Formula of zinc oxide in chemistry. Chemical properties of zinc and its compounds. What effect does zinc oxide have on humans?

Zinc oxide ZnO - semiconductor connection. Zinc oxide is a white compound that sublimates at 2000 K, melts at a temperature of 2250 K, exhibits both basic and acidic properties, and dissolves in acids and alkalis.

The most common crystal modification is the hexagonal wurtzite type. A rarer cubic type of sphalerite is also known.

Zinc oxide can be obtained by burning or oxidizing zinc, by roasting zinc sulfide in air, by calcination
salts, precipitation with ammonia from a boiling aqueous solution of zinc nitrate.

Compact samples of zinc oxide (zincite) are obtained by pressing blanks from a powdered compound and their subsequent sintering. Preliminary sintering is carried out at 1100 K. final sintering is carried out at 1700... 1800 K. Heating is carried out either in special high-temperature furnaces, or by directly passing current through the samples after they have been preheated to a temperature at which sufficient electrical conductivity occurs. At a final sintering temperature of 1700...1800 K, coarse-grained samples with crystals up to 2 mm are formed. To obtain a finer-grained structure, the sintering temperature is reduced to 1300... 1400 K. Zinc oxide single crystals are grown hydrothermally and from the gas phase.

Thin films of zinc oxide ZnO can be obtained by evaporation and condensation of zinc onto a substrate in a vacuum, followed by oxidation of the metal film when heated in an oxygen atmosphere or by reactive two-electrode ion sputtering Zn in an Ar + O 2 atmosphere.

ZnO thin films detect the piezoelectric effect.

Basic properties of zinc oxide

Molecular weight 81.38

Crystal structure G

Crystal lattice constants, nm:

A 0.3250

C 0.5206

Density, Mg/m 3 5.67

Temperature, K:

melting 2250

boiling point 2000

Specific heat capacity, J/(kg× K) 495

Temperature coefficient of linear expansion for
single crystal, α× I 0 6 , K -1 5.7 ||

A

5.2 || With

Specific resistance, Ohm× cm 10 8 …10 9

Thermal conductivity coefficient, W/(m

× K) 15…30

Hardness on the Mohs scale 4.0…5.0

Refractive index 1.96

Zinc oxide is used in radio electronics for the production of self-activated phosphor ZnO:Zn. This phosphor is obtained by calcination ZnO in a weakly reducing atmosphere of carbon monoxide at 1270 K - The glow color of the phosphor is blue-green, the emission is characterized by two maxima, occurring at wavelengths of 0.385 microns (ultraviolet region) and 0.505 microns (blue-green part of the spectrum). This phosphor has a very short afterglow, about 2 μs.

The main use of zinc oxide is in the production of varistors, devices whose electrical resistance strongly depends on the applied voltage. Based on varistors, surge suppressors (OSLs) are created that suppress overvoltages in electrical networks.

This is due to the special property of varistors - the nonlinearity of the current-voltage characteristic. Silicon carbide also has nonlinearity in the current-voltage characteristic, but the nonlinearity coefficient of varistors based on zinc oxide is 1-1.5 orders of magnitude greater.

To make varistors, submicron-sized ZnO powder, oxides of other metals ~5% (bismuth, cobalt, antimony, manganese, chromium) and inorganic binders are mixed, molded under pressure ~10 4 ... 10 6 MPa and fired for several hours at temperatures from 1200 to 1600 °C. During the reaction interaction, material is transferred through the liquid phase from zinc oxide grains with high surface energy to grains with lower surface energy. The material is compacted during the sintering process, resulting in a new polycrystalline structure.

A zinc oxide varistor is a polycrystalline semiconductor material whose individual grains are in electrical contact with each other. At the points of contact of zinc oxide grains there are thin insulating regions, which cause the nonlinearity of the current-voltage characteristic. The mechanism of varistor nonlinearity has not been sufficiently studied. Most likely, the nonlinearity is due to phenomena at grain boundaries, and additional additives in the varistors also have a decisive influence.

