Various reducing agents are used to obtain metals from oxides. Usage hydrogen allows you to obtain active metals that are not reduced by carbon monoxide (II). This method is also used to obtain metals with low impurity content, for example, for a chemical laboratory. The cost of this method is quite high. An example is the reaction of copper reduction from copper (II) oxide when heated in a hydrogen stream:
CuO + H 2 = Cu + H 2 O
Indicating the oxidation state of the elements:
Cu +2 O + H 2 0 = Cu 0 + H 2 +1 O
Although the reaction is reversible, carrying it out in a stream of hydrogen, and, as a consequence, removing water vapor from the reaction zone, allows the equilibrium to shift to the right and achieve complete reduction of copper.
Iron entering the school laboratory is often labeled with the words: “Reduced with hydrogen”:
Fe 2 O 3 + 3H 2 = 2Fe + 3H 2 O
Metal recovery method aluminum received the name "aluminothermy" or "aluminothermy". Aluminum is an even more active reducing agent. Chromium and manganese are obtained in this way:
2Al + Cr 2 O 3 = Al 2 O 3 + 2Cr
When iron (III) oxide reacts with aluminum powder (the mixture must be set on fire with magnesium tape), a lot of heat is released:
2Al + Fe 2 O 3 = Al 2 O 3 + 2Fe
Aluminothermy produces a certain amount of calcium. Please note that in the electrochemical voltage series calcium is to the left of aluminum, but this does not make it impossible this method- we should not forget that a number of voltages indicate the possibility or impossibility of reactions occurring only in solutions.
Carbon monoxide most widely used. For example, when smelting iron in a blast furnace, the reducing agents are coke and the resulting carbon monoxide (II). The overall equation for obtaining iron from red iron ore is:
Fe 2 O 3 + 3CO = 2Fe + 3CO 2
Pure metals in modern technology are used relatively rarely. Pure copper and aluminum are used for manufacturing electrical wires. Zinc, nickel, chromium, and gold are applied to the surface of steel products to protect against corrosion and give a beautiful appearance.
Alloys have higher strength. Light alloys based on aluminum, for example, duralumin (contain copper and magnesium) - are especially widely used in the manufacture aircraft, cars, high-speed ships.
Iron-based alloys - cast iron and steel - are the main structural materials of modern technology. Cast iron, due to its lower cost, corrosion resistance, and good casting qualities, is widely used for the manufacture of machine tools, stoves, decorative garden trellises, etc.
Steel is well processed and has high strength. Adding alloying additives to steel allows you to give it special properties: high hardness, resistance to corrosion (stainless steels), acids (acid-resistant), high temperatures (heat-resistant), etc.
Copper-based alloys - brass and bronze - have good thermal conductivity and resistance to corrosion (including sea water), beautiful appearance. They are used for the manufacture of radiators, in shipbuilding, and for decorative purposes.
Alloys of tin and lead - solders - have a lower melting point than tin and lead separately. Used for soldering.
You will need
- - chemical vessels;
- - copper (II) oxide;
- - zinc;
- - hydrochloric acid;
- - alcohol lamp;
- - muffle furnace.
Instructions
Copper from oxide you can restore with hydrogen. First, repeat the safety precautions when working with heating devices, as well as with acids and flammable gases. Write the reaction equations: - interaction with hydrochloric acid Zn + 2HCl = ZnCl2 + H2; - reduction of copper with hydrogen CuO + H2 = Cu + H2O.
Before conducting an experiment, prepare equipment for it, since both reactions must occur in parallel. Take two tripods. In one of them secure a clean and dry test tube for oxide copper, and in the other - a test tube with a gas outlet tube, into which put a few pieces of zinc. Light the alcohol lamp.
Pour black copper powder into the prepared bowl. Fill with zinc immediately. Direct the gas outlet tube towards the oxide. Remember that only . Therefore, bring the alcohol lamp to the bottom of the test tube with CuO. Try to do everything quickly enough, since zinc reacts violently with acid.
