Production and use of sulfur. Description of sulfur. Physical properties of sulfur
Sulfur and its compounds are among the most important classes of pesticides.
Sulfur is a yellow solid. There are crystalline and amorphous varieties. Sulfur does not dissolve in water, it dissolves well in carbon disulfide, aniline, phenol, benzene, gasoline, and poorly in alcohol and chloroform. At elevated temperatures it combines with oxygen, metals and many non-metals. Available in the form of 80-90% wetting powder, 70-75% colloidal sulfur, and ground sulfur.
Ground sulfur does not dissolve in water and is poorly wetted by it.
Colloidal sulfur It is well wetted with water and, when shaken or stirred, creates persistent cloudy suspensions. Evaporates weakly and slowly.
Produced and transported in metal and wooden barrels; and also in paper bags treated with a waterproof substance. When stored in loose containers, colloidal sulfur dries out, turning into lumps, and then mixes very poorly with water.
In livestock farming, colloidal sulfur is used to combat psoroptosis in cattle by spraying animals with a 3% aqueous suspension with a consumption of 3-4 liters per animal, twice, with an interval of 7-10 days.
Sulfur is low toxic. Acute poisoning when working with it is excluded. However, prolonged inhalation may cause respiratory problems.
Sulfur cuttings- molten sulfur turned into a cylindrical shape. Lit. When 1.4 g is burned, 1 liter of sulfur dioxide is obtained. The antiparasitic effect of sulfur is due to the formation of sulfur dioxide, hydrogen sulfide, oxygen, in the presence of moisture, alkalis and organic compounds. In concentrations of 5-8%, sulfur has a softening, keratoplastic, anti-inflammatory effect and a weak anti-scabies, and in high concentrations, due to the formation of sulfuric and sulfurous acids, irritating, drying and keratolytic effects develop. Sulfur cuttings are used to treat animals suffering from scabies, trichophytosis, microsporia, furunculosis, seborrhea, eczema, dermatitis in the form of 10-30% purified sulfur ointment or 5-10 and 20% precipitated sulfur ointment, as well as in the form of liniments and dusts.
To treat scabies, use sulfur ointment (sulfur 6 parts, green soap - 8, potassium carbonate - 1 and petroleum jelly - 10 parts).
Purified sulfur- sulfur, free from all impurities, is produced in powder in carefully closed containers. Purified sulfur has an antiparasitic and antidote effect against many poisonings. It is used in all cases as cutting sulfur.
Sulfur precipitated- purified from many impurities. Lit. When burned, sulfur dioxide is formed, which has antiparasitic and insecticidal effects. Pharmacodynamics and mechanism of action are the same as those of cutting sulfur. Available in powder form, in well-closed jars.
Sodium sulfate- a sulfur-containing substance with an antiparasitic effect. The mechanism of action is the formation of sulfur dioxide and sulfur during the interaction of sodium thiosulfate molecules with a molecule of acids or acid salts, as a result of which the redox processes in the parasites sharply change.
It is produced in powder form, which must be stored in a well-closed container.
Demos- an acaricidal drug, which includes sulfur and auxiliary components. This is a light brown liniment with a weak specific odor. The drug is produced in glass or plastic bottles with a capacity of 10, 15 and 20 ml. Store demos at a temperature of 0-25°C in a place protected from light. Shelf life - 2 years from the date of manufacture.
Demos is active against sarcoptoid mites - the causative agents of psoroptic mange in rabbits, otodectic mange in carnivores, notoedrosis in cats, as well as against the causative agent of demodicosis in dogs.
The drug has low toxicity for warm-blooded animals, it does not have an irritating or sensitizing effect.
When treating animals with ear scabies, first thoroughly clean the auricles from scabs with a swab soaked in camphor alcohol, then inject 1.5-3.0 ml of demos into the auricle using a pipette and lightly massage the auricle at the base. If other parts of the body are affected, the drug is rubbed into the affected areas using a cotton gauze swab at the rate of 0.1-0.3 cm of adjacent healthy skin.
Animals with large areas of skin lesions are treated in 2 doses, with an interval of 1 day, applying the drug first to one half and then to the other half of the affected surface of the body.