Ministry of Education and Science of the Russian Federation

federal state budgetary educational institution

higher professional education

PETROZAVODSK STATE UNIVERSITY

Faculty of Medicine

Abstract on the discipline "Pharmaceutical Chemistry"

Subject: Zinc oxide. Zinc sulfate.

The work was completed by a fourth-year student

Specialty: pharmacy

Correspondence department

Group: 73Z42

Rigoeva Anna Sergeevna

Checked the work

Teacher:

Ermakova Galina Vladimirovna

Petrozavodsk 2012

Zinc is an element of the secondary subgroup of the second group, the fourth period of the periodic table of chemical elements of D. I. Mendeleev, with atomic number 30.

Denoted by the symbol Zn (lat. Zincum).

The simple substance zinc under normal conditions is a brittle transition metal of a bluish-white color (it becomes dull in air, becoming covered with a thin layer of zinc oxide).

A typical example of a metal that forms amphoteric compounds. Zinc compounds ZnO and Zn(OH)2 are amphoteric. The standard electrode potential is −0.76 V, in the series of standard potentials it is located up to iron.

In air, zinc is coated with a thin film of ZnO oxide. When heated strongly, it burns to form amphoteric white oxide ZnO:

Zinc oxide reacts both with acid solutions:

and with alkalis:

Zinc of ordinary purity reacts actively with acid solutions:

and alkali solutions: 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 CuSO4 are added.

When heated, zinc reacts with halogens to form the halides ZnHal2. With phosphorus, zinc forms phosphides Zn3P2 and ZnP2. With sulfur and its analogues - selenium and tellurium - various chalcogenides, ZnS, ZnSe, ZnSe2 and ZnTe.

Zinc does not react directly with hydrogen, nitrogen, carbon, silicon and boron. Zn3N2 nitride is obtained by reacting zinc with ammonia at 550-600 °C.

In aqueous solutions, zinc ions Zn2+ form aqua complexes 2+ and 2+.

zinc sulfate

ZnSO4, colorless crystals. Dissolves in water. ZnSO4·7H2O - zinc sulfate - crystallizes from solutions. Used in the production of viscose, glazes, and to protect wood from rotting.

ZINC SULFATE

ZINC SULFATE (zinc sulphate) Zinci sulfas, ZnSO4. ZnSO4 · 7H2O - zinc sulfate - crystallizes from solutions. Used in the production of viscose, glazes, and to protect wood from rotting.

Characteristic:

Colorless transparent crystals or fine crystalline powder with an astringent taste, odorless. It erodes when exposed to air. Very easily soluble in water, practically insoluble in ethanol, slowly soluble in glycerol (1:10). Aqueous solutions are acidic.

Zinc sulfate has antimicrobial, astringent, drying and local anti-inflammatory effects.

Application:

Conjunctivitis, laryngitis, urethritis, vaginitis - locally; the need to induce vomiting - orally in high doses; zinc deficiency in the body with disturbances of anabolic, immunological and other processes (prevention and treatment) - orally; hypogonadism, alopecia areata, cerebral palsy, liver disease, diabetes mellitus, diffuse connective tissue diseases, etc. (as part of complex therapy) - orally.

Contraindications:

Hypersensitivity.

Side effects:

Nausea, vomiting, diarrhea (when taking high doses orally).

Zinc sulfate, zinc sulfate, ZnSO4 - zinc salt of sulfuric acid.

Colorless crystals, density 3.74 g/cm³. Solubility in water (%): 29.4 (0 °C), 37.7 (99 °C). From solutions at temperatures below 38.8 °C, ZnSO4 7H2O (zinc sulfate) crystallizes, in the range from 38.8 °C to 70 °C - ZnSO4 6H2O, above 70 °C ZnSO4 H2O monohydrate is formed. The latter is dehydrated at 238 °C. Zinc sulfate in the range of 600-900 °C decomposes into ZnO and SO3. Weak solutions of zinc sulfate become cloudy during hydrolysis due to the release of precipitate 3Zn(OH)2 ZnSO4 4H2O.

Receipt

Zinc sulfate is obtained by evaporation and crystallization from solutions (along with the production of zinc). Zn+H2SO4=ZnSO4+H2

Application

It is used in the production of viscose, mineral paints, glazes, in metallurgy (flotation agent) and in medicine.

