Carbon shows the smallest degree. Big encyclopedia of oil and gas
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However, it should be noted that in the reactions discussed above, the oxidation state of carbon 4 in formic acid and its salt and 2 in carbon monoxide (II) changes, and these reactions are actually redox reactions.
In organic compounds - methane CH4, methyl alcohol CH3OH, formaldehyde CH2O, formic acid HCOOH, as well as in carbon dioxide, the oxidation states of carbon are, respectively, - 4, - 2, 0, 2, 4, while the valence of carbon in all these substances is equal to four ...
In organic compounds - methane CH), methyl alcohol CH3OH, formaldehyde CH2O, formic acid HCOOH, as well as in carbon dioxide, the oxidation states of carbon are, respectively, - 4, - 2, 2, 4, while the valence of carbon in all these substances is four.
It should be noted that, despite the existence of reaction (1), carbon monoxide cannot be considered formic acid anhydride, because as a result of the interaction, the oxidation state of carbon changes: (4) in formic acid and (2) in carbon monoxide.
In most organic compounds, the polarity of the bond between atoms is weakly expressed, but the oxidation numbers of atoms in them are determined in the same way as in inorganic compounds with a zero bond; in hydrocarbons as compounds with non-polar connection, the oxidation states of carbon and hydrogen are obviously equal to zero.
The ability to donate electrons grows from top to bottom, and the ability to accept electrons - from bottom to top in the group Typical manifested valencies - 2 and 4, oxidation states - 4, 2, 4 For carbon, the most common compounds with valency 4, for lead - compounds with oxidation state 2 The simplest gaseous hydrogen compounds have the ENf formula, their strength decreases from carbon to lead, the oxidation state of carbon in CH4 - 4, in PbH4 - 4 Formulas of higher oxides EO2, their properties vary from acidic (CO2, SiO2) to amphoteric (SnO2, PbO2) indifferent (nonsol-forming) oxide, oxides of tin (II) and lead (II) - basic with the manifestation of some amphoteric properties.The strength of oxygen-containing acids such as Н2ЭО3 decreases from top to bottom in the group.
Carbides are compounds of elements with carbon, in which the latter plays the role of an electronegative element. The oxidation state of carbon in carbides can be different. However, such carbides are known only for a few comparatively active light metals.
Carbon combines directly with many metals to form carbides - compounds - in which carbon is electronegative. The oxidation state of carbon in carbides is different. Are different and Chemical properties carbides.
Carbides are compounds of elements with carbon, in which the latter plays the role of an electronegative element. The oxidation state of carbon in carbides can be different. However, such carbides are known only for a few comparatively active light metals, namely beryllium and aluminum. They are crystalline substances that resemble common salts in appearance.
Atoms of the same element in different compounds can have different values of the oxidation state. The oxidation states of carbon in the molecules СШ, СН3ОН, СН2О, НСООН, СО2 are, respectively, - 4, - 2, О, 2, 4, while the valence of carbon in all these compounds is equal to four. The oxidation state of nitrogen in the N2 and NH3 molecules is 0 and –3, respectively, while its valence in both compounds is three. From these examples, the formal nature of the concept of the oxidation state becomes clear. However, this concept is convenient to use when drawing up equations for redox reactions.
The decomposition of CO2 is facilitated by ultraviolet radiation and electrical discharge. The oxidation state of carbon in CO2 is maximum (4), and therefore dioxide cannot be a reducing agent, does not burn and does not support the combustion of conventional fuel. But in its atmosphere, simple substances burn, the atoms of which have a greater affinity for oxygen than carbon.
The decomposition of CO2 is facilitated by ultraviolet radiation and electrical discharge. The oxidation state of carbon in CO2 is maximum (4), and therefore dioxide cannot be a reducing agent, does not burn and does not support the combustion of conventional fuel. But in its atmosphere, simple substances burn, the atoms of which have a greater affinity for oxygen than carbon.
While decomposing others organic matter this ratio is subject to change. If the oxidation state of carbon in the starting compound is higher than in glucose, more carbon dioxide is produced, if the oxidation state of carbon is negative, more methane is produced.
In organic chemistry, as a rule, the oxidation states of carbon are not used, but if necessary, they are evaluated according to the same rules. In this case, the oxidation state of carbon is found for each atom separately.
What is the oxidation state of carbon in these compounds.
Each element is capable of forming a simple substance while in a free state. In this state, the movement of atoms is the same, they are symmetrical. V complex substances the matter is much more complicated. in this case, they are asymmetric, complex substances are formed in the molecules of complex substances
What is meant by oxidation
There are such compounds in which electrons are distributed as unevenly as possible, i.e. during the formation of complex substances, they pass from atom to atom. It is this uneven distribution in complex substances that is called oxidation or oxidation. The resulting charge of an atom in a molecule is called the oxidation state of the elements. Depending on the nature of the transition of electrons from atom to atom, a negative or positive degree is distinguished. In the case of recoil or acceptance by an atom of an element of several electrons, respectively, a positive and negative oxidation state is formed chemical elements(E + or E -). For example, writing K +1 means that the potassium atom donated one electron. In any, the central place is occupied by carbon atoms. The valency of this element corresponds to the 4th in any compound, however, in different compounds, the oxidation state of carbon will be different, it will be equal to -2, +2, ± 4. This nature of different values of valence and oxidation state is observed in almost any compound.