Plison(diphenyl disulfide), C12H10S2. Obtained by mixing coal oil 22-42%, diphenyl sulfide 6-10%, emulsifier OP-7 (rosin) or OP-10 (neonol) - 15-20% and water up to 100%. Diphenyl disulfide is produced as a by-product in the production of coal-tar phenols.
Plizon is a homogeneous, dark-colored oily liquid. The aqueous emulsion of this drug is stable for 4 hours at room temperature. The drug is low-toxic; when applied cutaneously, the LD50 is 12,500 mg/kg. 0.5% plison emulsion (therapeutic concentration) is well tolerated by sheep and is not accompanied by changes in the morphological picture of the blood. Plizone 2% causes a decrease in the activity of cholinesterase and alkaline phosphatase on the first day after purchase, without the manifestation of clinical signs of toxicosis.
Plizon, according to research by O.D. Yanyshevsky et al., is excreted from the internal organs and tissues of sheep treated with a 0.5% emulsion after 40 days, and from fat after 65. In animals treated with a 0.25% plison emulsion, diphenyl disulfide was absent in the internal organs and tissues after 20 days. It persists on sheep wool for up to 5 months in an amount of 15.1 mg/kg. It is not excreted in the milk of suckling ewes.
Lepran- a sulfur-containing product from the processing of benzothiophene coal tar. The liquid is dark brown in color with the smell of coal oil. When mixed with water, lepran forms a stable light brown emulsion. The drug consists of benzothiophene - 10-14%, coal oil 57-64, emulsifier 25-30 and water up to 100%. Lepran is low toxic, its LD50 when buying sheep is 14250 mg/kg. The cumulation coefficient is more than 5.28, which indicates weak cumulative properties, and does not have allergenic or irritating properties to the skin and mucous membranes. When treating sheep (one-time purchase) with 2% leprane emulsion (0.22% DDV), according to research by B.A. Timofeev, the drug does not have mutagenic properties, does not change hematological parameters of phosphatase, veterinary and sanitary indicators of the quality of sheep meat. 50 days after treatment, benzothiophene is not detected in the organs and tissues of sheep, the meat is suitable for release and sale for food purposes. Benzothiophene is not excreted in milk; the drug can be used to treat pregnant and lactating sheep.
In cases of poisoning of animals with sulfur-containing drugs, activated carbon, burnt magnesia, and a laxative are used internally.
In the VIA group, sulfur is also a widely known and widespread chemical element in nature. In the earth's crust, sulfur is found in the form of a number of minerals that form rich deposits. Native sulfur is often found, i.e. simple substance S (S 8). Sulfur compounds with metals are very common. Many of them are most valuable as ores for the production of metals: lead luster PbS, zinc blende ZnS, copper luster CuS, etc. The mineral pyrite FeS 2 (iron pyrite), which forms cubic crystals of brass color, serves mainly as a raw material for the production of sulfuric acid.
Some sulfates are also widespread. The minerals gypsum and anhydrite (crystalline hydrate CaS0 4 2H 2 0 and anhydrous calcium sulfate) form in some places entire mountains. Magnesium and sodium sulfates are found in sea water. Transparent crystals are formed by strontium sulfate SrS0 4 - celestine. Barite, or heavy spar BaS0 4, is widely used for the production of white and as a filler in the paper and rubber industries. For example, a layer of barite is applied to photographic paper. Coal contains significant amounts of sulfur and when it is burned it enters the atmosphere. The oxide cepbi(IV) S0 2 is constantly present in the air. If this sulfur were extracted from coal combustion products, it would be possible to sharply reduce the production of traditional sulfur ores. At the same time, the harmful effects of S0 2 on vegetation and fresh water bodies would be reduced. Sulfur is always present in proteins, since the amino acids cysteine and methionine contain sulfur. The total mass of sulfur in the human body is 120 g.
World sulfur production exceeds 60 million tons. More than half of this amount is used for the production of sulfuric acid, and the rest for the production of sulfites, rubber, and pest control products in agriculture.