Active ingredient/beginning: zinc (zinc sulfate, picolinate, asparaginate)

Bio-zinc; Solgar zinc picolinate; Zinc sulfate; Zinc aspartate; Zinc picolinate; Zinc sulfate; Zincite; Zincteral.

It is used for liver diseases (cirrhosis), enteritis, enteropathic dermatitis, psoriasis, collagenosis (rheumatoid arthritis, lupus erythematosus), cerebral palsy, and frequent colds. Used locally for conjunctivitis, laryngitis, urethritis, vaginitis.

Zinc (zinc sulfate, picolinate, aspartate).

Dosage forms:

Effervescent tablets.

Eye drops.

Solution for external use.

Zinc (zinc sulfate, picolinate, aspartate)

Properties / Action:

Zinc is an important trace element. It is a component of more than 90 different enzymes that synthesize DNA and participate in metabolic processes. Zinc stimulates the synthesis of nucleic acids, proteins, tissue regeneration, and promotes weight gain. Zinc is necessary for the functioning of insulin, sex hormones, maintains the stability of cell membranes, limiting the release of histamine from mast cells. It limits free radical reactions and prevents damage to cell membranes. Zinc is necessary for the normal activity of lymphoid tissue, alkaline phosphatase, carboxypeptidases, and alcohol dehydrogenase.

Zinc increases resistance to infectious diseases, promotes wound healing, accelerates growth, increases performance, improves memory, and prevents hair loss.

Certain population groups, such as pregnant women, nursing mothers, adolescents, athletes and vegetarians, have an increased need for zinc. The cause of zinc deficiency may be insufficient intake of it in the body or poor nutrition, unbalanced diets, impaired absorption of zinc (for example, in intestinal diseases) or increased release of zinc, for example, with alcoholism, taking laxatives or other medications.

Indications:

Elimination of hypozincemia, incl. with disturbances of anabolic, immunological and other processes, which can occur with liver diseases (especially with cirrhosis), steatorrhea, enteritis, helminthic infestation, enteropathic acrodermatitis, psoriasis, renal diseases, hypovitaminosis D, and burns.

Preventively for the following conditions: diabetes mellitus, collagenosis (rheumatoid arthritis, lupus erythematosus), hypogonadism, alopecia areata, cerebral palsy, frequent colds, taking glucocorticoids, pregnancy and lactation.

Topical (zinc sulfate):

Conjunctivitis, laryngitis, urethritis, vaginitis.

Directions for use and dosage:

On an empty stomach, in pills or effervescent tablets. To prevent hypozincemia, 10 mg of zinc 1-2 times a day. For therapeutic purposes - 20-50 mg 2-3 times a day.

Topical (zinc sulfate):

For conjunctivitis - eye drops 0.1-0.5%, for laryngitis - lubrication or spraying with a 0.25-0.5% solution, for urethritis and vaginitis - douching with a 0.1-0.5% solution.

Overdose:

Possible after oral administration: fever, pulmonary dysfunction, dehydration, plasma electrolyte imbalance, lethargy, muscle movement disorders, renal failure.

Contraindications:

active autoimmune processes, especially immune encephalitis;

acute renal failure, severe parenchymal kidney damage.

Use during pregnancy and lactation:

Use is possible only with proven zinc deficiency in the body.

Side effect:

Appears when taking large doses. In this case, dyspeptic disorders (nausea, vomiting, diarrhea), dehydration, imbalance of electrolytes in the blood plasma, lethargy, and renal failure are observed.

When used in therapeutic doses, complications occur extremely rarely.

Storage conditions:

At room temperature not higher than 25C.

Keep out of the reach of children.

Expiration dates are indicated on the packaging. The drug cannot be used after the expiration date.

Dispensed from a pharmacy: without a doctor's prescription.

Zinc oxide (Zincioxidum)

White or white with a yellowish tint, amorphous, odorless powder. Absorbs carbon dioxide from the air .

Practically insoluble in water and alcohol, soluble in alkali solutions, diluted mineral acids, and also in acetic acid.

