The more the person learns about the world around him, the more realizes the limitations and imperfection of their knowledge. Take, for example, carbonated water. As you know, this drink is different from other fact that it contains in small doses of coal acid, which immediately begins to disintegrate as soon as we unscrew the cork on the bottle. Therefore, we have no doubt approval in the chemistry textbook that this substance is extremely unstable. In the gas phase, it very quickly turns into a mixture of ordinary water and the usual carbon dioxide. However, as recent studies have shown, it is quite possible to argue with this. But first let's remember that it is a given substance.
What is coalic acid?
The formula of this chemical compound It looks quite simple: H 2 CO 3. The presence of two hydrogen atoms indicates that this acid is a biennial, and its instability speaks of its weakness. As it is known, dissociation of acids occurs in water, and the compound under consideration does not fall under the exception. However, there is one feature: due to the presence of two bases, this process takes place in two stages:
H 2 CO 3 ↔ H + + NSO 3 -,
NSO 3 - ↔ H + + CO3 2-.
When interacting with a strong base, coalic acid forms normal or acid carbonates. The latter differ in that they are not replaced by two, but only one hydrogen atom. A vivid example of a normal carbonate is the washing soda (Na 2 CO 3), and the role of the sample of the hydrocarbonate can play baking soda (NaHCO 3). 
What did you manage to detect scientists?
When protensioning the anhydrous potassium bicarbonate (KNSO 3) at a temperature of -110 ° C, hydrogen knocks at an atom K. The result is very clean coalic acid. Later, an even easier method was found - heating in Vacuum NH 4 HCO 3. As a result of this decomposition of ammonium bicarbonate, ammonium is distinguished and anhydrous coalic acid is formed. The latter exhibits amazing stability during sublimation in vacuum. When scientists began to explore this paradox, it turned out that the reason lies in the value of the energy barrier. For anhydrous compound H 2 CO 3, it is 44 kcal / mol, and when there is water, its value is almost twice below - 24 kcal / mol. So under the appropriate conditions, coalic acid may well be in free form. However, this discovery is interesting not only in terms of chemistry theory. Its practical value is that it allowed to study the respiratory process in a new way. Now scientists believe that the formation in the living organism of coalic acid accelerates with the help of a special enzyme, and just allows you to quickly remove carbon dioxide from the cells first into the blood, and then into the lungs. 
This discovery was also not confused to take advantage of astronomers: the free state of carbon dioxide allowed them to carry out its spectral analysis, and now this compound can be identified in the atmosphere of the planets around us. All this suggests that the world is still full of different secrets and secrets. It seems that modern textbooks will not have to rewrite, specifying old and opening new knowledge.
GENERAL INFORMATION Coal Acid Weak dibasic acid. It is not highlighted in its pure form. It is formed in small quantities in the dissolution of carbon dioxide in water, including carbon dioxide from the air. Forms a number of stable inorganic and organic derivatives: salts (carbonates and bicarbonates), esters, amides, etc.
Decomposition When increasing the temperature of the solution and / or decrease in the partial pressure of carbon dioxide, the equilibrium in the system is shifted to the left, which leads to the decomposition of a part of coalic acid into water and carbon dioxide. When boiling, coal acid decomposes completely:
Obtaining coalic acid is formed when a carbon dioxide is dissolved in water. The content of coalic acid in the solution increases with a decrease in the temperature of the solution and increasing the pressure of carbon dioxide. Also, coalic acid is formed in the interaction of its salts (carbonates and bicarbonates) with stronger acid. At the same time, most of the resulting coalic acid, as a rule, decomposes into water and carbon dioxide
The use of coalic acid is always present in aqueous solutions of carbon dioxide (carbonated water). In biochemistry, the property of the equilibrium system is used to change the gas pressure in proportion to the change in the content of oxonia ions (acidity) at a constant temperature. This allows you to register in real time the course of enzymatic reactions occurring with a change in the pH solution
Organic derivatives of coalic acid formally can be considered as carboxylic acid with a hydroxyl group instead of a hydrocarbon residue. In this capacity, it can form all derivatives characteristic of carboxylic acids. Some representatives of such connections are listed in the table. Class of compounds Example of compounds Polycarbonate polycarbonates Polycarbonates Chloranhydridridhosgen Amidimoevin Nitrilyucian acid anhydridyri-coronal acid
Carbon (IV) oxide, coalic acid and its salts
D. carbon EoxideCO 2 (carbon dioxide) - under normal conditions, it is gas without color and odor, a slightly acidic taste, heavy air is about 1.5 times, soluble in water, quite easily liquefied (at room temperature under pressure of about 60 ∙ 10 5 PA can be turned into a liquid). When cooling to -56.2ºС, carbon dioxide solidifies and turns into a snow-shaped mass.
In all over aggregate states It consists of non-polar linase molecules. Chemical structure CO 2 molecules are determined by the SP-hybridization of the central carbon atom and the formation of additional π pR: O \u003d C \u003d O.
Some of the dissolved in the will of CO 2 interacts with it with coal acid taking:
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, the decay begins only at a temperature of 2000ºС. For this reason, carbon dioxide is off and does not support the combustion of ordinary fuel. But in his atmosphere, some are burning simple substances, whose atoms show a large affinity for oxygen, for example, magnesium when heated lights up in atmosphere CO 2.
Coalic acid H 2 CO 3 - the interconnection is fragile, exists only in aqueous solutions. Most of the carbon dioxide dissolved in water is in the form of hydrated CO 2 molecules, smaller - forms coalic acid.
