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All possible reactions with zinc. Zinc: production and application

Zinc or Zincum is the 30th element of the periodic table chemical elements Mendeleev and denoted by the symbol Zn. It is mainly used to create deformed semi-finished products and as a part of various mixtures. In its pure form, it looks like a brittle metal of bluish-silver color, it quickly oxidizes and becomes covered with a protective film (oxide), due to which it noticeably tarnishes.

It is mined in Kazakhstan, Australia, Iran and Bolivia. Due to the difficulties in determining the metal, its often referred to as "bogus".

History reference

The very name "zinc" was first mentioned in the book "Liber Mineralium" by Paracelsus. According to some reports, it meant "prong". Zinc alloy with copper or brass has been known for a long time. It was used in Ancient Greece, India and Ancient egypt, later the material became known in China.

The pure metal was obtained only in the first half of the 18th century, in 1738, in Great Britain using a distillation method. It was discovered by William Champion. Industrial production began 5 years later, and in 1746 in Germany chemist Andreas Sigismund Marggraf developed and described in detail his own method of zinc production... He proposed using the method of calcining a mixture of metal oxide with coal in refractory clay retorts without air access. The subsequent condensation of the vapors had to take place in the refrigerator. Due to the detailed description and painstaking development, Marggraf is often called the discoverer of the substance.

At the beginning of the 19th century, a method was found for separating metal by rolling at 100 C about -150 C about. At the beginning of the next century, they learned how to extract zinc by the electrolytic method. In Russia, the first metal was received only in 1905.

Physical properties

  • Atomic number: 30.
  • Atomic mass: 65.37
  • Atomic volume: 9.15
  • Density: 7.133 g / cm 3.
  • Temperature required for melting: 419.5 C о.
  • Boiling point: 906 C о.
  • Surface energy: 105 mJ / m 2.
  • Specific electrical conductivity: 16.2 * 10 -6 S / m.
  • Molar heat capacity: 25.4 J / (K * mol).
  • Molar volume: 9.2 cm 3 / mol.

Zinc has weak mechanical properties, at normal temperatures it easily breaks and crumbles, but at a temperature of 100 C o -150 C obecomes quite stringy and easily deforms: forged, rolled into sheets. Plain water is safe for metal, and acids and alkalis are easily corroded. Because of this, pure zinc is not used for the manufacture of parts, only alloys.

Chemical properties

The external electronic configuration of one zinc atom can be written as 3 d 10 4 s 2. The metal is active and is an energetic reducing agent. At a temperature of 100 ° C in the open air, it becomes covered with a film consisting of basic carbonates, and dims greatly. When exposed to carbon dioxide and high humidity, the element begins to collapse. In an oxygenic or normal environment, when heated strongly, zinc burns out, forming a bluish flame and white smoke, which consists of zinc oxide. Dry elements of fluorine, bromine and chlorine have a flammable effect on zinc, but only with the participation of water vapor.

When a metal and strong mineral acids combine, the former dissolves, especially if the mixture is heated, as a result corresponding salts are formed... Alkalis, melts and solutions oxidize the substance, resulting in the formation of water-soluble zincites, and hydrogen is released. The intensity of the action of acids and alkalis depends on the presence of impurities in zinc. The more "pure" the metal, the weaker it interacts due to the overvoltage of hydrogen.

Zinc is not found in nature as an independent element. It can be mined from 66 minerals, including sphalerite, calamine, franklinite, zincite, willemite, smithsonite. The former is the most common source of the metal and is often referred to as "zinc blende". It consists of zinc sulfide and impurities that give the mineral a variety of colors. This complicates its search and correct definition.

You can find zinc in acidic and igneous rocks - in the latter it is slightly more. Often sulphide metal with lead found in thermal waters, migrates in surface and underground sources.

The temperature required to melt zinc should be less than 419 C o, but not more than 480 C o. Otherwise, metal waste will grow and the wear of the walls of the bath, which is usually made from iron, will increase. In the molten state, no more than 0.05% of iron impurity is allowed, otherwise the temperature required for melting will begin to rise. If the iron content exceeds 0.2%, the zinc cannot be rolled.