Natural sulfur consists of four stable isotopes, with 95% of this mixture being the isotope
In terms of chemical properties, sulfur does not show significant similarities with oxygen. The main thing that brings these two elements together is the divalent state in compounds with most chemical elements. It should be noted that in compounds between oxygen and sulfur, oxygen remains divalent, and sulfur can be four- or six-valent. Higher valence states of sulfur are possible due to the presence
free 3
One of the important and characteristic properties of sulfur atoms is the ability to form chains:
If oxygen atoms are combined into chains of more than three atoms (in an ozone molecule), then sulfur under certain conditions gives chains of hundreds of thousands of atoms. Two interconnected sulfur atoms -8-8- often serve as a bridge within a protein molecule.
Sulfur. Simple substances
Sulfur as a simple substance forms several varieties. Common sulfur is a yellow, crystalline, brittle substance called rhombic sulfur. Beautiful crystals of natural sulfur are found in places where volcanic gases emerge (Kamchatka, Kuril Islands). Rhombic sulfur, stable under normal conditions, melts at 112.8°C. But liquid sulfur at 119°C begins to crystallize in the form of dark yellow needle-shaped crystals of a monoclinic system. Thus, sulfur forms two different solid phases, but below 112.8°C orthorhombic sulfur is stable. The boiling point of sulfur is 444.6°C. Sulfur is insoluble in water, but soluble in carbon disulfide and benzene.
Solid sulfur and its solutions consist of molecules 8 8 . These are ring molecules shaped like a crown (Fig. 19.3).
Rice. 19.3.
When writing chemical reactions, the molecular structure of sulfur is usually not taken into account and is written in the form of atoms. Above the melting point, sulfur gradually darkens and at ~250°C turns into a viscous mass of red-brown color, consisting of very long chains of 8 R.
Above 300°C, sulfur again becomes a mobile liquid. Boiling sulfur produces orange-yellow vapors. Sulfur vapor contains molecules B 8, 5 b, 8 4 and $ 2. Molecules 5 2 are close in structure to oxygen molecules 0 2.
If molten sulfur, heated to a boil, is poured into cold water (Fig. 19.4), it turns into a brown, soft, rubbery mass that stretches into threads. This type of sulfur is called plastic gray. It consists of zigzag very long molecules B, where P reaches 100,000 or more. After a short time, plastic sulfur becomes brittle, acquires a yellow color and gradually turns into rhombic sulfur 5 8 .
Rice. 19.4.
Sulfur is extracted directly from natural deposits. The extracted sulfur is distilled for purification in special refining furnaces. First, sulfur vapor enters a large brick chamber. On cold walls, sulfur precipitates in the form of a light yellow powder known as sulfur color. On hot walls at a temperature of about 120°C, the sulfur turns into a liquid, which is released into wooden molds, where it hardens in the form of sticks. The sulfur obtained in this way is called Cherenkova.
There are also many known reactions in which sulfur is released from complex substances. Sulfur is formed by mixing gaseous hydrogen sulfide and seionic gas:
The combustion of hydrogen sulfide in conditions of lack of oxygen also leads to the formation of sulfur (see below).
Oxides of sulfur (IU) and carbon (H) react to release sulfur in the presence of a catalyst:
This reaction is used to purify fuel combustion products from sulfur impurities.
Sulfur can be obtained by reaction in an aqueous solution. When hydrochloric acid is added to a solution of sodium thiosulfate Na 2 5 2 0 3, the liquid becomes cloudy, and light yellow fine sulfur gradually precipitates:
Chemical transformations of sulfur occur mainly during heating. Without the participation of other reagents, sulfur forms a number of different molecules:
Sulfur combines with almost all non-metals and metals. Reaction; hydrogen reversible:
Sulfur reacts with halogens, forming compounds in the di- and tetravalent state. Only with fluorine in its excess does the gaseous stable compound BR 6 form.
In air and oxygen, sulfur burns with a blue flame:
When sulfur burns, the temperature exceeds 800°C, as a result of which the equilibrium of the second reaction is greatly shifted to the left and only ~5% of sulfur is converted into $0 3.
Sulfur reacts with metals with a large release of heat. When a mixture of sulfur and zinc powders is ignited, a bright flash occurs. White zinc sulfide is formed:
Sulfur reacts with some ^-elements of the 5th and 6th periods more easily than oxygen. Silver is resistant to oxygen, but when mixed with sulfur without heating it forms brown sulfide:
Sulfur reacts with oxides, acids and salts that exhibit strong oxidizing properties:
When heated with an alkali solution, sulfur reacts in the same way as halogens, i.e. disorportions:
Sulfur atoms from a simple substance can attach to sulfur in some complex substances:
In the resulting polysulfide sodium contains chains of sulfur atoms with negative charges at the ends:
A solution of sodium sulfite reacts with sulfur when boiled:
The resulting colorless solution contains salt thiosulfur acids - sodium thiosulfate.
