Acid-base properties of copper. Book traversal links for Copper native property formula

Copper

Copper(lat. Cuprum) - a chemical element of group I of the periodic system of Mendeleev (atomic number 29, atomic mass 63.546). In compounds, copper usually exhibits oxidation states +1 and +2, and a few compounds of trivalent copper are also known. The most important copper compounds: oxides Cu 2 O, CuO, Cu 2 O 3; hydroxide Cu (OH) 2, nitrate Cu (NO 3) 2. 3H 2 O, sulfide CuS, sulfate (copper sulfate) CuSO 4. 5H 2 O, CuCO 3 Cu(OH) 2 carbonate, CuCl 2 chloride. 2H2O.

Copper- one of the seven metals known from ancient times. The transitional period from the Stone Age to the Bronze Age (4th - 3rd millennium BC) was called copper age or chalcolithic(from the Greek chalkos - copper and lithos - stone) or Chalcolithic(from Latin aeneus - copper and Greek lithos - stone). During this period, copper tools appear. It is known that copper tools were used in the construction of the pyramid of Cheops.

Pure copper is a malleable and soft metal of reddish, pink in fracture, in places with brown and variegated tint, heavy (density 8.93 g / cm 3), an excellent conductor of heat and electricity, second only to silver in this respect (melting point 1083 ° C). Copper is easily drawn into a wire and rolled into thin sheets, but is relatively little active. In dry air and oxygen under normal conditions, copper does not oxidize. But it reacts quite easily: already at room temperature with halogens, for example, with wet chlorine, it forms CuCl 2 chloride, when heated with sulfur, it forms Cu 2 S sulfide, with selenium. But copper does not interact with hydrogen, carbon and nitrogen even at high temperatures. Acids that do not have oxidizing properties do not act on copper, for example, hydrochloric and dilute sulfuric acids. But in the presence of atmospheric oxygen, copper dissolves in these acids with the formation of the corresponding salts: 2Cu + 4HCl + O 2 = 2CuCl 2 + 2H 2 O.

In an atmosphere containing CO 2, H 2 O vapors, etc., it becomes covered with a patina - a greenish film of basic carbonate (Cu 2 (OH) 2 CO 3)), a toxic substance.

Copper is included in more than 170 minerals, of which only 17 are important for industry, including: bornite (variegated copper ore - Cu 5 FeS 4), chalcopyrite (copper pyrite - CuFeS 2), chalcocite (copper luster - Cu 2 S) , covelline (CuS), malachite (Cu 2 (OH) 2 CO 3). There is also native copper.

copper density, specific gravity copper and other characteristics of copper

Density - 8.93 * 10 3 kg / m 3;
Specific gravity - 8.93 g/cm3;
Specific heat at 20 °C - 0.094 cal/deg;
Melting temperature - 1083°C;
Specific heat of fusion - 42 cal/g;
Boiling temperature - 2600°C;
Linear expansion coefficient(at a temperature of about 20 ° C) - 16.7 * 10 6 (1 / deg);
Coefficient of thermal conductivity - 335 kcal / m * hour * hail;
Resistivity at 20 °C - 0.0167 Ohm * mm 2 / m;

Elastic modulus of copper and Poisson's ratio


COPPER COMPOUNDS

Copper (I) oxide Cu 2 O 3 and cuprous oxide (I) Cu2O, like other copper (I) compounds, are less stable than copper (II) compounds. Copper (I) oxide, or copper oxide Cu 2 O, occurs naturally in the form of the mineral cuprite. In addition, it can be obtained as a precipitate of red copper (I) oxide by heating a solution of copper (II) salt and alkali in the presence of a strong reducing agent.

Copper(II) oxide, or copper oxide, CuO- a black substance found in nature (for example, in the form of the mineral tenerite). It is obtained by calcining copper (II) hydroxocarbonate (CuOH) 2 CO 3 or copper (II) nitrate Cu(NO 2) 2 .
Copper(II) oxide is a good oxidizing agent. Copper hydroxide (II) Cu (OH) 2 precipitated from solutions of copper (II) salts under the action of alkalis in the form of a blue gelatinous mass. Already at low heating, even under water, it decomposes, turning into black oxide of copper (II).
Copper(II) hydroxide is a very weak base. Therefore, solutions of copper (II) salts in most cases are acidic, and with weak acids, copper forms basic salts.

Copper (II) sulfate CuSO 4 in the anhydrous state, it is a white powder, which turns blue when water is absorbed. Therefore, it is used to detect traces of moisture in organic liquids. An aqueous solution of copper sulfate has a characteristic blue-blue color. This color is characteristic of hydrated ions 2+, therefore, all dilute solutions of copper (II) salts have the same color, unless they contain any colored anions. From aqueous solutions, copper sulfate crystallizes with five molecules of water, forming transparent blue crystals of copper sulphate. Copper sulphate is used for the electrolytic coating of metals with copper, for the preparation of mineral paints, and also as a starting material in the preparation of other copper compounds. AT agriculture A dilute solution of copper sulphate is used to spray plants and dress grains before sowing to kill spores of harmful fungi.

Copper (II) chloride CuCl 2 . 2H2O. Forms dark green crystals, easily soluble in water. Very concentrated solutions of copper chloride (II) are green, dilute - blue-blue.

Copper (II) nitrate Cu (NO 3) 2. 3H2O. Obtained by dissolving copper in nitric acid. When heated, blue crystals of copper nitrate first lose water, and then easily decompose with the release of oxygen and brown nitrogen dioxide, turning into copper (II) oxide.