Zinc is obtained from polymetallic ores, in which can contain up to 4% of the item... If the ores were enriched by selective flotation, up to 60% of zinc concentrates can be obtained from them, the rest will be occupied by concentrates of other metals. Zinc concentrates are fired in a fluidized bed furnace, after which zinc sulfide is converted into oxide, and sulfur dioxide is released. The latter is consumed: sulfuric acid is obtained from it.

To convert zinc oxide into the metal itself, two methods are used.

  1. Distillation or pyrometallurgical. The concentrate is fired, then subjected to sintering to impart gas permeability and granularity, and is reduced with coke or coal when exposed to a temperature of 1200-1300 C about. During the reaction, metal vapors are formed, which are condensed and poured into molds. The purity of zinc reaches 98.7%, after which it can be increased to 99.995% using rectification, but the latter method is quite expensive and complicated.
  2. Electrolytic or hydrometallurgical. The fired concentrates are treated with sulfuric acid, the solution is purified from impurities using zinc dust and subjected to electrolysis in baths lined with lead or vinyl plastic. Zinc is deposited on aluminum cathodes, from where it is collected and melted in induction furnaces. The purity of the metal obtained by this method reaches 99.95%.

To enhance strength and increase the melting point, the metal is mixed with copper, aluminum, tin, magnesium and lead.

The most famous and demanded alloy is brass. This is a mixture of copper with the addition of zinc, sometimes tin, nickel, manganese, iron, lead are also found. The density of brass reaches 8700 kg / m 3... The temperature required for melting is kept at around 880 C o - 950 C o: the higher the zinc content in it, the lower it is. The alloy perfectly resists an unfavorable external environment, although it turns black in the air, if not covered with varnish, it is perfectly polished and welded by resistance welding.

There are two types of brass:

  1. Alpha brass: more plastic, bends well in any condition, but wears out more.
  2. Alpha + Beta Brass: Deforms only when heated, and is more wear resistant. It is often alloyed with magnesium, aluminum, lead and iron. This increases strength, but reduces ductility.

Zamak or Zamac alloy consists of made of zinc, aluminum, copper and magnesium... The name itself is formed from the first letters of the Latin names: Zink - Aluminum - Magnesium - Kupfer / Cuprum (Zinc-Aluminum-Magnesium-Copper). In the USSR, the alloy was known as TsAM: Zinc-Aluminum-Copper. It is actively used in injection molding, melting begins at a low temperature (381 C o - 387 C o) and has a low coefficient of friction (0.07). Has increased strength, which allows you to get products of complex shapes that are not afraid to break: doorknobs, golf clubs, firearms closures, construction accessories, fasteners of various types and fishing tackle.

A small percentage of zinc (no more than 0.01%) is contained in hart alloys used in the printing industry for casting typographic fonts and rulers, printing plates and typesetting. These are outdated mixtures, replaced by pure zinc with a small addition of impurities.

The low temperature required to melt zinc is often compensated for by alloys with other metals, but it also happens vice versa. If the temperature required to melt the "pure" metal is 419.5 C about, then the alloy with tin is reduced to 199 C o, and with tin and lead - to 150 C o. And although such alloys can be brazed and welded, most often mixtures with zinc are used only for sealing existing defects due to their weak strength. For example, an alloy of tin, lead and zinc is recommended for use only on nickel-plated products.

Most often, zinc alloys are used to create carburetors, speedometer frames, radiator grilles, hydraulic brakes, pumps and decorative elements, parts for washing machines, mixers and kitchen equipment, watch cases, typewriters, cash registers and household appliances. These parts cannot be used in industrial production: when the temperature rises to 100 ° C, the strength of the product decreases by a third, and the hardness - by almost 40%. When the temperature drops to 0 C, the zinc becomes too brittle, which can lead to breakage.

Application

Zinc is one of the most demanded metals in the world: it is in third place in terms of production among non-ferrous metals, behind only copper and aluminum. This is facilitated by its low price. Most often it is used for corrosion protection and as part of an alloy such as brass.

In living organisms

The human body contains about 2 grams of zinc, about 400 enzymes contain it. The latter include enzymes that catalyze the hydrolysis of proteins, esters and leptides, the polymerization of RNA and DNA, and the formation of aldehydes. The pure element is found in muscles, pancreas and liver. Men need 11 mg of zinc per day, women - 8 mg.