DEFINITION
Sulfur- the sixteenth element of the Periodic Table. Designation - S from the Latin "sulfur". Located in the third period, group VIA. Refers to non-metals. The nuclear charge is 16.
Sulfur occurs in nature both in a free state (native sulfur) and in various compounds. Sulfur compounds with various metals are very common. Many of them are valuable ores (for example, lead luster PbS, zinc blende ZnS, copper luster Cu 2 S) and serve as a source for non-ferrous metals.
Among sulfur compounds, sulfates are also common in nature, mainly calcium and magnesium. Finally, sulfur compounds are found in the organisms of plants and animals.
Atomic and molecular mass of sulfur
Relative molecular mass of the substance (M r) is a number showing how many times the mass of a given molecule is greater than 1/12 the mass of a carbon atom, and relative atomic mass of an element(A r) - how many times the average mass of atoms of a chemical element is greater than 1/12 the mass of a carbon atom.
The values of the atomic and molecular masses of sulfur are the same; they are equal to 32.059.
Allotropy and allotropic modifications of sulfur
Sulfur exists in the form of two allotropic modifications - orthorhombic and monoclinic.
At normal pressures, sulfur forms brittle yellow crystals that melt at 112.8 o C; the density is 2.07 g/cm3. It is insoluble in water, but quite soluble in carbon disulfide, benzene and some other liquids. When these liquids evaporate, sulfur is released from the solution in the form of yellow crystals of the orthorhombic system, in the shape of octahedrons, in which usually some of the corners or edges are cut off (Fig. 1). This modification of sulfur is called rhombic.
Rice. 1. Allotropic modifications of sulfur.
Crystals of a different shape are obtained if molten sulfur is slowly cooled and, when it partially solidifies, the liquid that has not yet had time to solidify is drained. Under these conditions, the walls of the vessel are covered from the inside with long dark yellow needle-shaped crystals of the monoclinic system. This modification of sulfur is called monoclinic. It has a density of 1.96 g/cm3, melts at 119.3 o C and is stable only at temperatures above 96 o C.
Sulfur isotopes
It is known that in nature sulfur can be found in the form of four stable isotopes 32 S, 33 S, 34 S and 36 S. Their mass numbers are 32, 33, 34 and 36, respectively. The nucleus of an atom of the sulfur isotope 32 S contains sixteen protons and sixteen neutrons, and the isotopes 33 S, 34 S and 36 S contain the same number of protons, seventeen, eighteen and twenty neutrons, respectively.
There are artificial isotopes of sulfur with mass numbers from 26 to 49, among which the most stable is 35 S with a half-life of 87 days.
Sulfur ions
The outer energy level of the sulfur atom has six electrons, which are valence electrons:
1s 2 2s 2 2p 6 3s 2 3p 4 .
As a result of chemical interaction, sulfur can lose its valence electrons, i.e. be their donor, and turn into positively charged ions or accept electrons from another atom, i.e. be their acceptor and turn into negatively charged ions:
S 0 -6e → S 6+ ;
S 0 -4e → S 4+ ;
S 0 -4e → S 2+ ;
S o +2e → S 2- .
