Organic compounds. Classes of organic compounds

d-ELEMENTS AND THEIR CONNECTIONS

1. general characteristics d-elements

The d-block includes 32 elements periodic table. d-Elements are included in the 4th-7th major periods. Group IIIB atoms have the first electron in the d-orbital. In subsequent B-groups, the d-sublevel is filled with up to 10 electrons (hence the name d-elements). The structure of the outer electron shells of the d-block atoms is described by the general formula (n-1)d a ns b , where a = 1-10, b = 1-2.

A feature of the elements of these periods is a disproportionately slow increase atomic radius with increasing number of electrons. This relatively slow change in radii is explained by the so-called lanthanide compression due to the penetration of ns electrons under the d electron layer. As a result, a slight change in atomic and chemical properties d-elements with increasing atomic number. The similarity of chemical properties is manifested in the characteristic feature of d-elements to form complex compounds with a variety of ligands.

An important property d-elements have a variable valency and, accordingly, a variety of oxidation states. This feature is associated mainly with the incompleteness of the pre-outer d-electron layer (except for elements of the IB and IIB groups). The possibility of the existence of d-elements in different oxidation states determines a wide range of redox properties of the elements. In lower oxidation states, d-elements exhibit the properties of metals. With an increase in the atomic number in groups B, the metallic properties naturally decrease.

In solutions, oxygen-containing anions of d-elements with highest degree oxidation exhibit acidic and oxidizing properties. Cationic forms of lower oxidation states are characterized by basic and reducing properties.

d-elements in intermediate oxidation states exhibit amphoteric properties. These patterns can be considered using the example of molybdenum compounds:

With a change in properties, the color of molybdenum complexes in different oxidation states (VI - II) changes:

In the period with increasing nuclear charge, a decrease in the stability of compounds of elements in higher oxidation states is observed. In parallel, the redox potentials of these compounds increase. The greatest oxidizing ability is observed in ferrate ions and permanganate ions. It should be noted that in d-elements, as the relative electronegativity increases, the acidic and nonmetallic properties increase.

As the stability of compounds increases when moving from top to bottom in B-groups, their oxidizing properties simultaneously decrease.

It can be assumed that during biological evolution, compounds of elements in intermediate oxidation states, which are characterized by mild redox properties, were selected. The advantages of such selection are obvious: they contribute to the smooth flow of biochemical reactions. A decrease in the RH potential creates the prerequisites for a more subtle “regulation” of biological processes, which ensures a gain in energy. The functioning of the body becomes less energy-intensive, and therefore more economical in food consumption.

From the point of view of evolution, the existence of d-elements in lower oxidation states becomes justified for the organism. It is known that Mn ions 2+, Fe 2+, Co 2+under physiological conditions they are not strong reducing agents, and Cu ions 2+and Fe 2+practically do not exhibit restorative properties in the body. An additional decrease in reactivity occurs when these ions interact with bioorganic ligands.

It may seem that the above is contradicted by the important role of bioorganic molybdenum(V) and (VI) complexes in various organisms. However, this is also consistent with general pattern. Despite the high degree of oxidation, such compounds exhibit weak oxidizing properties.

It is necessary to note the high complexing abilities of d-elements, which are usually significantly higher than those of s- and p-elements. This is primarily explained by the ability of d-elements to be both donors and acceptors of a pair of electrons forming a coordination compound.

In the case of chromium hydroxo complex [Cr(OH) 6]3-The metal ion is an electron pair acceptor. Hybridization 3d 24sp 3-orbitals of chromium provides a more stable energy state than when chromium electrons are located in the orbitals of hydroxo groups.

Compound [СrСl 4]2-is formed, on the contrary, as a result of the fact that the lone d-electrons of the metal occupy the free d-orbitals of the ligands, since in in this case the energy of these orbitals is lower.

Properties of the Cr cation 3+show the variability of the coordination numbers of d-elements. Most often, these are even numbers from 4 to 8; numbers 10 and 12 are less common. It should be noted that there are not only mononuclear complexes. Numerous di-, tri- and tetra-nuclear coordination compounds of d-elements are known.

An example is the binuclear cobalt complex [Co 2(NN 3)10(ABOUT 2)](NO 3)5, which can serve as a model of an oxygen carrier.

More than 1/3 of all microelements in the body are d-elements. In organisms they exist in the form of complex compounds or hydrated ions with an average hydration shell exchange time of 10 -1to 10 -10With. Therefore, it can be argued that “free” metal ions do not exist in the body: they are either their hydrates or hydrolysis products.

In biochemical reactions, d-elements most often manifest themselves as complexing metals. The ligands in this case are biologically active substances, usually of an organic nature or anions of inorganic acids.

Protein molecules form bioinorganic complexes with d-elements - clusters or bioclusters. The metal ion (metal complex-forming agent) is located inside the cluster cavity, interacting with the electronegative atoms of the binding groups of the protein: hydroxyl (-OH), sulfhydryl (-SH), carboxyl (-COOH) and amino groups of proteins (H 2N -). For a metal ion to penetrate into a cluster cavity, it is necessary that the diameter of the ion be commensurate with the size of the cavity. Thus, nature regulates the formation of bioclusters with ions of d-elements of certain sizes.

The most well-known metalloenzymes: carbonic anhydrase, xanthine oxidase, succinate dehydrogenase, cytochromes, rubredoxin. They are bioclusters, the cavities of which form centers for binding substrates with metal ions.

Bioclusters (protein complexes) perform various functions.

Transport protein complexes deliver oxygen and necessary elements to organs. Metal coordination occurs through the oxygen of the carboxyl groups and the nitrogen of the amino groups of the protein. In this case, a stable chelate compound is formed.

D-elements (cobalt, nickel, iron) act as coordinating metals. An example of an iron-containing transport protein complex is transferrin.

Other bioclusters can perform a battery (storage) role - these are iron-containing proteins: hemoglobin, myoglobin, ferritin. They will be considered when describing the properties of group VIIIB.

The elements Zn, Fe, Co, Mo, Cu are vitally important and are part of metalloenzymes. They catalyze reactions that can be divided into three groups:

1. Acid-base interactions. The zinc ion involved is part of the carbonic anhydrase enzyme, which catalyzes the reversible hydration of CO 2 in biosystems.
2. Redox interactions. Fe, Co, Cr, Mo ions are involved. Iron is part of cytochrome, during the process electron transfer occurs:

Fe 3+→ Fe 2++ e -

3.Oxygen transfer. Fe, Cu are involved. Iron is part of hemoglobin, copper is part of hemocyanin. It is assumed that these elements bind to oxygen, but are not oxidized by it.