In the body, zinc performs the following functions:

With a lack of an element in the body, fatigue, irritability, memory loss, loss of vision and weight for no objective reason, allergy attacks, depression. There is a decrease in insulin levels and the accumulation of certain elements in the body: iron, lead, copper, cadmium.

In food

The element is found in meats, cheese, sesame seeds, oysters, chocolate, legumes, oatmeal, sunflower and pumpkin seeds, and is often present in mineral water. Highest percentage of zinc contained in the following products (based on 100 grams):

  1. Oysters (up to 40 mg), anchovies (1.72 mg), octopus (1.68 mg), carp (1.48 mg), caviar (up to 1 mg), herring (about 1 mg).
  2. Pumpkin seeds (10 mg), sesame seeds (7 mg), sunflower seeds (5.3 mg), peanuts (4 mg), walnuts (3 mg), almonds (3 mg).
  3. Beef (up to 8.4 mg), lamb (up to 6 mg), beef liver (4 mg), pork (up to 3.5 mg), chicken (up to 3.5 mg).
  4. Cocoa powder without sugar and sweeteners (6.81 mg), pure dark chocolate (2.3 mg), chocolate candies (up to 2 mg, depending on the amount and type of chocolate).
  5. Lentils (4.78 mg), oats (3.97 mg), wheat (3.46 mg), soybeans (3 mg), rye (2.65 mg), bread (up to 1.5 mg), green peas (1.24 mg), peas (1.2 mg), bamboo shoots (1.1 mg), rice (1 mg), cereal cookies (up to 1 mg).
  6. Hard cheese (up to 4 mg).

Danger to humans

Zinc poisoning usually occurs with prolonged inhalation of its vapors... The first signs are intense thirst, loss of appetite, and a sweet taste in the mouth. Often there is fatigue, drowsiness, dry cough, a feeling of weakness, pressing pain in the chest. Long-term exposure can lead to infertility, anemia, and developmental delay. In everyday life, galvanized dishes, in which food is stored for a long time, are dangerous.

State educational institution

middle vocational education Leningrad region Podporozhsky Polytechnic College

Search and research work in chemistry

Theme:

"Zinc and its properties"

Completed: student of group No. 89

Full Name: Alexey Yurikov

Checked by the teacher: Yadykina Lyudmila Alekseevna

Podporozhye


1. Position in the periodic table and the structure of the atom


2. Discovery history


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 system

and the structure of the atom

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

He is in the fourth period of the second group.

atomic weight \u003d 65.37

valence II

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

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

Discovery history

Alloys of zinc with 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". Later, the secret of obtaining zinc in Europe was lost, since the zinc formed during the thermal reduction of zinc ores at 900 ° C turns into steam. Zinc vapor reacts with oxygen in the air to form loose zinc oxide, which alchemists call "white wool."

Metallic zinc

In the 16th century, the first attempts were made to smelt zinc in a factory. But the production "did not go well", the technological difficulties were insurmountable. They tried to get zinc in the same way as other metals. The ore was burned, turning zinc into oxide, then this oxide was reduced with coal ...

Zinc naturally recovered by interacting with coal, but ... it was not smelted. It was not smelted because this metal was already evaporating in the melting furnace - its boiling point was only 906 ° С. And there was air in the furnace. Meeting it, the vapors of active zinc reacted with oxygen, and the initial 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. Approximately the same "rough" zinc is obtained now, and it is purified by refining. About half of the zinc produced in the world is now obtained by the pyrometallurgical method, and the other half by the hydrometallurgical method.

It should be borne in mind that purely zinc ores are almost never found in nature. Zinc compounds (usually 1-5% in terms of metal) are included in polymetallic ores. Zinc concentrates obtained during ore dressing 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 ores containing zinc was one of the reasons why zinc production took a long and difficult time. There are still unresolved problems in the processing of polymetallic ores ... But let us return to zinc pyrometallurgy - in this process the purely individual characteristics of this element are manifested.