Sulfur molecule and atom
The sulfur molecule is monatomic - S. Here are some properties that characterize the sulfur atom and molecule:
Examples of problem solving
EXAMPLE 1
| Exercise | What mass of sulfur will be required to obtain aluminum sulfide Al 2 S 3 weighing 30 g? Under what conditions can this sulfide be obtained from simple substances? |
| Solution | Let us write the reaction equation for the production of sulfur sulfide: 2Al + 3S = Al 2 S 3. Let's calculate the amount of aluminum sulfide substance (molar mass - 150 g/mol): n(Al 2 S 3) = m(Al 2 S 3) / M(Al 2 S 3); n(Al 2 S 3) = 30 / 150 = 0.2 mol. According to the reaction equation n(Al 2 S 3) : n(S) = 1:3, it means: n(S) = 3 × n(Al 2 S 3); n(S) = 3 × 0.2 = 0.6 mol. Then the mass of sulfur will be equal (molar mass - 32 g/mol): m(S) = n(S) × M(S); DEFINITION Sulfur– element of the 3rd period of the VIA group, belongs to the family of p-elements. Serial number 16. The electron configuration is 1s 2 2s 2 2p 6 3s 2 3p 4. The symbol is S. Relative atomic mass – 32 amu. Boiling point – 444.67C, melting point – 112.85C. Non-metal. Chemical properties of sulfurSulfur interacts with simple substances - non-metals, exhibiting the properties of a reducing agent. Sulfur directly interacts only with fluorine. Reactions of interaction with other metals occur when heated: S + F 2 = SF 6; 2S + Cl 2 = S 2 Cl 2; S + Cl 2 = SCl 2; 5S + 2P = P 2 S 5 ; S + H 2 = H 2 S; S + O 2 = SO 2; 2S + Br 2 = S 2 Br 2. In reactions of interaction with simple substances - metals, sulfur exhibits the properties of an oxidizing agent. These reactions occur when heated and are very violent: 2Na + S = Na 2 S; 2Al + 3S = Al 2 S 3; Sulfur reacts with complex substances. It is able to dissolve in concentrated acids and molten alkalis, and in the latter case, sulfur is disproportionate. These reactions occur when the reaction mixture boils: 3S + 6KOH = K 2 SO 3 + 2K 2 S + 3H 2 O; S + 6HNO 3 = H 2 SO 4 + 6NO 2 + 2H 2 O; S + 2H 2 SO 4 = 3SO 2 + 2H 2 O. When sulfur reacts with metal sulfides, polysulfides are formed: Na 2 S + S = Na 2 S 2. Physical properties of sulfurSulfur is a yellow crystalline substance. It exists in the form of two allotropic modifications - α-sulfur (orthorhombic crystal lattice) and β-sulfur (monoclinic crystal lattice), as well as an amorphous form - plastic sulfur (Fig. 1). In the crystalline state, sulfur is built from non-planar cyclic S8 molecules. Sulfur is poorly soluble in ethanol, but soluble in carbon disulfide and liquid ammonia. Does not react with liquid water and iodine. Rice. 1. Forms of existence of sulfur. Production and use of sulfurOn an industrial scale, sulfur is obtained from natural deposits of native sulfur. Sulfur is the raw material for the production of sulfuric acid. E1 is used in the paper industry, agriculture, rubber, dyes, gunpowder, etc. Sulfur has found wide application in medicine, for example, sulfur is included in various ointments and powders used for skin diseases, etc. Examples of problem solvingEXAMPLE 1 SULFUR Dissolving sulfur Sulfur, which is known to be insoluble in water and dissolves in small quantities in benzene, alcohol or ether, is perfectly soluble in carbon disulfide cs2. If you slowly evaporate a solution of a small amount of sulfur in carbon disulfide on a watch glass, you will get large crystals of the so-called rhombic or a-sulfur. But let’s not forget about the flammability and toxicity of carbon disulfide, so let’s turn off all the burners and place the watch glass under the draft or in front of the window. Another form - monoclinic or b-cepa - can be obtained by patiently crystallizing needles about 1 cm long from toluene (toluene is also flammable!). Production of hydrogen sulfide and experiments with it Place a little (about the size of a pea) of the resulting iron sulfide in a test tube and add dilute hydrochloric acid. Substances interact with violent gas release: fes + 2hcl = h2s + fecl2 An unpleasant smell of rotten eggs comes from the test tube - this is hydrogen sulfide evaporating. If you pass it through water, it will partially dissolve. A weak acid is formed, a solution of which is often called hydrogen sulfide water. Extreme care must be taken when working with hydrogen sulfide, as the gas is almost as poisonous as hydrocyanic acid hcn. It causes paralysis of the respiratory tract and death if the concentration of