioxide is not so insidious and is less harmful to humans, which is why people actively use this substance even in the food industry.
The use of carbon oxides in industry and their impact on various aspects of life
Carbon oxides have a very wide application in various fields of human activity, and their spectrum is extremely rich. Thus, carbon monoxide is widely used in metallurgy in the process of smelting cast iron. CO has gained wide popularity as a material for refrigerated food storage. This oxide is used to process meat and fish to give them a fresh look and not change the taste. It is important not to forget about the toxicity of this gas and remember that the permissible dose should not exceed 200 mg per 1 kg of product. CO in lately It is increasingly used in the automotive industry as a fuel for gas-powered vehicles.
Carbon dioxide is non-toxic, so its applications are widely used in food industry, where it is used as a preservative or leavening agent. CO 2 is also used in the production of mineral and carbonated waters. In its solid form (“dry ice”), it is often used in freezers to maintain a consistently low temperature in a room or appliance.
Carbon dioxide fire extinguishers have become very popular, the foam of which completely isolates the fire from oxygen and prevents the fire from flaring up. Accordingly, another area of application is fire safety. The cylinders in air pistols are also charged with carbon dioxide. And of course, almost every one of us has read what a room air freshener consists of. Yes, one of the components is carbon dioxide.
As we can see, due to its minimal toxicity, carbon dioxide is more and more common in everyday life humans, while carbon monoxide has found application in heavy industry.
There are other carbon compounds with oxygen; fortunately, the formula of carbon and oxygen allows the use of various variants of compounds with different numbers of carbon and oxygen atoms. A number of oxides can vary from C 2 O 2 to C 32 O 8. And to describe each of them, it will take more than one page.
Carbon oxides in nature
Both types of carbon oxides considered here are present in one way or another in natural world. Thus, carbon monoxide can be a product of forest combustion or the result of human activity (exhaust gases and hazardous waste industrial enterprises).
Carbon dioxide, which we already know, is also part of complex composition air. Its content in it is about 0.03% of the total volume. When this indicator increases, the so-called “ greenhouse effect", which modern scientists fear so much.
Carbon dioxide is released by animals and humans through exhalation. It is the main source of such an element as carbon, which is useful for plants, which is why many scientists are firing on all cylinders, pointing out the unacceptability of large-scale deforestation. If plants stop absorbing carbon dioxide, then the percentage of its content in the air may increase to critical levels for human life.
Apparently, many in power have forgotten the textbook material they covered in childhood “ General chemistry. 8th grade”, otherwise the issue of deforestation in many parts of the world would be given more serious attention. This, by the way, also applies to the problem of carbon monoxide in the environment. The amount of human waste and the percentage of emissions of this unusually toxic material in environment growing day by day. And it is not a fact that the fate of the world described in the wonderful cartoon “Wally” will not repeat itself, when humanity had to leave the Earth, which had been polluted to its foundations, and go to other worlds in search of a better life.
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. Quantification 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:
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 finds its widest application as original 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 a product of CO polymerization. Its structure corresponds to a six-membered cycle formed carbon atoms, each of which is connected double bond with 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 ammonia solution CuCl, often used to absorb CO in gas analysis.
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 produced by incomplete combustion 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, consisting (in ideal case) from a mixture equal volumes CO and H 2 and giving 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 producing 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%. cubic meter when burned, it produces about 5400 kJ.
Application.
Water and mixed gases (they contain CO) are used as fuel and feedstock in the chemical industry. They are important, for example, as one of the sources for obtaining a nitrogen-hydrogen mixture for the synthesis of ammonia. When they are passed together with water vapor over a catalyst heated to 500 °C (mainly Fe 2 O 3), interaction occurs reversible reaction:
H 2 O + CO = CO 2 + H 2 + 42 kJ,
whose balance is strongly shifted to the right.
The resulting carbon dioxide is then removed by washing with water (under pressure), and the remaining CO is removed with an ammonia solution of copper salts. This leaves almost pure nitrogen and hydrogen. Accordingly, by adjusting the relative amounts of generator and water gases, it is possible to obtain N 2 and H 2 in the required volumetric ratio. Before being fed into the synthesis column, the gas mixture is dried and purified from catalyst-poisoning impurities.
CO 2 molecule
The CO molecule is characterized by d(CO) = 113 pm, its dissociation energy is 1070 kJ/mol, which is greater than that of others diatomic molecules. Let's consider electronic structure CO, where the atoms are double bonded covalent bond and one donor-acceptor, with oxygen being the donor and carbon being the acceptor.