D-element compounds selectively absorb light of different wavelengths. This leads to the appearance of color. Quantum theory explains the selectivity of absorption by the splitting of d-sublevels of metal ions under the influence of the ligand field.

The following color reactions to d-elements are well known:

Mn 2++S 2-= МnS↓ (flesh-colored sediment)

Нg 2++ 2I -= НgI 2↓(yellow or red precipitate)

TO 2Cr 2ABOUT 7+ N 2SO 4(conc.) = K 2SO 4+ N 2O + 2СrО 3↓

(crystals orange color)

The above reactions are used in analytical chemistry for qualitative determination of the corresponding ions. The equation for the reaction with dichromate shows what happens when preparing a “chromium mixture” for washing chemical dishes. This mixture is necessary to remove both inorganic and organic deposits from the surface of chemical bottles. For example, grease stains that always remain on the glass after touching with your fingers.

It is necessary to pay attention to the fact that d-elements in the body ensure the launch of most biochemical processes that ensure normal life.

General characteristics of d-elements of group VIB

Group VIB consists of elements (transition metals) - chromium, molybdenum and tungsten. These rare metals are found in nature in small quantities. However, thanks to a number of useful chemical and physical properties, are widely used not only in mechanical engineering and chemical technology, but also in medical practice (Cr-Co-Mo alloy is used in surgery and dentistry, molybdenum and its alloys are used as parts of X-ray tubes, anodes of X-ray tubes are made from tungsten, tungsten alloys are the basis screens for protection from γ -rays).

Configuration of valence electrons Cr and Mo - (n-1)d 5ns 1, W - 5d 46s 2. The sum of the valence electrons of chromium, molybdenum, and tungsten is 6, which determines their position in the VIB group. In Cr and Mo, the last electron layer is occupied by 13 electrons, in W - 12. Like most d-elements, this layer is unstable. Therefore, the valency of chromium, molybdenum and tungsten is not constant. For the same reason, compounds of group VIB metals are characterized by a set of oxidation states from +2 to +6.

In the group of d-elements, a general trend appears: with increasing atomic number, the stability of compounds with the highest oxidation state increases. The strongest oxidizing agent in the E state 6+is chrome. "Borderline" Mo 6+exhibits weak oxidizing properties. Molybdenum ion MoO 42-recovers only to Mo 6ABOUT 17(“molybdenum blue”), where some of the molybdenum atoms have an oxidation state of +5. This reaction is used in analytical chemistry for photometric determinations.

In lower valence states, following the same trend, Cr exhibits stronger reducing properties 2+. For Mo ions 2+and W 2+An increase in ionization energy leads to a decrease in reducing and metallic properties.

Complex compounds of this group of elements most often have a coordination number of 6 and hybridization of the sp type 3d 2, which is described in space by an octahedron.

A characteristic feature of compounds of this group is the tendency to polymerize (condensate) oxygen forms of group VI elements. This property intensifies when moving through the group from top to bottom. In this case, type M compounds are formed 6ABOUT 2412-, composed of MoO octahedra 4and W.O. 4. These octahedra form polymer crystals. Chromium (VI) oxide exhibits the ability to polymerize, but weakly. Therefore, molybdenum and tungsten oxides have a higher degree of polymerization.

Based on the structure of the electronic shell of atoms with an unfilled d-orbital, the combination of physical and chemical properties, and the tendency to form electropositive ions and coordination compounds, elements of group VI belong to transition metals.

Chemical properties of chromium compounds. Most chromium compounds have the brightest color different colors. The name comes from the Greek. chromos - color, coloring.

Compounds of trivalent chromium (unlike molybdenum compounds, and for tungsten the +3 oxidation state is not characteristic at all) are chemically inert.

In nature, chromium is found in trivalent form (spinel - double oxide MnСrO 4- magnochromite) and hexavalent state (PbСrO 4- crocoite). Forms oxides of basic, amphoteric and acidic nature.

Chromium (II) oxide CrO - red (red-brown) crystals or black pyrophoric powder, insoluble in water. Corresponds to hydroxide Cr(OH) 2. Hydroxide yellow (wet) or Brown. When heated in air it turns into Cr 2ABOUT 3(Green colour):

Cr(OH) 2+ 0.5О 2= Cr 2O 3+ 2H 2ABOUT

Cation Cr 2+- colorless, its anhydrous salts are white, and its aqueous salts are of blue color. Divalent chromium salts are energetic reducing agents. An aqueous solution of chromium (II) chloride is used in gas analysis to quantitatively absorb oxygen:

2СrСl 2+ 2НgО + 3Н 2O+0.5O 2= 2НgСl 2+ 2Cr(OH) 3↓

(dirty green residue)

Chromium(III) hydroxide has amphoteric properties. Easily goes into a colloidal state. Dissolving in acids and alkalis, it forms aqua or hydroxo complexes:

Cr(OH) 3+ 3H 3ABOUT += [Cr(H 2ABOUT) 6]3+(blue-violet solution)

Cr(OH) 3+ 3OH -= [Cr(OH) 6]3-(emerald green solution)

Compounds of trivalent chromium, like divalent chromium, exhibit reducing properties:

Cr 2(SO 4)z+KSlO 3+ 10KON = 2K 2СrO 4 + 3K 2SO 4 + KCl + 5H 2ABOUT

Chromium(VI) compounds are typically oxygen-containing complexes of chromium. Hexavalent chromium oxide corresponds to chromic acids.