Aqueous solutions that are equilibrium with CO 2 atmospheres are acidic: \u003d 0.04 m and pH ≈ 4.
Coalic acid - a two-axis, refers to weak electrolytes, dissociates stepwise (K 1 \u003d 4, 4 ∙ 10 -7; K 2 \u003d 4, 8 ∙ 10 -11). When CO 2 is dissolved in water, the following dynamic balance is set:
H 2 O + CO 2 ↔ CO 2 ∙ H 2 O ↔ H 2 CO 3 ↔ H + + HCO 3 -
When the aqueous solution of carbon dioxide is heated, the solubility of the gas decreases, CO 2 is released from the solution, and the equilibrium is shifted to the left.
Being a biennial, coalic acid forms two rows of salts: medium salts (carbonates) and acidic (hydrocarbonates). Most carbonic acid salts are colorless. From carbonates soluble in water only salts of alkali metal and ammonium.
In water, carbonates are subjected to hydrolysis, and in connection with this, their solutions have an alkaline reaction:
Na 2 CO 3 + H 2 O ↔ NaHCO 3 + NaOH.
Further hydrolysis with the formation of coalic acid under normal conditions practically does not go.
The dissolution in the water of hydrocarbonates is also accompanied by hydrolysis, but to a much lesser extent, and the medium is created by a slightly alkaline (pH ≈ 8).
Ammonium carbonate (NH 4) 2 CO 3 is characterized by a large volatility with elevated and even at normal temperature, especially in the presence of water vapor, which cause strong hydrolysis.
Strong acids and even weak acetic acid displaces carbonic acid from carbonates:
K 2 CO 3 + H 2 SO 4 \u003d k 2 SO 4 + H 2 O + CO 2.
In contrast to most carbonates, alone bicarbonates in water are soluble. ʜᴎʜᴎ less stable than carbonates of the same metals and when heated is easily decomposed, turning into the appropriate 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, bicarbonates are decomposed, like carbonates:
KHCO 3 + H 2 SO 4 \u003d KHSO 4 + H 2 O + CO 2
Sodium carbonate (soda), potassium carbonate (Potash), calcium carbonate (chalk, marble, limestone), sodium bicarbonate (drinking soda) and COOH main (Cuoh) 2 CO 3 (Malachite) are most important.
The main salts of carbonic acid in water are practically insoluble and when heated is easily decomposed:
(CuOH) 2 CO 3 \u003d 2CUO + CO 2 + H 2 O.
The thermal stability of carbonates depends on the polarization properties of ions included in the carbonate. The greater the polarizing action has a kation on carbonate ion, the lower the decomposition temperature of the salt. If the cation is able to be easily deformed, then the carbonate ion will also have a polarizing effect on the cation, which will lead to a sharp decrease in salt decomposition temperature.
Sodium and potassium carbonates melt without decomposition, and most of the remaining carbonates are decomposed on metal oxide and carbon dioxide:
MGCO 3 \u003d MGO + CO 2.
Carbon oxide (II)
CO molecule has the following structure
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Two bonds are formed due to the pairing of 2r-electrons of carbon and oxygen atoms, the third connection is formed by a donor-acceptor mechanism due to the free 2r-orbital carbon and 2r- electronic couple Oxygen atom. The dipole moment of the molecule is insignificant, while the effective charge on the carbon atom is negative, and on an oxygen atom is positive.
Since the structure of the molecule is similar to the structure of the nitrogen molecule. physical properties. Co has very low melting points (- 204ºС) and boiling (- 191.5ºС), it is a colorless, very poisonous gas, odorless, Sovs-a little lighter than air. We are not soluble in water, and it does not interact with it.
Co is considered non-forming oxide, because Under normal conditions, it does not interact with acids or with alkalis. It is formed during the burning of coal and carbon compounds with limited oxygen access, also with the interaction of carbon dioxide with hot coal: CO 2 + C \u003d 2SO.
In the laboratory, it is obtained from urvinic acid with a concentrated sulfuric acid on it when heated:
Nson + H 2 SO 4 (conc.) \u003d CO + H 2 SO 4 ∙ H 2 O.
It can also be used and oxidic acid. Sulfuric acid in these reactions acts as a watering agent.
Under normal conditions, it is chemically enough inerten, but when heated, rehabilitative properties exhibits, which is widely used in pyrometallurgy to obtain some metals: Fe 2 O 3 + 3CO \u003d 2FE + 3CO 2.
On the air CO is burning with a blue flame with a large amount of heat: 2 + o 2 \u003d 2 \u003d 2 + 569 kJ.
In addition to oxygen on the direct sunlight or in the presence of a catalyst (active coal) with the chlorine, forming phosgene:
CO + CL 2 \u003d COCL 2.
Phosgen is a colorless gas with a characteristic odor. In water, it is uninstalled, but as coal chloride chloride is gradually hydrolyzed according to the scheme: COCL 2 + 2H 2 O \u003d 2HCl + H 2 CO 3. Due to the high toxicity, phosgen was used as a combat poisoning to the first world war. It is possible to neutralize it with a hazed lime.
When heated with oxidizes and sulfur: CO + S \u003d COS.
CO molecule can act as a ligand in various complex allocations. Due to the unconvisory electronic pair of carbon, it shows σ-donor properties, and due to the free π-baking orbitals, the π-acceptor properties exhibit. Of particular interest are carbonyl complexes of D-metals, because The thermal decomposition of carbonyls is obtained by high purity metals.