Effect on the body.
Carbon monoxide is very poisonous. The first signs of acute CO poisoning are headache and dizziness, followed by loss of consciousness. The maximum permissible concentration of CO in the air of industrial enterprises is considered to be 0.02 mg/l. The main antidote for CO poisoning is fresh air. Short-term inhalation of ammonia vapor is also useful.
The extreme toxicity of CO, its lack of color and odor, as well as the very weak absorption of it by the activated carbon of a conventional gas mask make this gas especially dangerous. The issue of protection against it was resolved by the manufacture of special gas masks, the box of which was filled with a mixture of various oxides (mainly MnO 2 and CuO). The effect of this mixture (“hopkalite”) is reduced to the catalytic acceleration of the oxidation reaction of CO to CO 2 by atmospheric oxygen. In practice, hopcalite gas masks are very inconvenient, as they force you to breathe heated air (as a result of an oxidation reaction).
Being in nature.
Carbon monoxide is part of the atmosphere (10-5 vol.%). On average, 0.5% CO contains tobacco smoke and 3% - exhaust gases from internal combustion engines.
Signs that carbon monoxide (carbon monoxide (II), carbon monoxide, carbon monoxide) has formed in the air in a dangerous concentration are difficult to determine - invisible, may not smell, accumulates in the room gradually, imperceptibly. It is extremely dangerous for human life: it is highly toxic, excessive content in the lungs leads to severe poisoning and fatalities. A high mortality rate from gas poisoning is recorded annually. The risk of poisoning can be reduced by following simple rules and the use of special carbon dioxide sensors.
What is carbon monoxide
Natural gas is formed during the combustion of any biomass; in industry, it is a product of the combustion of any carbon-based compounds. In both cases, a prerequisite for the release of gas is a lack of oxygen. Large volumes of it enter the atmosphere as a result forest fires, in the form of exhaust gases generated during the combustion of fuel in car engines. For industrial purposes it is used in the production of organic alcohol, sugar, processing of animal meat and fish. Small quantity Monoxide is also produced by the cells of the human body.
Properties
From a chemical point of view, monoxide – inorganic compound with a single oxygen atom in the molecule, chemical formula– SO. This is a chemical substance that has no characteristic color, taste or smell, it is lighter than air, but heavier than hydrogen, and is inactive at room temperatures. A person who smells only feels the presence of organic impurities in the air. It belongs to the category of toxic products; death at a concentration in the air of 0.1% occurs within one hour. The maximum permissible concentration characteristic is 20 mg/cub.m.
Effect of carbon monoxide on the human body
Carbon monoxide is deadly to humans. Its toxic effect is explained by the formation of carboxyhemoglobin in blood cells, a product of the addition of carbon monoxide (II) to blood hemoglobin. High level carboxyhemoglobin content causes oxygen starvation, insufficient oxygen supply to the brain and other tissues of the body. With mild intoxication, its content in the blood is low, destruction naturally perhaps within 4-6 hours. At high concentrations, only medications are effective.
Carbon monoxide poisoning
Carbon monoxide is one of the most hazardous substances. In case of poisoning, intoxication of the body occurs, accompanied by deterioration general condition person. It is very important to recognize the signs of carbon monoxide poisoning early. The result of treatment depends on the level of the substance in the body and how quickly help arrives. In this case, minutes count - the victim can either be completely cured, or remain sick forever (it all depends on the speed of response of the rescuers).
Symptoms
Depending on the degree of poisoning, headaches, dizziness, tinnitus, rapid heartbeat, nausea, shortness of breath, flickering in the eyes, and general weakness may occur. Drowsiness is often observed, which is especially dangerous when a person is in a gas-filled room. If inhaled large quantity poisonous substances, convulsions, loss of consciousness, and in especially severe cases, coma are observed.
First aid for carbon monoxide poisoning
The victim should be provided with first aid on the spot in case of carbon monoxide poisoning. You must immediately move him to fresh air and call a doctor. You should also remember about your safety: when entering a room with a source of this substance, you should only take a deep breath, and do not breathe inside. Until the doctor arrives, it is necessary to facilitate the access of oxygen to the lungs: unbutton buttons, remove or loosen clothes. If the victim loses consciousness and stops breathing, artificial ventilation is necessary.
