What is sulfur? Sulfur beneficial properties for humans

Description and properties of sulfur

Sulfur is a substance that is in group 16, under the third period and has an atomic number of 16. It can be found both in native and bound form. Sulfur is designated by the letter S. Known sulfur formula– (Ne)3s 2 3p 4 . Sulfur as an element is included in many proteins.

The photo shows sulfur crystals

If we talk about atomic structure of the element sulfur, then in its outer orbit there are electrons whose valence number reaches six.

This explains the element's property of being maximally hexavalent in most combinations. There are four isotopes in the structure of a natural chemical element, and these are 32S, 33S, 34S and 36S. Speaking of external electron shell, the atom has a 3s2 3p4 scheme. The radius of the atom is 0.104 nanometers.

Properties of sulfur are primarily divided into physical types. This includes the fact that the element has a solid crystalline composition. Two allotropic modifications are the main state in which this sulfur element is stable.

The first modification is rhombic, lemon-yellow in color. Its stability is lower than 95.6 °C. The second is monoclinic, having a honey-yellow color. Its resistance ranges from 95.6 °C and 119.3 °C.

The photo shows the mineral sulfur

During the melting chemical element becomes a moving liquid that has a yellow color. It turns brown, reaching temperatures of more than 160 °C. And at 190 °C sulfur color turns into dark brown. After reaching 190 °C, a decrease in the viscosity of the substance is observed, which nevertheless becomes liquid after heating to 300 °C.

Other properties of sulfur:

Practically does not conduct heat or electricity.

Does not dissolve when immersed in water.

It is soluble in ammonia, which has an anhydrous structure.

It is also soluble in carbon disulfide and other organic solvents.

TO characteristics of the element sulfur it is important to add it too chemical features. She is active in this regard. If sulfur is heated, it can simply combine with almost any chemical element.

The photo shows a sample of sulfur mined in Uzbekistan

With the exception of inert gases. Upon contact with metals, chemicals. the element forms sulfides. Room temperature allows the element to react with. Increased temperature increases the activity of sulfur.

Let's consider how sulfur behaves with individual substances:

With metals it is an oxidizing agent. Forms sulfides.

Active interaction occurs with hydrogen at high temperatures – up to 200 °C.

With oxygen. Oxides form at temperatures up to 280 °C.

With phosphorus, carbon – it is an oxidizing agent. Only if there is no air during the reaction.

With fluorine it acts as a reducing agent.

With substances that have a complex structure - also as a reducing agent.

Sulfur deposits and production

The main source for obtaining sulfur is its deposits. In total, there are 1.4 billion tons of reserves of this substance worldwide. It is mined using both open and underground mining methods, and by smelting from underground.

The photo shows sulfur mining in the Kawa Ijen volcano

If the latter case applies, then water is used, which is overheated and melts the sulfur with it. In low-grade ores, the element is contained in approximately 12%. Rich – 25% and more.

Common types of deposits:

Stratiform – up to 60%.

Salt dome - up to 35%.

Volcanogenic – up to 5%.

The first type is associated with strata called sulfate-carbonate. At the same time, ore bodies that have a thickness of up to several tens of meters and a size of up to hundreds of meters are located in sulfate rocks.

Also, these strata deposits can be found among rocks of sulfate and carbonate origin. The second type is characterized by deposits gray, which are associated with salt domes.

The latter type is associated with volcanoes that have a young and modern structure. In this case, the ore element has a sheet-like, lens-shaped shape. It may contain sulfur in the amount of 40%. This type of deposit is common in the Pacific volcanic belt.

Sulfur deposit in Eurasia is located in Turkmenistan, the Volga region and other places. Sulfur rocks are found near the left banks of the Volga, which stretch from Samara. The width of the rock strip reaches several kilometers. Moreover, they can be found all the way to Kazan.

The photo shows sulfur in rock

In Texas and Louisiana, huge amounts of sulfur are found in the roofs of salt domes. Particularly beautiful Italians of this element are found in Romagna and Sicily. And on the island of Vulcano they find monoclinic sulfur. The element, which was oxidized by pyrite, was found in the Urals in the Chelyabinsk region.

For mining sulfur chemical element use different methods. It all depends on the conditions of its occurrence. At the same time, of course, special attention pay attention to safety.