Copper (II) hydroxocarbonate (CuOH) 2 CO 3. It occurs naturally in the form of the mineral malachite, which has a beautiful emerald green color. It is artificially prepared by the action of Na 2 CO 3 on solutions of copper (II) salts.
2CuSO 4 + 2Na 2 CO 3 + H 2 O \u003d (CuOH) 2 CO 3 ↓ + 2Na 2 SO 4 + CO 2
It is used to obtain copper chloride (II), for the preparation of blue and green mineral paints, as well as in pyrotechnics.

Copper (II) acetate Cu (CH 3 COO) 2. H2O. Obtained by treating metallic copper or copper (II) oxide with acetic acid. Usually it is a mixture of basic salts of various composition and color (green and blue-green). Under the name verdigris, it is used for the preparation of oil paint.

Complex compounds of copper are formed as a result of the combination of doubly charged copper ions with ammonia molecules.
Various mineral paints are obtained from copper salts.
All copper salts are poisonous. Therefore, in order to avoid the formation of copper salts, copper dishes are coated from the inside with a layer of tin (tinned).


COPPER PRODUCTION

Copper is mined from oxide and sulfide ores. 80% of all mined copper is smelted from sulfide ores. As a rule, copper ores contain a lot of waste rock. Therefore, an enrichment process is used to obtain copper. Copper is obtained by smelting it from sulfide ores. The process consists of a number of operations: roasting, melting, converting, fire and electrolytic refining. During the roasting process, most of the impurity sulfides are converted into oxides. So, the main impurity of most copper ores pyrite FeS 2 turns into Fe 2 O 3. The gases generated during roasting contain CO 2 , which is used to produce sulfuric acid. The oxides of iron, zinc and other impurities obtained during the roasting process are separated in the form of slag during smelting. Liquid copper matte (Cu 2 S with an admixture of FeS) enters the converter, where air is blown through it. During the conversion, sulfur dioxide is released and blister or raw copper is obtained. To extract valuable (Au, Ag, Te, etc.) and to remove harmful impurities, blister copper is first subjected to fire and then electrolytic refining. During fire refining, liquid copper is saturated with oxygen. In this case, impurities of iron, zinc and cobalt are oxidized, pass into slag and are removed. And copper is poured into molds. The resulting castings serve as anodes for electrolytic refining.
The main component of the solution during electrolytic refining is copper sulfate - the most common and cheap copper salt. To increase the low electrical conductivity of copper sulfate, sulfuric acid is added to the electrolyte. And to obtain a compact precipitate of copper, a small amount of additives is introduced into the solution. Metallic impurities contained in crude ("blister") copper can be divided into two groups.

1) Fe, Zn, Ni, Co. These metals have much more negative electrode potentials than copper. Therefore, they dissolve anode together with copper, but do not precipitate on the cathode, but accumulate in the electrolyte in the form of sulfates. Therefore, the electrolyte must be replaced periodically.

2) Au, Ag, Pb, Sn. Noble metals (Au, Ag) do not undergo anodic dissolution, but during the process they settle at the anode, forming, together with other impurities, anode sludge, which is periodically removed. Tin and lead dissolve together with copper, but in the electrolyte they form poorly soluble compounds that precipitate and are also removed.


COPPER ALLOYS

Alloys, which increase the strength and other properties of copper, are obtained by introducing additives into it, such as zinc, tin, silicon, lead, aluminum, manganese, nickel. More than 30% of copper goes to alloys.

Brass- alloys of copper with zinc (copper from 60 to 90% and zinc from 40 to 10%) - stronger than copper and less susceptible to oxidation. When silicon and lead are added to brass, its anti-friction qualities increase, and when tin, aluminum, manganese and nickel are added, anti-corrosion resistance increases. Sheets and cast products are used in mechanical engineering, especially in chemical engineering, in optics and instrumentation, and in the production of nets for the pulp and paper industry.

Bronzes. Previously, bronzes were called alloys of copper (80-94%) and tin (20-6%). Currently, tinless bronzes are produced, named after the main component after copper.

Aluminum bronzes contain 5-11% aluminum, have high mechanical properties combined with anti-corrosion resistance.

Lead bronzes, containing 25-33% lead, are used mainly for the manufacture of bearings operating under high pressures and high sliding speeds.

silicon bronzes containing 4-5% silicon are used as cheap substitutes for tin bronzes.

Beryllium bronzes, containing 1.8-2.3% beryllium, are distinguished by hardness after hardening and high elasticity. They are used for the manufacture of springs and spring products.

Cadmium bronzes- copper alloys with a small amount of cadmium (up to 1%) - are used for the manufacture of fittings for water and gas lines and in mechanical engineering.

Solders- non-ferrous metal alloys used in soldering to obtain a monolithic brazed seam. Among hard solders, a copper-silver alloy is known (44.5-45.5% Ag; 29-31% Cu; the rest is zinc).


COPPER APPLICATIONS

Copper, its compounds and alloys are widely used in various industries.

In electrical engineering, copper is used in its pure form: in the production of cable products, bare and contact wire tires, power generators, telephone and telegraph equipment and radio equipment. Heat exchangers, vacuum apparatuses, pipelines are made of copper. More than 30% of copper goes to alloys.

Alloys of copper with other metals are used in mechanical engineering, in the automotive and tractor industries (radiators, bearings), and for the manufacture of chemical equipment.

The high viscosity and ductility of the metal make it possible to use copper for the manufacture of various products with a very complex pattern. Red copper wire in the annealed state becomes so soft and ductile that all kinds of cords can be easily twisted from it and the most complex elements of the ornament can be bent. In addition, copper wire is easily soldered with scanned silver solder, it is well silvered and gilded. These properties of copper make it an indispensable material in the production of filigree products.