Chromic acids are formed when CrO is dissolved in water 3. These are highly toxic yellow, orange and red solutions with oxidizing properties. CrO 3forms polychromic acids of composition H 2Cr n ABOUT (3n+1) : nCrО 3+ N 2O → N 2Cr n ABOUT (3n+1) . There may be several such connections: N 2CrO 4, N 2Cr 2O 7, N 2

Natural, artificial and synthetic high molecular weight compounds
High molecular weight compounds are those with a high molecular weight, expressed in tens, hundreds of thousands and millions of unit units; Another name for them, now widely used, although less precise, is polymers.
Molecules of high molecular weight compounds that have significantly big sizes than molecules of substances with low molecular weight are therefore called macromolecules. They contain a large number, most often of the same groups of atoms, called elementary units. The units are connected to each other in a certain order by covalent bonds. The number of units in a macromolecule is called the degree of polymerization. For example, in natural high-molecular compounds the elementary units are: in cellulose and starch - glucose residues C6H10O6 (C6H10Ob) or cellulose (where n is the degree of polymerization, here reaching 10-20 thousand in cellulose, and dashes indicate the bonds connecting the units in macromolecule), in natural or natural rubber these are isoprene residues (-CH-C = CH-CH2-)i, where n = 2000-5000, natural rubber CH3, etc.
Some high-molecular compounds have macromolecules containing elementary units of different composition or structure; for example, in proteins - residues of various amino acids.
Characteristic difference The difference between high molecular weight compounds and substances with low molecular weight is that the macromolecules of any of the high molecular weight compounds are not the same, since they contain a different number of elementary units. Consequently, polymers are complex mixtures of so-called polymer homologs, differing from each other in the degree of polymerization, but similar in properties due to the similarity of structure; The molecular weight determined for polymers is therefore only the average molecular weight for all polymer homologs.
Since ancient times, people have used natural high-molecular compounds contained in various products for their needs. Protein and starch in food products formed the basis of the diet of people and domestic animals. Cotton and flax cellulose, proteins - silk fibroin and wool keratin - were used to make fabrics, and leather collagen was used to sew shoes. Dwellings, bridges, etc. were built from wood, consisting of cellulose, hemicelluloses and lignin. In the middle of the 19th century. production of rubber raincoats and shoes made from natural rubber began. At the end of the 19th century. by processing natural polymers - and during the processing process the entire structure of the macromolecule as a whole changes little, and only the transformation of some functional groups occurs - artificial high-molecular compounds begin to be obtained. First of all, cellulose was subjected to such processing into its esters: into trinitrocellulose for the production of smokeless gunpowder; dinitrocellulose for the production of plastics - celluloid, etc.; cellulose acetate for producing acetate silk, plastics; The production of xanthate and the regeneration of cellulose from it are the basis for the production of viscose fiber. An industry of artificial fibers and plastics is being created.
In the 10s of the XX century. For the first time, the production of synthetic high-molecular compounds—synthetic phenol-formaldehyde resins for the production of plastics—appears. Synthetic high-molecular compounds, unlike artificial ones, are obtained not by processing natural ones, but by synthesis from compounds with small molecular weights, in which one macromolecule arises from hundreds or thousands of molecules of the latter. Later in the 30s, under the leadership of S.V. Lebedev, the production of synthetic rubber was created for the first time on a large scale, and in the 40s - the production of synthetic fibers: first nylon, then nylon, etc. last years A large number of different synthetic resins are produced - for the production of plastics and synthetic fibers - and synthetic rubbers. Currently, the global production of synthetic and artificial high-molecular compounds has been greatly developed and its growth rate is several times higher than for the production of non-ferrous (except A1) and ferrous metals, as well as natural polymer products.
In 1959, synthetic and artificial products accounted for 44% of global rubber production, and 19.5% for fibers. The significant increase in the production of synthetic polymers is explained by their valuable properties and the associated rapid increase in the areas of their application, which will be discussed in more detail below.

8. Attracts additional material. 2 points.

9. Goes beyond the scope of the question by providing additional information about the artist and the history of the work. Maximum 4 points.

10. The text has unity and logic of construction. 2 points.

11. Literacy. 2 points. (For each mistake, 1 point is deducted, for an error in the spelling of a name or title - 2 points).

Grade 10

Task of the second type.Option 2

Task 2.2. Consider the painting by B.M. Nemensky, analyzing it, describe it and formulate your reasoning in the form of a literary text.

What I feel?

What do I know?

What I see?

What did the artist want to say?

"Soldier Fathers" B.M. Nemensky.

One of the main themes to which B.M. constantly returns in his work. Nemensky, - the theme of fatherhood: “Insecurity, gullibility, openness of childhood - and the power, right and most difficult duty of a father to decide and answer.” The memory of feelings returns to the first days of the war, when in a frozen city practically wiped off the face of the earth by the retreating fascists, the soldiers found a miraculously surviving girl. She was covered in wrinkles, like an old woman, and couldn’t even cry. “I remember how much care and pain there was in all the soldiers’ actions towards the girl. So much awkward tenderness... and barely restrained hatred: the perpetrators of the disaster were just around the corner,” the artist writes in his memoirs. In the picture real story takes on a symbolic meaning: a soldier is the savior of life, the feelings of a soldier are like the feelings of a father - the desire to protect. Against the backdrop of destroyed stoves and shell craters, a tiny girl surrounded by soldiers, like a light of a saved life in a tight protective ring. The light comes from a small figure, illuminating the faces of the soldiers, it is he who “warms their hearts, gives them strength to continue their mission.”

Analysis of the answer. Grade.

1. The participant conveys the mood of the work. 2 points.

4. The participant correctly reveals the meaning of the work of art. Maximum 4 points.

5. The depth of disclosure of the idea of ​​the work. Maximum 4 points.

6. The participant uses figurative and expressive language to convey the meaning and mood of the work. Maximum 4 points.

7. The answer contains a personal emotional assessment. 2 points.

Maximum score 30 points.

Grade 11

Task of the second type.Option 2.

Task 2.2. Consider the painting by B.M. Nemensky (1945), analyze it and formulate the reasoning in the form of a literary text.

Sample questions for analyzing a work of art:

What I feel?

What impression does the work of art make? What sensation might the viewer experience? How do its scale, format, and use of certain shapes and colors help the emotional impression of a work?

What do I know?

Does the film have a plot? What is shown? In what environment are the depicted characters and objects located? Conclusion about the genre of the work.

What I see?

How are objects arranged in the work (subject composition)? How are colors compared in the work (color composition)? Are there objects in the work that symbolize something? Is the composition of the work and its main elements symbolic in nature?

Who main character works?

Highlight the main thing from what you see. Explain why this seems most important to you? By what means did the artist highlight this?

What did the artist want to say?

What is the title of the work? How does it relate to the plot and symbolism? What do you think the author of the work wanted to convey to people? Are your first impressions of the work and your conclusions the same?

Suggested answer:"Mother" (1945). B.M. Nemensky.