Since hydrogen sulfide accumulates along with sulfur ore, it is necessary to take a particularly serious approach to any mining method, because this gas is poisonous to humans. Sulfur also tends to ignite.

Most often they use the open method. So, with the help of excavators, significant parts of the rocks are removed. Then the ore part is crushed using explosions. The lumps are sent to the factory for enrichment. Then - to the sulfur smelting plant, where sulfur is obtained from concentrate.

The photo shows sulfur in the port, brought by sea

In the case of deep occurrence of sulfur in many volumes, the Frasch method is used. The sulfur melts while still underground. Then, like oil, it is pumped out through a broken well. This approach is based on the fact that the element melts easily and has a low density.

A separation method using centrifuges is also known. Only this method has a drawback: sulfur is obtained with impurities. And then it is necessary to carry out additional cleaning.

In some cases, the borehole method is used. Other possibilities for mining the sulfur element:

Steam-water.

Filtration.

Thermal.

Centrifugal.

Extraction.

Application of sulfur

Most of the mined sulfur is used to make sulfuric acid. And the role of this substance is very huge in chemical production. It is noteworthy that to obtain 1 ton of sulfuric substance, 300 kg of sulfur is needed.

Sparklers, which glow brightly and have many dyes, are also produced using sulfur. The paper industry is another area where a significant portion of the extracted substance goes.

Pictured is sulfur ointment

More often application of sulfur finds when meeting production needs. Here are some of them:

Use in chemical production.

For the production of sulfites, sulfates.

Production of substances for fertilizing plants.

To obtain non-ferrous types of metals.

To give steel additional properties.

For making matches, materials for explosions and pyrotechnics.

Paints and fibers from artificial materials are produced using this element.

For bleaching fabrics.

In some cases sulfur element included in ointments that treat skin diseases.

Sulfur price

According to the latest news, the need for sulfur is actively growing. The cost of a Russian product is 130 dollars. For the Canadian version – $145. But in the Middle East, prices increased to $8, resulting in a cost of $149.

The photo shows a large specimen of the mineral sulfur

In pharmacies you can find ground sulfur powder at a price of 10 to 30 rubles. In addition, it is possible to buy it in bulk. Some organizations offer low price purchase granular technical gas sulfur.

IN free state sulfur is a yellow crystalline solid. Sulfur is characterized by the phenomenon of allotropy, i.e. existence in the form of several simple substances - allotropic modifications. Allotropic modifications of sulfur are orthorhombic (the most stable), monoclinic and plastic. Sulfur molecules in the orthorhombic modification consist of 8 atoms.

Sulfur belongs to the family of p-elements. The electronic configuration of sulfur is 3s 2 3p 4. Sulfur is characterized by the presence of three oxidation states “-2”, “+4” and “+6”.

To obtain sulfur, use the Wackenroeder reaction (1) or obtain it by incomplete oxidation of hydrogen sulfide (2):

2H 2 S + SO 2 = 3S↓ + 2H 2 O (1)

H 2 S + O 2 = 2S↓ + 2H 2 O (2)

Due to the presence of several oxidation states, sulfur is capable of exhibiting both oxidizing (in reactions with metals) and reducing (in reactions with strong oxidizing agents) properties:

Fe 0 -2e = Fe 2+ - oxidation process (reducing agent)

S 0 +2e = S 2- - reduction process (oxidizing agent)

S 0 – 4e = S 4+ - oxidation process (reducing agent)

O 2 0 + 2e = 2O 2- - reduction process (oxidizing agent)

Sulfur interacts with concentrated solutions of acids (dissolves in them) and with alkalis (disproportions):

S +2H 2 SO 4 = 3SO 2 + 2H 2 O

3S + NaOH = K 2 SO 3 + 2K 2 S + 3H 2 O

Hydrogen sulfide. Hydrogen sulfide acid. Sulfides

When sulfur is heated with hydrogen, a reversible reaction occurs as a result of which hydrogen sulfide is released - a colorless gas with the smell of rotten eggs, poisonous and poorly soluble in water:

S + H 2 ↔H 2 S

However, the yield of hydrogen sulfide in this reaction is small and to obtain it, the reaction of dilute acids on sulfides (salts of hydrosulfide acid) is most often used:

FeS + 2HCl = FeCl 2 + H 2 S

An aqueous solution of hydrogen sulfide is a very weak acid, the dissociation of which occurs in two stages:

H 2 S↔H + + HS —

HS - ↔ H + + S 2-

In this regard, hydrosulfide acid is characterized by the ability to form salts of two types - medium - sulfides (acid residue - S 2-) and acidic - hydrosulfides (acid residue - HS -).

