Metals that do not react with zinc. Zinc metal

State educational institution

secondary vocational education in the Leningrad region Podporozhye Polytechnic College

Research work in chemistry

Subject:

"Zinc and its properties"

Completed by: student of group No. 89

Full Name: Yurikov Alexey Alexandrovich

Checked by the teacher: Yadykina Lyudmila Alekseevna

Podporozhye

1. Position in the periodic table and atomic structure

2. History of discovery

3. Being in nature

4. Physical properties

5. Chemical properties

6. Obtaining metallic zinc

7. Application and significance for human health

8. My research

9. Literature

Position in the periodic table

and atomic structure

Element zinc (Zn) in the periodic table has a serial number 30.

He is in the fourth period of the second group.

atomic weight = 65.37

valency II

Natural zinc consists of a mixture of five stable nuclides: 64Zn (48.6% by weight), 66Zn (27.9%), 67Zn (4.1%), 68Zn (18.8%) and 70Zn (0.6%) .

Configuration of two outer electronic layers 3 s 2 p 6 d 10 4 s 2 .

History of discovery

Alloys of zinc and copper - brass - were known to the ancient Greeks and Egyptians. Zinc was obtained in the 5th century. BC e. in India. Roman historian Strabo in 60-20 BC. e. wrote about obtaining metallic zinc, or “fake silver.” Subsequently, the secret of obtaining zinc in Europe was lost, since the zinc formed during the thermal reduction of zinc ores turns into steam at 900°C. Zinc vapor reacts with oxygen in the air, forming loose zinc oxide, which alchemists called “white wool.”

Metal zinc

In the 16th century, the first attempts were made to smelt zinc in factories. But production did not go well; technological difficulties turned out to be insurmountable. They tried to obtain zinc in the same way as other metals. The ore was roasted, turning the zinc into oxide, then this oxide was reduced with coal...

Zinc, naturally, was reduced by interacting with coal, but... was not smelted. It was not smelted because this metal had already evaporated in the melting furnace - its boiling point was only 906° C. And there was air in the furnace. When they met it, active zinc vapors reacted with oxygen, and the original product, zinc oxide, was again formed.

It was possible to establish zinc production in Europe only after the ore began to be reduced in closed retorts without access to air. “Rough” zinc is obtained today in approximately the same way, and it is purified by refining. About half of the world's zinc is now produced by pyrometallurgical methods, and the other half by hydrometallurgical methods.

It should be borne in mind that pure zinc ores are almost never found in nature. Zinc compounds (usually 1-5% in terms of metal) are part of polymetallic ores. The zinc concentrates obtained during ore enrichment contain 48-65% zinc, up to 2% copper, up to 2% lead, and up to 12% iron. And plus a fraction of a percent of trace and rare metals...

The complex chemical and mineralogical composition of zinc-containing ores was one of the reasons why zinc production took a long and difficult time. There are still unsolved problems in the processing of polymetallic ores... But let’s return to the pyrometallurgy of zinc - in this process the purely individual characteristics of this element are manifested.

With sudden cooling, zinc vapor immediately, bypassing the liquid state, turns into solid dust. This complicates production somewhat, although elemental zinc is considered non-toxic. It is often necessary to preserve zinc in the form of dust, rather than melt it into ingots.

In pyrotechnics, zinc dust is used to produce a blue flame. Zinc dust is used in the production of rare and precious metals. In particular, such zinc displaces gold and silver from cyanide solutions. Paradoxically, when obtaining zinc (and cadmium) itself by a hydrometallurgical method, zinc dust is used to purify a solution of copper and cadmium sulfate. But that is not all. Have you ever wondered why metal bridges, factory floor spans and other large metal products are most often painted gray?

The main component of the paint used in all these cases is the same zinc dust. Mixed with zinc oxide and linseed oil, it turns into a paint that provides excellent corrosion protection. This paint is also cheap, flexible, adheres well to the metal surface and does not peel off due to temperature changes. The mouse color is more of an advantage than a disadvantage. Products that are coated with such paint must be unmarked and at the same time neat.

The properties of zinc are greatly affected by the degree of its purity. At 99.9 and 99.99% purity, zinc is highly soluble in acids. But it’s worth “adding” another nine (99.999%), and zinc becomes insoluble in acids even with strong heating. Zinc of such purity is also distinguished by its great ductility; it can be drawn into thin threads. But ordinary zinc can be rolled into thin sheets only by heating it to 100-150° C. Heated to 250° C and above, up to the melting point, zinc again becomes brittle - another restructuring of its crystalline structure occurs.

Zinc sheets are widely used in the production of galvanic cells. The first “voltaic column” consisted of circles of zinc and copper. And in modern chemical current sources, the negative electrode is most often made of zinc.

The role of this element in printing is significant. Zinc is used to make clichés that allow drawings and photographs to be reproduced in print. Specially prepared and processed printing zinc perceives a photographic image. This image is protected with paint in the right places, and the future cliche is etched with acid. The image acquires relief, experienced engravers clean it up, make impressions, and then these cliches go to printing machines.

There are special requirements for printing zinc: first of all, it must have a fine-crystalline structure, especially on the surface of the ingot. Therefore, zinc intended for printing is always cast in closed molds. To “level” the structure, annealing at 375°C is used, followed by slow cooling and hot rolling. The presence of impurities in such a metal, especially lead, is also strictly limited. If there is a lot of it, then it will be impossible to erase the clichés as needed. If the lead content is less than 0.4%, then it is difficult to obtain the desired fine-crystalline structure. It is along this edge that metallurgists “walk”, trying to satisfy the needs of the printing industry.