Antidote for poisoning
A special antidote for carbon monoxide poisoning is drug, which actively prevents the formation of carboxyhemoglobin. The action of the antidote leads to a decrease in the body's need for oxygen, supporting organs sensitive to lack of oxygen: the brain, liver, etc. It is administered intramuscularly in a dosage of 1 ml immediately after removing the patient from an area with a high concentration of toxic substances. The antidote can be re-administered no earlier than an hour after the first administration. Its use for prevention is allowed.
Treatment
In case of mild exposure to carbon monoxide, treatment is carried out on an outpatient basis; in severe cases, the patient is hospitalized. Already in the ambulance he is given an oxygen bag or mask. In severe cases, in order to give the body a large dose of oxygen, the patient is placed in a pressure chamber. An antidote is administered intramuscularly. Blood gas levels are constantly monitored. Further rehabilitation is medicinal, the actions of doctors are aimed at restoring the functioning of the brain, cardiovascular system, and lungs.
Consequences
Exposure to carbon monoxide on the body can cause serious illnesses: brain performance, behavior, and consciousness of a person change, and unexplained headaches appear. Especially the influence harmful substances memory is affected - that part of the brain that is responsible for the transition short term memory into the long term. The patient may feel the effects of carbon monoxide poisoning only after several weeks. Most victims recover fully after a period of rehabilitation, but some suffer the consequences for the rest of their lives.
How to determine carbon monoxide indoors
Carbon monoxide poisoning is easy at home, and it doesn't just happen during a fire. The concentration of carbon dioxide is formed due to careless handling of the stove damper, during the operation of a faulty gas water heater or ventilation. The source of carbon monoxide may be a gas stove. If there is smoke in the room, this is already a reason to sound the alarm. For constant monitoring There are special sensors for the gas level. They monitor the level of gas concentration and report if the norm is exceeded. The presence of such a device reduces the risk of poisoning.
Video
- UN hazard class 2.3
- Secondary hazard according to UN classification 2.1
Molecule structure
The CO molecule, like the isoelectronic nitrogen molecule, has a triple bond. Since these molecules are similar in structure, their properties are also similar - very low melting and boiling points, close values of standard entropies, etc.
Within the framework of the valence bond method, the structure of the CO molecule can be described by the formula: C≡O:, and the third bond is formed according to the donor-acceptor mechanism, where carbon is the acceptor of the electron pair, and oxygen is the donor.
Due to the presence of a triple bond, the CO molecule is very strong (dissociation energy 1069 kJ/mol, or 256 kcal/mol, which is greater than that of any other diatomic molecules) and has a small internuclear distance (d C≡O = 0.1128 nm or 1. 13Å).
The molecule is weakly polarized, electrical torque its dipole μ = 0.04·10 -29 C·m (direction of the dipole moment O - →C +). Ionization potential 14.0 V, force coupling constant k = 18.6.
History of discovery
Carbon monoxide was first produced French chemist Jacques de Lasson in heating zinc oxide with coal, but initially it was mistaken for hydrogen, as it burned with a blue flame. The fact that this gas contains carbon and oxygen was discovered by the English chemist William Cruickshank. Carbon monoxide outside the Earth's atmosphere was first discovered by the Belgian scientist M. Migeotte in 1949 by the presence of a main vibrational-rotational band in the IR spectrum of the Sun.
Carbon monoxide in the Earth's atmosphere
There are natural and anthropogenic sources of entry into the Earth's atmosphere. Under natural conditions, on the Earth's surface, CO is formed during incomplete anaerobic decomposition of organic compounds and during the combustion of biomass, mainly during forest and steppe fires. Carbon monoxide is formed in soil both biologically (released by living organisms) and non-biologically. The release of carbon monoxide due to phenolic compounds common in soils, containing OCH 3 or OH groups in ortho- or para-positions relative to the first hydroxyl group, has been experimentally proven.
The overall balance of non-biological CO production and its oxidation by microorganisms depends on specific environmental conditions, primarily from humidity and value. For example, carbon monoxide is released directly into the atmosphere from arid soils, thus creating local maximums in the concentration of this gas.
In the atmosphere, CO is the product of chains of reactions involving methane and other hydrocarbons (primarily isoprene).
The main anthropogenic source of CO is currently exhaust gases from internal combustion engines. Carbon monoxide is formed when hydrocarbon fuels are burned in internal combustion engines at insufficient temperatures or the air supply system is poorly tuned (insufficient oxygen is supplied to oxidize CO into CO 2). In the past, a significant portion of the anthropogenic input of CO into the atmosphere was provided by illuminating gas, which was used for indoor lighting in the 19th century. Its composition was approximately the same as water gas, that is, it contained up to 45% carbon monoxide. Currently, in the public utilities sector, this gas is replaced by a much less toxic gas. natural gas(lower representatives homologous series alkanes - propane, etc.)