The coefficient of linear and volumetric expansion of copper during heating is approximately the same as that of hot enamels, and therefore, when cooling, the enamel adheres well to the copper product, does not crack, does not rebound. Due to this, masters for the production of enamel products prefer copper to all other metals.

Like some other metals, copper is one of the vital trace elements. She is involved in the process. photosynthesis and assimilation of nitrogen by plants, promotes the synthesis of sugar, proteins, starch, vitamins. Most often, copper is applied to the soil in the form of pentahydrate sulfate - copper sulfate CuSO 4. 5H 2 O. In large quantities, it is poisonous, like many other copper compounds, especially for lower organisms. In small doses, copper is necessary for all living things.

Copper is a ductile metal of a golden-pink color, which in its pure form is found in nature more often than nuggets of gold or silver. But mostly copper is mined from copper ores - natural mineral formations. Most copper is found in sulfide ores. In oxidation zones, copper is found in most silicates, carbonates, and oxides. Copper is also found in sedimentary rocks: shales and cuprous sandstones.

Modern science knows more than 200 minerals containing copper. In industry, metal extracted from sulfates is most often used, including:

  • Chalcosine (79% copper);
  • Bornite (up to 65%);
  • Chalcopyrite, or copper pyrites (about 35%).

Copper is also found in copper-nickel compounds. The most famous of them is cubanite (up to 45% copper). Of the oxidized ores, it is worth noting cuprite (88%), malachite (up to 58%), azurite (up to 56%). Sometimes there are deposits of native copper.

Characteristics and types of copper

Copper is one of the first metals to be used by man. The chemical symbol is Cu (cuprum). This metal has high thermal conductivity, corrosion resistance, and electrical conductivity. Copper melts at low temperatures, lends itself perfectly to soldering, the metal is easy to cut and process.

Some copper compounds can be toxic to humans. Elevated levels of copper in water and food can cause diseases of the liver and gallbladder. Quarries left after copper mining become sources of toxins. For example, Lake Berkeley Pit, formed in the crater of a former copper mine, is considered the most toxic lake in the world. But, the bactericidal properties of copper are disproportionately higher. It has been proven that copper helps fight influenza viruses, destroys staphylococci.

Pure copper is rarely used in industry. Alloys found more use:

  • Brass (an alloy of copper and zinc);
  • Bronze (with tin);
  • Babbits (with lead);
  • Melchior (with nickel);
  • Dural (with aluminum);
  • Jewelry alloy (with gold).

Deposits and mining of copper

Most large deposit copper in the world is located in Chile - this is the Esconida quarry. Huge deposits of native copper have been discovered here.

Other major deposits:

  • Mines on the Kivino Peninsula (USA, Michigan);
  • Mine "Chukikamata" in Chile (up to 600 thousand tons per year);
  • Mine "Korokoro" Bolivia;
  • Gumishevsky mine (Middle Urals, Russia) - now exhausted;
  • Valley of the Levikha River (Middle Urals, Russia);
  • Massive gabbro (Italy).

According to the US Geological Survey, the largest copper deposits belong to Chile. This is followed by the USA, Russia, Peru and Mexico.

Copper mining methods:

  • Open;
  • Hydrometallurgical - when copper is leached from the rock with a weak solution of sulfuric acid;
  • Pyrometallurgical - consists of several stages (enrichment, roasting, melting to matte, blowing and refining).

Careful attitude to copper ores

Copper ores are non-renewable resources, and therefore their development requires careful treatment, both in mining methods and in industrial processing.

More and more industry is becoming demanding of constant volumes of resources received, which leads to their gradual depletion. For this, it is necessary to more carefully control the extraction of copper ores, along with other non-renewable resources, such as oil, natural gas, to be used more carefully and rationally, both in industrial and domestic consumption.

The use of copper

Copper is one of the most important non-ferrous metals, which has found application in almost all spheres of human life.

  • Electrical industry (wires, wire);
  • Mechanical engineering (starter, power windows, radiators, coolers, bearings);
  • Shipbuilding (hull cladding);
  • Construction (pipes, pipelines, roofing and cladding materials, bathtubs, faucets, sinks);
  • In art (jewelry, statues, coinage);
  • In everyday life (air conditioners, microwave ovens, coins, food additives, musical instruments).

Interestingly, the Statue of Liberty is made of copper. It took about 80 tons of metal for its construction. And in Nepal, copper is considered a sacred metal.

Most industries use a metal such as copper. Due to its high electrical conductivity, no area of ​​electrical engineering can do without this material. From it are formed conductors with excellent operational features. In addition to these features, copper has ductility and refractoriness, corrosion resistance and aggressive environments. And today we will consider the metal from all sides: we will indicate the price for 1 kg of copper scrap, we will tell about its use and production.

Concept and features

Copper is a chemical element belonging to the first group of the Mendeleev Periodic Table. This ductile metal has a golden-pink color and is one of three metals with a pronounced coloration. Since ancient times, it has been actively used by man in many areas of industry.

The main feature of the metal is its high electrical and thermal conductivity. Compared with other metals, the conduction of electric current through copper is 1.7 times higher than that of aluminum, and almost 6 times higher than that of iron.

Copper has a number distinctive features before other metals:

  1. Plastic. Copper is a soft and ductile metal. If we take into account the copper wire, it easily bends, takes any position and does not deform. The metal itself is enough to press a little to check this feature.
  2. Corrosion resistance. This photosensitive material is highly resistant to corrosion. If the copper long term left in a humid environment, a green film will begin to appear on its surface, which protects the metal from negative impact moisture.
  3. Response to rising temperature. Copper can be distinguished from other metals by heating it. In the process, the copper will begin to lose its color and then become darker. As a result, when the metal is heated, it will reach a black color.

These features make it possible to distinguish given material from, and other metals.

The video below will tell you about beneficial features copper:

Pros and cons

The advantages of this metal are:

  • High thermal conductivity;
  • Corrosion resistance;
  • Sufficiently high strength;
  • High plasticity, which is maintained up to a temperature of -269 degrees;
  • Good electrical conductivity;
  • Possibility of alloying with various additional components.

Read about the characteristics, physical and chemical properties of the substance-metal of copper and its alloys below.

Properties and characteristics

Copper, as a low-active metal, does not interact with water, salts, alkalis, and also with weak sulfuric acid, but at the same time it is subject to dissolution in concentrated sulfuric and nitric acid.

Physical properties of metal:

  • The melting point of copper is 1084°C;
  • The boiling point of copper is 2560°C;
  • Density 8890 kg/m³;
  • Electrical conductivity 58 MΩ/m;
  • Thermal conductivity 390 m*K.

Mechanical properties:

  • The tensile strength in the deformed state is 350-450 MPa, in the annealed state - 220-250 MPa;
  • The relative narrowing in the deformed state is 40-60%, in the annealed state - 70-80%;
  • The relative elongation in the deformed state is 5-6 δ ψ%, in the annealed state - 45-50 δ ψ%;
  • The hardness in the deformed state is 90-110 HB, in the annealed state - 35-55 HB.

At temperatures below 0°C, this material has higher strength and ductility than at +20°C.

Structure and compound

Copper, which has a high electrical conductivity, has the lowest content of impurities. Their share in the composition can be equal to 0.1%. In order to increase the strength of copper, various impurities are added to it: antimony, and so on. Depending on its composition and the degree of content of pure copper, several of its grades are distinguished.

The structural type of copper may also include crystals of silver, calcium, aluminum, gold and other components. All of them are distinguished by comparative softness and plasticity. A particle of copper itself has a cubic shape, the atoms of which are located at the tops of the F-cell. Each cell is made up of 4 atoms.

For information on where to get copper, see this video:

Materials production

AT natural conditions this metal is found in native copper and sulfide ores. Widespread in the production of copper received ores called "copper shine" and "copper pyrite", which contain up to 2% of the required component.

Most (up to 90%) of the primary metal is due to the pyrometallurgical method, which includes a lot of stages: enrichment process, roasting, smelting, processing in a converter and refining. The rest is obtained by the hydrometallurgical method, which consists in its leaching of dilute sulfuric acid.

Areas of use

in the following areas:

  • Electrical industry, which consists, first of all, in the production of electrical wires. For these purposes, copper must be as pure as possible, without impurities.
  • Making filigree products. Copper wire in the annealed state is characterized by high ductility and strength. That is why, it is actively used in the production of various cords, ornaments and other designs.
  • Remelting cathode copper into wire. A wide variety of copper products are melted down into ingots, which are ideal for further rolling.

Copper is actively used in the most various fields industry. It can be part of not only wire, but also weapons and even jewelry. Its properties and wide scope of application favorably influenced its popularity.

The video below will show you how copper can change its properties:

The ancient Greeks called this element chalkos, in Latin it is called cuprum (Cu) or aes, and medieval alchemists called this chemical element none other than Mars or Venus. Mankind has long been acquainted with copper due to the fact that in natural conditions it could be found in the form of nuggets, often of very impressive size.

The easy reducibility of carbonates and oxides of this element contributed to the fact that, according to many researchers, our ancient ancestors learned to restore it from ore before all other metals.

At first, copper rocks were simply heated over an open fire, and then cooled sharply. This led to their cracking, which made it possible to carry out the restoration of the metal.

Having mastered such a simple technology, a person began to gradually develop it. People learned to blow air into fires with the help of bellows and pipes, then they thought of installing walls around the fire. In the end, the first shaft furnace was also constructed.

Numerous archaeological excavations have made it possible to establish a unique fact - the simplest copper products already existed in the 10th millennium BC! And copper began to be mined and used more actively after 8-10 thousand years. It is since then that humanity has been using this chemical element, unique in many respects (density, specific gravity, magnetic characteristics, and so on), for its needs.

Today, copper nuggets are extremely rare. Copper is mined from various, among which the following can be distinguished:

  • bornite (it contains up to 65% cuprum);
  • copper luster (aka chalcosine) with a copper content of up to 80%;
  • copper pyrites (in other words, chalcoperite), containing about 30% of the chemical element of interest to us;
  • covelline (it contains up to 64% Cu).

Cuprum is also mined from malachite, cuprite, other oxide ores, and nearly 20 minerals containing it in various quantities.

2

In a simple form, the described element is a pinkish-red metal, characterized by high plasticity. Natural cuprum includes two nuclides with a stable structure.

The radius of a positively charged copper ion has the following values:

  • with a coordination index of 6 - up to 0.091 nm;
  • with an indicator of 2 - up to 0.060 nm.

A neutral atom of an element is characterized by a radius of 0.128 nm and an electron affinity of 1.8 eV. With sequential ionization, the atom has values ​​from 7.726 to 82.7 eV.

Cuprum is a transition metal, so it has variable oxidation states and a low electronegativity (1.9 Pauling units). (coefficient) is 394 W / (m * K) at a temperature range from 20 to 100 ° C. The electrical conductivity of copper (specific index) is a maximum of 58, a minimum of 55.5 MS/m. Only silver is characterized by a higher value, the electrical conductivity of other metals, including aluminum, is lower.

Copper cannot displace hydrogen from acids and water, since it is to the right of hydrogen in the standard potential series. The described metal is characterized by a face-centered cubic lattice with a value of 0.36150 nm. Copper boils at a temperature of 2657 degrees, melts at a temperature of just over 1083 degrees, and its density is 8.92 grams / cubic centimeter (for comparison, the density of aluminum is 2.7).

Other mechanical properties of copper and important physical indicators:

  • pressure at 1628 ° C - 1 mm Hg. Art.;
  • thermal value of expansion (linear) - 0.00000017 units;
  • in tension, a tensile strength of 22 kgf / mm2 is achieved;
  • copper hardness - 35 kgf / mm2 (Brinell scale);
  • specific gravity - 8.94 g / cm3;
  • modulus of elasticity - 132000 MN/m2;
  • elongation (relative) - 60%.

The magnetic properties of copper are somewhat unique. The element is completely diamagnetic, its magnetic atomic susceptibility index is only 0.00000527 units. The magnetic characteristics of copper (however, like all its physical parameters - weight, density, etc.) determine the demand for the element for the manufacture of electrical products. Aluminum has approximately the same characteristics, therefore, with the described metal, they make up a "sweet couple" used for the production of conductive parts, wires, cables.

It is almost impossible to change many mechanical properties of copper (the same magnetic properties, for example), but the tensile strength of the element in question can be improved by hardening. AT this case it will approximately double (up to 420–450 MN/m2).

3

Cuprum in the Mendeleev system is included in the group of noble metals (IB), it is in the fourth period, has serial number 29, and has a tendency to complex formation. The chemical characteristics of copper are no less important than its magnetic, mechanical and physical characteristics, whether it be its weight, density or other value. Therefore, we will talk about them in detail.

The chemical activity of cuprum is low. Copper in a dry atmosphere changes slightly (one might even say that it almost does not change). But with an increase in humidity and the presence of environment carbon dioxide, a greenish film usually forms on its surface. It contains CuCO3 and Cu(OH)2, as well as various copper sulfide compounds. The latter are formed due to the fact that there is almost always a certain amount of hydrogen sulfide and sulfur dioxide in the air. This greenish film is called patina. It protects the metal from destruction.

If copper is heated in air, the processes of oxidation of its surface will begin. At temperatures from 375 to 1100 degrees as a result of oxidation, a two-layer scale is formed, and at temperatures up to 375 degrees - copper oxide. At ordinary temperatures, however, a combination of Cu with wet chlorine is usually observed (the result of such a reaction is the appearance of chloride).

With other elements of the halogen group, copper also interacts quite easily. In sulfur vapor, it ignites; it also has a high level of affinity for selenium. But Cu does not combine with carbon, nitrogen and hydrogen even at elevated temperatures. Upon contact of copper oxide with dilute sulfuric acid, sulfate and pure copper are obtained, with hydroiodic and hydrobromic acid, copper iodide and copper bromide, respectively.

If the oxide is combined with one or another alkali, the result of a chemical reaction will be the appearance of cuprate. But the most famous reducing agents (carbon monoxide, ammonia, methane and others) are able to restore cuprum to a free state.

Of practical interest is the ability of this metal to react with iron salts (in the form of a solution). In this case, the reduction of iron and the transition of Cu into solution are fixed. This reaction is used to remove a sprayed layer of copper from decorative items.

In mono- and divalent forms, copper is able to create complex compounds with high rate sustainability. Such compounds include ammonia mixtures (they are of interest for industrial enterprises) and double salts.

4

The main scope of aluminum and copper is known, perhaps, to everyone. They make a variety of cables, including power ones. This is facilitated by the low resistance of aluminum and cuprum, their special magnetic capabilities. In the windings of electric drives and in transformers (power), copper wires are widely used, which are characterized by a unique purity of copper, which is the feedstock for their production. If only 0.02 percent of aluminum is added to such a pure raw material, the electrical conductivity of the product will decrease by 8–10 percent.

Cu, having a high density and strength, as well as low weight, can be easily machined. This allows you to produce excellent copper pipes, which demonstrate their high performance in gas, heating, water supply systems. In many European states it is copper pipes that are used in the vast majority of cases for arranging internal engineering networks of residential and administrative buildings.

We have said a lot about the electrical conductivity of aluminum and copper. Let's not forget about the excellent thermal conductivity of the latter. This characteristic makes it possible to use copper in the following designs:

  • in heat pipes;
  • in coolers of personal computers;
  • in heating systems and air cooling systems;
  • in heat exchangers and many other devices that remove heat.

The density and light weight of copper materials and alloys have led to their widespread use in architecture.

5

It is clear that the density of copper, its weight and all kinds of chemical and magnetic indicators, by and large, are of little interest ordinary person. But the healing properties of copper want to know many.

Ancient Indians used copper to treat the organs of vision and various skin ailments. The ancient Greeks healed ulcers, severe swelling, bruises and bruises, as well as more serious diseases (inflammation of the tonsils, congenital and acquired deafness) with copper plates. And in the east, copper red powder dissolved in water was used to restore broken bones of the legs and arms.

The healing properties of copper were well known to the Russians. Our ancestors used this unique metal to cure cholera, epilepsy, polyarthritis and radiculitis. Currently, copper plates are usually used for treatment, which are applied to special points on the human body. The healing properties of copper with such therapy are manifested in the following:

  • the protective potential of the human body increases;
  • infectious diseases are not terrible for those who are treated with copper;
  • there is a decrease in pain and removal of inflammation.

Copper (Cu) belongs to the d-elements and is located in the IB group of the periodic table of D.I. Mendeleev. Electronic configuration copper atom in the ground state is written as 1s 2 2s 2 2p 6 3s 2 3p 6 3d 10 4s 1 instead of the expected formula 1s 2 2s 2 2p 6 3s 2 3p 6 3d 9 4s 2 . In other words, in the case of a copper atom, the so-called “electron jump” from the 4s sublevel to the 3d sublevel is observed. For copper, in addition to zero, oxidation states +1 and +2 are possible. The oxidation state +1 is prone to disproportionation and is stable only in insoluble compounds such as CuI, CuCl, Cu 2 O, etc., as well as in complex compounds, for example, Cl and OH. Copper compounds in the +1 oxidation state do not have a specific color. So, copper (I) oxide, depending on the size of the crystals, can be dark red (large crystals) and yellow (small crystals), CuCl and CuI are white, and Cu 2 S is black-blue. More chemically stable is the oxidation state of copper, equal to +2. Salts containing copper in a given oxidation state are blue and blue-green in color.

Copper is a very soft, malleable and ductile metal with high electrical and thermal conductivity. The color of metallic copper is red-pink. Copper is in the activity series of metals to the right of hydrogen, i.e. refers to low-active metals.

with oxygen

Under normal conditions, copper does not interact with oxygen. Heat is required for the reaction between them to proceed. Depending on the excess or lack of oxygen and temperature conditions, it can form copper (II) oxide and copper (I) oxide:

with sulfur

The reaction of sulfur with copper, depending on the conditions of carrying out, can lead to the formation of both copper (I) sulfide and copper (II) sulfide. When a mixture of powdered Cu and S is heated to a temperature of 300-400 ° C, copper (I) sulfide is formed:

With a lack of sulfur and the reaction is carried out at a temperature of more than 400 ° C, copper (II) sulfide is formed. However, a simpler way to obtain copper (II) sulfide from simple substances is the interaction of copper with sulfur dissolved in carbon disulfide:

This reaction proceeds at room temperature.

with halogens

Copper reacts with fluorine, chlorine and bromine to form halides with general formula CuHal 2, where Hal is F, Cl or Br:

Cu + Br 2 = CuBr 2

In the case of iodine, the weakest oxidizing agent among halogens, copper (I) iodide is formed:

Copper does not interact with hydrogen, nitrogen, carbon and silicon.

with non-oxidizing acids

Almost all acids are non-oxidizing acids, except for concentrated sulfuric acid and nitric acid of any concentration. Since non-oxidizing acids are able to oxidize only metals that are in the activity series up to hydrogen; this means that copper does not react with such acids.

with oxidizing acids

- concentrated sulfuric acid

Copper reacts with concentrated sulfuric acid both when heated and at room temperature. When heated, the reaction proceeds in accordance with the equation:

Since copper is not a strong reducing agent, sulfur is reduced in this reaction only to the +4 oxidation state (in SO 2).

- with dilute nitric acid

The reaction of copper with dilute HNO 3 leads to the formation of copper (II) nitrate and nitrogen monoxide:

3Cu + 8HNO 3 (diff.) = 3Cu(NO 3) 2 + 2NO + 4H 2 O

- with concentrated nitric acid

Concentrated HNO 3 readily reacts with copper under normal conditions. The difference between the reaction of copper with concentrated nitric acid and the interaction with dilute nitric acid lies in the product of nitrogen reduction. In the case of concentrated HNO 3, nitrogen is reduced to a lesser extent: instead of nitric oxide (II), nitric oxide (IV) is formed, which is associated with greater competition between nitric acid molecules in concentrated acid for reducing agent electrons (Cu):

Cu + 4HNO 3 \u003d Cu (NO 3) 2 + 2NO 2 + 2H 2 O

with non-metal oxides

Copper reacts with some non-metal oxides. For example, with oxides such as NO 2 , NO, N 2 O, copper is oxidized to copper (II) oxide, and nitrogen is reduced to oxidation state 0, i.e. a simple substance N 2 is formed:

In the case of sulfur dioxide, instead of a simple substance (sulfur), copper (I) sulfide is formed. This is due to the fact that copper with sulfur, unlike nitrogen, reacts:

with metal oxides

When sintering metallic copper with copper oxide (II) at a temperature of 1000-2000 ° C, copper oxide (I) can be obtained:

Also, metallic copper can reduce iron (III) oxide upon calcination to iron (II) oxide:

with metal salts

Copper displaces less active metals (to the right of it in the activity series) from solutions of their salts:

Cu + 2AgNO 3 \u003d Cu (NO 3) 2 + 2Ag ↓

An interesting reaction also takes place, in which copper is dissolved in a salt of a more active metal - iron in the +3 oxidation state. However, there are no contradictions, because copper does not displace iron from its salt, but only restores it from the +3 oxidation state to the +2 oxidation state:

Fe 2 (SO 4) 3 + Cu \u003d CuSO 4 + 2FeSO 4

Cu + 2FeCl 3 = CuCl 2 + 2FeCl 2

The latter reaction is used in the production of microcircuits at the stage of etching of copper boards.

Corrosion of copper

Copper corrodes over time when exposed to moisture, carbon dioxide and atmospheric oxygen:

2Cu + H 2 O + CO 2 + O 2 \u003d (CuOH) 2 CO 3

As a result of this reaction, copper products are covered with a loose blue-green coating of copper (II) hydroxocarbonate.

Chemical properties of zinc

Zinc Zn is in the IIB group of the IVth period. Electronic configuration of valence orbitals of atoms of a chemical element in the ground state 3d 10 4s 2 . For zinc, only one single oxidation state is possible, equal to +2. Zinc oxide ZnO and zinc hydroxide Zn(OH) 2 have pronounced amphoteric properties.

Zinc tarnishes when stored in air, becoming covered with a thin layer of ZnO oxide. Oxidation proceeds especially easily at high humidity and in the presence of carbon dioxide due to the reaction:

2Zn + H 2 O + O 2 + CO 2 → Zn 2 (OH) 2 CO 3

Zinc vapor burns in air, and a thin strip of zinc, after glowing in a burner flame, burns in it with a greenish flame:

When heated, metallic zinc also interacts with halogens, sulfur, phosphorus:

Zinc does not directly react with hydrogen, nitrogen, carbon, silicon and boron.

Zinc reacts with non-oxidizing acids to release hydrogen:

Zn + H 2 SO 4 (20%) → ZnSO 4 + H 2

Zn + 2HCl → ZnCl 2 + H 2

Industrial zinc is especially easily soluble in acids, since it contains impurities of other less active metals, in particular, cadmium and copper. High-purity zinc is resistant to acids for certain reasons. To speed up the reaction, a sample of high purity zinc is brought into contact with copper, or a small amount of copper salt is added to the acid solution.

At a temperature of 800-900 o C (red heat), metallic zinc, being in a molten state, interacts with superheated water vapor, releasing hydrogen from it:

Zn + H 2 O \u003d ZnO + H 2

Zinc also reacts with oxidizing acids: concentrated sulfuric and nitric.

Zinc as an active metal can form sulfur dioxide, elemental sulfur and even hydrogen sulfide with concentrated sulfuric acid.

Zn + 2H 2 SO 4 \u003d ZnSO 4 + SO 2 + 2H 2 O

The composition of the products of nitric acid reduction is determined by the concentration of the solution:

Zn + 4HNO 3 (conc.) = Zn(NO 3) 2 + 2NO 2 + 2H 2 O

3Zn + 8HNO 3 (40%) = 3Zn(NO 3) 2 + 2NO + 4H 2 O

4Zn + 10HNO 3 (20%) = 4Zn (NO 3) 2 + N 2 O + 5H 2 O

5Zn + 12HNO 3 (6%) = 5Zn(NO 3) 2 + N 2 + 6H 2 O

4Zn + 10HNO 3 (0.5%) = 4Zn(NO 3) 2 + NH 4 NO 3 + 3H 2 O

The direction of the process is also affected by the temperature, the amount of acid, the purity of the metal, and the reaction time.

Zinc reacts with alkali solutions to form tetrahydroxozincates and hydrogen:

Zn + 2NaOH + 2H 2 O \u003d Na 2 + H 2

Zn + Ba (OH) 2 + 2H 2 O \u003d Ba + H 2

With anhydrous alkalis, zinc, when fused, forms zincates and hydrogen:

In a highly alkaline environment, zinc is an extremely strong reducing agent, capable of reducing nitrogen in nitrates and nitrites to ammonia:

4Zn + NaNO 3 + 7NaOH + 6H 2 O → 4Na 2 + NH 3

Due to complexation, zinc slowly dissolves in an ammonia solution, reducing hydrogen:

Zn + 4NH 3 H 2 O → (OH) 2 + H 2 + 2H 2 O

Zinc also restores less active metals (to the right of it in the activity series) from aqueous solutions of their salts:

Zn + CuCl 2 \u003d Cu + ZnCl 2

Zn + FeSO 4 \u003d Fe + ZnSO 4

Chemical properties of chromium

Chromium is an element of the VIB group of the periodic table. The electronic configuration of the chromium atom is written as 1s 2 2s 2 2p 6 3s 2 3p 6 3d 5 4s 1, i.e. in the case of chromium, as well as in the case of the copper atom, the so-called "electron slip" is observed

The most frequently exhibited oxidation states of chromium are +2, +3 and +6. They should be remembered, and within the framework of the USE program in chemistry, we can assume that chromium has no other oxidation states.

Under normal conditions, chromium is resistant to corrosion both in air and in water.

Interaction with non-metals

with oxygen

Heated to a temperature of more than 600 o C, powdered metallic chromium burns in pure oxygen to form chromium (III) oxide:

4Cr + 3O 2 = o t=> 2Cr 2 O 3

with halogens

Chromium reacts with chlorine and fluorine at lower temperatures than with oxygen (250 and 300 o C, respectively):

2Cr + 3F 2 = o t=> 2CrF 3

2Cr + 3Cl 2 = o t=> 2CrCl 3

Chromium reacts with bromine at a red heat temperature (850-900 o C):

2Cr + 3Br 2 = o t=> 2CrBr 3

with nitrogen

Metallic chromium interacts with nitrogen at temperatures above 1000 o C:

2Cr + N 2 = ot=> 2CrN

with sulfur

With sulfur, chromium can form both chromium (II) sulfide and chromium (III) sulfide, depending on the proportions of sulfur and chromium:

Cr+S= o t=> CRS

2Cr+3S= o t=> Cr 2 S 3

Chromium does not react with hydrogen.

Interaction with complex substances

Interaction with water

Chromium belongs to the metals of medium activity (located in the activity series of metals between aluminum and hydrogen). This means that the reaction proceeds between red-hot chromium and superheated water vapor:

2Cr + 3H 2 O = o t=> Cr 2 O 3 + 3H 2

Interaction with acids

Chromium is passivated under normal conditions with concentrated sulfuric acid and nitric acid, however, dissolves in them during boiling, while being oxidized to an oxidation state of +3:

Cr + 6HNO 3 (conc.) = t o=> Cr(NO 3) 3 + 3NO 2 + 3H 2 O

2Cr + 6H 2 SO 4 (conc) = t o=> Cr 2 (SO 4) 3 + 3SO 2 + 6H 2 O

In the case of dilute nitric acid, the main product of nitrogen reduction is a simple substance N 2:

10Cr + 36HNO 3 (razb) \u003d 10Cr (NO 3) 3 + 3N 2 + 18H 2 O

Chromium is located in the activity series to the left of hydrogen, which means that it is able to release H 2 from solutions of non-oxidizing acids. In the course of such reactions, in the absence of access to atmospheric oxygen, chromium (II) salts are formed:

Cr + 2HCl \u003d CrCl 2 + H 2

Cr + H 2 SO 4 (razb.) \u003d CrSO 4 + H 2

When carrying out the reaction in the open air, divalent chromium is instantly oxidized by oxygen contained in the air to an oxidation state of +3. In this case, for example, the equation with hydrochloric acid will take the form:

4Cr + 12HCl + 3O 2 = 4CrCl 3 + 6H 2 O

When chromium metal is fused with strong oxidizing agents in the presence of alkalis, chromium is oxidized to an oxidation state of +6, forming chromates:

Chemical properties of iron

Iron Fe, a chemical element in group VIIIB and having serial number 26 in the periodic table. The distribution of electrons in an iron atom is as follows 26 Fe1s 2 2s 2 2p 6 3s 2 3p 6 3d 6 4s 2 , that is, iron belongs to d-elements, since the d-sublevel is filled in its case. It is most characteristic of two oxidation states +2 and +3. FeO oxide and Fe(OH) 2 hydroxide are dominated by basic properties, Fe 2 O 3 oxide and Fe(OH) 3 hydroxide are markedly amphoteric. So the oxide and hydroxide of iron (lll) dissolve to some extent when boiled in concentrated solutions of alkalis, and also react with anhydrous alkalis during fusion. It should be noted that the oxidation state of iron +2 is very unstable, and easily passes into the oxidation state +3. Iron compounds are also known in a rare oxidation state of +6 - ferrates, salts of the non-existent "iron acid" H 2 FeO 4. These compounds are relatively stable only in the solid state or in strongly alkaline solutions. With insufficient alkalinity of the medium, ferrates quickly oxidize even water, releasing oxygen from it.

Interaction with simple substances

With oxygen

When burned in pure oxygen, iron forms the so-called iron scale, having the formula Fe 3 O 4 and actually representing a mixed oxide, the composition of which can be conditionally represented by the formula FeO∙Fe 2 O 3 . The combustion reaction of iron has the form:

3Fe + 2O 2 = t o=> Fe 3 O 4

With sulfur

When heated, iron reacts with sulfur to form ferrous sulfide:

Fe+S= t o=> FeS

Or with an excess of sulfur iron disulfide:

Fe + 2S = t o=> FeS2

With halogens

With all halogens except iodine, metallic iron is oxidized to an oxidation state of +3, forming iron halides (lll):

2Fe + 3F 2 = t o=> 2FeF 3 - iron fluoride (lll)

2Fe + 3Cl 2 = t o=> 2FeCl 3 - iron chloride (lll)

Iodine, as the weakest oxidizing agent among halogens, oxidizes iron only to the +2 oxidation state:

Fe + I 2 = t o=> FeI 2 - iron iodide (ll)

It should be noted that ferric iron compounds easily oxidize iodide ions in an aqueous solution to free iodine I 2 while recovering to the +2 oxidation state. Examples of similar reactions from the FIPI bank:

2FeCl 3 + 2KI = 2FeCl 2 + I 2 + 2KCl

2Fe(OH) 3 + 6HI = 2FeI 2 + I 2 + 6H 2 O

Fe 2 O 3 + 6HI \u003d 2FeI 2 + I 2 + 3H 2 O

With hydrogen

Iron does not react with hydrogen (only alkali metals and alkaline earth metals react with hydrogen from metals):

Interaction with complex substances

Interaction with acids

With non-oxidizing acids

Since iron is located in the activity series to the left of hydrogen, this means that it is able to displace hydrogen from non-oxidizing acids (almost all acids except H 2 SO 4 (conc.) and HNO 3 of any concentration):

Fe + H 2 SO 4 (diff.) \u003d FeSO 4 + H 2

Fe + 2HCl \u003d FeCl 2 + H 2

It is necessary to pay attention to such a trick in USE assignments, as a question on the topic to what degree of oxidation iron will be oxidized under the action of dilute and concentrated hydrochloric acid on it. The correct answer is up to +2 in both cases.

The trap here lies in the intuitive expectation of a deeper oxidation of iron (up to s.o. +3) in the case of its interaction with concentrated hydrochloric acid.

Interaction with oxidizing acids

Under normal conditions, iron does not react with concentrated sulfuric and nitric acids due to passivation. However, it reacts with them when boiled:

2Fe + 6H 2 SO 4 = o t=> Fe 2 (SO 4) 3 + 3SO 2 + 6H 2 O

Fe + 6HNO 3 = o t=> Fe(NO 3) 3 + 3NO 2 + 3H 2 O

Please note that diluted sulphuric acid oxidizes iron to an oxidation state of +2, and concentrated to +3.

Corrosion (rusting) of iron

In moist air, iron rusts very quickly:

4Fe + 6H 2 O + 3O 2 \u003d 4Fe (OH) 3

Iron does not react with water in the absence of oxygen either under normal conditions or when boiled. The reaction with water proceeds only at a temperature above the red heat temperature (> 800 ° C). those..

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