Hydrogen sulfide acid is a strong reducing agent, because sulfur, which is part of this substance, is in the lowest oxidation state and can increase it to “+4” or “+6”, therefore the composition of the reaction products is determined by the strength and amount of the oxidizing agent:

H 2 S + 4Cl 2 + 4H 2 O = H 2 SO 4 + 8HCl

H 2 S + 3H 2 SO 4 = 4SO 2 + 4H 2 O

H 2 S + 4Br 2 = S + 3HBr

Sulfides, as salts formed by a weak acid, are characterized by the ability to hydrolyze. Sulfides of metals located in the activity series to the left of iron are soluble in strong acids:

ZnS + H 2 SO 4 = ZnSO 4 + H 2 S

The qualitative reaction to H 2 S and water-soluble sulfides is:

H 2 S + Pb(NO 3) 2 = PbS↓ + 2HNO 3

S 2- + Pb 2+ = PbS↓ (black precipitate)

Sulfur(IV) oxide. Sulfurous acid

In the oxidation state “+4”, sulfur forms an oxide, which corresponds to an acid. Sulfur(IV) oxide is gaseous substance(sulfur dioxide) is colorless, but has a pungent odor and is highly soluble in water.

There are industrial and laboratory methods for producing sulfur (IV) oxide. So, in industry (1), it is obtained by roasting sulfides, and in the laboratory (2) - by the action of strong acids on sulfites:

4FeS 2 + 11O 2 = 2Fe 2 O 3 + 8SO 2 (1)

Na 2 SO 3 + 2HCl = 2NaCl + SO 2 + H 2 O (2)

In an aqueous solution of sulfur (IV) oxide, the simultaneous existence of several chemical equilibria is possible:

H 2 O + SO 2 ↔ H 2 SO 3 ↔H + + HSO 3 — ↔ 2H + + SO 3 2-

The resulting sulfurous acid (H 2 SO 3) is dibasic, therefore capable of forming two types of salts - medium - sulfites (acid residue SO 3 2) and acidic - hydrosulfites (acid residue HSO 2 -).

For sulfur(IV) oxide, sulfurous acid and its salts are characteristic chemical properties, which can be divided into 3 groups: acid-base reactions (1), oxidation reactions (2) and reduction reactions (2):

Ca(OH) 2 + SO 2 = CaSO 3 ↓ + H 2 O (1)

Na 2 SO 3 + Cl 2 + H 2 O = Na 2 SO 4 + 2HCl (2)

SO 2 + C= S↓ + CO 2 (3)

Qualitative reaction to SO 2 and sulfites - discoloration of a solution of potassium permanganate:

5SO 2 + 2KMnO 4 + 2H 2 O = 2H 2 SO 4 + K 2 SO 4 + MnSO 4

Sulfur(VI) oxide. Sulfuric acid

Sulfur (VI) oxide is a colorless liquid that is obtained by oxidizing sulfur (IV) oxide with oxygen in the presence of a catalyst (V 2 O 5):

2SO 2 + O 2 ↔ 2SO 3

Sulfur oxide (VI) is highly soluble in water (forms sulfuric acid) and in 100% sulfuric acid (oleum is formed):

SO 3 + H 2 O = H 2 SO 4

Sulfuric acid is a heavy, viscous liquid that mixes well with water in all proportions. An aqueous solution of sulfuric acid is a strong acid. Since H 2 SO 4 is a dibasic acid, it is capable of forming two types of salts - medium - sulfates (acid residue SO 4 2-) and acidic - hydrosulfites (acid residue HSO 4 -).