When heated, the substance changes color: white at room temperature, zinc oxide becomes yellow. This is explained by a decrease in the band gap and a shift of the edge in the absorption spectrum from the UV region to the blue.

Zinc oxide is amphoteric - reacts with acids to form salts; when interacting with alkali solutions, it forms complex tritetra- and hexahydroxyzincates (Na2, Ba2):

OH-2-

Zinc oxide dissolves in an aqueous ammonia solution, forming complex ammonia:

ZnO + 4NH3 + H20 - (OH)2

When fused with alkalis and metal oxides, zinc oxide forms zincates:

ZnO + 2NaOH Na2ZnO2 + H2O

ZnO + CoO CoZnO2

When fused with boron and silicon oxides, zinc oxide forms glassy borates and silicates:

ZnO + B2O3 Zn(BO2)2

ZnO + SiO2 ZnSiO3

Receipt

natural mineral zincite

burning zinc vapor in oxygen (“French process”)

thermal decomposition of compounds:

acetate Zn(CH3COO)2

hydroxide Zn(OH)2

carbonate ZnCO3

nitrate Zn(NO3)2

oxidative roasting of ZnS sulfide

hydrothermal synthesis

extraction from dust and sludge of metallurgical plants, especially those that operate on scrap metal as a raw material (it contains a significant proportion of galvanized iron).

extraction from the ternary phase equilibrium system “zinc nitrate-amine nitrate-water” (with pyridine and quinoline nitrate, particle size of the order of 5-10 nm up to 75%)

Application

vulcanization activator for some rubbers

vulcanizing agent for chloroprene rubbers

methanol synthesis catalyst

white pigment in the production of paints and enamels (currently (2007) replaced by non-toxic titanium dioxide TiO2)

filler and pigment in production:

plastics

perfumes and cosmetics

In medicine in the form of powders and as part of ointments as an antiseptic.

animal feed additive

in the production of glass and paints based on liquid glass

as one of the components of a rust converter

It is also known that zinc oxide has photocatalytic activity, which is used in practice to create self-cleaning surfaces, bactericidal coatings for walls and ceilings in hospitals, etc. Zinc oxide is not currently used for photocatalytic water purification on an industrial scale.

In addition, zinc oxide powder is a promising material as a working medium for powder lasers. A blue LED was created based on zinc oxide. Thin films and other nanostructures based on zinc oxide can be used as sensitive gas and biological sensors.

The properties of zinc oxide make it widely used in the pharmaceutical industry. Zinc oxide has found wide application in the creation of abrasive toothpastes and cements in therapeutic dentistry, in tanning creams and cosmetic procedures, in the production of electrical cables, artificial leather and rubber products. In addition, the application is widespread in the tire, paint and varnish, and oil refining industries. Zinc oxide is involved in the production of glass and ceramics.

Zinc oxide preparations are anti-inflammatory dermatotropic agents with a drying effect for external use. Zinc oxide also has an adsorbent, astringent and antiseptic effect; forms albuminates and denatures proteins. Reduces the phenomena of exudation, inflammation and tissue irritation, forms a protective barrier against irritating factors. Soothes irritated skin. Used as a remedy with a protective effect for eczema (in the acute stage), dermatitis (diaper dermatitis, contact dermatitis), diaper rash, prickly heat, bedsores, superficial wounds, cuts, scratches, burns, ulcerative skin lesions, herpes simplex, streptoderma, trophic ulcers.

Active ingredient:

Zinc oxide / Zinc oxide.

Dosage forms:

Liniment.

Zinc oxide

Properties / Action:

Zinc oxide exhibits a weak astringent effect and is used as a remedy with a protective effect for eczema and flaking of the skin.

Indications:

intertrigo;

dermatitis, incl. diaper dermatitis (diaper rash in infants), contact dermatitis;

bedsores;

superficial wounds, cuts, scratches;

burns (thermal, solar);

ulcerative skin lesions;

eczema in the acute stage;

herpes simplex;

streptoderma;

trophic ulcers.

Directions for use and dosage:

Zinc oxide preparations are used externally, in the form of ointments, pastes, and liniment.