Determination of the oxidation state
To determine correctly, you need to know the fundamental postulates. 
Metals are not capable of having a minus degree, however, there are rare exceptions when the metal forms bonds with the metal. In the periodic system, the group number of an atom corresponds to the maximum possible oxidation state: carbon, oxygen, hydrogen and any other element. An electronegative atom, when displaced towards another atom, one electron receives a charge of -1, two electrons -2, etc. This rule does not apply to the same atoms. For example, for the H-H bond, it will be equal to 0. The C-H bond = -1. The oxidation state of carbon in the C-O bond = + 2. The metals of the first and second groups of the Mendeleev system and fluorine (-1) have the same degree. In hydrogen, this degree in almost all compounds is +1, with the exception of hydrides, in which it is -1. For elements with a variable degree, it can be calculated knowing the compound formula. The basic rule is that the sum of the degrees in any molecule is 0. 
An example of calculating the oxidation state
Let us consider the calculation of the oxidation state using the example of carbon in the CH3CL compound. Let's take the initial data: the degree of hydrogen is +1, chlorine is -1. For convenience, in calculating x, we will consider the oxidation state of carbon. Then, for CH3CL the equation will be x + 3 * (+ 1) + (- 1) = 0. By performing simple arithmetic operations, you can determine that the oxidation state of carbon will be +2. In this way, calculations can be made for any element in a complex connection.
In most inorganic compounds, carbon exhibits oxidation states of –4, +4, +2.
In nature, the carbon content is 0.15% (mole fraction) and is found mainly in the composition of carbonate minerals (primarily limestone and marble CaCO 3, magnesite MgCO 3, dolomite MgCO 3 ∙ CaCO 3, siderite FeCO 3), coal, oil, natural gas and also in the form graphite and less often diamond... Carbon - home component living organisms.
Simple substances. Simple substances of the element carbon have a polymer structure, and in accordance with the characteristic hybrid states of the orbitals, carbon atoms can combine into polymer formations of coordination ( sp 3), layered (sp 2) and linear ( sp) structure, which corresponds to the types simple substances: diamond(β-C), graphite(α-C) and carbyne(C 2) n... In 1990, the fourth carbon modification was obtained - fullerene C 60 and C 70.
Diamond- a colorless crystalline substance with a cubic lattice, in which each carbon atom is bonded by σ-bonds with four neighboring ones - this leads to exceptional hardness and the absence of electronic conductivity under normal conditions.
Carbin- black powder with a hexagonal lattice built of rectilinear σ- and π-bonds: –C≡C – C≡C – C≡ ( polyyne) or = C = C = C = C = C = ( polycumulene).
Graphite- a stable form of existence of the element carbon; gray-black, with a metallic sheen, greasy to the touch, soft non-metal, conductive. At ordinary temperatures, it is very inert. At high temperatures, it directly interacts with many metals and non-metals (hydrogen, oxygen, fluorine, sulfur). Typical reducing agent; reacts with water vapor, concentrated nitric and sulfuric acids, metal oxides. In the "amorphous" state (coal, coke, soot) it burns easily in air.
C + H 2 O (steam, 800-1000 ° C) = CO + H 2
C + 2H 2 SO 4 (conc.) = CO 2 + 2SO 2 + 2H 2 O
C + 4HNO 3 (conc.) = CO 2 + 4NO 2 + 2H 2 O
C + 2H 2 (600 ° C, kat. Pt) = CH 4
C + O 2 (600-700 ° C) = CO 2
2C + O 2 (above 1000 ° C) = 2CO
2C + Ca (550 ° C) = CaC 2
C + 2PbO (600 ° C) = 2Pb + CO 2
C + 2F 2 (above 900 ° C) = CF 4
Due to the very high activation energy, the transformations of carbon modifications are possible only under special conditions. Thus, diamond turns into graphite when heated to 1000–1500 ° C (without air access). The transition from graphite to diamond requires a very high pressure (6 ∙ 10 9 –10 ∙ 10 10 Pa); the method of obtaining diamond at low pressure has been mastered.
C (diamond) = C (graphite) (above 1200 ° C)
(C 2) n(carbyne) = 2 n C (graphite) (2300 ° C)
Receiving and applying. Graphite is used to make electrodes, melting crucibles, lining of electric furnaces and industrial electrolysis baths, etc. In nuclear reactors it is used as a neutron moderator. Graphite is also used as a lubricant, etc. The exceptional hardness of diamond makes it widely used for processing extremely hard materials, during drilling operations, for pulling wire, etc. The most perfect diamond crystals are used after cutting and grinding for making jewelry (diamonds).
Due to the high adsorption capacity of charcoal and animal coals (coke, charcoal, bone charcoal, soot), they are used to remove impurities from substances. Coke obtained from dry processing of bituminous coal is mainly used in metallurgy in the smelting of metals. Soot is used in the production of black rubber, for the manufacture of paints, ink, etc.