CO input from natural and anthropogenic sources about the same.
Carbon monoxide in the atmosphere is in rapid circulation: its average residence time is about 0.1 year, being oxidized by hydroxyl to carbon dioxide.
Receipt
Industrial method
2C + O 2 → 2CO (thermal effect of this reaction is 22 kJ),
2. or when reducing carbon dioxide with hot coal:
CO 2 + C ↔ 2CO (ΔH=172 kJ, ΔS=176 J/K).
This reaction often occurs in a stove fire when the stove damper is closed too early (before the coals have completely burned out). The carbon monoxide formed in this case, due to its toxicity, causes physiological disorders (“fumes”) and even death (see below), hence one of the trivial names - “carbon monoxide”. A picture of the reactions occurring in the furnace is shown in the diagram.
The reduction reaction of carbon dioxide is reversible; the effect of temperature on the equilibrium state of this reaction is shown in the graph. The reaction to the right is ensured by the entropy factor, and to the left by the enthalpy factor. At temperatures below 400°C the equilibrium is almost completely shifted to the left, and at temperatures above 1000°C to the right (towards the formation of CO). At low temperatures the rate of this reaction is very low, so carbon monoxide at normal conditions quite stable. This balance carries special name Boudoir balance.
3. Mixtures of carbon monoxide with other substances are obtained by passing air, water vapor, etc. through a layer of hot coke, coal or brown coal, etc. (see generator gas, water gas, mixed gas, synthesis gas).
Laboratory method
TLV (maximum threshold concentration, USA): 25 MAC r.z. according to Hygienic standards GN 2.2.5.1313-03 is 20 mg/m³
Carbon Monoxide Protection
Due to this good calorific value, CO is a component of various technical gas mixtures(see, for example, generator gas), used, among other things, for heating.
halogens. Greatest practical application got a reaction with chlorine:
CO + Cl 2 → COCl 2
The reaction is exothermic, its thermal effect is 113 kJ, and in the presence of a catalyst (activated carbon) it occurs at room temperature. As a result of the reaction, phosgene is formed, a substance that is widely used in different industries chemistry (and also as a chemical warfare agent). By similar reactions, COF 2 (carbonyl fluoride) and COBr 2 (carbonyl bromide) can be obtained. Carbonyl iodide was not obtained. The exothermicity of reactions quickly decreases from F to I (for reactions with F 2 the thermal effect is 481 kJ, with Br 2 - 4 kJ). It is also possible to obtain mixed derivatives, for example COFCl (for more details, see halogen derivatives of carbonic acid).
By reacting CO with F 2 , in addition to carbonyl fluoride, one can obtain a peroxide compound (FCO) 2 O 2 . Its characteristics: melting point −42°C, boiling point +16°C, has a characteristic odor (similar to the smell of ozone), when heated above 200°C it decomposes explosively (reaction products CO 2, O 2 and COF 2), in acidic medium reacts with potassium iodide according to the equation:
(FCO) 2 O 2 + 2KI → 2KF + I 2 + 2CO 2
Carbon monoxide reacts with chalcogens. With sulfur it forms carbon sulfide COS, the reaction occurs when heated, according to the equation:
CO + S → COS ΔG° 298 = −229 kJ, ΔS° 298 = −134 J/K
Similar selenoxide COSe and telluroxide COTe were also obtained.
Restores SO 2:
SO 2 + 2CO → 2CO 2 + S
With transition metals it forms very volatile, flammable and toxic compounds - carbonyls, such as Cr(CO) 6, Ni(CO) 4, Mn 2 CO 10, Co 2 (CO) 9, etc.
As stated above, carbon monoxide is slightly soluble in water, but does not react with it. It also does not react with solutions of alkalis and acids. However, it reacts with alkali melts:
CO + KOH → HCOOK
The reaction of carbon monoxide with potassium metal in an ammonia solution is interesting. This produces the explosive compound potassium dioxodicarbonate:
2K + 2CO → K + O - -C 2 -O - K +
By reacting with ammonia at high temperatures, one can obtain an important compound for industry - hydrogen cyanide HCN. The reaction occurs in the presence of a catalyst (oxide