More copper can be restored. Write down the reaction equation: 2CuO + C = 2Cu + CO2 Take copper(II) powder and dry it over a fire in an open porcelain cup (the powder should be colored). Then pour the resulting reagent into a porcelain crucible and add fine wood (coke) at the rate of 10 parts CuO to 1 part coke. Grind everything thoroughly with a pestle. Close the lid loosely so that the resulting product evaporates during the reaction. carbon dioxide, and place in a muffle furnace with a temperature of about 1000 degrees Celsius.
After the reaction is complete, cool the crucible and fill the contents with water. After this, stir the resulting suspension and you will see how the coal particles are separated from the heavy reddish balls. Take out the resulting metal. Later, if you wish, you can try to fuse the copper together in a furnace.
Before heating the bottom of the copper oxide tube, warm the entire tube. This will help avoid cracks in the glass.
Sources:
- how to get copper oxide
- Reduction of copper with hydrogen from copper oxide
Copper(Cuprum) is a chemical element of group I periodic table Mendeleev, having atomic number 29 and atomic mass 63,546. Most often, copper has valency II and I, less often – III and IV. In the periodic system, copper is located in the fourth period and is also included in group IB. This includes noble metals such as gold (Au) and silver (Ag). Now we will describe the methods for obtaining copper.
Instructions
Industrial copper production is complex and multi-stage. The mined metal is crushed and then purified from waste rock using the flotation beneficiation method. Next, the resulting concentrate (20-45% copper) is fired in an air-blast oven. After firing, a cinder should form. It is a solid that contains admixtures of many metals. Melt the cinder in a reverberatory or electric oven. After such smelting, in addition to slag, there is matte containing 40-50% copper.
The matte is further converted. This means that the heated matte is blown through with compressed and enriched air. Add quartz flux (SiO2 sand). During conversion, the unwanted FeS sulfide will go into the slag and be released in the form of sulfur dioxide SO2. At the same time, cuprous sulfide Cu2S will be oxidized. At the next stage, Cu2O oxide will be formed, which will react with copper sulfide.
As a result of all the described operations, blister copper will be obtained. The copper content in it is about 98.5-99.3% by weight. Blister copper is subjected to refining. This is the first stage of melting copper and passing oxygen through the resulting melt. The impurities of more active metals contained in copper immediately react with oxygen, immediately turning into oxide slag.
In the final part of the copper production process, it is subjected to electrochemical sulfur refining. In this case, blister copper is the anode, and purified copper is the cathode. Thanks to this purification, impurities of less active metals that were present in the blister copper precipitate. Impurities of more active metals are forced to remain in the electrolyte. It is worth noting that the purity of cathode copper that has passed all stages of purification reaches 99.9% or even more.
Copper– a widespread metal, which was one of the first to be mastered by man. Since ancient times, due to its relative softness, copper has been used mainly in the form of bronze, an alloy with tin. It is found both in nuggets and in the form of compounds. It is a ductile metal of a golden-pinkish color; in air it quickly becomes covered with an oxide film, giving the copper a yellow-red tint. How to determine whether a product contains copper?
Instructions
In order to find copper, you can carry out a fairly simple qualitative reaction. To do this, plan a piece of metal into shavings. If you want to analyze the wire, it must be cut into small pieces.
Then pour some concentrated nitrogen into the test tube. Carefully lower the shavings or pieces of wire there. The reaction begins almost immediately and requires great care and caution. It is good if it is possible to carry out this operation in a fume hood or, in as a last resort, fresh, because they are poisonous, very harmful to. They are easy because they are brown in color - you get the so-called “fox tail”.
The resulting solution must be evaporated on a burner. It is also highly advisable to do this in a fume hood. At this point, not only safe water vapor is removed, but also acid vapor and remaining nitrogen oxides. There is no need to completely evaporate the solution.