hydrogen sulfide in the air is 1.2-2.8 mg/l. Chemically, hydrogen sulfide is detected using wet lead reagent paper. To obtain it, we moisten filter paper with a dilute solution of lead acetate or nitrate, dry it and cut it into strips 1 cm wide. Hydrogen sulfide reacts with lead ions, resulting in the formation of black lead sulfide. This method can detect hydrogen sulfide in spoiled food products (eggs, meat). We recommend producing hydrogen sulfide using the dry method, since in this case the gas flow can be easily adjusted and shut off at the right time. For this purpose, melt about 25 g of paraffin in a porcelain cup and mix 15 g of sulfur with the melt. Then remove the burner and stir the mixture until it hardens. Grind the solid mass and save it for further experiments. When it is necessary to obtain hydrogen sulfide, we heat several pieces of a mixture of paraffin and sulfur in a test tube to a temperature above 170°C. As the temperature rises, the gas output increases, and if the burner is removed, it stops. During the reaction, paraffin hydrogen interacts with sulfur, resulting in the formation of hydrogen sulfide, and carbon remains in the test tube, for example: c40h82 + 41s = 41h2s + 40c We obtain sulfides To examine the color of precipitated metal sulfides, let us pass hydrogen sulfide through solutions of various metal salts. Sulfides of manganese, zinc, cobalt, nickel and iron will precipitate if an alkaline environment is created in the solution (for example, by adding ammonium hydroxide). Lead, copper, bismuth, cadmium, antimony and tin sulfides will precipitate in the hydrochloric acid solution. Hydrogen sulfide combustion Having made a preliminary test for detonating gas, let’s ignite the hydrogen sulfide coming out of a glass tube drawn at the end. Hydrogen sulfide burns with a pale flame with a blue halo: ЗН2s + ЗО2 = 2h2o + 2so2 As a result of combustion, sulfur oxide (iv) or sulfur dioxide is produced. It is easily identified by its pungent odor and the redness of wet blue litmus paper. If there is insufficient access to oxygen, hydrogen sulfide is oxidized only to sulfur. Activated carbon catalytically accelerates this process. This method is often used for fine purification of industrial gases, the sulfur content of which should not exceed 25 g/m3: 2h2s + O2 = 2H2O + 2s It is not difficult to reproduce this process. The installation diagram is shown in the figure. The main thing is to pass air and hydrogen sulfide through activated carbon in a ratio of 1: 3. Yellow sulfur will be released on the carbon. Activated carbon can be cleaned of sulfur by washing it in carbon disulfide. In technology, a solution of ammonium sulfide (nh4)2s is most often used for this purpose. Experiments with sulfurous acid Sulfur oxide (iv) - sulfur dioxide - is extremely soluble in water, resulting in the formation of sulfurous acid: h2o + so2 = h2so3 It kills germs and has a whitening effect; In breweries and wineries, barrels are fumigated with sulfur. Sulfur dioxide is also used to bleach wicker baskets, wet wool, straw, cotton and silk. Stains From blueberries, for example, they are eliminated if you keep a moist, contaminated area in the “vapor” of burning sulfur for a long time. Let's check the bleaching effect of sulfurous acid. To do this, let’s lower the cylinder, where pieces of sulfur have been burning for some time, into various colored objects (flowers, wet pieces of fabric, important litmus paper, etc.), cover the cylinder well with a glass plate and wait for a while. Anyone who has ever studied the atomic structure of elements knows that the sulfur atom has six so-called valence electrons in its outer orbit. Therefore, sulfur can be maximally hexavalent in compounds. This oxidation state corresponds to sulfur oxide (vi) with the formula so3. It is a sulfuric anhydride: h2o + so3 = h2so4 When sulfur is burned under normal conditions, sulfur oxide (iv) is always produced. And if a certain amount of sulfur oxide (vi) is formed, then most often it immediately decomposes under the influence of heat into sulfur oxide (iv) and oxygen: 2so3 = 2so2 + o2 In the production of sulfuric acid, the main problem is the conversion of sO2 to so3. For this purpose, two methods are now used: chamber (or improved - tower) and contact. (see experiment "Preparation of sulfuric acid) Preparation of sulfuric acid Chamber method
