Carbon dioxide, also known as 4, reacts with a number of substances to form compounds of varying composition and chemical properties. Consisting of non-polar molecules, it has very weak intermolecular bonds and can only be found if the temperature is higher than 31 degrees Celsius. Carbon dioxide is a chemical compound made up of one carbon atom and two oxygen atoms.

Carbon monoxide 4: formula and basic information

Carbon dioxide is present in Earth's atmosphere at low concentration and acts as a greenhouse gas. Its chemical formula is CO 2 . At high temperatures, it can only exist in the gaseous state. In its solid state, it is called dry ice.

Carbon dioxide is an important component of the carbon cycle. It comes from a variety of natural sources, including volcanic degassing, the burning of organic matter, and the respiratory processes of living aerobic organisms. Anthropogenic sources of carbon dioxide are mainly associated with the combustion of various fossil fuels for electricity generation and transportation.

It is also produced by various microorganisms from fermentation and cellular respiration. Plants turn carbon dioxide into oxygen during a process called photosynthesis, using both carbon and oxygen to form carbohydrates. In addition, plants also release oxygen into the atmosphere, which is then used for respiration by heterotrophic organisms.

Carbon dioxide (CO2) in the body

Carbon monoxide 4 reacts with various substances and is a gaseous waste product from metabolism. There is more than 90% of it in the blood in the form of bicarbonate (HCO 3). The rest is either dissolved CO 2 or carbonic acid (H2CO 3). Organs such as the liver and kidneys are responsible for balancing these compounds in the blood. Bicarbonate is a chemical that acts as a buffer. It keeps the pH level of the blood at the required level, avoiding an increase in acidity.

Structure and properties of carbon dioxide

Carbon dioxide (CO 2 ) is a chemical compound that is a gas at room temperature and above. It consists of one carbon atom and two oxygen atoms. Humans and animals release carbon dioxide when they exhale. In addition, it is always formed when something organic is burned. Plants use carbon dioxide to produce food. This process is called photosynthesis.

The properties of carbon dioxide were studied by the Scottish scientist Joseph Black as early as the 1750s. capable of capturing thermal energy and influencing the climate and weather on our planet. It is he who is the cause of global warming and an increase in the temperature of the Earth's surface.

Biological role

Carbon monoxide 4 reacts with various substances and is an end product in organisms that obtain energy from the breakdown of sugars, fats and amino acids. This process is known to be characteristic of all plants, animals, many fungi and some bacteria. In higher animals, carbon dioxide travels in the blood from body tissues to the lungs, where it is exhaled. Plants obtain it from the atmosphere for use in photosynthesis.

Dry ice

Dry ice or solid carbon dioxide is solid state gas CO 2 with a temperature of -78.5 °C. In its natural form, this substance does not occur in nature, but is produced by man. It is colorless and can be used to make carbonated drinks, as a cooling element in ice cream containers and in cosmetology, for example, to freeze warts. Dry ice fumes cause suffocation and can be fatal. Care and professionalism should be exercised when using dry ice.

At normal pressure, it will not melt from a liquid, but instead goes directly from a solid to a gas. This is called sublimation. It will change directly from solid body to gas at any temperature above extremely low temperatures. Dry ice sublimates at normal air temperature. This releases carbon dioxide, which is odorless and colorless. Carbon dioxide can be liquefied at pressures above 5.1 atm. The gas that is released from dry ice is so cold that when mixed with air, it cools the water vapor in the air into a mist that looks like thick white smoke.

Preparation, chemical properties and reactions

In industry, carbon monoxide 4 is obtained in two ways:

1. By burning fuel (C + O 2 = CO 2).
2. By thermal decomposition of limestone (CaCO 3 = CaO + CO 2).

The resulting volume of carbon monoxide 4 is purified, liquefied and pumped into special cylinders.

Being acidic, carbon monoxide 4 reacts with substances such as:

• Water. When dissolved, carbonic acid (H 2 CO 3) is formed.
• alkaline solutions. Carbon monoxide 4 (formula CO 2) reacts with alkalis. In this case, medium and acidic salts (NaHCO 3) are formed.
• These reactions form carbonate salts (CaCO 3 and Na 2 CO 3).
• Carbon. When carbon monoxide 4 reacts with hot coal, carbon monoxide 2 (carbon monoxide) is formed, which can cause poisoning. (CO 2 + C \u003d 2CO).
• Magnesium. As a rule, carbon dioxide does not support combustion, only at very high temperatures it can react with some metals. For example, ignited magnesium will continue to burn in CO 2 during the redox reaction (2Mg + CO 2 = 2MgO + C).