With a sharp cooling of the zinc vapor immediately, bypassing liquid state, turn into solid dust. This complicates production somewhat, although elemental zinc is considered non-toxic. It is often necessary to preserve the zinc as 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, in the production of zinc itself (and cadmium) by a hydrometallurgical method, zinc dust is used to purify a solution of copper and cadmium sulfate. But that's not all. Have you ever wondered why metal bridges, factory floor spans and other large metal items are often painted gray?

home component the paint used in all these cases is still the same zinc dust. Mixed with zinc oxide and linseed oil, it turns into a paint that protects against corrosion. This paint is also cheap, flexible, adheres well to the metal surface and does not flake off at temperature extremes. Mouse color is more of an advantage than a disadvantage. Products that are coated with such paint should not be brand and at the same time neat.

The properties of zinc are strongly affected by the degree of its purity. At 99.9 and 99.99% purity, zinc dissolves well in acids. But it is necessary to "add" one more nine (99.999%), and zinc becomes insoluble in acids, even with strong heating. Zinc of this purity is also distinguished by its great plasticity, it can be drawn into thin threads. And ordinary zinc can be rolled into thin sheets, only by heating it to 100-150 ° C. Heated up to 250 ° C and above, up to the melting point, zinc again becomes brittle - another restructuring of its crystal structure occurs.

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

The role of this element in the printing industry is significant. Zinc is used to make cliches that can be used to reproduce drawings and photographs in print. Specially prepared and processed printing zinc perceives the photographic image. This image in the right places protect with paint, and acid etch the future clichés. The image acquires relief, experienced engravers clean it up, make prints, and then these clichés 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 into closed molds. To "flatten" 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 not be possible to etch out the cliché as it should. If the lead 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 demands of the printing industry.

Being in nature

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

SPHALERITE (zinc blende, ZnS) has the form 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, lead as impurities.

IN crystal lattice sphalerite 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.

WURTZIT (ZnS) is a brown-black hexagonal crystals 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 the wurtzite layers is different from the arrangement of the sphalerite layers.

SMITHSONYTH (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.

CALAMIN (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.

WILLEMITE (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 these, other zinc minerals are known:

mongheimite (Zn, Fe) CO 3

hydrocyclite ZnCO 3 * 2Zn (OH) 2

trustite (Zn, Mn) SiO 4

heterolite Zn

franklinite (Zn, Mn)

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

goslarite ZnSO 4 * 7H 2 O

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

adamine Zn 2 (AsO 4) OH

tarbuttite Zn 2 (PO 4) OH

dekloisite (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 bluish - white metal 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 fragile, but at 100-110 ° C it bends well and rolls into sheets. In air it is 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 is destroyed even at normal temperatures. When heated strongly in air or oxygen, Zinc burns intensely with a bluish flame to form white smoke of zinc oxide ZnO. Dry fluorine, chlorine and bromine do not interact 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 dissolve zinc vigorously, especially when heated, to form the corresponding salts. When interacting with diluted 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 with the release of Н 2 and the formation of 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 with respect to these reagents due to the high overvoltage of hydrogen on it. In water, zinc salts hydrolyze when heated, giving off a white precipitate of Zn (OH) 2 hydroxide. Known complex compounds containing Zinc, such as SO 4 and others.

The external electronic configuration of the Zn atom is 3d104s2. The oxidation state in compounds is +2. The normal redox potential of 0.76 volts characterizes zinc as an active metal and an energetic reducing agent. 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 CO2, the metal is destroyed with the formation of basic zinc bicarbonate even at ordinary temperatures.

At red-hot temperatures, it can be oxidized by water vapor to release hydrogen and carbon dioxide. When heated sufficiently in air, it burns with a bright greenish-blue flame to form zinc oxide with a significant release of energy.

In accordance with the place occupied by zinc in the series of voltages, it readily dissolves in dilute acids with the evolution of hydrogen. Wherein concentrated acid reduced to nitrogen oxides, diluted to ammonia. Dissolution in conc. H3S04 is accompanied by the release of sulfur dioxide rather than hydrogen.

A mixture of zinc powder with sulfur reacts explosively when heated.

Zinc does not interact with nitrogen even in vapors, but rather easily at red heat it reacts with ammonia, forming zinc nitride - Zn3Na.

Zinc carbide ZnC, formed by heating zinc in a stream of acetylene, decomposes with water and dilute acids.

When zinc metal is heated in phosphorus vapor to 440-780 ° C, phosphides - Zn3Ps and ZnP2 are formed.