When the flask is filled with gas, close it with a stopper with three holes. In one, as shown in the figure, we insert a glass tube bent at a right angle, connected to the side outlet of the test tube, in which, when pieces of copper and nitric acid interact, nitric oxide is formed (iv): 4hno3 + Сu = cu(no3)2 + 2h2o + 2no2 The acid concentration should be about 60% (wt). Attention! no2 is a strong poison! Into another hole we will insert a glass tube connected to the test tube, through which water vapor will later flow. In the third hole we insert a short piece of tube with a Bunsen valve - a short piece of rubber hose with a slot. First, let's create a strong influx of nitrogen oxide into the flask. (Caution! Poison!) But there is no reaction yet. The flask contains a mixture of brown no2 and colorless so2. As soon as we pass water vapor, a change in color will indicate that the reaction has begun. Under the influence of water vapor, nitrogen oxide (iv) oxidizes sulfur oxide (iv) to sulfur oxide (vi), which immediately, interacting with water vapor, turns into sulfuric acid: 2no2 + 2so2 = 2no + so3 Colorless condensate will collect at the bottom of the flask, and excess gas and vapor will escape through the Bunsen valve. Let's pour the colorless liquid from the flask into a test tube, check the acidic reaction with litmus paper and detect the sulfate ion so42- of the resulting sulfuric acid by adding a solution of barium chloride. A thick white precipitate of barium sulfate will indicate to us that the experiment was successful. By this principle, but on a much larger scale, sulfuric acid is produced in technology. Previously, reaction chambers were lined with lead, as it is resistant to sulfuric acid vapor. In modern tower installations, ceramic-based reactors are used. But larger quantities of sulfuric acid are now produced using the contact method. Contact method
4fes2 + 11O2 = 3fe2o3 + 8so2 The resulting iron(iii) oxide is removed from the furnace as scale and further processed in iron production plants. Crush several pieces of pyrite in a mortar and place them in a refractory glass tube, which we close with a stopper with a hole. Then use a burner to heat the tube strongly, while simultaneously passing air through it using a rubber bulb. In order for the volatile dust from the roasting gas to settle, we will take it into an empty glass vessel, and from it into a second refractory tube, which contains a catalyst heated to 400-500 °C. In technology, vanadium (v) oxide v2o5 or sodium vanadate navo3 is most often used as a catalyst, and for this purpose we will use red iron oxide (iii) fe2O3. Apply finely ground iron oxide onto glass wool, which we distribute in a tube in a layer 5 cm long. Heat the tube with the catalyst until it reaches red heat. On the catalyst, sulfur oxide (iv) interacts with atmospheric oxygen; as a result, sulfur oxide (vi) is formed 2so2 + o2 = 2so3 which we distinguish by its ability to form fog in moist air. Collect so2 in an empty flask and, shaking vigorously, mix with a small amount of water. We will obtain sulfuric acid - we will prove its presence, as in the previous method. You can also place the glass wool and catalyst separated in one of the glass tubes. You can also work in a test tube with a side outlet. Let's put pyrite on the test tubes, a layer of glass wool on it, and then glass wool with a catalyst. We introduce air from above into the tube, which should fit close to the catalyst. On the side branch we will attach a tube bent at an angle, which leads into the test tube. If there is no pyrite, then in a test tube with a side outlet we will obtain sulfur oxide (iv) from sodium sulfite or hydrosulfite of sulfuric acid, and then pass the resulting gas over the catalyst along with a stream of air or oxygen. Chromium oxide (III) can also be used as a catalyst, which should be calcined in an iron crucible and finely crushed in a mortar. For the same purpose, you can soak a clay shard with a solution of iron (ii) sulfate and then strongly calcinate it. In this case, a fine powder of oxide iron (iii) is formed on the clay. Acid from gypsum If there are few metal sulfides (as, for example, in Germany), the starting products for the production of sulfuric acid can be caso4 anhydrite and caso4-h2o gypsum. The method for obtaining sulfur oxide (iv) from these products was developed by Müller and Kuehne 60 years ago.