A qualitative reaction of carbon monoxide 4 is manifested when it is passed through limestone water (Ca (OH) 2) or through barite water (Ba (OH) 2. Cloudiness and precipitation can be observed. If after that you continue to pass carbon dioxide further, the water will again become transparent , since insoluble carbonates are converted into soluble hydrocarbons (acid salts of carbonic acid).

Carbon dioxide is also produced when all carbonaceous fuels are burned, such as methane (natural gas), petroleum distillates (gasoline, diesel, kerosene, propane), coal or wood. In most cases, water is also released.

Carbon dioxide (carbon dioxide) is made up of one carbon atom and two oxygen atoms, which are held together by covalent bonds (or electron sharing). Pure carbon is very rare. It occurs in nature only in the form of minerals, graphite and diamond. Despite this, it is the building block of life, which, in combination with hydrogen and oxygen, forms the basic compounds that make up everything on the planet.

Hydrocarbons such as coal, oil and natural gas are compounds made up of hydrogen and carbon. This element is found in calcite (CaCo 3), minerals in sedimentary and metamorphic rocks, limestone and marble. It is the element that contains all organic matter, from fossil fuels to DNA.

Carbon monoxide (IV) (carbon dioxide, carbon dioxide) in normal conditions is a colorless gas, heavier than air, thermally stable, and when compressed and cooled, it easily turns into a liquid and solid state.

Density - 1.997 g / l. Solid CO2, called dry ice, sublimates at room temperature. Poorly soluble in water, partially reacting with it. Shows acidic properties. It is restored by active metals, hydrogen and carbon.

Chemical formula of carbon monoxide 4
Chemical formula of carbon monoxide (IV) CO2. It shows that this molecule contains one carbon atom (Ar = 12 a.m.u.) and two oxygen atoms (Ar = 16 a.m.u.). According to the chemical formula, you can calculate the molecular weight of carbon monoxide (IV):

Mr(CO2) = Ar(C) + 2×Ar(O);

Mr(CO2) = 12+ 2×16 = 12 + 32 = 44.

Examples of problem solving
EXAMPLE 1
Task When burning 26.7 g of amino acid (CxHyOzNk) in excess of oxygen, 39.6 g of carbon monoxide (IV), 18.9 g of water and 4.2 g of nitrogen are formed. Determine the amino acid formula.
Solution Let's draw up a scheme for the combustion reaction of an amino acid, denoting the number of carbon, hydrogen, oxygen and nitrogen atoms as "x", "y", "z" and "k", respectively:
CxHyOzNk+ Oz→CO2 + H2O + N2.

Let us determine the masses of the elements that make up this substance. The values ​​of relative atomic masses taken from the Periodic Table of D.I. Mendeleev, rounded to integers: Ar(C) = 12 a.m.u., Ar(H) = 1 a.m.u., Ar(O) = 16 a.m.u., Ar(N) = 14 amu

M(C) = n(C)×M(C) = n(CO2)×M(C) = ×M(C);

M(H) = n(H)×M(H) = 2×n(H2O)×M(H) = ×M(H);

Calculate the molar masses of carbon dioxide and water. As is known, molar mass molecule is equal to the sum of the relative atomic masses of the atoms that make up the molecule (M = Mr):

M(CO2) = Ar(C) + 2×Ar(O) = 12+ 2×16 = 12 + 32 = 44 g/mol;

M(H2O) = 2×Ar(H) + Ar(O) = 2×1+ 16 = 2 + 16 = 18 g/mol.

M(C)=×12=10.8 g;

M(H) = 2×18.9 / 18×1= 2.1 g.

M(O) \u003d m (CxHyOzNk) - m (C) - m (H) - m (N) \u003d 26.7 - 10.8 - 2.1 - 4.2 \u003d 9.6 g.

Let's define chemical formula amino acids:

X:y:z:k = m(C)/Ar(C) : m(H)/Ar(H) : m(O)/Ar(O) : m(N)/Ar(N);

X:y:z:k= 10.8/12:2.1/1:9.6/16: 4.2/14;

X:y:z:k= 0.9: 2.1: 0.41: 0.3 = 3: 7: 1.5: 1 = 6: 14: 3: 2.