Video on the topic
note
It must be remembered that nitric acid, and especially concentrated nitric acid, is a very caustic substance; you must work with it with extreme caution! It is best to wear rubber gloves and safety glasses.
Helpful advice
Copper has high thermal and electrical conductivity, low resistivity, second only to silver in this regard. Why does this metal find wide application in electrical engineering for the manufacture of power cables, wires, printed circuit boards. Copper-based alloys are also used in mechanical engineering, shipbuilding, military affairs, and the jewelry industry.
Sources:
- where can you find copper in 2019
Today metals are used everywhere. Their role in industrial production difficult to overestimate. Most metals on Earth are in a coherent state - in the form of oxides, hydroxides, and salts. Therefore, industrial and laboratory preparation pure metals, as a rule, is based on certain reduction reactions.
You will need
- - salts, metal oxides;
- - laboratory equipment.
Instructions
Restore the colored ones metals by carrying out electrolysis of aqueous them with a high solubility index. This method is used in industrial scale to get some . This process can also be carried out in laboratory conditions using special equipment. For example, you can recover copper in an electrolyzer from a solution of its sulfate CuSO4 (copper sulfate).
Reduce metal by electrolysis of molten salt. In this way you can even obtain alkaline metals, for example, sodium. This method is also used in industry. To recover metal from molten salt, special equipment is required (has high temperature, and the gases formed during the electrolysis process must be effectively removed).
Reduce metals from their salts and weak organic ones by calcination. For example, in laboratory conditions it is possible to produce iron from its oxalate (FeC2O4 - iron oxalate) by strong heating in a quartz glass flask.
Obtain a metal from its oxide or mixture of oxides by reduction with carbon or. In this case, carbon monoxide can form directly in the reaction zone due to incomplete oxidation of carbon by atmospheric oxygen. A similar process occurs in blast furnaces when smelting iron from ore.
Reduce the metal from its oxide with a stronger metal. For example, it is possible to carry out the reduction reaction of iron with aluminum. To carry it out, a mixture of iron oxide powder and aluminum powder is prepared, after which it is set on fire using a magnesium tape. This one takes place with the release of very large quantity heat (thermite bombs are made from iron oxide and aluminum powder).
Video on the topic
note
Perform metal reduction reactions only in laboratory conditions, using special equipment and in compliance with all safety regulations.
Past inflammatory lung diseases, harmful production, allergens, smoking cessation and other factors require active recovery. Resins, wastes and toxins accumulate in the respiratory system for years. They become the source inflammatory processes. To restore the lungs, a complex effect on them is necessary. They will come to the rescue breathing exercises, physical activity on fresh air and, of course, herbal medicine.
You will need
- - marshmallow root;
- - resin, granulated sugar;
- - pine buds;
- - licorice root, sage leaf, coltsfoot leaves, anise fruits;
- - essential oils eucalyptus, fir, pine, marjoram;
- - thyme.
Instructions
What types of copper oxides exist?
In addition to the above-mentioned main copper oxide CuO, there are oxides of monovalent copper Cu2O and trivalent copper oxide Cu2O3. The first of them can be obtained by heating copper at a relatively low temperature, about 200 °C. However, such a reaction occurs only in the absence of oxygen, which is again impossible. The second oxide is formed by the interaction of copper hydroxide with strong oxidizing agent in an alkaline environment, also at low temperatures.
Thus, we can conclude that there is no need to worry about copper oxide conditions. In laboratories and in production, when working and its connections, it is necessary to strictly observe safety regulations.
There are many representatives of each of them, but the leading position is undoubtedly occupied by oxides. One chemical element There can be several different binary compounds with oxygen at once. Copper also has this property. It has three oxides. Let's look at them in more detail.
Copper(I) oxide
Its formula is Cu 2 O. In some sources, this compound may be called cuprous oxide, dicopper oxide or cuprous oxide.
Properties
It is a crystalline substance with a brown-red color. This oxide is insoluble in water and ethyl alcohol. It can melt without decomposing at a temperature slightly above 1240 o C. This substance does not interact with water, but can be transferred into solution if the participants in the reaction with it are concentrated hydrochloric acid, alkali, nitric acid, ammonia hydrate, ammonium salts, sulfuric acid .
Preparation of copper(I) oxide
It can be obtained by heating copper metal, or in an environment where oxygen has a low concentration, as well as in a flow of certain nitrogen oxides and together with copper (II) oxide. In addition, it can become a product of the thermal decomposition reaction of the latter. Copper (I) oxide can also be obtained if copper (I) sulfide is heated in a stream of oxygen. There are others, more complex ways its preparation (for example, reduction of one of the copper hydroxides, ion exchange of any monovalent copper salt with alkali, etc.), but they are practiced only in laboratories.
Application
Needed as a pigment when painting ceramics and glass; a component of paints that protect the underwater part of a vessel from fouling. Also used as a fungicide. Copper oxide valves cannot do without it.
Copper(II) oxide
Its formula is CuO. In many sources it can be found under the name copper oxide.
Properties
It is a higher oxide of copper. The substance has the appearance of black crystals that are almost insoluble in water. It reacts with acid and during this reaction forms the corresponding cupric salt, as well as water. When it is fused with alkali, the reaction products are cuprates. The decomposition of copper (II) oxide occurs at a temperature of about 1100 o C. Ammonia, carbon monoxide, hydrogen and coal are capable of extracting metallic copper from this compound.
Receipt
It can be obtained by heating copper metal in air environment under one condition - the heating temperature must be below 1100 o C. Also, copper (II) oxide can be obtained if carbonate, nitrate, or divalent copper hydroxide is heated.
Application
This oxide is used to color green or Blue colour enamel and glass, and also produce a copper-ruby variety of the latter. In the laboratory, this oxide is used to detect the reducing properties of substances.
Copper(III) oxide
Its formula is Cu 2 O 3. It has a traditional name, which probably sounds a little unusual - copper oxide.
Properties
It looks like red crystals that do not dissolve in water. The decomposition of this substance occurs at a temperature of 400 o C, the products of this reaction are copper (II) oxide and oxygen.
Receipt
It can be prepared by oxidizing copper hydroxide with potassium peroxydisulfate. Prerequisite reaction is an alkaline environment in which it must occur.
Application
This substance is not used by itself. In science and industry, its decomposition products - copper (II) oxide and oxygen - are more widely used.
Conclusion
That's all copper oxides. There are several of them due to the fact that copper has a variable valence. There are other elements that have several oxides, but we’ll talk about them another time.
The ability of hydrogen to reduce metals from oxides is usually demonstrated by its reaction with copper (II) oxide. To do this, hydrogen from a Kipp apparatus (check for purity!) is passed over heated copper (II) oxide. The test tube is fixed in a stand with the hole slightly inclined downward so that the water formed during the reaction drains. To better detect red copper, the residue after the experiment is ground in a porcelain mortar, on which a coating of metallic copper can be seen. It must be borne in mind that the resulting copper must be cooled in a stream of hydrogen, otherwise part of the reduced copper will oxidize again. If you take more copper (II) oxide, then after passing hydrogen through it and heating it strongly, you can put the heating device aside for a while. Self-heating of copper(II) oxide is observed, since its reduction with hydrogen is an exothermic reaction. (The same experiment can be carried out in a setup (Fig.) consisting of a dry glass tube (4), closed at both ends with plugs (6) with tubes. Place a little copper (II) oxide (5) in the glass tube (4) and secure it in a stand (9).Pass hydrogen into the tube from a test tube (1), closed with a stopper with a gas outlet tube (2) and connected by a rubber adapter (3) to a glass tube (4).
Visual observations ___
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Rice. Reduction of copper(II) oxide with hydrogen.
Reaction equation ______
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Experience 3. Comparison of the reducing properties of molecular and atomic hydrogen
To study the reducing properties of molecular and atomic hydrogen, pour a dilute solution of sulfuric acid into the first test tube, add a few drops of a solution of potassium permanganate and a piece of zinc, pour a dilute solution of H 2 SO 4 into the second test tube, add a few drops of KMnO 4 solution and pass hydrogen from the Kip apparatus .
Visual observations _______________________________________________
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Reaction equation ___________________________________________________
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Test questions for laboratory work “HYDROGEN”.
1. Hydrogen. Electronic structure of an atom. Isotopes.
2. Basic industrial and laboratory methods for producing hydrogen.
3. Physical properties hydrogen.
4. Chemical properties hydrogen.
5. What are the similarities between hydrogen and halogens, hydrogen and alkali metals?
6. Lead structural formula hydrogen peroxide and indicate the nature of the chemical bonds.
7. Write reaction equations for the interaction of hydrogen peroxide with potassium iodide, potassium nitrite, lead sulfide and silver oxide. Indicate whether hydrogen peroxide is the oxidizing or reducing agent in these reactions.
8. Finish the equations chemical reactions, name the substances obtained and indicate the type chemical bond:
Na + H 2 = H 2 + F 2 =
9. Write reaction equations that can be used to carry out the following transformations:
NaOH → H 2 → H 2 O → NaOH → NaHCO 3 → Na 2 SO 4
10. What volume of hydrogen (n.s.) will be released when aluminum weighing 32.4 g is exposed to a solution of hydrochloric acid with a volume of 200 ml (ρ = 1.11 g/cm 3) with a mass fraction of 25%?
11. 12 g of sodium hydride was dissolved in 50 g of water. Determine the mass fraction of sodium hydroxide (in percent) in the resulting solution.
12. Establish the formula of a hydrogen-nitrogen compound containing 12.5% hydrogen. The vapor density of this substance in air is 1.104.
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LABORATORY WORK No. 2. HALOGENS
Experience 1. Obtaining chlorine and chlorine water.
Place manganese (IV) oxide in a Wurtz flask equipped with a dropping funnel (see figure) and add concentrated hydrochloric acid drop by drop. Place the gas outlet tube in a bottle for collecting chlorine (or a bottle with distilled water (to obtain chlorine water) or with an alkali solution).
In 1 volume of water at room temperature 2.5 volumes of chlorine are dissolved. A solution of chlorine in water is called chlorine water. To prepare chlorine water, pass a strong current of chlorine through cold water under draft for 5-8 minutes. When the water turns yellow, the passage of chlorine is completed. Chlorine water is stored in the dark, in the cold, in a well-closed bottle, preferably with a ground-in glass stopper and a ground-in cap. In the absence of draft, chlorine water can be obtained in the device shown in the figure. Water is poured into the flask, excess chlorine is absorbed by the alkali solution.
Close the bottle with chlorine water and save it for the next experiments.
Visual observations _______________________________________________
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Reaction equation ___________________________________________________
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Experience 2. Decolorization of organic dyes with chlorine
Pour about 1 ml of distilled water into three test tubes. Add 2-3 drops of litmus solution to the first test tube, indigo to the second, and methyl violet to the third. Then add freshly prepared chlorine water to each test tube.
Visual observations _____________________________________________
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Experience 3. Comparative characteristics oxidative properties halogens
Add 3-5 drops of freshly prepared sodium bromide into a test tube, and 3-5 drops of potassium iodide into the other two. Add 4-5 drops of organic solvent (benzene or gasoline) to all test tubes. Add 2-4 drops of chlorine water to two test tubes containing a solution of bromide and iodide, and add bromine water to a third test tube containing a solution of iodide.
Visual observations _____________________________________________
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Reaction equation ___________________________________________________
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Experience 4. Qualitative reactions to halide ions
Add 3-5 drops of concentrated solutions of the following salts into three test tubes: sodium chloride into the first test tube, sodium bromide into the second, potassium iodide into the third. Add 1-2 drops of silver nitrate solution to each test tube.
Visual observations _____________________________________________
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Reaction equation ___________________________________________________
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Experiment 5. Sublimation of iodine.
Iodine sublimation can be carried out different ways
a) In a dry test tube, 2-3 iodine crystals are heated. In this case, the test tube is filled with violet iodine vapor, which, upon cooling, settles on its cold walls in the form of shiny small crystals.
B) Place several iodine crystals at the bottom of the glass, then cover it with a porcelain cup of water and place it on an asbestos mesh. After careful heating, violet vapor appears from below, and iodine crystallizes on the cold walls of the glass and at the bottom of the cup.
Visual observations _____________________________________________
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Reaction equation ___________________________________________________
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A clean, dry test tube with a small amount of copper oxide CuO is placed on the inclined gas outlet tube of the device for producing hydrogen. The slope should be such that the copper oxide powder does not slide down the walls of the test tube. An acid solution is added to the zinc poured into the reservoir of the device (p. 59), the purity of hydrogen is tested, and a test tube with pre-filled copper oxide powder is placed on the gas outlet tube. After carefully heating the test tube with the flame of an alcohol lamp (do not bring the flame closer to the hole: the hydrogen will flare up and in this case it will be difficult to extinguish it), copper oxide CuO is heated at some distance from the bottom of the test tube. As soon as slight heating begins, the alcohol lamp is set aside - the exothermic reaction itself reaches its end. Droplets of water condense on the walls of the test tube. At the end of the reaction, the test tube is heated again (without stopping the flow of hydrogen) to remove water from the walls (precaution, see above), and the resulting copper is left to cool in the flow of hydrogen, otherwise air will enter the test tube and the metal that has not had time to cool will oxidize. Copper metal powder is poured onto an anvil and hammered into small thin plates. You can grind some of the powder in a clean porcelain mortar. A thin layer of copper forms on its walls characteristic color. It is easy to remove it from the walls by moistening them with nitric acid.
The experiment can be performed in any device designed for laboratory work students with hydrogen and copper. To do this, you only need to replace the plug with a regular gas outlet tube with a plug with an inclined tube. If part of the gas outlet tube is rubber, instead of a short glass tip, attach a long (about 20 cm) glass tube to it, put it on the last drilled plug and secure it in a slightly inclined position in the tripod clamp. This is how a demonstration experience is usually designed, which requires more powerful source hydrogen (Kipp apparatus or other automatic device). When using automatic devices and even if there is a rubber gas outlet tube in a device with a funnel, it is relatively easy to extinguish the hydrogen flame that suddenly flares up at the opening of the test tube during heating by briefly closing the tap or clamping the rubber tube. Sometimes for a demonstration experiment they use a ball tube instead of a test tube, but there is no particular need for this.
b) If it is desirable to collect the water formed during the reaction, the experiment is carried out in the apparatus shown in Figure 81. A reaction bent and drawn tube, the length of which is about 18 cm, the outer diameter of 1.5 cm, can be made from a suitable glass tube on a good burner (t . I, p. 224) or order (betterfromrefractory glass). Placed in the tubezerthin or “wired” copper oxide CuO column up to 5 cm between two loose plugs of calcined asbestos wool. Hydrogen from the Kipp apparatus is dried by passing it through sulfuric acid. The resulting water condenses in a flask placed in a glass with cold water. It has a curved gas outlet tube to remove excess hydrogen. At the end of this tube, the purity of the escaping hydrogen is tested before heating begins.
In the absence of a curved reaction tube, you can use a ball or straight (1.5 cm in diameter) tube with a gas outlet tube bent at a right angle, and instead of a flask, use a water-cooled test tube.
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