Being in nature

In nature, zinc is found only in the form of compounds.

SPHALERITE(zinc blende, ZnS) has the appearance of cubic yellow or brown crystals; density 3.9-4.2 g/cm 3, hardness 3-4 on the Mohs scale. Contains cadmium, indium, gallium, manganese, mercury, germanium, iron, copper, tin, and lead as impurities.

In the sphalerite crystal lattice, zinc atoms alternate with sulfur atoms and vice versa. Sulfur atoms in the lattice form a cubic packing. The zinc atom is located in these tetrahedral voids.

WURTZITE(ZnS) is a brown-black hexagonal crystal with a density of 3.98 g/cm 3 and a hardness of 3.5-4 on the Mohs scale. Usually contains more zinc than sphalerite. In the wurtzite lattice, each zinc atom is tetrahedrally surrounded by four sulfur atoms and vice versa. The arrangement of wurtzite layers differs from the arrangement of sphalerite layers.

SMITHSONITE(zinc spar, ZnCO 3) occurs in the form of white (green, gray, brown depending on impurities) trigonal crystals with a density of 4.3-4.5 g/cm 3 and a hardness of 5 on the Mohs scale.

CALAMINA(Zn 2 SiO 4 *H 2 O*ZnCO 3 or Zn 4 (OH) 4 *H 2 O*ZnCO 3) is a mixture of zinc carbonate and silicate; forms white (green, blue, yellow, brown depending on impurities) rhombic crystals with a density of 3.4-3.5 g/cm 3 and a hardness of 4.5-5 on the Mohs scale.

WILLEMYTH(Zn 2 SiO 4) occurs in the form of colorless or yellow-brown rhombohedral crystals with a density of 3.89-4.18 g/cm 3 and a hardness of 5-5.5 on the Mohs scale.

ZINCITE(ZnO) - hexagonal crystals of yellow, orange or red color with a wurtzite-type lattice and a hardness of 4-4.5 on the Mohs scale.

GANIT(Zn) has the form of dark green crystals with a density of 4-4.6 g/cm 3 and a hardness of 7.5-8 on the Mohs scale.

In addition to the above, other zinc minerals are known:

monheimite (Zn, Fe)CO 3

hydrocycite ZnCO 3 *2Zn(OH) 2

trustite (Zn, Mn)SiO 4

heterolite Zn

franklinite (Zn, Mn)

chalcophanite (Mn, Zn) Mn 2 O 5 *2H 2 O

goslarite ZnSO 4 *7H 2 O

zinc chalcanite (Zn, Cu)SO 4 *5H 2 O

adamine Zn 2 (AsO 4)OH

tarbuttite Zn 2 (PO 4)OH

decloisite (Zn, Cu)Pb(VO 4)OH

legrandite Zn 3 (AsO 4) 2 *3H 2 O

hopeite Zn 3 (PO 4)*4H 2 O

Physical properties

Zinc is a bluish-white metal of medium hardness, melting at 419 ° C, and turning into steam at 913 ° C; its density is 7.14 g/cm 3 . At ordinary temperatures, zinc is quite brittle, but at 100-110°C it bends well and is rolled into sheets. In air it becomes covered with a protective oxide film.

Chemical properties

In air at temperatures up to 100°C, zinc quickly tarnishes, becoming covered with a surface film of basic carbonates. In humid air, especially in the presence of CO 2, metal destruction occurs even at normal temperatures. When strongly heated in air or oxygen, Zinc burns intensely with a bluish flame, producing white smoke of zinc oxide ZnO. Dry fluorine, chlorine and bromine do not react with Zinc in the cold, but in the presence of water vapor the metal can ignite, forming, for example, ZnCl 2. A heated mixture of Zinc powder with sulfur gives Zinc sulfide ZnS. Strong mineral acids vigorously dissolve Zinc, especially when heated, to form the corresponding salts. When interacting with dilute HCl and H 2 SO 4, H 2 is released, and with HNO 3, in addition, NO, NO 2, NH 3. Zinc reacts with concentrated HCl, H 2 SO 4 and HNO 3, releasing H 2, SO 2, NO and NO 2, respectively. Solutions and melts of alkalis oxidize Zinc, releasing H2 and forming water-soluble zincites. The intensity of the action of acids and alkalis on zinc depends on the presence of impurities in it. Pure Zinc is less reactive towards these reagents due to its high hydrogen overvoltage. In water, Zinc salts hydrolyze when heated, releasing a white precipitate of Zn(OH) 2 hydroxide. Complex compounds containing Zinc are known, for example SO 4 and others.

Zinc is a typical representative of the group of metallic elements and has the full range of their characteristics: metallic luster, ductility, electrical and thermal conductivity. However, the chemical properties of zinc differ somewhat from the basic reactions inherent in most metals. An element can behave like a nonmetal under certain conditions, for example, react with alkalis. This phenomenon is called amphotericity. In our article we will study the physical properties of zinc, and also consider typical reactions characteristic of the metal and its compounds.