So the simplest formula of the amino acid is C6H14O3N2.

Answer C6H14O3N2
EXAMPLE 2
Task Make the simplest formula of a compound in which the mass fractions of elements are approximately equal: carbon - 25.4%, hydrogen - 3.17%, oxygen - 33.86%, chlorine - 37.57%.
Solution The mass fraction of element X in a molecule of composition HX is calculated by the following formula:
ω (X) = n × Ar (X) / M (HX) × 100%.

Let us denote the number of carbon atoms in the molecule as "x", the number of hydrogen nitrogen atoms as "y", the number of oxygen atoms as "z", and the number of chlorine atoms as "k".

Let us find the corresponding relative atomic masses of the elements carbon, hydrogen, oxygen and chlorine (the values ​​of the relative atomic masses taken from the Periodic Table of D.I. Mendeleev will be rounded up to whole numbers).

Ar(C) = 12; Ar(H) = 14; Ar(O) = 16; Ar(Cl) = 35.5.

We divide the percentage of elements by the corresponding relative atomic masses. Thus, we will find the relationship between the number of atoms in the molecule of the compound:

X:y:z:k = ω(C)/Ar(C) : ω(H)/Ar(H) : ω(O)/Ar(O) : ω(Cl)/Ar(Cl);

X:y:z:k= 25.4/12: 3.17/1: 33.86/16: 37.57/35.5;

X:y:z:k= 2.1: 3.17: 2.1: 1.1 = 2: 3: 2: 1.

This means that the simplest formula for the combination of carbon, hydrogen, oxygen and chlorine will be C2H3O2Cl.

Carbon monoxide (IV), carbonic acid and their salts

The complex purpose of the module: know the methods of obtaining oxide and hydroxide of carbon (IV); describe their physical properties; know the characteristics of acid-base properties; characterize redox properties.

All elements of the carbon subgroup form oxides with general formula EO 2 . CO 2 and SiO 2 exhibit acidic properties, GeO 2 , SnO 2 , PbO 2 exhibit amphoteric properties with a predominance of acidic ones, and in the subgroup from top to bottom, acidic properties weaken.

The oxidation state (+4) for carbon and silicon is very stable, so oxidizing properties compounds are shown with great difficulty. In the germanium subgroup, the oxidizing properties of compounds (+4) are enhanced due to destabilization the highest degree oxidation.

Carbon monoxide (IV), carbonic acid and their salts

Carbon dioxide CO 2 (carbon dioxide) - under normal conditions, it is a colorless and odorless gas, slightly sour in taste, about 1.5 times heavier than air, soluble in water, liquefies quite easily - at room temperature it is fashionable to turn it into a liquid under a pressure of about 60 10 5 Pa. When cooled to? 56.2 ° C, liquid carbon dioxide solidifies and turns into a snowy mass.

In all states of aggregation it consists of non-polar linear molecules. Chemical structure CO 2 is determined by the sp hybridization of the central carbon atom and the formation of additional p rr-bonds: O = C = O

Some of the CO 2 dissolved in the will interacts with it by the formation of carbonic acid

CO 2 + H 2 O - CO 2 H 2 O - H 2 CO 3.

Carbon dioxide is very easily absorbed by alkali solutions with the formation of carbonates and bicarbonates:

CO 2 + 2NaOH \u003d Na 2 CO 3 + H 2 O;

CO 2 + NaOH \u003d NaHCO 3.

CO 2 molecules are very stable thermally, decomposition begins only at a temperature of 2000ºC. Therefore, carbon dioxide does not burn and does not support the combustion of conventional fuels. But in its atmosphere some are burning simple substances, whose atoms show a high affinity for oxygen, for example, magnesium, when heated, ignites in an atmosphere of CO 2.

Carbonic acid and its salts

Carbonic acid H 2 CO 3 - the connection is fragile, exists only in aqueous solutions. Most of carbon dioxide dissolved in water is in the form of hydrated CO 2 molecules, the smaller one forms carbonic acid.

Aqueous solutions in equilibrium with atmospheric CO 2 are acidic: = 0.04 M and pH? 4.