In the molten state, zinc mixes unlimitedly with many metals: Cu, Ag, Au, Cd, Hg, Ca, Mg, Mn, Fe, Co, Ni, Al, Sn.

Zinc forms compounds with many metals, for example: Cu, Ag, Au, Mn, Fe, Co, Ni, Pf, Pd, Rh, Sb, Mg, Ca, Li, Na, K.

Zinc dissolves quite easily in alkalis, as well as in aqueous solutions of ammonia and ammonium chloride, especially when heated. The rate of dissolution of zinc not only in alkalis, but also in acids depends on its purity. Very pure zinc dissolves slowly, and to speed up the process, it is recommended to add a few drops of a highly diluted solution of copper sulfate to the solution (the appearance of galvanic vapors).

Interaction with non-metals

When heated strongly in air, it burns with a bright bluish flame to form zinc oxide:

When ignited, reacts vigorously with sulfur:

It reacts with halogens under normal conditions in the presence of water vapor as a catalyst:

Zn + Cl2 \u003d ZnCl2

Under the action of phosphorus vapors on zinc, phosphides are formed:

Zn + 2P \u003d ZnP2 or

3Zn + 2P \u003d Zn3P2

Zinc does not interact with hydrogen, nitrogen, boron, silicon, carbon.

Interaction with water

Reacts with water vapor at red heat to form zinc oxide and hydrogen:

Zn + H2O \u003d ZnO + H2

5interactions with acids

In the electrochemical series of metal voltages, zinc is found before hydrogen and displaces it from non-oxidizing acids:

Zn + 2HCl \u003d ZnCl2 + H2

Zn + H2SO4 \u003d ZnSO4 + H2

Reacts with dilute nitric acid to form zinc nitrate and ammonium nitrate:

4Zn + 10HNO3 \u003d 4Zn (NO3) 2 + NH4NO3 + 3H2O

Reacts with concentrated sulfuric and nitric acids to form zinc salts and acid reduction products:

Zn + 2H2SO4 \u003d ZnSO4 + SO2 + 2H2O

Zn + 4HNO3 \u003d Zn (NO3) 2 + 2NO2 + 2H2O

Interaction with alkalis

Reacts with alkali solutions to form hydroxo complexes:

Zn + 2NaOH + 2H2O \u003d Na2 + H2

when fusion forms zincates:

Zn + 2KOH \u003d K2ZnO2 + H2

Interaction with ammonia

Forms zinc nitride with gaseous ammonia at 550-600 ° C:

3Zn + 2NH3 \u003d Zn3N2 + 3H2

dissolves into aqueous solution ammonia, forming tetraamminezinc hydroxide:

Zn + 4NH3 + 2H2O \u003d (OH) 2 + H2

Interaction with oxides and salts

Zinc displaces metals in the voltage row to the right of it from solutions of salts and oxides:

Zn + CuSO4 \u003d Cu + ZnSO4

Zinc is an element of a secondary subgroup of the second group, the fourth period of the periodic system of chemical elements of D. I. Mendeleev, with atomic number 30. It is designated by the symbol Zn (Latin Zincum). The simple substance zinc under normal conditions is a brittle transition metal bluish white (fades in air, becoming covered with a thin layer of zinc oxide).

In the fourth period, zinc is the last d-element, its valence electrons 3d 10 4s 2. In education chemical bonds only electrons of the external energy level are involved, since the d 10 configuration is very stable. In compounds for zinc, the oxidation state is +2.

Zinc is a chemically active metal with pronounced reducing properties, and is inferior in activity to alkaline earth metals. Shows amphoteric properties.

Interaction of zinc with non-metals
When heated strongly in air, it burns with a bright bluish flame to form zinc oxide:
2Zn + O 2 → 2ZnO.

When ignited, reacts vigorously with sulfur:
Zn + S → ZnS.

It reacts with halogens under normal conditions in the presence of water vapor as a catalyst:
Zn + Cl 2 → ZnCl 2.

Under the action of phosphorus vapors on zinc, phosphides are formed:
Zn + 2P → ZnP 2 or 3Zn + 2P → Zn 3 P 2.

Zinc does not interact with hydrogen, nitrogen, boron, silicon, carbon.