Carbon dioxide CO 2 is used in the production of soda, for extinguishing fires, preparation of mineral water, as an inert medium for various syntheses.
Compounds with a negative oxidation state. With elements less electronegative than itself, carbon gives carbides. Since it is typical for carbon to form homochains, the composition of most carbides does not correspond to the oxidation state of carbon –4. Type chemical bond one can distinguish covalent, ionic-covalent and metal carbides.
Covalent silicon carbides SiC and boron B 4 C are polymeric substances characterized by very high hardness, refractoriness and chemical inertness.
The simplest covalent carbide is methane CH 4 is a chemically very inert gas; it is not affected by acids and alkalis, but it ignites easily, and its mixtures with air are extremely explosive. Methane is the main component of natural (60–90%) mine and bog gas. Methane-rich gases are used as fuel and feedstock for chemical production.
Carbon forms a variety of percarbides, for example, some of the simplest hydrocarbons - ethane C 2 H 6, ethylene C 2 H 4, acetylene C 2 H 2.
Ionic-covalent carbides are crystalline salt-like substances. When exposed to water or dilute acid, they are destroyed with the release of hydrocarbons. Therefore, carbides of this type can be considered as derivatives of the corresponding hydrocarbons. Methane derivatives - methanides, for example, carbides Be 2 C and AlC 3. They decompose in water, releasing methane:
АlС 3 + 12Н 2 О = 4Al (ОН) 3 + 3СН 4
Of the salt-like percarbides, the most studied acetylides type M 2 +1 C 2, M +2 C 2 and M 2 +3 (C 2) 3. Most important calcium acetylide CaS 2 (called carbide) are obtained by heating CaO with coal in electric furnaces:
СaO + 3C = CaC 2 + CO
Acetylides more or less readily decompose with water to form acetylene:
CaC 2 + 2H 2 O = Ca (OH) 2 + C 2 H 2
This reaction is used in engineering to produce acetylene.
Carbides are metallic d-elements of IV-VIII groups. The most common carbides of medium composition are MC (TiC, ZrC, HfC, VC, NbC, TaC), M 2 C (Mo 2 C, W 2 C), M 3 C (Mn 3 C, Fe 3 C, Co 3 C) ... Metal carbides are found in cast irons and steels, giving them hardness, wear resistance and other valuable qualities. Superhard and refractory alloys are produced on the basis of tungsten, titanium and tantalum carbides, which are used for high-speed processing of metals.
Carbon (IV) compounds. The oxidation state of carbon +4 is manifested in its compounds with more electronegative than itself, non-metals: СНаl 4, СОНаl 2, СО 2, COS, CS 2 and anionic complexes CO 3 2–, COS 2 2–, CS 3 2–.
By chemical nature these carbon (IV) compounds are acidic. Some of them interact with water to form acids:
CO 2 + H 2 O = H 2 CO 3
СOCl 2 + 3Н 2 О = Н 2 СО 3 + 2НCl
and with basic compounds, forming salts:
2KON + CO 2 = K 2 CO 3 + H 2 O
Of the tetrahalides CHal 4, the most widely used tetrachloride methaneСCl 4 as a non-combustible solvent for organic substances, as well as a liquid for fire extinguishers. It is obtained by chlorination of carbon disulfide in the presence of a catalyst:
CS 2 + Cl 2 = CCl 4 + S 2 Cl 2
Mixed carbon fluoride-chloride CCl 2 F 2 - freon(t boiling –30 ° С) is used as a refrigerant in refrigerating machines and installations. Not poisonous. When released into the atmosphere, it destroys the ozone layer.
Carbon disulfide or carbon disulfide CS 2 (poisonous) is obtained by the interaction of sulfur vapors with hot coal: C + 2S = CS 2
Carbon disulfide readily oxidizes, ignites in air with slight heating: СS 2 + 3O 2 = CO 2 + 2SO 2
All oxodihalides (carbonyl halides) COHal 2 are significantly more reactive than tetrahalides; in particular, they are readily hydrolyzed:
СОСl 2 + Н 2 O = СО 2 + 2НCl
The greatest application is found by COCl 2 ( phosgene, carbonyl chloride) – extremely poisonous gas. It is widely used in organic synthesis.
Carbon dioxide CO 2 ( carbon dioxide) in technology is usually obtained by thermal decomposition of CaCO 3, and in the laboratory - by the action on CaCO 3 with hydrochloric acid.
CaCO 3 = CaO + CO 2 CaCO 3 + 2HCl = CaCl 2 + CO 2
Carbon dioxide is readily absorbed by alkali solutions, with the formation of a corresponding carbonate, and with an excess of CO 2 - bicarbonate:
Ca (OH) 2 + CO 2 = CaCO 3 ↓ + H 2 O
CaCO 3 ↓ + CO 2 = Ca (HCO 3) 2
Hydrocarbonates, unlike carbonates, are mostly water-soluble.
The solubility of CO 2 in water is low, some of the dissolved carbon dioxide reacts with water to form an unstable average carbonic acid H 2 CO 3 (hydrogen trioxocarbonate).