Carbonic acid is dibasic, belongs to weak electrolytes, dissociates in steps (K 1 \u003d 4.4 10 -7; K 2 \u003d 4.8 10 -11). When CO 2 is dissolved in water, the following dynamic equilibrium is established:

H 2 O + CO 2 - CO 2 H 2 O - H 2 CO 3 - H + + HCO 3?

When an aqueous solution of carbon dioxide is heated, the solubility of the gas decreases, CO 2 is released from the solution, and the equilibrium shifts to the left.

Salts of carbonic acid

Being dibasic, carbonic acid forms two series of salts: medium salts (carbonates) and acidic (hydrocarbonates). Most salts of carbonic acid are colorless. Of the carbonates, only salts are soluble in water. alkali metals and ammonium.

In water, carbonates undergo hydrolysis, and therefore their solutions have an alkaline reaction:

Na 2 CO 3 + H 2 O - NaHCO 3 + NaOH.

Further hydrolysis with the formation of carbonic acid practically does not occur under normal conditions.

The dissolution of bicarbonates in water is also accompanied by hydrolysis, but to a much lesser extent, and the medium is slightly alkaline (pH? 8).

Ammonium carbonate (NH 4) 2 CO 3 is highly volatile at elevated and even normal temperatures, especially in the presence of water vapor, which causes strong hydrolysis

Strong acids and even weak acetic acid displace carbonic acid from carbonates:

K 2 CO 3 + H 2 SO 4 \u003d K 2 SO 4 + H 2 O + CO 2 ^.

Unlike most carbonates, all hydrocarbons are soluble in water. They are less stable than carbonates of the same metals and easily decompose when heated, turning into the corresponding carbonates:

2KHCO 3 \u003d K 2 CO 3 + H 2 O + CO 2 ^;

Ca (HCO 3) 2 \u003d CaCO 3 + H 2 O + CO 2 ^.

Strong acids decompose bicarbonates, like carbonates:

KHCO 3 + H 2 SO 4 \u003d KHSO 4 + H 2 O + CO 2

From salts of carbonic acid highest value have: sodium carbonate (soda), potassium carbonate (potash), calcium carbonate (chalk, marble, limestone), sodium bicarbonate (baking soda) and basic copper carbonate (CuOH) 2 CO 3 (malachite).

The basic salts of carbonic acid are practically insoluble in water and easily decompose when heated:

(CuOH) 2 CO 3 \u003d 2CuO + CO 2 + H 2 O.

In general, the thermal stability of carbonates depends on the polarization properties of the ions that make up the carbonate. The greater the polarizing effect of the cation on the carbonate ion, the lower the decomposition temperature of the salt. If the cation can be easily deformed, then the carbonate ion itself will also have a polarizing effect on the cation, which will lead to a sharp decrease in the temperature of salt decomposition.

Sodium and potassium carbonates melt without decomposition, while most of the remaining carbonates decompose into metal oxide and carbon dioxide when heated.

Carbon (C) is a typical non-metal; in periodic system is in the 2nd period of the IV group, the main subgroup. Ordinal number 6, Ar = 12.011 amu, nuclear charge +6.

Physical properties: carbon forms many allotropic modifications: diamond one of the hardest substances graphite, coal, soot.

A carbon atom has 6 electrons: 1s 2 2s 2 2p 2 . The last two electrons are located in separate p-orbitals and are unpaired. In principle, this pair could occupy one orbital, but in this case the interelectron repulsion strongly increases. For this reason, one of them takes 2p x, and the other, either 2p y , or 2p z-orbitals.

The difference between the energies of the s- and p-sublevels of the outer layer is small, therefore, the atom quite easily passes into an excited state, in which one of the two electrons from the 2s-orbital passes to a free 2r. A valence state arises having the configuration 1s 2 2s 1 2p x 1 2p y 1 2p z 1 . It is this state of the carbon atom that is characteristic of the diamond lattice - the tetrahedral spatial arrangement of hybrid orbitals, the same length and energy of bonds.

This phenomenon is known to be called sp 3 -hybridization, and the resulting functions are sp 3 -hybrid . The formation of four sp 3 bonds provides the carbon atom with a more stable state than three rr- and one s-s-bond. In addition to sp 3 hybridization, sp 2 and sp hybridization are also observed at the carbon atom . In the first case, there is a mutual overlap s- and two p-orbitals. Three equivalent sp 2 - hybrid orbitals are formed, located in the same plane at an angle of 120 ° to each other. The third orbital p is unchanged and directed perpendicular to the plane sp2.