Position of the element in the periodic table and distribution in nature

The metal is located in a secondary subgroup of the second group of the periodic table. In addition to zinc, it contains cadmium and mercury. Zinc belongs to the d-elements and is in the fourth period. In chemical reactions, its atoms always give up electrons of the last energy level, therefore, in such compounds of the element as oxide, intermediate salts and hydroxide, the metal exhibits an oxidation state of +2. The structure of the atom explains all the physical and chemical properties of zinc and its compounds. The total metal content in the soil is approximately 0.01 weight. %. It is found in minerals such as galmea and zinc blende. Since the zinc content in them is low, the rocks are first subjected to enrichment, which is carried out in shaft furnaces. Most zinc-containing minerals are sulfides, carbonates and sulfates. These are zinc salts, the chemical properties of which underlie their processing processes, such as roasting.

Metal production

The severe oxidation reaction of zinc carbonate or sulfide produces its oxide. The process takes place in a fluidized bed. This is a special method based on close contact of finely ground mineral and a stream of hot air moving at high speed. Next, zinc oxide ZnO is reduced with coke and the resulting metal vapors are removed from the reaction sphere. Another method of producing metal, based on the chemical properties of zinc and its compounds, is electrolysis of a solution of zinc sulfate. It is a redox reaction that occurs under the influence of electric current. High purity metal is deposited on the electrode.

Physical characteristics

A bluish-silver, brittle metal under normal conditions. In the temperature range from 100° to 150°, zinc becomes flexible and can be rolled into sheets. When heated above 200°, the metal becomes unusually brittle. Under the influence of atmospheric oxygen, pieces of zinc are covered with a thin layer of oxide, and upon further oxidation it turns into hydroxycarbonate, which plays the role of a protector and prevents further interaction of the metal with atmospheric oxygen. The physical and chemical properties of zinc are interrelated. Let's consider this using the example of the interaction of a metal with water and oxygen.

Severe oxidation and reaction with water

When heated strongly in air, zinc filings burn with a blue flame, forming zinc oxide.

It exhibits amphoteric properties. In water vapor heated to a red-hot temperature, the metal displaces hydrogen from H 2 O molecules, in addition, zinc oxide is formed. The chemical properties of the substance prove its ability to interact with both acids and alkalis.

Redox reactions involving zinc

Since the element comes before hydrogen in the activity series of metals, it is able to displace it from acid molecules.

The reaction products between zinc and acids will depend on two factors:

• type of acid
• its concentration

Zinc oxide

A white porous powder that turns yellow when heated and returns to its original color when cooled is a metal oxide. The chemical properties of zinc oxide and the reaction equations for its interaction with acids and alkalis confirm the amphoteric nature of the compound. Thus, the substance cannot react with water, but interacts with both acids and alkalis. The reaction products will be medium salts (in case of interaction with acids) or complex compounds - tetrahydroxocinates.

Zinc oxide is used in the production of white paint, which is called zinc white. In dermatology, the substance is included in ointments, powders and pastes that have an anti-inflammatory and drying effect on the skin. Most of the zinc oxide produced is used as a filler for rubber. Continuing to study the chemical properties of zinc and its compounds, let's consider Zn(OH) 2 hydroxide.

Amphoteric nature of zinc hydroxide

The white precipitate that falls out under the action of alkali on solutions of metal salts is the base of zinc. The compound dissolves quickly when exposed to acids or alkalis. The first type of reaction ends with the formation of medium salts, the second - zincates. Complex salts—hydroxycinates—are isolated in solid form. A special feature of zinc hydroxide is its ability to dissolve in an aqueous solution of ammonia to form tetraamminium zinc hydroxide and water. Zinc base is a weak electrolyte, therefore both its average salts and zincates in aqueous solutions are hydrolyzable, that is, their ions react with water and form zinc hydroxide molecules. Solutions of metal salts such as chloride or nitrate will be acidic due to the accumulation of excess hydrogen ions.

Characteristics of zinc sulfate

The chemical properties of zinc that we examined earlier, in particular, its reactions with dilute sulfate acid, confirm the formation of an average salt - zinc sulfate. These are colorless crystals, which, when heated to 600° and above, can produce oxosulfates and sulfur trioxide. With further heating, zinc sulfate is converted to zinc oxide. The salt is soluble in water and glycerin. The substance is isolated from solution at temperatures up to 39°C in the form of a crystalline hydrate, the formula of which is ZnSO 4 × 7H 2 O. In this form it is called zinc sulfate.

In the temperature range 39°-70°, a hexahydrate salt is obtained, and above 70° only one molecule of water remains in the crystalline hydrate. The physicochemical properties of zinc sulfate make it possible to use it as a bleach in paper production, as a mineral fertilizer in crop production, and as a fertilizer in the diet of domestic animals and poultry. In the textile industry, the compound is used in the production of viscose fabric and in dyeing chintz.

Zinc sulfate is also included in the electrolyte solution used in the process of galvanic coating of iron or steel products with a layer of zinc using the diffuse method or hot-dip galvanizing method. A layer of zinc protects such structures from corrosion for a long time. Considering the chemical properties of zinc, it should be noted that in conditions of high salinity of water, significant fluctuations in temperature and air humidity, galvanizing does not give the desired effect. Therefore, metal alloys with copper, magnesium and aluminum are widely used in industry.