This picture immediately left no one indifferent, neither critics nor viewers, splashing out longing for home, quiet tenderness for the mother and sons separated by the war. A common motif for that time: soldiers sleeping on the floor in a peasant hut. But it sounded new under the brush of the young artist. The desire to paint a picture about ordinary Russian women who motherly greeted soldiers in every village, in every city, the desire to write about their mother, who also cared for Greek artists in her Moscow apartment before or after trips to the front, resulted in an expression of gratitude to the woman -mother, “great gratitude to ordinary Russian women who warmed us with maternal affection, women whose grief and whose services to the Motherland can neither be measured nor rewarded.” It is no coincidence that the author’s features can be discerned in the image of a young soldier, carefully covered with a warm scarf. The painting exhibited at the All-Union Exhibition immediately became famous and was acquired by the Tretyakov Gallery.

For reference. Works by B.M. Nemensky are paintings-thoughts filled with polyphonic content. The process of creating them is always long, but this does not mean that the canvas itself takes a long time to paint; the artist strives to “paint quickly, in one breath.” It is the process that is complex and sometimes painful - from the inception of an idea to its maturation: numerous sketches, sketches, sketches, doubts.

Analysis of the answer. Grade.

1. The participant conveys the mood of the work. 2 points.

2. The participant names the genre of work. 2 points.

3. The participant analyzes the composition of the work. 2 points.

4. The participant correctly reveals the meaning of the work of art. Maximum 4 points.

5. The depth of disclosure of the idea of ​​the work. Maximum 4 points.

6. The participant uses figurative and expressive language to convey the meaning and mood of the work. Maximum 4 points.

7. The answer contains a personal emotional assessment. 2 points.

8. Attracts additional material. 2 points for each extension. Maximum 4 points.

9. Goes beyond the scope of the question by providing additional information about the artist and the history of the work. Maximum 4 points.

10. Literacy. 2 points. (For each mistake, 1 point is deducted, for an error in the spelling of a name or title - 2 points).

Maximum score 30 points.

Third type tasks

9th grade

Task of the third type.Option 1

Task 3.1.

3. What part of the composition does the presented fragment occupy?

4. Describe the general composition of the work and indicate the number of figures depicted on it, name significant memorable details.

5. Formulate and write down the theme and idea of ​​the work.

6. Indicate famous works by the same artist.

“Bogatyrs” V.M. Vasnetsov, author of “Alyonushka”, “Ivan Tsarevich on the Gray Wolf”. The canvas depicts the three most famous epic heroes - Dobrynya Nikitich, Ilya Muromets and Alyosha Popovich on patrol. The fragment represents the left side of the canvas - Dobrynya Nikitich on a white horse. He takes the sword out of its sheath. In the middle, on a black horse, is depicted the most powerful of them, Ilya Muromets. He looks into the distance from under his palm, holding a spear in one hand and a damask club in the other. On the right, on a bay horse, Alyosha Popovich holds a bow and arrows in his hands. Compared to his comrades, he is young and slender. Alyosha Popovich has a harp on his side. Three heroes stand on a wide plain, turning into low hills, in the middle of withered grass and occasionally peeking out small fir trees. The sky is cloudy and alarming. The work conveys the idea that Rus' has reliable defenders.

Analysis of the answer. Grade.

The participant correctly identifies the artist's name. 2 points.

2. The participant correctly determines the name of the painting 2 points.

3. Correctly determines the place of the fragment in the composition. 2 points.

4. Correctly names 12 other objects and their compositional position. Maximum 12 points for this part of the task.

5. Describes the general composition of the work. 2 points.

6. Correctly indicates the number of figures. 2 points.

7. Names the theme of the work. 2 points.

8. Reveals the idea of ​​the work. 2 points.

9. Presents the answer competently and coherently. 2 points.

10. Goes beyond the question and conveys the mood of the picture, its semantic load. 2 points.

Maximum score 30 points.

The maximum score for the third type of task is 30 points.

Grade 10

Task of the third type.Option 1

Task 3.1.Identify works by fragment:

1. Write the titles of three works.

3. Write by what characteristic features of the writing style you recognize the author.

4. Write general artistic characteristics of the three submitted works.

5. Indicate famous works by the same artist.

6. Indicate the time when the artist worked.

7. Name the features characteristic of this period of development of art.

Suggested answer.

Fragments of works by M. Vrubel “Demon”, “Pan”, “Portrait of Savva Mamontov” are presented. Vrubel’s artistic style is recognizable by the large and bold strokes characteristic of this artist, with which he conveys the volume and texture of what is depicted, as well as a rather dark coloring. Both features can be read in all three works. The artist's creativity is associated with late XIX century, which is characterized by a mood of premonition of the end of the world and the search for new means of representation. Other famous works of Vrubel are “The Swan Princess”, “Lilac”, “Fortune Teller”, “Pearl”, “Princess Dream”.

Analysis of the answer. Grade.

2. Indicates the exact title of each work - 2 points (for an inaccurate title 1 point is awarded) = 6 points.

3. Correctly points out 2 features of writing style - 2 points for each = 4 points.

4. Correctly finds the named features in the presented three works – 2 points.

5. Additionally indicates the function of one of the traits – 2 points.

6. Correctly indicates the artist’s creative time – 2 points.

7. Correctly points out two features characteristic of this period in the development of art - 2 points for each = 4 points.

8. Correctly names a famous work by an artist – 2 points.

9. Competently prepares the work – 2 points.

A comment: Already in the task of the school stage, the participant can demonstrate higher awareness than provided by the program and receive a higher score.

Grade 11

Task of the third type.Option 1

Task 3.1.Identify the artistic canvas by fragment:

1. Write what is shown on it.

3.What part of the composition does the presented fragment occupy?

4.Describe the general composition of the work and indicate the number of figures depicted on it.

5.Name significant, memorable details.

6.Name the main genre in which the artist worked.

7.Indicate famous works by the same artist.

Suggested answer.

A fragment of the famous work by Valentin Serov “Girl with Peaches” is the foreground of the painting (var. ill. 1), which depicts a girl in a soft pink blouse, contrasting with her dark skin color, sitting at a table covered with a white tablecloth, on which she lies knife and peaches without any utensils, directly on the leaves, which creates the impression of freshness and cleanliness, reinforced sunlight from the window behind the girl. One of the peaches is in the hands of a girl, which makes the viewer remember the velvety feeling when touching the surface of this fruit. Other famous works by the master include “The Rape of Europa”, “Portrait of M.N. Ermolova”, “Portrait of Chaliapin”. Serov was a brilliant portrait painter.

Analysis of the answer. Grade.