In sp hybridization, the s and p orbitals overlap. An angle of 180° arises between the two equivalent hybrid orbitals formed, while the two p-orbitals of each of the atoms remain unchanged.

Allotropy of carbon. diamond and graphite

In a graphite crystal, carbon atoms are located in parallel planes, occupying the vertices of regular hexagons in them. Each of the carbon atoms is linked to three adjacent sp 2 hybrid bonds. Between parallel planes, the connection is carried out due to van der Waals forces. Free p-orbitals of each of the atoms are directed perpendicular to the planes of covalent bonds. Their overlap explains the additional π-bond between carbon atoms. So from the valence state in which carbon atoms are in a substance, the properties of this substance depend.

Chemical properties of carbon

The most characteristic oxidation states: +4, +2.

At low temperatures, carbon is inert, but when heated, its activity increases.

Carbon as a reducing agent:

- with oxygen
C 0 + O 2 - t ° \u003d CO 2 carbon dioxide
with a lack of oxygen - incomplete combustion:
2C 0 + O 2 - t° = 2C +2 O carbon monoxide

- with fluorine
C + 2F 2 = CF 4

- with steam
C 0 + H 2 O - 1200 ° \u003d C + 2 O + H 2 water gas

— with metal oxides. In this way metal is smelted from ore.
C 0 + 2CuO - t ° \u003d 2Cu + C +4 O 2

- with acids - oxidizing agents:
C 0 + 2H 2 SO 4 (conc.) \u003d C +4 O 2 + 2SO 2 + 2H 2 O
С 0 + 4HNO 3 (conc.) = С +4 O 2 + 4NO 2 + 2H 2 O

- forms carbon disulfide with sulfur:
C + 2S 2 \u003d CS 2.

Carbon as an oxidizing agent:

- forms carbides with some metals

4Al + 3C 0 \u003d Al 4 C 3

Ca + 2C 0 \u003d CaC 2 -4

- with hydrogen - methane (as well as a huge amount organic compounds)

C 0 + 2H 2 \u003d CH 4

- with silicon, forms carborundum (at 2000 ° C in an electric furnace):

Finding carbon in nature

Free carbon occurs as diamond and graphite. In the form of compounds, carbon is found in minerals: chalk, marble, limestone - CaCO 3, dolomite - MgCO 3 * CaCO 3; bicarbonates - Mg (HCO 3) 2 and Ca (HCO 3) 2, CO 2 is part of the air; carbon is the main component of natural organic compounds - gas, oil, coal, peat, is part of organic matter, proteins, fats, carbohydrates, amino acids that are part of living organisms.

Inorganic carbon compounds

Neither C 4+ nor C 4- ions are formed in any conventional chemical processes: there are covalent bonds of different polarity in carbon compounds.

Carbon monoxide (II) SO

Carbon monoxide; colorless, odorless, sparingly soluble in water, soluble in organic solvents, poisonous, bp = -192°C; t sq. = -205°C.

Receipt
1) In industry (in gas generators):
C + O 2 = CO 2

2) In the laboratory - thermal decomposition formic or oxalic acid in the presence of H 2 SO 4 (conc.):
HCOOH = H2O + CO

H 2 C 2 O 4 \u003d CO + CO 2 + H 2 O

Chemical properties

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

1) with oxygen

2C +2 O + O 2 \u003d 2C +4 O 2

2) with metal oxides

C +2 O + CuO \u003d Cu + C +4 O 2

3) with chlorine (in the light)

CO + Cl 2 - hn \u003d COCl 2 (phosgene)

4) reacts with alkali melts (under pressure)

CO + NaOH = HCOONa (sodium formate)

5) forms carbonyls with transition metals

Ni + 4CO - t° = Ni(CO) 4

Fe + 5CO - t° = Fe(CO) 5

Carbon monoxide (IV) CO2

Carbon dioxide, colorless, odorless, solubility in water - 0.9V CO 2 dissolves in 1V H 2 O (under normal conditions); heavier than air; t°pl.= -78.5°C (solid CO 2 is called "dry ice"); does not support combustion.

Receipt

1. Thermal decomposition of salts of carbonic acid (carbonates). Limestone firing:

CaCO 3 - t ° \u003d CaO + CO 2

1. The action of strong acids on carbonates and bicarbonates:

CaCO 3 + 2HCl \u003d CaCl 2 + H 2 O + CO 2

NaHCO 3 + HCl \u003d NaCl + H 2 O + CO 2

ChemicalpropertiesCO2
Acid oxide: reacts with basic oxides and bases to form carbonic acid salts

Na 2 O + CO 2 \u003d Na 2 CO 3

2NaOH + CO 2 \u003d Na 2 CO 3 + H 2 O

NaOH + CO 2 \u003d NaHCO 3

May exhibit oxidizing properties at elevated temperatures

C +4 O 2 + 2Mg - t ° \u003d 2Mg +2 O + C 0

Qualitative reaction

Turbidity of lime water:

Ca (OH) 2 + CO 2 \u003d CaCO 3 ¯ (white precipitate) + H 2 O

It disappears when CO 2 is passed through lime water for a long time, because. insoluble calcium carbonate is converted to soluble bicarbonate:

CaCO 3 + H 2 O + CO 2 \u003d Ca (HCO 3) 2

carbonic acid and itssalt

H2CO3 — Weak acid, exists only in aqueous solution:

CO 2 + H 2 O ↔ H 2 CO 3

Dual base:
H 2 CO 3 ↔ H + + HCO 3 - Acid salts - bicarbonates, bicarbonates
HCO 3 - ↔ H + + CO 3 2- Medium salts - carbonates

All properties of acids are characteristic.

Carbonates and bicarbonates can be converted into each other:

2NaHCO 3 - t ° \u003d Na 2 CO 3 + H 2 O + CO 2

Na 2 CO 3 + H 2 O + CO 2 \u003d 2NaHCO 3

Metal carbonates (except alkali metals) decarboxylate when heated to form an oxide:

CuCO 3 - t ° \u003d CuO + CO 2

Qualitative reaction- "boiling" under the action of a strong acid:

Na 2 CO 3 + 2HCl \u003d 2NaCl + H 2 O + CO 2

CO 3 2- + 2H + = H 2 O + CO 2

Carbides

calcium carbide:

CaO + 3 C = CaC 2 + CO

CaC 2 + 2 H 2 O \u003d Ca (OH) 2 + C 2 H 2.

Acetylene is released when zinc, cadmium, lanthanum and cerium carbides react with water:

2 LaC 2 + 6 H 2 O \u003d 2La (OH) 3 + 2 C 2 H 2 + H 2.

Be 2 C and Al 4 C 3 are decomposed by water to form methane:

Al 4 C 3 + 12 H 2 O \u003d 4 Al (OH) 3 \u003d 3 CH 4.

Titanium carbides TiC, tungsten W 2 C (hard alloys), silicon SiC (carborundum - as an abrasive and material for heaters) are used in technology.

cyanides

obtained by heating soda in an atmosphere of ammonia and carbon monoxide:

Na 2 CO 3 + 2 NH 3 + 3 CO \u003d 2 NaCN + 2 H 2 O + H 2 + 2 CO 2

Hydrocyanic acid HCN is an important chemical industry product widely used in organic synthesis. Its world production reaches 200 thousand tons per year. Electronic structure cyanide anion, similarly to carbon monoxide (II), such particles are called isoelectronic:

C = O:[:C = N:]-

Cyanides (0.1-0.2% water solution) are used in gold mining:

2 Au + 4 KCN + H 2 O + 0.5 O 2 \u003d 2 K + 2 KOH.

When cyanide solutions are boiled with sulfur or when solids are fused, thiocyanates:
KCN + S = KSCN.

When cyanides of low-active metals are heated, cyanide is obtained: Hg (CN) 2 \u003d Hg + (CN) 2. cyanide solutions are oxidized to cyanates:

2KCN + O2 = 2KOCN.

Cyanic acid exists in two forms:

H-N=C=O; H-O-C = N:

In 1828, Friedrich Wöhler (1800-1882) obtained urea from ammonium cyanate: NH 4 OCN \u003d CO (NH 2) 2 by evaporating an aqueous solution.

This event is usually seen as the victory of synthetic chemistry over "vitalistic theory".

There is an isomer of cyanic acid - fulminic acid

H-O-N=C.
Its salts (mercury fulminate Hg(ONC) 2) are used in impact igniters.