Application of alloys containing zinc

Transporting many chemicals, such as ammonia, through pipelines requires special requirements for the composition of the metal from which the pipes are made. They are made on the basis of alloys of iron with magnesium, aluminum and zinc and have high anti-corrosion resistance to aggressive chemical environments. In addition, zinc improves the mechanical properties of alloys and neutralizes the harmful effects of impurities such as nickel and copper. Copper and zinc alloys are widely used in industrial electrolysis processes. Tankers are used to transport petroleum products. They are built from aluminum alloys containing, in addition to magnesium, chromium and manganese, a large proportion of zinc. Materials of this composition not only have high anti-corrosion properties and increased strength, but also cryogenic resistance.

The role of zinc in the human body

The Zn content in cells is 0.0003%, so it is classified as a microelement. The chemical properties and reactions of zinc and its compounds play an important role in metabolism and maintaining a normal level of homeostasis, both at the level of the cell and the entire organism as a whole. Metal ions are part of important enzymes and other biologically active substances. For example, it is known that zinc has a serious effect on the formation and functions of the male reproductive system. It is part of the coenzyme of the hormone testosterone, which is responsible for the fertility of seminal fluid and the formation of secondary sexual characteristics. The non-protein part of another important hormone, insulin, produced by the beta cells of the islets of Langerhans in the pancreas, also contains a trace element. The immune status of the body is also directly related to the concentration in cells of Zn +2 ions, which are found in the thymus hormone - thymulin and thymopoietin. A high concentration of zinc is recorded in nuclear structures - chromosomes containing deoxyribonucleic acid and participating in the transmission of hereditary information of the cell.

In our article, we studied the chemical functions of zinc and its compounds, and also determined its role in the life of the human body.

ZINC (chemical element) ZINC (chemical element)

ZINC (lat. Zincum), Zn (read “zinc”), chemical element with atomic number 30, atomic mass 65.39. Natural zinc consists of a mixture of five stable nuclides: 64 Zn (48.6% by weight), 66 Zn (27.9%), 67 Zn (4.1%), 68 Zn (18.8%) and 70 Zn ( 0.6%). Located in the fourth period in group IIB of the periodic table. Configuration of two outer electronic layers 3 s 2 p 6 d 10 4s 2 . In compounds it exhibits an oxidation state of +2 (valence II).
The radius of the Zn atom is 0.139 nm, the radius of the Zn 2+ ion is 0.060 nm (coordination number 4), 0.0740 nm (coordination number 6) and 0.090 nm (coordination number 8). The sequential ionization energies of the atom correspond to 9.394, 17.964, 39.7, 61.6 and 86.3 eV. Electronegativity according to Pauling (cm. PAULING Linus) 1,66.
Historical reference
Alloys of zinc with copper - brass (cm. BRASS)- were known to the ancient Greeks and Egyptians. Zinc was obtained in the 5th century. BC e. in India. Roman historian Strabo (cm. STRABO) in 60-20 BC. e. wrote about obtaining metallic zinc, or “fake silver.” Subsequently, the secret of obtaining zinc in Europe was lost, since the zinc formed during the thermal reduction of zinc ores turns into steam at 900°C. Zinc vapor reacts with oxygen (cm. OXYGEN) air, forming loose zinc oxide, which alchemists called “white wool.”
In 1743, the first zinc metal plant was opened in Bristol, where zinc ore was reduced in retorts without access to air. (cm. In 1746 A. S. Marggraff MARGGRAF Andreas Sigismund)
developed a method for producing metal by calcining a mixture of its oxide and coal without air access in retorts, followed by condensation of zinc vapor in refrigerators. (cm. The word "zinc" appears in the writings of Paracelsus PARACELSUS)
Being in nature
and other researchers of the 16-17 centuries. and goes back, perhaps, to the ancient German “zinc” - plaque, eyesore. The name of this metal has changed several times during its history. The name “zinc” became commonly used only in the 1920s. (cm. The zinc content in the earth's crust is 8.3·10–3% by mass, in the water of the World Ocean 0.01 mg/l. There are 66 known zinc minerals, the most important of which are sphalerite SPHALERITE) (cm., cleiophanes CLEIOPHANES) (cm., marmatite MARMATITE) (cm., wurtzite, WURTZITE) (cm. smithsonite SMITHSONITE) (cm. ZnCO 3, calamine CALAMINA) (cm. Zn 4 (OH) 4 Si 2 O 7 H 2 O, zincite ZINCITE) (cm. ZnO, willemite WILLEMITH) , . Zinc is part of polymetallic ores, which also contain copper, lead, cadmium (cm. indium, INDIUM) (cm. gallium, GALLIUM) (cm. thallium THALLIUM)
and others. Zinc is an important biogenic element: living matter contains 5·10–4% by weight.
Receipt
Zinc is mined from polymetallic ores containing 1-4% Zn in the form of sulfide. The ore is enriched to produce zinc concentrate (50-60%). Zinc concentrates are fired in fluidized bed furnaces, converting zinc sulfide into ZnO. There are two routes from ZnO to Zn. According to the pyrometallurgical method, the concentrate is sintered and then reduced with coal or coke at 1200-1300°C. Then the zinc vapors evaporated from the furnace are condensed.
ZnO + C = Zn + CO.
The main method of obtaining zinc is hydrometallurgical. The burned concentrates are treated with sulfuric acid. Impurities are removed from the resulting sulfate solution by precipitating them with zinc dust. The purified solution is subjected to electrolysis. Zinc is deposited on aluminum cathodes. The purity of electrolytic zinc is 99.95%. (cm. To obtain high-purity zinc, zone melting is used.
ZONE MELTING)
Physical and chemical properties
Zinc is a bluish-white metal. Has a hexagonal lattice with parameters A = 0.26649 nm, With
In air, zinc is coated with a thin film of ZnO oxide. When heated strongly, it burns to form an amphoteric (cm. AMPHOTERIC) white ZnO oxide.
2Zn + O 2 = 2ZnO
Zinc oxide reacts both with acid solutions:
ZnO + 2HNO 3 = Zn(NO 3) 2 + H 2 O
and with alkalis:
ZnO + 2NaOH (fusion) = Na 2 ZnO 2 + H 2 O
In this reaction, sodium zincate Na 2 ZnO 2 is formed.
Zinc of ordinary purity reacts actively with acid solutions:
Zn + 2HCl = ZnCl 2 + H 2
Zn + H 2 SO 4 = ZnSO 4 + H 2
and alkali solutions:
Zn + 2NaOH + 2H 2 O = Na 2 + H 2,
forming hydroxinates. Very pure zinc does not react with solutions of acids and alkalis. The interaction begins when a few drops of copper sulfate solution CuSO 4 are added.
When heated, zinc reacts with halogens (cm. HALOGEN) with the formation of ZnHal 2 halides. With phosphorus (cm. PHOSPHORUS) zinc forms phosphides Zn 3 P 2 and ZnP 2. With sulfur (cm. SULFUR) and its analogues - selenium (cm. SELENIUM) and tellurium (cm. TELLURIUM)- various chalcogenides (cm. CHALCOGENIDES), ZnS, ZnSe, ZnSe 2 and ZnTe.
With hydrogen (cm. HYDROGEN), nitrogen (cm. NITROGEN), carbon (cm. CARBON), silicon (cm. SILICON) and boron (cm. BOR (chemical element)) zinc does not react directly. Nitride Zn 3 N 2 is obtained by the reaction of zinc with ammonia (cm. AMMONIA) NH 3 at 550-600°C.
In aqueous solutions, zinc ions Zn 2+ form aqua complexes 2+ and 2+.
Application
The bulk of the zinc produced is spent on the manufacture of anti-corrosion coatings for iron and steel. Zinc is used in batteries and dry cell batteries. Zinc sheets are used in printing. Zinc alloys (brass, nickel silver and others) are used in technology. ZnO serves as a pigment in zinc white. Zinc compounds are semiconductors. Railway sleepers are impregnated with a solution of zinc chloride ZnCl 2, protecting them from rotting.
Physiological action
Zinc is part of more than 40 metalloenzymes that catalyze the hydrolysis of peptides, proteins and other compounds in the human body. Zinc is part of the hormone insulin. (cm. INSULIN) Zinc enters the human body with meat, milk, and eggs.
Plants with a lack of zinc in the soil become sick.
Zinc metal is slightly toxic. Zinc phosphide and oxide are poisonous. The ingestion of soluble zinc salts into the body leads to indigestion and irritation of the mucous membranes. The maximum permissible concentration for zinc in water is 1.0 mg/l.