Wash and dry the affected area. Apply to cleansed and dried skin.

Zinc oxide preparations are applied in a thin layer to the affected areas of the skin 4-6 times a day.

The course of treatment is up to 1 month.

The amount of the drug applied depends on the extent of the lesion.

Minor thermal and sunburns, cuts, scratches, wounds - apply a thin layer to the affected surface, if necessary, apply a gauze bandage.

Diaper rash in children - if the first signs of hyperemia, diaper rash or minor skin irritation appear, the ointment is applied 3 or more times a day, if necessary, during each diaper change; Preventively treat areas of the body that are in prolonged contact with wet laundry with the drug.

Contraindications:

individual intolerance (including a history of hypersensitivity) to zinc oxide.

Side effects:

Allergic reactions (skin itching, hyperemia, skin rash).

Special instructions and precautions:

For external use only. Avoid contact with eyes.

The ointment is applied only to superficial and uninfected lesions and is not used to treat pustular skin lesions. Not intended for prescribing treatment without the participation of a physician.

The drug is not contraindicated during pregnancy and breastfeeding.

Drug interactions:

Not described.

Storage conditions:

At temperatures up to 30°C, away from heat sources and direct sunlight.

The shelf life is indicated on the packaging.

Dispensed from a pharmacy - without a doctor's prescription.

A trace element that plays an important role in cell metabolism and stabilization of cell membranes. It is an integral part of many enzyme systems, in which it is either a coenzyme or an integral part of the enzyme. Takes part in the regulation of protein and carbohydrate synthesis. The presence of zinc is a necessary condition for the normal functioning of the immune system. Zinc has a positive effect on memory, promotes the absorption of vitamin A, necessary for maintaining vision, facilitates accumulation in the body and prolongs its effect, supports the process of tissue repair and wound healing. Zinc is essential for normal growth and reproduction. Zinc deficiency occurs in cases of parenteral treatment without appropriate nutritional supplements, in chronic intestinal diseases (such as colitis and Crohn's disease), in patients with intestinal fistulas, in certain skin diseases (for example, in acrodermatitis enteropathica), less often in the case of cirrhosis of the liver, in renal failure, gastric resection. In cases of zinc deficiency, there is impaired concentration, taste disorders, lack of appetite, decreased immunity, poor wound healing, increased blood pressure, hypercholesterolemia, night blindness, prostatic hyperplasia, impaired growth in children, and in cases of significant zinc deficiency - dermatological diseases such such as focal and malignant alopecia. The average zinc content in the body is 1.4–2.3 g, of which about 98% is found inside cells (mainly in red blood cells, skin, sperm, prostate gland, bones, intestinal mucosa). Some zinc compounds (for example, zinc oxide) have astringent and drying properties. Zinc sulfate has anti-inflammatory properties. After oral administration, zinc salts are poorly absorbed from the gastrointestinal tract (by approximately 20–40%). The average concentration of zinc in the blood is 11.3–17.6 mmol/l. Zinc is excreted from the body mainly in feces.

Zinc oxide: application

Treatment of diseases associated with zinc deficiency or its low content in the body, such as enteropathic acrodermatitis, focal and malignant alopecia, purulent acne, chronic neurodermatitis when replacing steroids with corticosteroids, hair fragility, impaired wound healing, immune disorders, psychoneurological disorders, sexual dysfunctions in men, growth and vision disorders in children. The drug in the form of chewable tablets is used to remove bad breath. Helpful for Wilson's disease. Externally in dermatology for itchy places on the skin, difficult-to-heal wounds, for chronic inflammation of the skin, eczema; in ophthalmology - for conjunctivitis.

Contraindications

Hypersensitivity to the drug; renal failure. Should not be used externally on wounds that are oozing or covered with scabs. Interaction with other drugs You should not take zinc-containing drugs and tetracycline at the same time (zinc reduces its absorption), as well as iron compounds, acetylsalicylic acid, indomethacin, thiazide diuretics, chelating agents (D-penicillamine), corticosteroids. Side effects Nausea, vomiting, abdominal pain, diarrhea, headache, metallic taste in the mouth. As a result of long-term use of zinc salts, anemia and copper deficiency in the body may occur.