Sulfide carbonates (IV) (thiocarbonates) in many ways resemble trioxocarbonates (IV). They can be obtained by the interaction of carbon disulfide with basic sulfides, for example:
K 2 S + CS 2 = K 2 [CS 3]
Aqueous solution of Н 2 СS 3 - weak thiocarbonic acid... Gradually decomposes with water, forming carbonic acid and hydrogen sulfide:
H 2 CS 3 + 3H 2 O = H 2 CO 3 + 3H 2 S
From nitridocarbonates important is calcium cyanamide CaCN 2, obtained by oxidation of calcium carbide CaC 2 with nitrogen when heated:
CaC 2 + N 2 = CaCN 2 + C
Of the hydrogen oxonitridocarbonates, the most important is urea(urea) CO (NH 2) 2, obtained by the action of CO 2 on an aqueous solution of ammonia at 130 ° C and 1 ∙ 10 7 Pa:
CO 2 + 2N 3 H = CO (NH 2) 2 + H 2 O
Urea is used as a fertilizer and for feeding livestock, as an initial product for obtaining plastics, pharmaceuticals (Veronal, Luminal, etc.), etc.
Hydrogen sulfidonitridocarbonate (IV) or hydrogen thiocyanateНSCN in aqueous solution forms a strong (such as НCl) thiocyanic acid... Thiocyanites are mainly used for dyeing fabrics; NH 4 SCN is used as a reagent for Fe 3+ ions.
Compounds of carbon (II). Derivatives of carbon (II) are CO, CS, HCN.
Carbon monoxide (II) CO ( carbon monoxide) is formed during the combustion of carbon or its compounds in a lack of oxygen, as well as as a result of the interaction of carbon monoxide (IV) with hot coal.
СО 2 + С ↔ 2СО
The CO molecule has a triple bond, as in N 2 and the cyanide ion CN -. Under normal conditions, carbon monoxide (II) is chemically very inert. When heated, it exhibits reducing properties, which is widely used in pyrometallurgy.
When heated, CO is oxidized by sulfur, when exposed to radiation or in the presence of a catalyst, it interacts with chlorine, etc.
CO + S = COS (carbon oxosulfide IV);
CO + Cl 2 = COCl 2 (carbon oxochloride IV)
Hydrogen cyanide HCN has a linear structure H – C≡N; there is also its tautomeric form ( hydrogen isocyanide) H – N≡C. Hydrogen cyanide aqueous solution is a very weak acid called bluish or cyanide.
HCN is the strongest inorganic poison.
Cyanides exhibit reducing properties. So, when their solutions are heated, they are gradually oxidized by atmospheric oxygen, forming cyanates:
2KCN + O 2 = 2KOCN
and when boiling solutions of cyanide with sulfur, thiocyanates are formed (this is the basis for the production of thiocyanates):
2KCN + S = 2KSCN
Hydrogen cyanide is used in organic synthesis, NaCN and KCN - in gold mining, for the production of complex cyanides, etc.
When the cyanides of low-activity metals are heated, cyanus(CN) 2 is a highly reactive poisonous gas.
Hg (CN) 2 = Hg + (CN) 2
End of work -
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CHEMISTRY
Department of Modern Natural Science ... VM Vasyukov OV Savenko AV Ivanova ...
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All topics in this section:
Part I. THEORETICAL CHEMISTRY
Chapter 1. Basic concepts and laws of chemistry .......................................... ......................................... 3 Chapter 2. The structure of the atom and the periodic law .................
Part II. INORGANIC CHEMISTRY
Chapter 11. The most important classes of inorganic compounds ........................................... ........... 55 Chapter 12. Elements of group I (hydrogen, lithium, sodium, subgroup
Part III. ORGANIC CHEMISTRY
Chapter 20. general characteristics organic compounds ................................................ ..... 124 Chapter 21. Alkanes ........................................ ....
The main provisions of the atomic-molecular theory
1. All substances are made up of molecules. Molecule - smallest particle substance with its chemical properties. 2. Molecules are made up of atoms. An atom is the smallest particle
The law of equivalents - for molecular compounds, the number of constituent elements is proportional to their chemical equivalents.
Equivalent (E) - a particle of a substance that in a given acid-base reaction is equivalent to one hydrogen ion or in a given redox reaction one
Gas laws
Studying properties gas exchange different substances and chemical reactions involving gases played such an important role in the formation of atomic-molecular theory that gas laws deserve cn
Charles's Law: With a constant volume, the gas pressure changes in direct proportion to the absolute temperature.
P1 / T1 = P2 / T2, or P / T = const. These three laws can be combined into one universal gas law
Atomic structure models
Direct evidence of the complexity of the structure of the atom was the discovery of the spontaneous decay of atoms of some elements, called radioactivity (A. Becquerel, 1896). Follow-up of this
Quantum numbers of electrons
The principal quantum number n determines the total energy of an electron in a given orbital (n = 1, 2, 3, ...). The principal quantum number for atoms is known
Electronic configurations of atoms
Since during chemical reactions the nuclei of the reacting atoms remain unchanged (with the exception of radioactive transformations), the chemical properties of atoms depend on the structure of their ele
Pauli's principle or Pauli's ban (1925): an atom cannot have two electrons with the same properties.