encyclopedic Dictionary. 2009 .

See what "ZINC (chemical element)" is in other dictionaries:

Zinc (lat. Zincum), Zn, chemical element of group II of the periodic system of Mendeleev; atomic number 30, atomic mass 65.38, bluish white metal. There are 5 known stable isotopes with mass numbers 64, 66, 67, 68 and 70; most common... ... Great Soviet Encyclopedia

The silver chloride element is a primary chemical source of current in which the anode is zinc, the cathode is silver chloride, and the electrolyte is an aqueous solution of ammonium chloride (ammonia) or sodium chloride. Contents 1 History of invention 2 Parameters ... Wikipedia

- (French Chlore, German Chlor, English Chlorine) an element from the group of halogens; its sign is Cl; atomic weight 35.451 [According to Clarke's calculation of Stas data.] at O ​​= 16; Cl 2 particle, which is well matched by its densities found by Bunsen and Regnault in relation to... ...

- (Argentum, argent, Silber), chemical. Ag sign. S. is one of the metals known to man since ancient times. In nature, it is found both in the native state and in the form of compounds with other bodies (with sulfur, for example Ag 2S... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (Argentum, argent, Silber), chemical. Ag sign. S. is one of the metals known to man since ancient times. In nature, it is found both in the native state and in the form of compounds with other bodies (with sulfur, for example Ag2S silver ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (Platine French, Platina or um English, Platin German; Pt = 194.83, if O = 16 according to K. Seibert). P. is usually accompanied by other metals, and those of these metals that are adjacent to it in their chemical properties are called... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (Bromum; chemical form Br, atomic weight 80) a non-metallic element from the group of halogens, discovered in 1826 by the French chemist Balard in mother solutions of seawater salts; B. received its name from the Greek word Βρωμος stench.… … Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (Soufre French, Sulfur or Brimstone English, Schwefel German, θετον Greek, Latin Sulfur, whence the symbol S; atomic weight 32.06 at O ​​= 16 [Determined by Stas from the composition of silver sulfide Ag 2 S]) belongs among the most important non-metallic elements.... ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

One of the metals that was discovered quite a long time ago, but to this day has not lost its relevance in use due to its remarkable properties, is zinc. Its physical and chemical properties make it possible to use the material in a wide variety of industries and everyday life. It also has a significant impact on human health.

A Brief History of the Element's Discovery

People knew what zinc was even before our era. After all, it was then that they learned to use alloys containing this metal. The Egyptians used ores containing copper and zinc, smelted them and obtained a very strong, oxidation-resistant material. Household items and dishes made from this material were found.

The name zinc appears in the writings of the physician Paracelsus in the 16th century AD. During the same period, the Chinese began to actively use the metal, casting coins from it. Gradually, knowledge about this substance and its good technical properties is spreading to Europe. Then in Germany and England they also learned what zinc is and where it can be used.

Brass was one of the first and most famous alloys, used since ancient times in Cyprus and later in Germany and other countries.

The name comes from the Latin zincum, but the etymology is not entirely clear. There are several versions.

1. From the German zinke, which translates as "edge".
2. From the Latin zincum, meaning "white coating".
3. Persian "cheng", that is, stone.
4. Old German zinco, which translates as “plaque”, “eyesore”.

The element received its current name only at the beginning of the 20th century. The importance of zinc ions in the human body also became known only relatively recently (20th century). Before this, no ailments were associated with this element.

However, it is known that already in ancient times, many peoples used soups made from young lamb meat as a means of recovery from illness and for a speedy recovery. Today we can say that the effect was achieved due to zinc ions, which this dish contains quite a lot. It helped restore blood circulation, relieve fatigue and activated brain activity.

Element Zinc: characteristics

This element is located in the periodic table in the second group, a secondary subgroup. Serial number 30, mass of Zinc - 65.37. The only and constant oxidation state is +2. Electronic configuration of the outer layer of the 4s 2 atom.

In the table, Zinc, Copper, Cadmium, Chromium, Manganese and many others are transition metals. These include all those whose electrons fill the outer and pre-external d and f energy sublevels.

Zinc salts

Almost all salts that are not double and complex, that is, do not contain foreign colored ions, are colorless. The most popular in terms of human use are the following.

1. Zinc chloride - ZnCL 2. Another name for the compound is soldering acid. Externally, it appears as white crystals that absorb air moisture well. Used to clean the surface of metals before soldering, to obtain fiber, in batteries, to impregnate wood before processing as a disinfectant.
2. Zinc sulfide. White powder, quickly turning yellow when heated. It has a high melting point, unlike pure metal. It is used in the production of luminescent compounds applied to screens, panels and other objects. Is a semiconductor.
3. - a common poison used to get rid of gnawing animals (mice, rats).
4. Smithsonite, or zinc carbonate - ZnCO 3. Colorless crystalline compound, insoluble in water. It is used in petrochemical production, as well as in silk production reactions. It is a catalyst in organic synthesis and is used as a soil fertilizer.
5. Zinc acetate - (CH 3 COO) 2 Zn. Colorless crystals, highly soluble in all solvents of any nature. It is widely used in the chemical, medical and food industries. Used to treat nosopharyngitis. Used as a food additive E650 - freshens breath, prevents the appearance of plaque on teeth when included in chewing gum. It is also used for etching dyes, preserving wood, producing plastics and other organic syntheses. Almost everywhere it plays the role of an inhibitor.
6. Zinc iodide is a white crystal used in radiography, as an electrolyte in batteries, and as a dye for electron microscopy.
7. Black or dark green crystals that cannot be obtained by direct synthesis, since zinc does not react with nitrogen. Formed from metal ammonia. At high temperatures it decomposes with the release of zinc, therefore it is used for its production.
8. Zinc nitrate. Colorless hygroscopic crystals. Zinc is used in this form in the textile and leather industries for treating fabrics.

Zinc alloys

As mentioned above, the most common zinc alloy is brass. It has been known since ancient times and is still actively used by people to this day. What is he like?

Brass is copper and zinc, which are combined harmoniously with several other metals, giving additional shine, strength and refractoriness to the alloy. Zinc is included as an alloying element, copper as the main one. The color of the material is yellow and shiny, but can turn black in the open air in a humid environment. The melting point is about 950 o C, it can vary depending on the zinc content (the more it is, the lower the temperature).

The material is well rolled into sheets, pipes, and contact welded. It has good technical characteristics, so the following elements are made from it:.

1. Machine parts and various technical devices.
2. Sleeves and stamped products.
3. Nuts, bolts, pipes.
4. Fittings, bushings, anti-corrosion parts for various types of transport.
5. Watch details.

Most of the metal we are considering mined in the world goes specifically to the production of this alloy.

Another type of intermetallic compound is zinc antimonide. Its formula is Zn 4 Sb 3. It is also an alloy that is used as a semiconductor in transistors, thermal imagers, and magnetoresistive devices.

It is obvious that the use of zinc and its compounds is very wide and almost everywhere. This metal is as popular as copper and aluminum, silver and gold, manganese and iron. Its importance is especially great for technical purposes as an anti-corrosion material. After all, various alloys and products are coated with zinc to protect them from this destructive natural process.

Biological role

What is zinc from a medical and biological point of view? Does it matter for the life of organisms and how great is it? It turns out that zinc ions simply must be present in living beings. Otherwise, the deficit will lead to the following consequences:

• anemia;
• decreased insulin;
• allergies;
• weight loss and memory;
• fatigue;
• depression;
• blurred vision;
• irritability and others.

The main places of concentration of zinc ions in the human body are the liver and muscles. It is also this metal that is part of most enzymes (for example, carbonic anhydrase). Therefore, most catalytic reactions occur with the participation of zinc.

What exactly do ions do?

1. Participate in the synthesis of male hormones and seminal fluid.
2. Promotes the absorption of vitamin E.
3. Participate in the breakdown of alcohol molecules in the body.
4. They are direct participants in the synthesis of many hormones (insulin, growth hormone, testosterone and others).
5. Takes part in hematopoiesis and healing of damaged tissues.
6. Regulates the secretion of the sebaceous glands, maintains normal hair and nail growth, and promotes regeneration processes in the skin.
7. It has the ability to eliminate toxins from the body and strengthen the immune system.
8. Affects the formation of taste sensations, as well as the sense of smell.
9. Takes part in transcription processes, vitamin A metabolism, nucleic synthesis and decay.
10. It is a participant in all stages of cell growth and development, and also accompanies the process of gene expression.

All this once again proves how important this metal is. Its role in biological systems was clarified only in the 20th century. Many troubles and illnesses in the past could have been avoided if people had known about treatment with zinc-based drugs.

How can you maintain the required amount of this element in the body? The answer is obvious. It is necessary to consume foods containing zinc. The list can be long, so we will indicate only those with the maximum number of the element in question:

• nuts and seeds;
• legumes;
• meat;
• seafood, especially oysters;
• cereals and bread;
• milk products;
• greens, vegetables and fruits.

Human use

We have already generally indicated in which sectors and areas of industry zinc is used. The price of this metal and its alloys is quite high. For example, a sheet of brass measuring 0.6 x 1.5 is approximately valued at 260 rubles. And this is quite justified, because the quality of the material is quite high.

So, metallic zinc, that is, as a simple substance, is used:

• for anti-corrosion coating on iron and steel products;
• in batteries;
• printing houses;
• as a reducing agent and catalyst in organic syntheses;
• in metallurgy for isolating other metals from their solutions.

It is used not only for cosmetic purposes, which we have already mentioned, but also as a filler in the production of rubber, as a white pigment in paints.

We talked about where various zinc salts are used when considering these compounds. It is obvious that, in general, zinc and its substances are important and significant components in industry, medicine and other fields, without which many processes would be impossible or very difficult.

Element zinc(Zn) in the periodic table has serial number 30. It is in the fourth period of the second group. Atomic weight - 65.37. Distribution of electrons across layers 2-8-18-2.

Element 30 of the periodic table Zinc is a bluish-white metal that melts at 419 (C, and at 913 (C) it turns into steam; its density is 7.14 g/cm3. At ordinary temperatures, zinc is quite fragile, but at 100-110 ( It bends well and is rolled into sheets. In air, zinc is coated with a thin layer of oxide or basic carbonate, which protects it from further oxidation. Water has almost no effect on zinc, although it is much to the left of hydrogen in the series of stresses. This is explained by the fact that the formed on the surface of zinc, when it interacts with water, the hydroxide is practically insoluble and prevents the further course of the reaction. In dilute acids, zinc easily dissolves to form the corresponding salts. In addition, zinc, like beryllium and other metals that form amphoteric hydroxides, dissolves in alkalis if zinc is heated. in air to the boiling point, its vapor ignites and burns with a greenish-white flame, forming zinc oxide.

The average zinc content in the earth's crust is 8.3·10-3%; in basic igneous rocks it is slightly higher (1.3·10-2%) than in acidic rocks (6·10-3%). Zinc is an energetic aquatic migrant; its migration in thermal waters along with lead is especially typical. Zinc sulfides, which are of industrial importance, precipitate from these waters. Zinc also migrates vigorously in surface and underground waters; the main precipitant for it is hydrogen sulfide; sorption by clays and other processes play a lesser role.
Zinc is an important biogenic element; living organisms contain an average of 5·10-4% zinc. But there are exceptions - so-called hub organisms (for example, some violets).

Zinc deposits

Zinc deposits are known in Iran, Australia, Bolivia, and Kazakhstan. In Russia, the largest producer of lead-zinc concentrates is JSC MMC Dalpolimetal

Obtaining zinc

Zinc does not occur in nature as a native metal.
Zinc is extracted from polymetallic ores containing 1-4% Zn in the form of sulfide, as well as Cu, Pb, Ag, Au, Cd, Bi. Ores are enriched by selective flotation, obtaining zinc concentrates (50-60% Zn) and at the same time lead, copper, and sometimes also pyrite concentrates. Zinc concentrates are fired in fluidized bed furnaces, converting zinc sulfide into ZnO oxide; The resulting sulfur dioxide SO2 is used to produce sulfuric acid. Pure zinc is obtained from ZnO oxide in two ways. According to the pyrometallurgical (distillation) method, which has existed for a long time, the calcined concentrate is subjected to sintering to impart granularity and gas permeability, and then reduced with coal or coke at 1200-1300 °C: ZnO + C = Zn + CO. The resulting metal vapors are condensed and poured into molds. At first, reduction was carried out only in retorts made of baked clay, operated manually, later they began to use vertical mechanized retorts made of carborundum, then - shaft and arc electric furnaces; Zinc is obtained from lead-zinc concentrates in blast furnaces. Productivity gradually increased, but zinc contained up to 3% impurities, including valuable cadmium. Distillation zinc is purified by segregation (that is, by settling the liquid metal from iron and part of the lead at 500 °C), achieving a purity of 98.7%. Sometimes used, more complex and expensive purification by rectification gives the metal a purity of 99.995% and allows the recovery of cadmium.

The main method of obtaining zinc is electrolytic (hydrometallurgical). Calcined concentrates are treated with sulfuric acid; the resulting sulfate solution is cleaned of impurities (by precipitating them with zinc dust) and subjected to electrolysis in baths tightly lined inside with lead or vinyl plastic. Zinc is deposited on aluminum cathodes, from which it is removed (stripped off) daily and melted in induction furnaces. Typically, the purity of electrolytic zinc is 99.95%, the completeness of its extraction from the concentrate (taking into account waste processing) is 93-94%. Zinc sulfate, Pb, Cu, Cd, Au, Ag are obtained from production waste; sometimes also In, Ga, Ge, Tl.

Biological role

The adult body contains on average about 2 g of zinc, which is concentrated mainly in the muscles, liver and pancreas. More than 400 enzymes contain zinc. Among them are enzymes that catalyze the hydrolysis of peptides, proteins and esters, the formation of aldehydes, and the polymerization of DNA and RNA. Zn2+ ions in enzymes cause polarization of water molecules and organic substances, promoting their deprotonation according to the reaction:

Zn2+ + H2O = ZnOH+ + H+
The most studied enzyme is carbonic anhydrase, a protein containing zinc and consisting of approximately 260 amino acid residues. This enzyme is found in red blood cells and promotes the conversion of carbon dioxide formed in tissues during their vital activity into bicarbonate ions and carbonic acid, which are transported by the blood to the lungs, where they are excreted from the body in the form of carbon dioxide. In the absence of the enzyme, the conversion of CO2 to the anion HCO3- occurs at a very low rate. In the carbonic anhydrase molecule, the zinc atom is bonded to three imidazole groups of histidine amino acid residues and a water molecule, which is easily deprotonated, turning into a coordinated hydroxide. The carbon atom of the carbon dioxide molecule, which has a partial positive charge, interacts with the oxygen atom of the hydroxyl group. Thus, the coordinated CO2 molecule is converted into a bicarbonate anion, which leaves the active center of the enzyme, being replaced by a water molecule. The enzyme speeds up this hydrolysis reaction by 10 million times.

Applications of zinc

Pure zinc metal is used to recover precious metals mined by underground leaching (gold, silver). In addition, zinc is used to extract silver, gold (and other metals) from crude lead in the form of zinc-silver-gold intermetallic compounds (so-called “silver foam”), which are then processed by conventional refining methods.
It is used to protect steel from corrosion (galvanization of surfaces not subject to mechanical stress, or metallization - for bridges, tanks, metal structures).
Zinc is used as a material for the negative electrode in chemical power sources, that is, in batteries and accumulators, for example: manganese-zinc cell, silver-zinc battery (EMF 1.85 V, 150 Wh / kg, 650 Wh / dm³, low resistance and colossal discharge currents), mercury-zinc element (EMF 1.35 V, 135 Wh/kg, 550-650 Wh/dm³), dioxysulfate-mercury element, zinc iodate element, copper- oxide galvanic cell (EMF 0.7-1.6 Volts, 84-127 Wh/kg, 410-570 Wh/dm³), chromium-zinc cell, zinc-silver chloride cell, nickel-zinc battery (EMF 1 .82 Volt, 95–118 Wh/kg, 230–295 Wh/dm³), lead-zinc cell, zinc-chlorine battery, zinc-bromine battery, etc.

The role of zinc in zinc-air batteries, which have a very high specific energy capacity, is very important. They are promising for starting engines (lead battery - 55 Wh/kg, zinc-air - 220-300 Wh/kg) and for electric vehicles (range up to 900 km).

Zinc plates are widely used in printing, in particular, for printing illustrations in large-circulation publications. For this purpose, zincography has been used since the 19th century - making cliches on a zinc plate by etching the design in it with acid. Impurities, with the exception of a small amount of lead, impair the etching process. Before etching, the zinc plate is annealed and rolled in a heated state.
Zinc is added to many hard solders to reduce their melting point.
Zinc oxide is widely used in medicine as an antiseptic and anti-inflammatory agent. Zinc oxide is also used to produce paint - zinc white.

Zinc- an important component of brass. Zinc alloys with aluminum and magnesium (ZAM, ZAMAK), due to their relatively high mechanical and very high casting qualities, are very widely used in mechanical engineering for precision casting. In particular, in the arms industry, pistol bolts are sometimes cast from the ZAMAK (-3, −5) alloy, especially those designed for the use of weak or traumatic cartridges. Also, all kinds of technical accessories are cast from zinc alloys, such as car handles, carburetor bodies, scale models and all kinds of miniatures, as well as any other products that require precise casting with acceptable strength.

Zinc chloride- an important flux for soldering metals and a component in the production of fiber.
Zinc sulfide is used in the manufacture of short-lasting phosphors and other luminescent compounds, usually mixtures of ZnS and CdS, activated with ions of other metals. Phosphors based on zinc and cadmium sulfides are also used in the electronics industry for the manufacture of luminous flexible panels and screens as electroluminophores and compositions with a short glow time.
Zinc telluride, selenide, phosphide, and sulfide are widely used semiconductors. Zinc sulfide is an integral part of many phosphors. Zinc phosphide is used as a rodent poison.
Zinc selenide is used to make optical glasses with very low absorption coefficients in the mid-infrared region, such as in carbon dioxide lasers.

The different uses of zinc include:

galvanizing - 45-60%
medicine (zinc oxide as an antiseptic) - 10%
production of alloys - 10%
production of rubber tires - 10%
oil paints - 10%