1. The participant correctly identifies the artist’s name. 2 points.

2. The participant correctly determines the name of the painting 2 points.

3. Correctly determines the place of the fragment in the composition. 2 points.

4. Correctly names the details, their compositional meaning and position. Maximum 8 points for this part of the task.

5. Describes the general composition of the work. 2 points.

6. Correctly indicates the number of figures. 2 points.

7. Names the main genre in which the artist works. 2 points.

8.Names 3 famous works of the artist. 2 points for each = 6 points.

9. Presents the answer competently and coherently. 2 points.

10. Goes beyond the question and gives an analysis of the composition of the painting. 2 points.

Maximum score 30 points.

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Tasks of the fourth type

9th grade

Task of the fourth type.Option 1

Task 4.1. What or who is ODD in the row? Underline the extra word, write it in the table and briefly explain your choice.

1. Aeschylus, Sophocles, Euripides, Aristophanes.

2. Iambic, sonnet, amphibrachium, trochee, anapest.

3. Painting, graphics, sculpture, music, architecture.

4. Hieroglyph, letter, rune, graphic, number.

5. Filigree, stained glass, batik, mosaic, landscape.

6. Frock coat, boots, toga, tunic, chiton.

Answer:

Analysis of the answer. Grade.

1. The participant correctly identifies 6 names and concepts. One point for each correct selection. 6 points.

2. The participant correctly justifies the choice. 2 points for each correct justification. 12 points.

3. The participant writes out the answer correctly and accurately. 2 points.

Grade 10

Task of the fourth type.Option 1

Task 4.1. What or who is ODD in the row? Underline the extra word, write it in the table and briefly explain your choice.

1. Classicism, romanticism, psychologism, modernism, sentimentalism.

2. Five-domed, single-domed, bulbous and helmet-shaped domes, spire, tent.

3. Vivaldi, Bach, Haydn, Verdi, Mozart, Handel.

4. Schena, orchestra, buskins, protagonist, spotlights.

5. “The Marriage of Figaro”, “The Barber of Seville”, “Don Juan”, “The Magic Flute”.

Answer:

Analysis of the answer. Grade.

1. The participant correctly identifies 5 names and concepts. Two points for each correct selection. 10 points.

2. The participant correctly justifies the choice. 2 points for each justification 10 points.

Maximum score 20 points.

Grade 11

Task of the fourth type.Option 2

Task 4.1. Match the concept with its definition. Insert the appropriate letters into the table. Define the remaining concepts.

1 - Adagio. 2 - High relief. 3 - Life. 4 - Impasto. 5 - Buttress. 6 - Metaphor. 7 - Performance. 8 - Plein air. 9 - Syncope. 10 - Eclecticism.

A. a shift in rhythmic support in music from a strong beat to a weak beat, that is, a discrepancy between the rhythmic and metric accents.

B. a thick, rich application of paints, often used in oil painting, especially to enhance the light effect.

IN. additional support that takes on the weight of the floor. A vertical support inside or outside a building.

G. slow pace; a piece of music or part of it performed at this tempo is usually one of the middle movements of a symphony, quartet, sonata, etc.

D. painting technique images of objects in natural light and in natural conditions.

E. a genre of church literature that describes the lives and deeds of saints.

AND. a type of artistic trope (Greek tropos - “turnaround”), one of the methods of artistic formation, which consists in bringing together and connecting individual images that are not interconnected in real life into a whole.

Z. a form of modern art in which the work is composed of the actions of an artist or group in a specific place and time.

AND. artificial combination of elements of content and form that have different origins.

Answer:

Response analysis, evaluation.

1. The participant correctly correlates 9 concepts with definitions. 2 points for each correct correlation. 18 points.

2. The participant gives the correct definition of the remaining concept. 2 points.

Maximum score 20 points.

The maximum score for the first round is 124 points.

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SAMPLE SUBJECTS OF THE SECOND ROUND TASKS

9th grade

1. Present in the form of a presentation a plan for a television broadcast dedicated to the 115th anniversary of the State Russian Museum (opened to visitors in 1898). Suggest how you can popularize information about his collection using reproductions in the urban environment.

2. Present in the form of a presentation the scenario of the evening dedicated to the 200th anniversary of the birth of A. S. Dargomyzhsky (1813-1869). Determine the scale of the event: whether this evening will be school or citywide.

3. Present in the form of a presentation the concept of an exhibition dedicated to the 135th anniversary of the birth of B. Kustodiev (1878-1927). Suggest how we can popularize information about his works using reproductions in the urban environment.

4. Present in the form of a presentation the program of the evening concert dedicated to the 140th anniversary of the birth of S.V. Rachmaninov. Use audio files. Suggest how you can popularize information about his works using reproductions and audio files in the urban environment.

Grade 10

Present in the form of a presentation a plan for a museum exhibition dedicated to the first printed books:

To the 450th anniversary of the first Russian printing house of Ivan Fedorov and Pyotr Mstislavets in Moscow (1563);

To the 435th anniversary of Ivan Fedorov’s “ABC” (1578) - the first book for worldly purposes (Russian primer “ABC”);

To the 310th anniversary of “Arithmetic” by Leonty Magnitsky, who first replaced letters with Arabic numerals (1703);

To the 50th anniversary of the State Public Historical Library in Moscow (1863).

Reveal the main stages in the history of book illustration. Suggest how you can popularize the information you collected using reproductions in the urban environment.

Present in presentation form architectural features the first buildings in which the Russian Academy of Sciences was located:

To the 230th anniversary of its establishment Russian Academy (1783);

To the 270th anniversary of the birth of Princess Ekaterina Romanovna Dashkova (1743-1810).

Suggest how you can popularize the information you collected using reproductions in the urban environment.

7. Present in the form of a presentation the plan of the exhibition dedicated to the 165th anniversary of the birth of V.I. Surikov (1848-1916). Explain the selection of paintings and the logic behind their arrangement. Suggest how you can popularize information about his life and work using reproductions in the urban environment.

8. Make a slide film (presentation) about F.I. Chaliapin (on the 140th anniversary of his birth). Suggest how you can popularize information about his works using reproductions and audio files in the urban environment.

9. Present in the form of a presentation a plan for an excursion around the Mikhailovskoye Nature Reserve. Tell us about the gardening culture and the nature of the buildings (for the 110th anniversary of the birth of S.S. Geichenko). Suggest how you can popularize the information you collected using reproductions in the urban environment.

Grade 11

10. Present in the form of a presentation material on the history of the creation and the first years of activity of the Moscow Art Theater. Reveal the artistic principles that distinguish the new theater from others (for the 150th anniversary of the birth of K.S. Stanislavsky). Suggest how you can popularize the information you have collected using reproductions, film clips and audio files in the urban environment.

11. Present in presentation form television program, dedicated to the Maly Theater:

To the 190th anniversary of the birth of A.N. Ostrovsky (1823-1886);

To the 85th anniversary of the birth of Elina Bystritskaya (1928).

Suggest how you can popularize the information you have collected using reproductions, film clips and audio files in the urban environment.

12. Compose and present in the form of a presentation a quiz on the history of Russian theater. Think over and imagine the form of its implementation on the scale of your settlement and the method for determining the winners.

13. Present in the form of a presentation a story about the activities of S.M. Eisenstein (1898-1948) (on the 115th anniversary of his birth). Conclude the presentation with a quiz based on its materials. Suggest how you can popularize the information you have collected using reproductions, film clips and audio files in the urban environment.

14. Present in the form of a presentation a story about artistic originality creativity of A.A. Plastova (1893-1972) (on the 120th anniversary of his birth). End your presentation with creative assignments. Suggest how you can popularize the information you collected using reproductions in the urban environment.

Evaluation criteria for the second round (homework)

Ability to formulate the topic, problem and purpose of the statement – ​​4 points.

2. Knowledge of the history of the issue, the use of cultural and art history material - 4 points for each quote or presentation of the point of view of an art critic or historian (no more than 16 points).

3. Reasonably attracted illustrations – 1 point for each (no more than 18 points);

4. Originality of approach to structuring the material – 2 points.

5. Meaningful and logical use of illustrative material – 2 points.

6. Competent speech – 2 points.

7. Convincing presentation – 2 points.

8. Clarity of presentation – 2 points.

9. Freedom of presentation – 2 points.

10. Independence of development – ​​2 points.

11. Ability to understand questions asked, find answers, lead a discussion 4 points.

12. Strong-willed qualities (readiness for dialogue, goodwill, contact) 4 points.

Tasks Document

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Transition d-elements and their connections are widely used in laboratory practice, industry and technology. They also play an important role in biological systems. In the previous section and sect. 10.2 it was already mentioned that ions of d-elements such as iron, chromium and manganese play an important role in redox titrations and other laboratory techniques. Here we will only touch on the applications of these metals in industry and technology, as well as their role in biological processes.

Applications as structural materials. Iron alloys

Some d-elements are widely used in structural materials, mainly in the form of alloys. An alloy is a mixture (or solution) of a metal with one or more other elements.

Alloys whose main constituent is iron are called steels. We have already said above that all steels are divided into two types: carbon and alloy.

Carbon steels. Based on carbon content, these steels are in turn divided into low-carbon, medium-carbon and high-carbon steels. The hardness of carbon steels increases with increasing carbon content. For example, low carbon steel is malleable and malleable. It is used in cases where mechanical load is not critical. The various uses of carbon steels are listed in Table. 14.10. Carbon steels account for up to 90% of total steel production.

Alloy steels. Such steels contain up to 50% admixture of one or more metals, most often aluminum, chromium, cobalt, molybdenum, nickel, titanium, tungsten and vanadium.

Stainless steels contain chromium and nickel as iron impurities. These impurities increase the hardness of the steel and make it resistant to corrosion. The latter property is due to the formation of a thin layer of chromium (III) oxide on the surface of the steel.

Tool steels are divided into tungsten and manganese. The addition of these metals increases hardness, strength and resistance to

Table 14.10. Carbon steels

high temperatures (heat resistance) of steel. Such steels are used for drilling wells, making cutting edges of metalworking tools and those machine parts that are subject to high mechanical loads.

Silicon steels are used for the manufacture of various electrical equipment: motors, electric generators and transformers.

Other alloys

In addition to iron alloys, there are also alloys based on other d-metals.

Titanium alloys. Titanium can be easily alloyed with metals such as tin, aluminum, nickel and cobalt. Titanium alloys are characterized by lightness, corrosion resistance and strength at high temperatures. They are used in the aircraft industry to make turbine blades in turbojet engines. They are also used in the medical industry to make electronic devices implanted into a patient's chest wall to normalize abnormal heart rhythms.

Nickel alloys. One of the most important nickel alloys is Monel. This alloy contains 65% nickel, 32% copper and small amounts of iron and manganese. It is used to make refrigerator condenser tubes, propeller axles, and in the chemical, food, and pharmaceutical industries. Another important nickel alloy is nichrome. This alloy contains 60% nickel, 15% chromium and 25% iron. An alloy of aluminum, cobalt and nickel called alnico is used to make very strong permanent magnets.

Copper alloys. Copper is used to make a wide variety of alloys. The most important of them are listed in table. 14.11.

Table 14.11. Copper alloys

Industrial catalysts

d-Elements and their compounds are found wide application as industrial catalysts. The examples below apply only to the d-elements of the first transition row.

Titanium chloride. This compound is used as a catalyst for the polymerization of alkenes using the Ziegler method (see Chapter 20):

Oxide. This catalyst is used in the next stage of the contact process for the production of sulfuric acid (see Chapter 7):

Iron or oxide. These catalysts are used in the Haber process for the synthesis of ammonia (see Chapter 7):

Nickel. This catalyst is used for curing vegetable oils in the hydrogenation process, for example in the production of margarine:

Copper or copper(II) oxide. These catalysts are used to dehydrogenate ethanol to produce ethanal (acetic aldehyde):

Rhodium (an element of the second transition series) and platinum (an element of the third transition series) are also used as industrial catalysts. Both are used, for example, in the Ostwald process for producing nitric acid (see Chapter 15).

Pigments

We have already mentioned that one of the most important distinctive features d-elements is their ability to form colored compounds. For example, the coloring of many precious stones due to the presence in them of a small amount of d-metal impurities (see Table 14.6). Oxides of d-elements are used to make colored glasses. For example, cobalt (II) oxide gives glass a dark blue color. A number of d-metal compounds are used in various industries industry as pigments.

Titanium oxide. World production of titanium oxide exceeds 2 million tons per year. It is mainly used as a white pigment in the paint industry and also in the paper, polymer and textile industries.

Chromium compounds. Chromium alum (chromium sulfate dodecahydrate) has a violet color. They are used for dyeing in the textile industry. Chromium oxide is used as a green pigment. Pigments such as chrome green, chrome yellow and chrome red are made from lead (IV) chromate.

Potassium hexacyanoferrate(III). This compound is used in dyeing, etching and for the manufacture of blueprint paper.

Cobalt compounds. Cobalt blue pigment consists of cobalt aluminate. Purple and violet cobalt pigments are produced by precipitating cobalt salts with alkaline earth phosphates.

Other industrial applications

So far we have looked at the applications of α-elements as structural alloys, industrial catalysts and pigments. These elements also have many other uses.

Chromium is used to apply a chrome coating to steel objects, such as car parts.

Cast iron. This is not an alloy, but crude iron. It is used to make a variety of items, such as frying pans, manhole covers and gas stoves.

Cobalt. The isotope is used as a source of gamma radiation for the treatment of cancer.

Copper is widely used in the electrical industry to make wire, cables and other conductors. It is also used to make copper sewer pipes.

d-Elements in biological systems

d-Elements play an important role in many biological systems. For example, the adult human body contains about 4 g of iron. About two-thirds of this amount comes from hemoglobin, the red pigment in blood (see Fig. 14.11). Iron is also part of the muscle protein myoglobin and, in addition, accumulates in organs such as the liver.

Elements found in biological systems in very small quantities are called trace elements. In table 14.12 shows the mass of various minerals

Table 14.12. Average content of macro- and microelements in the adult human body

Manganese is an essential component of poultry food.

Micronutrients that play a vital role in the healthy growth of crop plants include many d-metals.

elements and some microelements in the adult body. It should be noted that five of these elements belong to the d-metals of the first transition rad. These and other d-metal trace elements perform a variety of important functions in biological systems.

Chromium takes part in the process of glucose absorption in the human body.

Manganese is a component of various enzymes. It is necessary for plants and is an essential component of bird food, although it is not so important for sheep and cattle. Manganese has also been found in the human body, but it has not yet been established how necessary it is for us. A lot of manganese is found in. Good sources of this element are nuts, spices and cereals.

Cobalt is essential for sheep, cattle and humans. It is found, for example, in the vitamin This vitamin is used to treat pernicious anemia; it is also necessary for the formation of DNA and RNA (see Chapter 20).

Nickel has been found in the tissues of the human body, but its role has not yet been established.

Copper is an important component of a number of enzymes and is necessary for the synthesis of hemoglobin. Plants need it, and sheep and large cattle are especially sensitive to copper deficiency in the diet. With a lack of copper in the food of sheep, lambs appear with congenital deformities, in particular paralysis of the hind limbs. In the human diet, the only food that contains significant amounts of copper is liver. Small amounts of copper are found in seafood, legumes, dried fruits and cereals.

Zinc is part of a number of enzymes. It is necessary for the production of insulin and is an integral part of the enzyme anhydrase, which plays an important role in the process of respiration.

Diseases associated with cynic deficiency

In the early 1960s. Dr. A. S. Prasad discovered in Iran and India a disease associated with zinc deficiency in food, which manifests itself in slow growth of children and anemia. Since then, dietary zinc deficiency has been considered main reason stunted development of children suffering from severe malnutrition. Zinc is necessary for the action of T-lymphocytes, without which the immune system The human body cannot fight infections.

Zinc preparations help with severe metal poisoning, as well as with some hereditary diseases, for example in sickle cell anemia. Sickle cell anemia is a congenital defect of red blood cells found in indigenous populations of Africa. In people with sickle cell anemia, the red blood cells have an abnormal (sickle) shape and are therefore unable to carry oxygen. This occurs due to the oversaturation of red blood cells with calcium, which changes the distribution of charges on the cell surface. Adding zinc to the diet causes the zinc to compete with calcium and reduce the abnormal cell membrane shape.

Zinc supplements also help in the treatment of anorexia (loss of appetite) caused by disorders of the nervous system.

So let's say it again!

1. The most common element on Earth is iron, followed by titanium.

2. d-Elements are found as trace elements in plants, animals, and precious stones.

3. For industrial production iron two ores are used: hematite and magnetite

4. Iron is produced in a blast furnace by reducing iron ore with carbon monoxide. To remove impurities in the form of slag, limestone is added to the ore.

5. Carbon steels are produced mainly using the oxygen converter process (Linz-Donawitz process).

6. An electric melting furnace is used to produce high-quality alloy steels.

7. Titanium is obtained from ilmenite ore using the Croll process. In this case, the oxide contained in the ore is first converted into

8. Nickel is obtained from pentlandite ore. The nickel sulfide it contains is first converted into an oxide which is then reduced with carbon (coke) to metallic nickel.

9. To obtain copper, chalcopyrite ore (copper pyrite) is used. The sulfide contained in it is reduced by heating under conditions of limited air access.

10. An alloy is a mixture (or solution) of a metal with one or more other elements.

11. Steels are alloys of iron, which is their main component.

12. The higher the carbon content in them, the greater the hardness of carbon steels.

13. Stainless steel, tool steel and silicon steel are types of alloy steels.

14. Alloys of titanium and nickel are widely used in technology. Copper alloys are used to make coins.

15. Chloride oxide is nickel oxide and is used as industrial catalysts.

16. Metal oxides are used to make colored glasses, other metal compounds are used as pigments.

17. d-Metals play an important role in biological systems. For example, hemoglobin, which is the red pigment in blood, contains iron.

The d-block includes 32 elements of the periodic table. d-Elements are included in the 4th--7th major periods. Group IIIB atoms have the first electron in the d-orbital. In subsequent B-groups, the d-sublevel is filled with up to 10 electrons (hence the name d-elements). The structure of the outer electron shells of the d-block atoms is described by the general formula (n-1)d a ns b, where a = 1--10, b = 1--2.

A feature of the elements of these periods is a disproportionately slow increase in atomic radius with increasing number of electrons. This relatively slow change in radii is explained by the so-called lanthanide compression due to the penetration of ns electrons under the d electron layer. As a result, there is a slight change in the atomic and chemical properties of d-elements with increasing atomic number. The similarity of chemical properties is manifested in the characteristic feature of d-elements to form complex compounds with a variety of ligands.

An important property of d-elements is variable valence and, accordingly, a variety of oxidation states. This feature is associated mainly with the incompleteness of the pre-outer d-electron layer (except for elements of the IB and IIB groups). The possibility of the existence of d-elements in different oxidation states determines a wide range of redox properties of the elements. In lower oxidation states, d-elements exhibit the properties of metals. With an increase in the atomic number in groups B, the metallic properties naturally decrease.

In solutions, oxygen-containing anions of d-elements with the highest oxidation state exhibit acidic and oxidizing properties. Cationic forms of lower oxidation states are characterized by basic and reducing properties.

d-elements in intermediate oxidation states exhibit amphoteric properties. These patterns can be considered using the example of molybdenum compounds:

With a change in properties, the color of molybdenum complexes in different oxidation states (VI - II) changes:

In the period with increasing nuclear charge, a decrease in the stability of compounds of elements in higher oxidation states is observed. In parallel, the redox potentials of these compounds increase. The greatest oxidizing ability is observed in ferrate ions and permanganate ions. It should be noted that in d-elements, as the relative electronegativity increases, the acidic and nonmetallic properties increase.

As the stability of compounds increases when moving from top to bottom in B-groups, their oxidizing properties simultaneously decrease.

It can be assumed that during biological evolution, compounds of elements in intermediate oxidation states, which are characterized by mild redox properties, were selected. The advantages of such selection are obvious: they contribute to the smooth flow of biochemical reactions. A decrease in the RH potential creates the prerequisites for a more subtle “regulation” of biological processes, which ensures a gain in energy. The functioning of the body becomes less energy-intensive, and therefore more economical in food consumption.

From the point of view of evolution, the existence of d-elements in lower oxidation states becomes justified for the organism. It is known that Mn 2+, Fe 2+, Co 2+ ions under physiological conditions are not strong reducing agents, and Cu 2+ and Fe 2+ ions practically do not exhibit reducing properties in the body. An additional decrease in reactivity occurs when these ions interact with bioorganic ligands.

The above may seem to contradict the important role of bioorganic molybdenum(V) and (VI) complexes in various organisms. However, this is also consistent with the general pattern. Despite the high degree of oxidation, such compounds exhibit weak oxidizing properties.

It is necessary to note the high complexing abilities of d-elements, which are usually significantly higher than those of s- and p-elements. This is primarily explained by the ability of d-elements to be both donors and acceptors of a pair of electrons forming a coordination compound.

In the case of the chromium hydroxo complex [Cr(OH) 6 ], the 3-metal ion is an acceptor of a pair of electrons. Hybridization of the 3d 2 4sp 3 orbitals of chromium provides a more stable energy state than when the chromium electrons are located in the orbitals of hydroxo groups.

The compound [CrCl 4 ] 2- is formed, on the contrary, as a result of the fact that the unshared d-electrons of the metal occupy the free d-orbitals of the ligands, since in this case the energy of these orbitals is lower.

The properties of the Cr 3+ cation show the variability of the coordination numbers of d-elements. Most often, these are even numbers from 4 to 8; numbers 10 and 12 are less common. It should be noted that there are not only mononuclear complexes. Numerous di-, tri- and tetra-nuclear coordination compounds of d-elements are known.

An example is the binuclear cobalt complex [Co 2 (NH 3) 10 (O 2)] (NO 3) 5, which can serve as a model of an oxygen carrier.

More than 1/3 of all microelements in the body are d-elements. In organisms they exist in the form of complex compounds or hydrated ions with an average hydration shell exchange time of 10 -1 to 10 -10 s. Therefore, it can be argued that “free” metal ions do not exist in the body: they are either their hydrates or hydrolysis products.

In biochemical reactions, d-elements most often manifest themselves as complexing metals. The ligands in this case are biologically active substances, usually of an organic nature or anions of inorganic acids.

Protein molecules form bioinorganic complexes with d-elements - clusters or bioclusters. The metal ion (metal complex-forming agent) is located inside the cluster cavity, interacting with the electronegative atoms of the binding groups of the protein: hydroxyl (--OH), sulfhydryl (--SH), carboxyl (--COOH) and amino groups of proteins (H 2 N - ). For a metal ion to penetrate into a cluster cavity, it is necessary that the diameter of the ion be commensurate with the size of the cavity. Thus, nature regulates the formation of bioclusters with ions of d-elements of certain sizes.

The most well-known metalloenzymes: carbonic anhydrase, xanthine oxidase, succinate dehydrogenase, cytochromes, rubredoxin. They are bioclusters, the cavities of which form centers for binding substrates with metal ions.

Bioclusters (protein complexes) perform various functions.

Transport protein complexes deliver oxygen and necessary elements to organs. Metal coordination occurs through the oxygen of the carboxyl groups and the nitrogen of the amino groups of the protein. In this case, a stable chelate compound is formed.

D-elements (cobalt, nickel, iron) act as coordinating metals. An example of an iron-containing transport protein complex is transferrin.

Other bioclusters can perform a battery (storage) role - these are iron-containing proteins: hemoglobin, myoglobin, ferritin. They will be considered when describing the properties of group VIIIB.

The elements Zn, Fe, Co, Mo, Cu are vitally important and are part of metalloenzymes. They catalyze reactions that can be divided into three groups:

Acid-base interactions. The zinc ion involved is part of the carbonic anhydrase enzyme, which catalyzes the reversible hydration of CO 2 in biological systems.

Redox interactions. Fe, Co, Cr, Mo ions are involved. Iron is part of cytochrome, during the process electron transfer occurs:

Fe 3+ > Fe 2+ + e -

3. Oxygen transfer. Fe, Cu are involved. Iron is part of hemoglobin, copper is part of hemocyanin. It is assumed that these elements bind to oxygen, but are not oxidized by it.

D-element compounds selectively absorb light of different wavelengths. This leads to the appearance of color. Quantum theory explains the selectivity of absorption by the splitting of d-sublevels of metal ions under the influence of the ligand field.

The following color reactions to d-elements are well known:

Mn 2+ + S 2- = MnSv (flesh-colored sediment)

Нg 2+ + 2I - = НgI 2 v (yellow or red precipitate)

K 2 Cr 2 O 7 + H 2 SO 4 (conc.) = K 2 SO 4 + H 2 O + 2CrO 3 v

(orange crystals)

The above reactions are used in analytical chemistry for the qualitative determination of the corresponding ions. The equation for the reaction with dichromate shows what happens when preparing a “chromium mixture” for washing chemical dishes. This mixture is necessary to remove both inorganic and organic deposits from the surface of chemical bottles. For example, grease stains that always remain on the glass after touching with your fingers.

It is necessary to pay attention to the fact that d-elements in the body ensure the launch of most biochemical processes that ensure normal life.