caso4 + 2c = cas + 2co2 cas + 3caso4 = 4cao + 4so2 It is possible to decompose calcium sulfate in laboratory conditions only when using appropriate high temperature. We will work with equipment similar to that which was used for firing pyrite, only we will take a porcelain or iron tube for combustion. Close the tube with plugs wrapped in asbestos fabric for thermal insulation. We will insert a capillary into the hole in the first plug, and into the second, a simple glass tube, which we will connect with a washing bottle half filled with water or a fuchsin solution. Let's prepare the reaction mixture as follows. Grind 10 g of gypsum, 5 g of kaolin (clay) and 1.5 g of active powdered carbon in a mortar. Dry the mixture by heating it for some time at 200 °C in a porcelain cup. After cooling (preferably in a desiccator), add the mixture to the middle of the combustion tube. At the same time, pay attention to ensure that it does not fill the entire cross-section of the tube. Then we heat the tube strongly using two burners (one from below, the second obliquely from above) and, when the tube is heated, we pass a not too strong air flow through the entire system. Within 10 minutes, due to the formation of sulfurous acid, the fuchsin solution in the washing bottle will become discolored. Turn off the water jet pump and stop heating. We can also get a high temperature if we wrap a porcelain tube as tightly as possible with a 750-1000 W heating coil (see figure). We connect the ends of the spiral with thick copper wire, which we also wrap around the tube many times, and then insulate it with porcelain beads and connect it to the plug. (Careful when working with 220 V!) Naturally, a glass torch or blowtorch can also be useful as a heating source. The technique works with a mixture of anhydrite, coke, clay, sand and pyrite cinder fe2o3. A worm conveyor delivers the mixture to a 70-meter rotating tube furnace, where the pulverized coal is burned. The temperature at the end of the furnace, at the combustion site, is approximately 1400 °C. At this temperature, the quicklime formed during the reaction is fused with clay, sand and pyrite cinder to form cement clinker. The cooled clinker is ground and mixed with a few percent of gypsum. The resulting high-quality Portland cement goes on sale. With careful implementation and control of the process, from 100 tons of anhydrite (plus clay, sand, coke and pyrite cinder) you can get about 72 tons of sulfuric acid and 62 tons of cement clinker. Sulfuric acid can also be obtained from kieserite (magnesium sulfate mgso4 -H2O). For the experiment, we will use the same setup as for the decomposition of gypsum, but this time we will take a tube made of refractory glass. We obtain the reaction mixture by calcining 5 g of magnesium sulfate in a porcelain bowl, and 0.5 g of active carbon in an iron crucible with a lid, and then mixing them and growing in a mortar to a dusty state. Transfer the mixture to a porcelain boat and place it in the reaction tube. The white mass that will be obtained at the end of the experiment in a porcelain boat consists of magnesium oxide. In technology, it is processed into Sorel cement, which is the basis for the production of xylolite. The production of derivative products such as cement clinker and xylolite, which are important for the construction industry, makes the production of sulfuric acid from local raw materials particularly economical. Processing intermediates and by-products into valuable raw materials or final products is an important principle of the chemical industry. Let's get xylolite Mix equal parts of magnesium oxide and sawdust with a solution of magnesium chloride and apply a layer of the resulting slurry about 1 cm thick to the substrate. After 24-48 hours the mass will harden like stone. It does not burn, it can be drilled, sawed and nailed. In the construction of houses, xylolite is used as a flooring material. Wood fiber, hardened without filling the gaps with Sorel cement (magnesium cement), pressed and glued into slabs, is used as a lightweight, heat- and sound-proof building material (Heraclitus slabs). Editor's Choice
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Let's fill a large vessel (500 ml round-bottomed flask) with sulfur oxide (iv) so2, placing burning pieces of sulfur in it for a while or supplying gas from the apparatus where it is formed. Sulfur oxide (iv) can also be prepared relatively easily by dropping concentrated sulfuric acid into a concentrated solution of sodium sulfite na2so3. In this case, sulfuric acid, being stronger, will displace the weak acid from its salts.
Various cheeses are used in the production of sulfuric acid. Pure sulfur began to be used only in the 60s. In most cases, enterprises produce sulfur oxide (iv) by roasting sulfide ores. In a rotary tube kiln or multi-deck kiln, pyrite reacts with atmospheric oxygen according to the following equation:
Methods for producing sulfuric acid from anhydrite will continue to be important in the future, since sulfuric acid is the most common chemical product. Sulfates can be decomposed using high (up to 2000 °C) temperatures. Müller found that the decomposition temperature of calcium sulfate could be reduced to 1200 °C by adding finely ground coke. First, at 900 °C, coke reduces calcium sulfate to sulfide, which in turn, at a temperature of 1200 °C, reacts with undecomposed sulfate; in this case, sulfur oxide (iv) and quicklime are formed: