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Copper is an element of the secondary subgroup of the first group, the fourth period of the periodic system of chemical elements of D.I. Mendeleev, with atomic number 29. It is designated by the symbol Cu (lat. Cuprum). The simple substance copper (CAS number: 7440-50-8) is a ductile transition metal of a golden-pink color (pink in the absence of an oxide film). It has been widely used by people for a long time.

History and origin of the name

Copper is one of the first metals widely mastered by man due to its comparative availability from ore and low melting point. In ancient times it was used mainly in the form of an alloy with tin - bronze for the manufacture of weapons, etc. (see Bronze Age).
The Latin name for copper Cuprum (ancient Aes cuprium, Aes cyprium) comes from the name of the island of Cyprus, where already in the 3rd millennium BC. e. There were copper mines and copper smelting was carried out.
Strabo calls copper chalkos, from the name of the city of Chalkis on Euboea. From this word came many ancient Greek names for copper and bronze objects, blacksmithing, blacksmithing and casting. The second Latin name for copper Aes (Sanskrit, ayas, Gothic aiz, German erz, English ore) means ore or mine. Proponents of the Indo-Germanic theory of the origin of European languages ​​derive the Russian word copper (Polish miedz, Czech med) from Old German smida (metal) and Schmied (blacksmith, English Smith). Of course, the relationship of the roots in this case is undoubtedly, however, both of these words are derived from the Greek. mine, mine independently of each other. From this word came related names - medal, medallion (French medaille). The words copper and copper are found in the most ancient Russian literary monuments. Alchemists called copper Venus. In more ancient times the name Mars was found.

Physical properties

Copper is a golden-pink ductile metal; in air it quickly becomes covered with an oxide film, which gives it a characteristic intense yellowish-red hue. Thin films of copper have a greenish-blue color when exposed to light.
Copper forms a cubic face-centered lattice, space group F m3m, a = 0.36150 nm, Z = 4.
Copper has high thermal and electrical conductivity (it ranks second in electrical conductivity after silver).
It has two stable isotopes - 63 Cu and 65 Cu, and several radioactive isotopes. The longest-lived of these, 64 Cu, has a half-life of 12.7 hours and two decay modes with different products.
There are a number of copper alloys: brass - with zinc, bronze - with tin and other elements, cupronickel - with nickel, babbit - with lead and others.

Chemical properties

Does not change in air in the absence of moisture and carbon dioxide. It is a weak reducing agent and does not react with diluted water. hydrochloric acid. It is transferred into solution with non-oxidizing acids or ammonia hydrate in the presence of oxygen, potassium cyanide. It is oxidized by concentrated sulfuric and nitric acids, aqua regia, oxygen, halogens, chalcogens, and non-metal oxides. Reacts when heated with hydrogen halides.

Modern mining methods

90% of primary copper is obtained by pyrometallurgical method, 10% by hydrometallurgical method. The hydrometallurgical method is the production of copper by leaching it with a weak solution of sulfuric acid and subsequent separation of copper metal from the solution. The pyrometallurgical method consists of several stages: enrichment, roasting, smelting for matte, purging in a converter, refining.
To enrich copper ores, the flotation method is used (based on the use of different wettability of copper-containing particles and waste rock), which allows one to obtain copper concentrate containing from 10 to 35% copper.
Copper ores and concentrates with high sulfur content are subjected to oxidative roasting. In the process of heating the concentrate or ore to 700-800 °C in the presence of atmospheric oxygen, sulfides are oxidized and the sulfur content is reduced by almost half of the original. Only poor concentrates (with a copper content of 8 to 25%) are fired, and rich concentrates (from 25 to 35% copper) are melted without firing.
After roasting, the ore and copper concentrate are smelted into matte, which is an alloy containing copper and iron sulfides. Matte contains from 30 to 50% copper, 20-40% iron, 22-25% sulfur, in addition, matte contains impurities of nickel, zinc, lead, gold, and silver. Most often, smelting is carried out in fiery reverberatory furnaces. The temperature in the melting zone is 1450 °C.
In order to oxidize sulfides and iron, the resulting copper matte is subjected to blowing with compressed air in horizontal converters with side blast. The resulting oxides are converted into slag. The temperature in the converter is 1200-1300 °C. Interestingly, heat is released in the converter due to chemical reactions, without fuel supply. Thus, the converter produces blister copper containing 98.4 - 99.4% copper, 0.01 - 0.04% iron, 0.02 - 0.1% sulfur and a small amount of nickel, tin, antimony, silver, gold. This copper is poured into a ladle and poured into steel molds or a casting machine.
Next, to remove harmful impurities, blister copper is refined (fire refining and then electrolytic refining are carried out). The essence of fire refining of blister copper is the oxidation of impurities, removing them with gases and converting them into slag. After fire refining, copper with a purity of 99.0 - 99.7% is obtained. It is poured into molds and ingots are obtained for further smelting of alloys (bronze and brass) or ingots for electrolytic refining.
Electrolytic refining is carried out to obtain pure copper (99.95%). Electrolysis is carried out in baths where the anode is made of fire-refined copper, and the cathode is made of thin sheets of pure copper. The electrolyte is an aqueous solution. When skipping direct current the anode dissolves, copper goes into solution, and, cleaned of impurities, is deposited on the cathodes. Impurities settle to the bottom of the bath in the form of slag, which is processed to extract valuable metals. The cathodes are unloaded after 5-12 days, when their weight reaches 60 to 90 kg. They are thoroughly washed and then melted in electric furnaces.

Historical information about copper, chemical and physical properties; application in medicine and in the national economy. Copper is the first metal that was first used by humans several millennia BC; soft metal, element group 11.

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1. Historical background on copper

2. Physical properties of copper. Application in medicine and national economy

3. Chemical properties copper

Bibliography

1. Historical background on copper

Copper is the first metal that people first began to use in ancient times several thousand years BC. The first copper tools were made from native copper, which is quite common. The largest copper nugget was found in the United States; it weighed 420 tons.

But due to the fact that copper is a soft metal, copper in ancient times could not replace stone tools. Only when man learned to smelt copper and invented bronze (an alloy of copper and tin) did metal replace stone. The widespread use of copper began in the 4th millennium BC. e.

COPPER is an element of group 11 of the Periodic Table, density 8.9 g cm -3, one of the first metals known to man. It is believed that copper began to be used around 5000 BC. Copper is rarely found in nature as a metal. The first metal tools were made from copper nuggets, possibly with the help of stone axes. The Indians who lived on its shores of the lake. Upper (North America), where there is very pure native copper, methods of cold processing were known before the time of Columbus.

Around 3500 BC In the Middle East, they learned to extract copper from ores; it was obtained by reducing coal. There were copper mines in Ancient Egypt. It is known that the blocks for the famous Cheops pyramid were processed with a copper tool.

By 3000 BC In India, Mesopotamia and Greece, tin was added to copper to smelt harder bronze. The discovery of bronze may have happened by accident, but its advantages over pure copper quickly brought this alloy to first place. This is how the “Bronze Age” began.

The Assyrians, Egyptians, Hindus and other peoples of antiquity had bronze products. However, ancient craftsmen learned to cast solid bronze statues no earlier than the 5th century. BC. Around 290 BC Chares created the Colossus of Rhodes in honor of the sun god Helios. It was 32 m high and stood above the entrance to the inner harbor of the ancient port of the island of Rhodes in the eastern Aegean Sea. The giant bronze statue was destroyed by an earthquake in 223 AD.

The ancestors of the ancient Slavs, who lived in the Don basin and the Dnieper region, used copper to make weapons, jewelry and household items. The Russian word “copper,” according to some researchers, comes from the word “mida,” which among the ancient tribes that inhabited Eastern Europe meant metal in general.

The symbol Cu comes from the Latin aes cyproum (later, Cuprum), since Cyprus was the site of the copper mines of the ancient Romans.

The relative content of copper in the earth's crust is 6.8/10 -3%. Native copper is very rare. Typically the element is found in the form of sulfide, oxide or carbonate. The most important copper ores are chalcopyrite CuFeS 2, which is estimated to constitute about 50% of all deposits of this element, copper luster (chalcocite) Cu 2 S, cuprite Cu 2 O and malachite Cu 2 CO 3 (OH) 2. Large deposits of copper ores have been found in various parts of North and South America, in Africa and in our country. In the 18th-19th centuries. Near Lake Onega, native copper was mined and sent to the mint in St. Petersburg. The discovery of industrial copper deposits in the Urals and Siberia is associated with the name of Nikita Demidov. It was he who, by decree of Peter I, began minting copper money in 1704.

2. Physical properties of copper. Use in medicine and folk art O farming

Copper is a heavy pink-red metal, soft and malleable, its melting point is 1083 ° C, it is an excellent conductor of electric current and heat; the electrical conductivity of copper is 1.7 times higher than aluminum and 6 times higher than iron.

Copper is a ductile, pinkish-red metal with a metallic sheen; thin films of copper have a greenish-blue color when examined through translucency. Crystallizes in a face-centered cubic lattice with a metallic type of chemical bond. It has high thermal and electrical conductivity; its electrical conductivity is second only to silver. Melting point 1083°C, boiling point 2567°C, density 8.92 g/cm 3 .

In air, copper is covered with a dense green-gray film of basic carbonate, which protects it from further oxidation.

In everyday life, we always have to deal with copper and its alloys: we turn on a computer or a table lamp - current flows through copper wires, we use metal money, which, both yellow and white, are made from copper alloys. Some houses are decorated with bronze items, and dishes are made from copper. Meanwhile, copper is far from the most common element in nature: the copper content in the earth's crust is 0.01%, which allows it to occupy only 23rd place among all elements.

The main use of metal is as a conductor electric current. In addition, copper is used in coin alloys, which is why it is often called a "coin metal". It is also found in traditional bronzes (alloys of copper with 7-10% tin) and brass (alloys of copper and zinc) and specialty alloys such as Monel (alloys of nickel and copper). Metalworking tools made of copper alloys do not spark and can be used in explosive workshops. Copper-based alloys are used to make wind instruments and bells.

The healing properties of copper have been known for a very long time. The ancients believed that the healing effect of copper was associated with its analgesic, antipyretic, antibacterial and anti-inflammatory properties. Avicenna and Galen also described copper as a medicine, and Aristotle, pointing to the general strengthening effect of copper on the body, preferred to fall asleep with a copper ball in his hand. Queen Cleopatra wore the finest copper bracelets, preferring them to gold and silver, knowing medicine and alchemy well. In copper armor, ancient warriors were less tired, and their wounds festered less and healed faster. The ability of copper to positively influence “male strength” was noticed and widely used in the Ancient world.

Nomadic peoples used copper utensils in everyday life, which protected them from infectious diseases, and the gypsies wore a copper hoop on their heads for the same purposes. Historical fact: the epidemic of cholera and plague bypassed people working with copper or living near copper mines. It is no coincidence that door handles in hospitals used to be made of copper in order to prevent the transmission of infection from infectious patients to healthy people.

A very important area of ​​application of copper is the production of copper alloys. With many metals, copper forms so-called solid solutions, which are similar to ordinary solutions in that in them the atoms of one component (metal) are evenly distributed among the atoms of another (Fig. 34). Most copper alloys are solid solutions.

A copper alloy known since ancient times - bronze - contains 4-30% tin (usually 8-10%). It is interesting that bronze is superior in its hardness to pure copper and tin taken separately. Bronze is more fusible than copper. Bronze products from masters of Ancient Egypt, Greece, and China have survived to this day. In the Middle Ages, tools and many other products were cast from bronze. The famous Tsar Cannon and Tsar Bell in the Moscow Kremlin are also cast from an alloy of copper and tin.

3. Chemical properties of copper

In the form of a simple substance, copper has a characteristic reddish color. Copper metal is soft and ductile. In terms of electrical and thermal conductivity, copper is second only to silver. Metallic copper, like silver, has antibacterial properties.

Copper is stable in clean dry air at room temperature, however, at red heat temperatures it forms oxides. It also reacts with sulfur and halogens. In an atmosphere containing sulfur compounds, copper becomes covered with a green film of basic sulfate. In the electrochemical voltage series, copper is located to the right of hydrogen, so it practically does not interact with non-oxidizing acids. The metal dissolves in hot concentrated sulfuric acid, as well as in dilute and concentrated nitric acid. In addition, copper can be dissolved by the action of aqueous solutions of cyanide or ammonia:

2Cu + 8NH 3 ЇH 2 O + O 2 = 2(OH) 2 + 6H 2 O

According to the position of copper in the Periodic Table, its only stable oxidation state should be (+I), but this is not the case. Copper is capable of accepting higher oxidation states, and the most stable, especially in aqueous solutions, is the oxidation state (+II). Copper(III) may be involved in biochemical electron transfer reactions. This oxidation state is rare and is very easily reduced by even weak reducing agents. Several copper(+IV) compounds are known.

When a metal is heated in air or oxygen, copper oxides are formed: yellow or red Cu 2 O and black CuO. An increase in temperature promotes the formation of predominantly copper(I) oxide Cu 2 O. In the laboratory, this oxide can be conveniently obtained by reducing an alkaline solution of copper(II) salt with glucose, hydrazine or hydroxylamine:

2CuSO 4 + 2NH 2 OH + 4NaOH = Cu 2 O + N 2 + 2Na 2 SO 4 + 5H 2 O

This reaction is the basis of Fehling's sensitive test for sugars and other reducing agents. A solution of copper(II) salt in an alkaline solution is added to the test substance. If the substance is a reducing agent, a characteristic red precipitate appears.

Since the Cu + cation is unstable in an aqueous solution, when Cu 2 O is exposed to acids, either dismutation or complexation occurs:

Cu 2 O + H 2 SO 4 = Cu + CuSO 4 + H 2 O

Cu 2 O + 4HCl = 2 H + H 2 O

Cu 2 O oxide noticeably interacts with alkalis. This creates a complex:

Cu 2 O + 2NaOH + H 2 O 2Na

To obtain copper(II) oxide CuO, it is best to use the decomposition of nitrate or basic copper(II) carbonate:

2Cu(NO 3) 2 = 2CuO + 4NO 2 + O 2

(CuOH) 2 CO 3 = 2CuO + CO 2 + H 2 O

Copper oxides are insoluble in water and do not react with it. The only copper hydroxide, Cu(OH) 2, is usually prepared by adding an alkali to an aqueous solution of copper(II) salt. A pale blue precipitate of copper(II) hydroxide, which exhibits amphoteric properties (the ability of chemical compounds to exhibit either basic or acidic properties), can be dissolved not only in acids, but also in concentrated alkalis. In this case, dark blue solutions containing particles of type 2- are formed. Copper(II) hydroxide also dissolves in ammonia solution:

Cu(OH) 2 + 4NH 3 . H 2 O = (OH) 2 + 4H 2 O

Copper(II) hydroxide is thermally unstable and decomposes when heated:

Cu(OH) 2 = CuO + H 2 O

There is information about the existence of dark red oxide Cu 2 O 3, formed by the action of K 2 S 2 O 8 on Cu(OH) 2. It is a strong oxidizing agent; when heated to 400° C, it decomposes into CuO and O 2.

Great interest in the chemistry of copper oxides in the last two decades has been associated with the production of high-temperature superconductors, of which YBa 2 Cu 3 O 7 is the best known. In 1987 it was shown that at liquid nitrogen temperature this compound is a superconductor. The main problems preventing its large-scale practical application lie in the field of material processing. Nowadays, the production of thin films is considered the most promising.

Many of the copper chalcogenides are non-stoichiometric compounds. Copper(I) sulfide Cu 2 S is formed when copper is strongly heated in sulfur vapor or in hydrogen sulfide. When hydrogen sulfide is passed through aqueous solutions containing Cu 2+ cations, a colloidal precipitate of CuS composition is released. However, CuS is not a simple copper(II) compound. It contains the S 2 group and is better described by the formula Cu I 2 Cu II (S 2)S. Copper selenides and tellurides exhibit metallic properties, and CuSe 2, CuTe 2, CuS and CuS 2 are superconductors at low temperatures.

By heating copper with halogens, anhydrous difluoride, dichloride and dibromide can be synthesized. It is more convenient to obtain solutions of copper(II) halides by reacting the metal, its oxide, hydroxide or carbonate with the corresponding hydrohalic acid. Crystal hydrates are always released from aqueous solutions.

Attempts to obtain copper(II) iodide lead to the formation of copper(I) iodide CuI:

2Cu 2+ + 4I - = 2CuI + I 2

In this case, the solution and precipitate turn brown due to the presence of iodine. The resulting iodine can be removed by the action of thiosulfate ion:

I 2 + 2SO 3 S 2- = 2I - + S 4 O 6 2-

However, when adding excess thiosulfate ion, copper(I) iodide dissolves:

CuI + 2SO 3 S 2- = 3- + I -

Similarly, attempts to produce copper(II) cyanide result in the formation of CuCN. On the other hand, with electronegative fluorine it is not possible to obtain a copper(I) salt. Three other copper(I) halides, which are white insoluble compounds, precipitate from aqueous solutions upon reduction of copper(II) halides.

In aqueous solutions, the colorless copper(I) ion is very unstable and disproportionate

2Cu I Cu II + Cu(p)

Perhaps the reason for this is the size of the atom. The Cu II ion is smaller than Cu I, and, having twice the charge, interacts much more strongly with water (heats of hydration are ~2100 and ~580 kJ mol -1, respectively). The difference is significant because it outweighs the second ionization energy for copper. This makes the Cu II ion more stable in aqueous solution (and ionic solids) than Cu I, despite the latter's stable d 10 configuration. However, CuI can be stabilized in compounds with very low solubility or through complexation. Complexes are easily formed in aqueous solution upon interaction of Cu 2 O with the corresponding ligands. In aqueous solutions, chloro- and ammine complexes of copper(I) are slowly oxidized by atmospheric oxygen to the corresponding copper(II) compounds.

The copper(II) cation, on the contrary, is quite stable in aqueous solution. Copper(II) salts are mainly soluble in water. The blue color of their solutions is associated with the formation of the 2+ ion. They often crystallize as hydrates. Aqueous solutions are slightly susceptible to hydrolysis and basic salts often precipitate from them. The main carbonate exists in nature - this is the mineral malachite, the main sulfates and chlorides are formed during atmospheric corrosion of copper, and the main acetate (verdigris) is used as a pigment.

The verdigris has been known since the time of Pliny the Elder (23-79 AD). Russian pharmacies began receiving it at the beginning of the 17th century. Depending on the method of production, it may be green or blue. The walls of the royal chambers in Kolomenskoye in Moscow were painted with it.

The most famous simple salt - copper(II) sulfate pentahydrate CuSO 4 Ї5H 2 O - is often called copper sulfate. The word vitriol apparently comes from the Latin Cipri Rosa - rose of Cyprus. In Russia copper sulfate called blue, Cypriot, then Turkish. The fact that vitriol contains copper was first established in 1644 by Van Helmont. In 1848, R. Glauber first obtained copper sulfate from copper and sulfuric acid. Copper sulfate is widely used in electrolytic processes, water purification, and plant protection. It is the starting material for the production of many other copper compounds.

Tetraammines are easily formed by adding ammonia to aqueous solutions of copper(II) until the initial precipitate is completely dissolved. Dark blue solutions of copper tetraammines dissolve cellulose, which can be re-precipitated by acidification, which is used in one of the processes to obtain viscose. Adding ethanol to the solution causes the precipitation of SO 4 ЇH 2 O. Recrystallization of tetraammines from a concentrated ammonia solution leads to the formation of violet-blue pentaammines, but the fifth molecule of NH 3 is easily lost. Hexaammines can only be prepared in liquid ammonia and are stored in an ammonia atmosphere.

Copper(II) forms a square-planar complex with the macrocyclic ligand phthalocyanine. Its derivatives are used to produce a range of blue to green pigments that are stable up to 500°C and are widely used in inks, paints, plastics and even colored cements.

Bibliography

1. Azimov A. A brief history of chemistry. St. Petersburg, Amphora, 2002

2. Vanyukov A.V., Utkin M.I. Complex processing of copper and nickel raw materials. Chelyabinsk, 1988

3. Copper smelting production - development and prospects. Alma-Ata, 1978

4. Stepin B.D., Alikberova L.Yu. A book on chemistry for home reading. M., Chemistry, 1994

5. Chemistry and Life (Solter chemistry). Part 1. Chemistry concepts. M.: publishing house of Russian Chemical Technical University named after. D.I.Mendeleeva, 1997

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