Synthesis urea(carbamide):

CO 2 + 2 NH 3 \u003d CO (NH 2) 2 + H 2 O. At 130 0 C and 100 atm.

Urea is an amide of carbonic acid, there is also its "nitrogen analogue" - guanidine.

Carbonates

The most important inorganic compounds of carbon are salts of carbonic acid (carbonates). H 2 CO 3 is a weak acid (K 1 \u003d 1.3 10 -4; K 2 \u003d 5 10 -11). Carbonate buffer supports carbon dioxide balance in the atmosphere. The oceans have a huge buffer capacity because they are an open system. The main buffer reaction is the equilibrium during the dissociation of carbonic acid:

H 2 CO 3 ↔ H + + HCO 3 -.

With a decrease in acidity, additional absorption of carbon dioxide from the atmosphere occurs with the formation of acid:
CO 2 + H 2 O ↔ H 2 CO 3.

With an increase in acidity, carbonate rocks (shells, chalk and limestone deposits in the ocean) dissolve; this compensates for the loss of hydrocarbonate ions:

H + + CO 3 2- ↔ HCO 3 -

CaCO 3 (tv.) ↔ Ca 2+ + CO 3 2-

Solid carbonates are converted into soluble hydrocarbons. It is this process of chemical dissolution of excess carbon dioxide that counteracts the "greenhouse effect" - global warming due to the absorption of Earth's thermal radiation by carbon dioxide. Approximately one third of the world's production of soda (sodium carbonate Na 2 CO 3) is used in the manufacture of glass.

Oxides of carbon (II) and (IV)

Integrated lesson in chemistry and biology

Tasks: to study and systematize knowledge about carbon oxides (II) and (IV); reveal the relationship between animate and inanimate nature; consolidate knowledge about the effect of carbon oxides on the human body; to consolidate the skills of working with laboratory equipment.

Equipment: Hcl solution, litmus, Ca (OH) 2, CaCO 3, glass rod, homemade tables, portable board, ball-and-stick model.

DURING THE CLASSES

Biology teacher communicates the topic and objectives of the lesson.

Chemistry teacher. Based on the doctrine of the covalent bond, make up the electronic and structural formulas of carbon oxides (II) and (IV).

The chemical formula of carbon monoxide (II) is CO, the carbon atom is in its normal state.

Due to the pairing of unpaired electrons, two covalent polar bonds are formed, and the third covalent bond is formed according to the donor-acceptor mechanism. The donor is an oxygen atom, because it provides a free pair of electrons; the acceptor is a carbon atom, because provides a free orbital.

In industry, carbon monoxide (II) is obtained by passing CO 2 over hot coal at high temperature. It is also formed during the combustion of coal with a lack of oxygen. ( The student writes the reaction equation on the blackboard)

In the laboratory, CO is produced by the action of concentrated H 2 SO 4 on formic acid. ( The reaction equation is written by the teacher.)

Biology teacher. So, you got acquainted with the production of carbon monoxide (II). And what physical properties possesses carbon monoxide (II)?

Student. It is a colorless gas, poisonous, odorless, lighter than air, poorly soluble in water, boiling point -191.5 °C, solidifies at -205 °C.

Chemistry teacher. Carbon monoxide in quantities hazardous to human life found in car exhaust gases. Therefore, garages must be well ventilated, especially when starting the engine.

Biology teacher. What effect does carbon monoxide have on the human body?

Student. Carbon monoxide is extremely toxic to humans - this is due to the fact that it forms carboxyhemoglobin. Carboxyhemoglobin is a very strong compound. As a result of its formation, blood hemoglobin does not interact with oxygen, and in case of severe poisoning, a person can die from oxygen starvation.

Biology teacher. What first aid should be given to a person with carbon monoxide poisoning?

Students. It is necessary to call an ambulance, the victim must be taken out into the street, artificial respiration should be done, the room should be well ventilated.

Chemistry teacher. Write the chemical formula of carbon monoxide (IV) and, using the ball-and-stick model, build its structure.

The carbon atom is in an excited state. All four covalent polar bonds formed by pairing unpaired electrons. However, due to its linear structure, its molecule is generally non-polar.
In industry, CO 2 is obtained from the decomposition of calcium carbonate in lime production.
(The student writes down the reaction equation.)

In the laboratory, CO 2 is obtained by reacting acids with chalk or marble.
(Students perform laboratory experiments.)