Since the properties of electrons are characterized by quantum numbers, Pauli's principle is often formulated as follows: an atom cannot have two electrons in which all four quantum numbers are one
Atomic nucleus and radioactive transformations
Along with chemical reactions, in which only electrons take part, there are various transformations in which the nuclei of atoms undergo changes (nuclear reactions).
Periodic law
Opened in 1869 by D.I. Mendeleev Periodic law represents one of the fundamental laws in modern natural science. Arranging all the elements in the order of increasing atomic masses D
Valence and oxidation state
The ability of an atom of a chemical element to attach or replace a certain number of atoms of another element to form a chemical bond is called the valence of the element.
A covalent bond is a bond carried out due to the formation of electron pairs, equally belonging to both atoms.
H + H® H: H or H - H
A bond is a bond that occurs when the electron clouds of two atoms are socialized, if the clouds overlap along a line connecting the atoms.
But in the acetylene molecule, each of the carbon atoms contains two more p-electrons, which do not take part in the formation of σ-bonds. Acetylene molecule has a flat line
A bond can be called a covalent bond formed by overlapping atomic orbitals outside the line connecting the atoms.
σ-bonds are stronger than π-bonds, which explains the greater reactivity of unsaturated hydrocarbons in comparison with the limiting ones. Another kind of g
Ionic bond
Ionic bond- electrostatic attraction between ions formed by the complete displacement of an electron pair to one of the atoms. Na +
Metal bond
Metals combine properties that are general in nature and differ from those of other substances. These properties are relatively high melting points, the ability to
Intermolecular interactions
Electrically neutral atoms and molecules are capable of additional interactions with each other. Hydrogen bond - the bond between positively
Units of measurement for temperature T, pressure p and volume V.
When measuring temperature, two scales are most often used. The absolute temperature scale uses kelvin (K) as the unit of measure. Absolute zero point (0 K) n
Chemical thermodynamics
Chemical thermodynamics answers questions about the fundamental possibility of a given chemical reaction under certain conditions and about the final equilibrium state of the system.
Reactions as a result of which the enthalpy increases (ΔH> 0) and the system absorbs heat from the outside (Qp< 0) называются эндотермическими.
So, the oxidation of glucose with oxygen occurs with the release a large number heat (Qp = 2800 kJ / mol), i.e. this process is exothermic. The corresponding thermochemical y
The rate of a chemical reaction is determined by the amount of a substance that has reacted per unit of time per unit of volume.
v = ∆С / ∆τ mol / (l · s) The reaction rate depends on the nature of the reacting substances and on the conditions under which the reaction proceeds. The most important of them are
Reversible and irreversible reactions. State of chemical equilibrium
A chemical reaction does not always "reach the end", i.e. the starting materials are not always completely converted into reaction products. This is because as food accumulates
The state in which the rate of the reverse reaction becomes equal to the rate of the forward reaction is called chemical equilibrium.
The state of chemical equilibrium of reversible processes is quantitatively characterized by the equilibrium constant. So for a reversible chemical reaction: aA + bB
Perfect and real solutions. Dissolution as a physicochemical process
There are two main theories of solutions: physical and chemical. The physical theory of solutions was proposed by Van't Hoff and Arrhenius. According to this theory, the solvent
Dependence of the solubility of various substances on the nature of the solvent, temperature and pressure
The solubility of substances in various solvents, such as water, varies widely. If more than 10 g of a substance dissolves in 100 g of water at room temperature
Dilute solution laws
When a non-volatile substance is dissolved in a solvent, the vapor pressure of the solvent above the solution decreases, which causes an increase in the boiling point of the solution and a decrease in temperature
Ways of expressing the concentration (composition) of solutions
The quantitative composition of the solution is most often expressed using the concept of "concentration", i.e. solute content per unit of mass or volume. eleven.
Electrolytes and electrolytic dissociation
Solutions that conduct electric current are called electrolyte solutions. There are two main reasons for the passage of electric current through conductors: either due to transfer
Optical and molecular kinetic properties of dispersed systems
Optical property colloidal systems - opalescence, i.e. scattering of light by small particles, leading, in particular, to the appearance of the Faraday-Tyndall effect
Surface and adsorption phenomena
Differences in the composition and structure of the contacting phases, as well as the nature of molecular interactions in their volume, cause the appearance of a kind of molecular force field on the surface of the section.
Colloidal (colloidal-dispersed) systems
Colloidal systems (sols) are heterogeneous systems consisting of particles of the order of 10–7–10–9 m. In terms of particle size, colloidal systems occupy n
Redox reactions are reactions accompanied by a change in the oxidation state of the elements that make up the reactants.