Pregnancy and lactation

There is no information regarding the safety of using drugs containing zinc during pregnancy and lactation.

Dosage

The daily requirement for zinc, depending on age, is: children under 10 years old: 5 mg, children and adolescents 10–15 years old: 15 mg, adults: 15–20 mg. During pregnancy and lactation, the need for zinc increases to 25 mg/day. Acrodermatitis enteropathica, alopecia areata: orally before meals, an average of 45 mg 3 times a day, reducing the dose as the condition improves. The tablets should not be split or chewed. Externally – lubricate sore spots on the skin 1–3 times a day. See also: descriptions of drugs.

• Designation - Zn (Zincum);
• Period - IV;
• Group - 12 (IIb);
• Atomic mass - 65.39;
• Atomic number - 30;
• Atomic radius = 138 pm;
• Covalent radius = 125 pm;
• Electron distribution - 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 ;
• melting temperature = 419.88°C;
• boiling point = 907°C;
• Electronegativity (according to Pauling/according to Alpred and Rochow) = 1.65/1.66;
• Oxidation state: +2.0;
• Density (no.) = 7.13 g/cm3;
• Molar volume = 9.2 cm 3 /mol.

People used zinc even before our era in the form of its alloy with copper - brass. For the first time, pure zinc was isolated by the Englishman William Champion in the 18th century.

The earth's crust contains 8.3·10 -3% zinc by mass. A lot of zinc is contained in thermal springs, from which the precipitation of zinc sulfides, which are of industrial importance, occurs. Zinc plays an active role in the life of animals and plants, being an important biogenic microelement.

Rice. Structure of the zinc atom.

The electronic configuration of the zinc atom is 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 2 (see Electronic structure of atoms). The penultimate electron layer of the zinc atom is completely filled, and on the outer layer there are two s-electrons, which interact with other elements, therefore the oxidation state +2 appears in zinc compounds. (see Valence). Zinc has high chemical activity.

Physical properties of zinc:

• bluish-white metal;
• fragile when n. y.;
• when heated above 100°C, it is well forged and rolled;
• has good thermal and electrical conductivity.

Chemical properties of zinc:

• in air it quickly oxidizes, becoming covered with a thin film of zinc oxide, which protects the metal from further reaction;
• when heated, it reacts with oxygen, chlorine, sulfur, forming oxides, chlorides, sulfides, respectively:
  2Zn + O 2 = 2ZnO; Zn + Cl 2 = ZnCl 2; Zn + S = ZnS.
• reacts with dilute sulfuric acid and solutions of non-oxidizing acids, displacing hydrogen from them:
  Zn + H 2 SO 4 (rzb.) = ZnSO 4 + H 2; Zn + 2HCl = ZnCl 2 + H 2;
• reacts with nitric and concentrated sulfuric acid, reducing nitrogen or sulfur, respectively:
  Zn + H 2 SO 4 (conc.) = ZnSO 4 + SO 2 + 2H 2 O;
• reacts when heated with alkali solutions, forming hydrozincates: Zn + 2NaOH + 2H 2 O = Na 2 + H 2 ;
• displaces less active metals (see electrochemical series of metal voltages) from solutions of their salts: Zn + CuCl 2 = ZnCl 2 + Cu.

Obtaining zinc:

• pure zinc is obtained by electrolysis of its salts;
• Industrially, zinc is obtained from sulfide ores:
  • at the first stage, zinc oxide is obtained by subjecting the ore to oxidative roasting: 2ZnS + 3O 2 = 2ZnO + 2SO 2;
  • in the second stage, zinc oxide is reduced with coal at high temperature: ZnO + C = Zn + CO.

Applications of zinc:

• as an anti-corrosion coating for metal products (zinc plating);
• for the production of alloys widely used in mechanical engineering;
• in batteries and dry cells;
• in the paint and varnish industry (production of zinc white);
• as a reducing agent in organic synthesis reactions.

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 wt. %. 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 H2O 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 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 the dyeing of 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.