Interaction of zinc with water
Reacts with water vapor at red-hot temperatures to form zinc oxide and hydrogen:
Zn + H 2 O → ZnO + H 2.

Interaction of zinc with acids
In the electrochemical series of metal voltages, zinc is found before hydrogen and displaces it from non-oxidizing acids:
Zn + 2HCl → ZnCl 2 + H 2;
Zn + H 2 SO 4 → ZnSO 4 + H 2.

Reacts with dilute nitric acid to form zinc nitrate and ammonium nitrate:
4Zn + 10HNO 3 → 4Zn (NO 3) 2 + NH 4 NO 3 + 3H 2 O.

Reacts with concentrated sulfuric and nitric acids to form zinc salts and acid reduction products:
Zn + 2H 2 SO 4 → ZnSO 4 + SO 2 + 2H 2 O;
Zn + 4HNO 3 → Zn (NO 3) 2 + 2NO 2 + 2H 2 O

Interaction of zinc with alkalis
Reacts with alkali solutions to form hydroxo complexes:
Zn + 2NaOH + 2H 2 O → Na 2 + H 2

when fusion forms zincates:
Zn + 2KOH → K 2 ZnO 2 + H 2.

Interaction with ammonia
Forms zinc nitride with gaseous ammonia at 550–600 ° C:
3Zn + 2NH 3 → Zn 3 N 2 + 3H 2;
dissolves in an aqueous solution of ammonia, forming tetraamminezinc hydroxide:
Zn + 4NH 3 + 2H 2 O → (OH) 2 + H 2.

Interaction of zinc with oxides and salts
Zinc displaces metals in the voltage row to the right of it from solutions of salts and oxides:
Zn + CuSO 4 → Cu + ZnSO 4;
Zn + CuO → Cu + ZnO.

Zinc (II) oxide ZnO - white crystals, when heated, acquire a yellow color. Density 5.7 g / cm 3, sublimation temperature 1800 ° C. At temperatures above 1000 ° C, it is reduced to metallic zinc by carbon, carbon monoxide and hydrogen:
ZnO + C → Zn + CO;
ZnO + CO → Zn + CO 2;
ZnO + H 2 → Zn + H 2 O.

Does not interact with water. Shows amphoteric properties, reacts with solutions of acids and alkalis:
ZnO + 2HCl → ZnCl 2 + H 2 O;
ZnO + 2NaOH + H 2 O → Na 2.

When fusion with metal oxides forms zincates:
ZnO + CoO → CoZnO 2.

When interacting with non-metal oxides, forms salts, where it is a cation:
2ZnO + SiO 2 → Zn 2 SiO 4,
ZnO + B 2 O 3 → Zn (BO 2) 2.

Zinc (II) hydroxide Zn (OH) 2 - a colorless crystalline or amorphous substance. Density 3.05 g / cm 3, at temperatures above 125 ° C decomposes:
Zn (OH) 2 → ZnO + H 2 O.

Zinc hydroxide exhibits amphoteric properties, easily dissolves in acids and alkalis:
Zn (OH) 2 + H 2 SO 4 → ZnSO 4 + 2H 2 O;
Zn (OH) 2 + 2NaOH → Na 2;

also readily dissolves in aqueous ammonia to form tetraamminezinc hydroxide:
Zn (OH) 2 + 4NH 3 → (OH) 2.

It is obtained in the form of a white precipitate when zinc salts react with alkalis:
ZnCl 2 + 2NaOH → Zn (OH) 2 + 2NaCl.

Element zinc(Zn) in the periodic table has a serial number 30. It is in the fourth period of the second group. The atomic weight is 65.37. Distribution of electrons in 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 turns into vapor; its density is 7.14 g / cm3. At ordinary temperatures, zinc is quite fragile, but at 100-110 ( With it bends well and rolls into sheets. In air, zinc is covered 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 in the series of voltages much more to the left of hydrogen. This is due to 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 dissolves easily to form the corresponding salts. In addition, zinc, like beryllium and other metals that form amphoteric hydroxides, dissolves in alkalis. If you heat zinc in air to the boiling point, then its vapors ignite and burn with a greenish-white flame, forming zinc oxide.

Average zinc content in earth crust - 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 water migrant; its migration in thermal waters together with lead is especially characteristic. Zinc sulfides, which are of great industrial importance, are precipitated from these waters. Zinc also vigorously migrates to surface and groundwater, the main precipitant for it is hydrogen sulfide, a lesser role is played by sorption by clays and other processes.
Zinc is an important biogenic element; living organisms contain on average 5 · 10-4% zinc. But there are exceptions - the so-called concentrating organisms (for example, some violets).

Zinc deposits

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

Getting zinc

Zinc in nature as a native metal is not found.
Zinc is mined from polymetallic ores containing 1-4% Zn in the form of sulfide, as well as Cu, Pb, Ag, Au, Cd, Bi. The ores are enriched by selective flotation, obtaining zinc concentrates (50-60% Zn) and simultaneously 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 consumed in the production of 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 roasted concentrate is subjected to sintering to impart granularity and gas permeability, and then reduced with coal or coke at 1200-1300 ° C: ZnO + C \u003d Zn + CO. The resulting metal vapors are condensed and poured into molds. At first, restoration was carried out only in manually operated baked clay retorts; later, vertical mechanized carborundum retorts began to be used, then - shaft and electric arc furnaces; zinc is obtained from lead-zinc concentrates in blast shaft furnaces. The 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), reaching a purity of 98.7%. Sometimes used more complex and expensive cleaning rectification gives a metal with a purity of 99.995% and allows you to extract cadmium.

The main method for producing zinc is electrolytic (hydrometallurgical). Fired concentrates are treated with sulfuric acid; the resulting sulfate solution is purified from impurities (by precipitating them with zinc dust) and subjected to electrolysis in baths tightly lined with lead or vinyl plastic. Zinc is deposited on aluminum cathodes, from which it is removed (stripped) daily and melted in induction furnaces. Usually, the purity of electrolyte 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 wastes; sometimes also In, Ga, Ge, Tl.

Biological role

The body of an adult contains an average of 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 matter, promoting their deprotonation by reaction:

Zn2 + + H2O \u003d ZnOH + + H +
The most studied enzyme is carbonic anhydrase - a protein containing zinc and consisting of about 260 amino acid residues. This enzyme is contained 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 is transported by blood to the lungs, where it is excreted from the body in the form of carbon dioxide. In the absence of the enzyme, the conversion of CO2 into the HCO3- anion proceeds at a very low rate. In the carbonic anhydrase molecule, a zinc atom is linked to three imidazole groups of the amino acid residues histidine and a water molecule, which is easily deprotonated, turning into a coordinated hydroxide. The carbon atom of the carbon dioxide molecule, on which there is 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 a factor of 10 million.

Application of zinc

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

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

Zinc plates are widely used in printing, in particular, for printing illustrations in large editions. For this, since the 19th century, zincography has been used - the manufacture of a cliche on a zinc plate by etching the pattern in it with acid. Impurities, with the exception of a small amount of lead, impair the etching process. Before etching, the zinc plate is subjected to annealing and rolled in a heated state.
Zinc is incorporated into many brazing alloys to lower their melting point.
Zinc oxide is widely used in medicine as an antiseptic and anti-inflammatory agent. Zinc oxide is also used for the production of paint - zinc white.

Zinc - an important component of brass. Alloys of zinc with aluminum and magnesium (TsAM, 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 weaponry, pistol bolts are sometimes cast from 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 pens, carburetor bodies, scale models and all kinds of miniatures, as well as any other products that require precision casting with acceptable strength.

Zinc chloride Is an important flux for brazing metals and components in fiber production.
Zinc sulfide is used in the manufacture of short afterglow phosphors and other luminescent compounds, usually mixtures of ZnS and CdS, activated by ions of other metals. Phosphors based on zinc and cadmium sulphides are also used in the electronics industry for the production of luminous flexible panels and screens as electroluminescent phosphors and compositions with a short decay time.
Telluride, selenide, phosphide, zinc sulfide are widely used semiconductors. Zinc sulphide is a constituent of many phosphors. Zinc phosphide is used as a poison for rodents.
Zinc selenide is used to make optical glasses with very low absorption in the mid-infrared, for example, in carbon dioxide lasers.

Different uses of zinc account for:

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