The oxidation state is the conditional charge of an atom in a molecule, calculated on the assumption that the molecule consists of ions and is generally electrically neutral. Substance, composition
The electrochemical oxidation-reduction reaction can be carried out in such a way that electrons will pass from the reducing agent to the oxidizing agent in the form of an electric current, i.e. transformation x
Corrosion of metals
Corrosion - destruction of metals by chemical or electrochemical action environment... Corrosion is a spontaneous process that decreases with
Electrolysis
Electrolysis is a redox process that occurs on the electrodes when a direct electric current is passed through a solution or electrolyte melt
Electrolysis of electrolyte melts
Scheme for recording electrolysis of an electrolyte melt: KtAn ↔ Ktn + + Anm– Cathode– | Ktn +
Electrolysis of aqueous solutions of electrolytes
The electrolysis of solutions differs from the electrolysis of electrolyte melts by the presence of water molecules, which can also participate in the redox reactions of electrolysis. Due to its
Water is recovered Water and metal cations are recovered Metal cations are recovered
Anodic process: 1. On insoluble anodes with competition of the anion of anoxic acids (Cl–, Br–, I–, S2–
Qualitative analysis
The task of qualitative analysis is to define chemical composition test compound. Qualitative analysis carried out by chemical, physical and physical-chemical
Quantitative analysis
Task quantitative analysis- determination of the quantitative content of chemical elements (or their groups) in compounds. Quantitative analysis methods
Acid
An acid is a compound that, when dissociating in an aqueous solution from positive ions, only hydrogen ions H + (according to the theory of electrolytic
Hydrogen
Hydrogen is the first element and one of the two representatives of the first period Periodic table... A hydrogen atom consists of two particles - a proton and an electron, between which there are only gravitational forces. V
Beryllium
In all stable compounds, the oxidation state of beryllium is +2. Beryllium content in earth crust small. Essential minerals: beryl Be3Al2 (SiO
Aluminum
Aluminum is a typical amphoteric element, with the oxidation state +3 being the most typical. Unlike boron, it is characterized not only by anionic, but also cationic complexes.
Lanthanides
The lanthanide family includes cerium Ce 4f25s25p65d06s2, praseodymium Pr 4f3, neodymium Nd 4f4, promethium
Actinides
The actinide family includes thorium Th 5f06s26p66d27s2, protactinium Pr 5f2 6d17s2
Silicon
Silicon in compounds has oxidation states of +4 and –4. For it, the most characteristic bonds are Si – F and Si – O. In terms of prevalence on Earth, 20% (mole fractions) silicon is inferior to that
Oxygen
Like fluorine, oxygen forms compounds with almost all elements (except helium, neon, and argon). The oxidation state of oxygen in the overwhelming majority of compounds is –2. Chrome
Formulas of organic compounds
The molecular formula reflects the qualitative and quantitative elemental composition of a substance. In the molecular formula, carbon atoms are first written, then hydrogen atoms, then -
Nomenclature of organic compounds
The IUPAC systematic nomenclature is now recognized (IUPAC - International Union of Pure and Applied Chemistry). Among the options
Isomerism of organic compounds
Isomerism is the existence of different substances with the same molecular formula. This phenomenon is due to the fact that the same atoms can connect in different ways
And the reactivity of organic compounds
The chemical properties of the atoms that make up a molecule change depending on what other atoms they are associated with. Directly bound atoms influence each other most strongly, however
General characteristics of organic reactions
The classification of organic reactions can be based on various principles. I. Classification of chemical reactions by the result of chemical transformation: 1.
Industrial production of organic compounds
The growing role of organic compounds in modern world causes the need for the creation of industrial production capable of producing them in sufficient quantities. For such production
Nomenclature and isomerism
Alkanes are saturated, or saturated, hydrocarbons, since all free valences of carbon atoms are occupied (completely "saturated") with hydrogen atoms. The simplest pr
Physical properties
Under normal conditions, the first four members of the homologous series of alkanes (C1 - C4) are gases. Normal alkanes from pentane to heptadecane (C5 - C17) - liquids
Methods of obtaining
The main natural sources of alkanes are oil and natural gas. Various oil fractions contain alkanes from C5H12 to C30H62. Natural gas is composed of methane
Chemical properties
Under normal conditions, alkanes are chemically inert. They are resistant to the action of many reagents: they do not interact with concentrated sulfuric and nitric acids, with concentrated and melted liquids
Nomenclature and isomerism
Cycloalkanes are saturated cyclic hydrocarbons. The simplest representatives of this series: Common
Chemical properties
In terms of chemical properties, small and ordinary cycles differ significantly from each other. Cyclopropane and cyclobutane are prone to addition reactions, i.e. are similar in this respect to alkenes. Cyclopentane and
Nomenclature and isomerism
Alkenes are called unsaturated hydrocarbons, the molecules of which contain one double bond. The first representative of this class is ethylene CH2 = CH2,
Receiving
Alkenes are rare in nature. Since alkenes are a valuable raw material for industrial organic synthesis, many methods for their preparation have been developed. 1. The main industrial source
Chemical properties
The chemical properties of alkenes are determined by the presence of a double bond in their molecules. The electron density of the π-bond is quite mobile and easily reacts with electrophilic
Application
Lower alkenes are important starting materials for industrial organic synthesis. Ethyl alcohol, polyethylene, and polystyrene are obtained from ethylene. Propene is used to synthesize polypropylene, phenol,
Nomenclature and isomerism
Alkadienes are unsaturated hydrocarbons containing two double bonds. General formula of alkadienes СnН2n-2. If double bonds are separated in a carbon chain
Receiving
The main industrial method for producing dienes is the dehydrogenation of alkanes. Butadiene-1,3 (divinyl) is obtained from butane:
Chemical properties
Alkadienes are characterized by the usual reactions of electrophilic addition of AE, characteristic of alkenes. A feature of conjugated dienes is that two double bonds in their
Nomenclature and isomerism
Alkines are called unsaturated hydrocarbons, the molecules of which contain one triple bond. General formula of the homologous series of alkynes СnН2
Physical properties
The physical properties of alkynes are similar to those of alkanes and alkenes. Under normal conditions (C2 - C4) - gases, (C5 - C16) - liquids, starting from C17
Receiving
1. The general method of obtaining alkynes is the elimination of two molecules of hydrogen halide from dihaloalkanes, which contain two halogen atoms either at the neighboring ones or at one carbon atom, under
Chemical properties
The chemical properties of alkynes are due to the presence in their molecules triple bond... Typical reactions for acetylene and its homologues are the reactions of electrophilic addition of AE
Application
Many branches of the organic synthesis industry have developed on the basis of acetylene. Above, we have already noted the possibility of obtaining acetaldehyde from acetylene and various ketones from homologues of acetyle
Nomenclature and isomerism
Aromatic hydrocarbons (arenes) are substances whose molecules contain one or more benzene rings - cyclic groups of carbon atoms with wasps
Physical properties
The first members of the homologous series of benzene are colorless liquids with a specific odor. They are lighter than water and insoluble in it. They dissolve well in organic solvents and are choruses themselves.
Methods of obtaining
1. Obtaining from aliphatic hydrocarbons. To obtain benzene and its homologues, the industry uses aromatization of saturated hydrocarbons that make up oil. When pro
Chemical properties
The aromatic nucleus, which has a mobile system of π-electrons, is a convenient object for attack by electrophilic reagents. This is also facilitated by the spatial arrangement of π-
Orientation (substitution) rules in the benzene ring
The most important factor determining the chemical properties of a molecule is the electron density distribution in it. The nature of the distribution depends on the mutual influence of the atoms. In molecules
Application
Aromatic hydrocarbons are the most important raw material for the synthesis of valuable substances. Phenol, aniline, styrene are obtained from benzene, from which, in turn, phenol-formaldehyde resins, dyes, polys
Nomenclature and isomerism
The general formula of the homologous series of saturated monohydric alcohols is CnH2n + 1OH. Depending on which carbon atom is the hydroxyl group
Receiving
1. The general method of obtaining alcohols, which is of industrial importance, is the hydration of alkenes. The reaction proceeds by passing an alkene with water vapor over a phosphate catalyst (H3PO
Chemical properties
The chemical properties of alcohols are determined by the presence of the -OH group in their molecules. The C – O and O – H bonds are strongly polar and capable of breaking. There are two main types of reactions of alcohols with participation
Reactions with O – H bond cleavage.
1. The acidic properties of alcohols are very weak. Lower alcohols react violently with alkali metals:
Reactions with C – O bond cleavage.
1) Dehydration reactions occur when alcohols are heated with dehydrating substances. With strong heating, intramolecular dehydration occurs with the formation of alkenes:
Application
Alcohols are mainly used in the organic synthesis industry. Methyl alcohol CH3OH is a poisonous liquid with a boiling point of 65 ° C, easy to mix
Chemical properties
For di- and trihydric alcohols, the main reactions of monohydric alcohols are characteristic. One or two hydroxyl groups can be involved in the reactions. The mutual influence of hydroxyl groups is manifested in
Application
Ethylene glycol is used for the synthesis of polymeric materials and as antifreeze. V large quantities it is also used to obtain dioxane, an important (albeit toxic) laboratory
Physical properties
Phenols are mostly crystalline substances (m-cresol is liquid) at room temperature. They have a characteristic odor, are rather poorly soluble in cold water,
Methods of obtaining
1. Obtaining from halogenbenzenes. When chlorobenzene and sodium hydroxide are heated under pressure, sodium phenolate is obtained, upon further processing of which with an acid phenol is formed:
Chemical properties
In phenols, the p-orbital of the oxygen atom forms a single π-system with the aromatic ring. Due to this interaction, the electron density at the oxygen atom decreases, and in benzene col
Nomenclature and isomerism
Organic compounds, in the molecule of which there is a carbonyl group, are called carbonyl
Receiving
1. Hydration of alkynes. Aldehyde is obtained from acetylene, ketones are obtained from its homologues:
Chemical properties
The chemical properties of aldehydes and ketones are determined by the fact that their molecules include a carbonyl group with a polar double bond. Aldehydes and ketones - chemically active compounds
Application
Formaldehyde is a gas with a strong, irritating odor. A 40% aqueous solution of formaldehyde is called formalin. Formaldehyde is produced industrially on a large scale by the oxidation of methane or methanol
Nomenclature and isomerism
Compounds containing a carboxylic group are called carboxylic acids.
Physical properties
Saturated aliphatic monocarboxylic acids form a homologous series characterized by the general formula CnH2n + 1COOH. The lower members of this series are usually
Receiving
1. Oxidation of primary alcohols is a common method for the production of carboxylic acids. KMnO4 and K2Cr2O7 are used as oxidants.
Chemical properties
Carboxylic acids are stronger acids than alcohols, since the hydrogen atom in the carboxyl group has increased mobility due to the influence of the –CO group. In aqueous solution, carbonic acid
Application
Saturated acids. Formic acid HCOOH. The name is due to the fact that the acid is contained in the secretions of ants. Widely used in the pharmaceutical and food industries
Nomenclature and isomerism
Among the functional derivatives of carboxylic acids, esters occupy a special place - compounds representing carboxylic acids in which the hydrogen atom in the carboxyl group is replaced
Physical properties
Esters of lower carboxylic acids and alcohols are volatile, slightly soluble or practically water-insoluble liquids. Many of them have a pleasant smell. So, for example
Chemical properties
1. Reaction of hydrolysis or saponification. The esterification reaction is reversible, therefore, in the presence of acids, a reverse reaction will occur, called hydrolysis, as a result
Fats and oils
Among the esters, a special place is occupied by natural esters - fats and oils, which are formed by the trihydric alcohol glycerin and higher fatty acids with unbranched carbon
Nomenclature and isomerism
The simplest monosaccharide is glycerol aldehyde, С3Н6О3: Rest
Physical and chemical properties of glucose
Glucose С6Н12О6 is a white crystals, sweet in taste, well soluble in water. In a linear form, glucose molecules contain one al
Disaccharides
The most important disaccharides are sucrose, maltose and lactose. All of them are isomers and have the formula C12H22O11, but their structure is different. Molek
Polysaccharides
Polysaccharide molecules can be considered as a polycondensation product of monosaccharides. The general formula of polysaccharides is (C6H10O5) n. We will consider the most important pr
Nomenclature and isomerism
The general formula of saturated aliphatic amines is CnH2n + 3N. Amines are usually named by listing hydrocarbon radicals (in alphabetical order) and doba
Physical properties
Methylamine, dimethylamine and trimethylamine are gases, the middle members of the aliphatic series are liquids, the higher ones are solids. Between the amine molecules in the liquid phase, weak hydrogen bonds, poe
Receiving
1. The main method for producing amines is the alkylation of ammonia, which occurs when alkyl halides are heated with ammonia:
Chemical properties
1. Due to the presence of an electron pair on the nitrogen atom, all amines have basic properties, and aliphatic amines are stronger bases than ammonia. Aqueous solutions of amines have
Aromatic amines
Aniline (phenylamine) C6H5NH2 is the ancestor of the class of aromatic amines, in which the amino group is directly bonded to the benzene ring. This St.
Physical properties
Aniline is a colorless oily liquid, slightly heavier than water, slightly soluble in water, soluble in ethyl alcohol and benzene. The main method for producing aniline is the reduction of nitrob
Chemical properties
1. Aniline is a much weaker base than aliphatic amines (Kb = 5.2-10-10). This is due to the fact that the electron pair of the nitrogen atom, which determines the basic
Nomenclature and isomerism
Amino acids are organic bifunctional compounds, which include a carboxyl group —COOH and an amino group —NH2. Depending on the relative position of both functions
Chemical properties
Amino acids are organic amphoteric compounds. They contain two opposite functional groups in the molecule: an amino group with basic properties and a carboxyl group
Peptides
Peptides can be thought of as condensation products of two or more amino acid molecules. Two amino acid molecules can react with each other to split off a water molecule and form a product
Chemical properties
1. The destruction of the secondary and tertiary structure of the protein while maintaining the primary structure is called denaturation. It occurs when heated, a change in acidity with
The biological significance of proteins
The biological significance of proteins is extremely high. 1.Absolutely all chemical reactions in the body occur in the presence of catalysts - enzymes. Even such a simple reaction
Six-membered heterocycles
Pyridine C5H5N is the simplest six-membered aromatic heterocycle with one nitrogen atom. It can be considered as an analogue of benzene, in which one CH group for
Five-membered heterocycles
Pyrrole C4H4NH is a five-membered heterocycle with one nitrogen atom.
Nucleic acid structure
Nucleic acids are natural high molecular weight compounds (polynucleotides) that play a huge role in the storage and transmission of hereditary information in living organisms. Molecule
The biological role of nucleic acids
DNA is the main molecule in a living organism. It stores genetic information that is passed on from one generation to the next. In DNA molecules, the encoded composition of all proteins organ
Cytosine guanine
Thus, the information contained in DNA is, as it were, reprinted into mRNA, and the latter delivers it to the ribosomes. 2. Transport RNA (tRNA) transfers amino acids to ribosomes,
General characteristics of polymers
Quite often, the general formula of polymers can be written in the form (-X-) n, where the -X- fragment is called an elementary unit, and the number n is the degree of polymerization
Plastics
Plastics are materials based on polymers that can change their shape when heated and retain their new shape after cooling. Due to this property, plastics lend themselves easily to furs.
Fiber
One of the important fields of application of polymers is in the manufacture of fibers and fabrics. Consider two wa
Rubbers
Rubbers are polymerization products of dienes and their derivatives. Natural rubber is obtained from latex - the sap of some tropical plants. Its structure can be installed
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