Biology teacher. What processes produce carbon dioxide in the body?

Student. Carbon dioxide is formed in the body as a result of oxidation reactions of organic substances that make up the cell.

(Students perform laboratory experiments.)

The lime mortar has become cloudy because calcium carbonate is formed. In addition to the process of respiration, CO2 is released as a result of fermentation, decay.

Biology teacher. Does physical activity affect breathing?

Student. With excessive physical (muscle) stress, the muscles use oxygen faster than the blood has time to deliver it, and then they synthesize the ATP necessary for their work by fermentation. Lactic acid C 3 H 6 O 3 is formed in the muscles, which enters the bloodstream. The accumulation of large amounts of lactic acid is harmful to the body. After heavy physical exertion, we still breathe heavily for some time - we pay off the “oxygen debt”.

Chemistry teacher. A large amount of carbon monoxide (IV) is released into the atmosphere during the combustion of fossil fuels. At home, we use natural gas as fuel, and it consists of almost 90% methane (CH 4). I suggest that one of you come to the blackboard, write an equation for the reaction and break it down in terms of redox.

Biology teacher. Why can't gas stoves be used for space heating?

Student. Methane is an integral part of natural gas. When it burns, the carbon dioxide content in the air rises, and the oxygen content decreases. ( Working with the Table of Contents CO 2 in the air".)
When the content in the air is 0.3% CO 2, a person has rapid breathing; at 10% - loss of consciousness, at 20% - instant paralysis and quick death. Particularly in need of clean air a child, because the consumption of oxygen by the tissues of a growing organism is greater than that of an adult. Therefore, it is necessary to regularly ventilate the room. If there is an excess of CO 2 in the blood, the excitability of the respiratory center increases and breathing becomes more frequent and deep.

Biology teacher. Consider the role of carbon monoxide (IV) in plant life.

Student. In plants, the formation of organic substances occurs from CO 2 and H 2 O in the light, in addition to organic substances, oxygen is formed.

Photosynthesis regulates the amount of carbon dioxide in the atmosphere, which prevents the temperature of the planet from rising. Every year, plants absorb 300 billion tons of carbon dioxide from the atmosphere. In the process of photosynthesis, 200 billion tons of oxygen are annually released into the atmosphere. Ozone is formed from oxygen during thunderstorms.

Chemistry teacher. Consider Chemical properties carbon monoxide (IV).

Biology teacher. What is the importance of carbonic acid in the human body in the process of respiration? ( Filmstrip fragment.)
Enzymes contained in the blood convert carbon dioxide into carbonic acid, which dissociates into hydrogen and bicarbonate ions. If the blood contains an excess of H + ions, i.e. if the acidity of the blood is increased, then part of the H + ions combines with bicarbonate ions, forming carbonic acid and thereby freeing the blood from excess H + -ions. If there are too few H + -ions in the blood, then carbonic acid dissociates and the concentration of H + -ions in the blood rises. At a temperature of 37 ° C, the pH of the blood is 7.36.
Carbon dioxide is transported in the blood in the form of chemical compounds- bicarbonates of sodium and potassium.

Fixing the material

Test

Of the proposed processes of gas exchange in the lungs and tissues, those who perform the first option must choose the ciphers of the correct answers on the left, and the second on the right.

(1) Transition of O 2 from the lungs to the blood. (13)
(2) Transition of O 2 from blood to tissues. (fourteen)
(3) Transfer of CO 2 from tissues to blood. (15)
(4) Transfer of CO 2 from the blood to the lungs. (16)
(5) O 2 uptake by erythrocytes. (17)
(6) Release of O 2 from erythrocytes. (eighteen)
(7) Transformation of arterial blood into venous. (19)
(8) Transformation of venous blood into arterial. (twenty)
(9) Breaking the chemical bond of O 2 with hemoglobin. (21)
(10) Chemical binding of O 2 to hemoglobin. (22)
(11) Capillaries in tissues. (23)
(12) Pulmonary capillaries. (24)

Questions of the first option

1. Processes of gas exchange in tissues.
2. Physical processes during gas exchange.

Questions of the second option

1. The processes of gas exchange in the lungs.
2. Chemical processes during gas exchange

A task

Determine the volume of carbon monoxide (IV) that is released during the decomposition of 50 g of calcium carbonate.