When interacting with metals (both those in the activity series before and after hydrogen), sulfuric acid is reduced to sulfur oxide (IV):

Zn + H 2 SO 4 = ZnSO 4 + SO 2 +2H 2 O

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

Dilute sulfuric acid oxidizes only metals in the activity series before hydrogen:

Zn + H 2 SO 4 = ZnSO 4 + H 2

A qualitative reaction to sulfuric acid and soluble sulfates is the formation of a precipitate of barium sulfate - sediment white, insoluble in alkalis and acids:

Ba 2+ + SO 4 2- = BaSO 4 ↓

Examples of problem solving

EXAMPLE 1

EXAMPLE 2

Exercise	When sulfur reacts with concentrated nitric acid ( mass fraction 60%, solution density 1.27 g, ml) sulfuric acid and nitrogen oxide (II) with a volume of 67.2 l (n.s.) were formed. Calculate the mass of sulfur and the volume of solution nitric acid that reacted.
Solution	Let's write the reaction equation: S + 2HNO3 = 2NO + H2SO4 Let's find the amount of nitrogen oxide: mole. Let's calculate the mass of sulfur:

Sulfur is an essential element in modern industry.

What is sulfur and what does it look like?

Sulfur is a chemical element, number 16 in D.I. Mendeleev’s table and denoted by the letter S (after the first letter of the Latin name Sulfur).

The molar mass of sulfur is 32.065 g/mol, atomic mass- 32.066 a. e.m. This substance can be either bright yellow or brown.

There are powdered (ground) and liquid sulfur.

Characteristics of sulfur

Sulfur is a substance with a variable oxidation state. There are six valence electrons in the outer electron orbital of sulfur; two more are missing to fill it, so in compounds with metals and hydrogen it exhibits a valence of -2.

When interacting with oxygen and halogens, i.e., with elements with higher electronegativity, sulfur can exhibit positive valency, for example, +4 and +6.

Physical properties

As a simple substance, sulfur forms several allotropic modifications:

1. Rhombic is what we used to call ordinary sulfur. It is stable under normal conditions and is most often found near active or extinct volcanoes.
2. Plastic - represents closed or open chains of interconnected sulfur, usually obtained by burning it. Has the biggest molecular weight among all varieties of sulfur.
3. Monoclinic (S8) is a sulfur compound, which in molecular form is an octagon with sulfur atoms at the vertices. It looks like many needle-like cylinders. At room temperature quickly turns into a rhombic shape.

Approximate molar mass one molecule of monoclinic sulfur – 256 g/mol. In Russia, sulfur mainly comes in only two forms: commodity types: granular and lump.

Sulfur is a fusible substance, the melting point is about 120 degrees. Insoluble in water and does not get wet upon contact with it.

Does not have electrolytic properties and thermal conductivity. Sulfur density is 2.070 g/cm³.

Chemical properties

In compounds with hydrogen it forms sulfuric acid ( chemical formula H2SO4) with the oxidation state of sulfur +6 and sulfurous (H2SO3) with the oxidation state +4 acids, which give sulfates and sulfites, respectively.

IN normal conditions react with active metals and mercury, forming sulfides:

Also forms sulfides when heated with most inactive metals except platinum and gold:

Fe + S (t) = Fe2S3

It exhibits reducing properties in reaction with oxygen when heated, forming an acid oxide:

In reactions with hydrogen it forms sulfur dioxide, a volatile, colorless substance with unpleasant smell rotten eggs:

Applications

In low concentrations, it promotes the formation of new epidermal cells, which is why it is often used to treat inflammation. In addition, sulfur has a laxative effect, and when taken orally it has an expectorant effect.

Due to its flammability and combustible properties, sulfur burns well. For example, the easiest place to get sulfur is to open a full matchbox - sulfur is part of the match head.

When rubbed, the head touches a rough surface (such as sandpaper), and the match easily ignites.

Sulfuric acid (H2SO4) is an important product of the chemical industry; it is used as an electrolyte in lead batteries and is used to produce hydrochloric, nitric, boric and other acids.

Sulfuric acid is a necessary sulfonating agent in the preparation of many medicinal substances and paints.

Hydrogen sulfide (H2S) is used to separate pure sulfur, sulfites and sulfuric acid from solutions.

Sulfur oxides (SO2 and SO3) are used in the production of sulfuric and nitric acids, and are also used in household chemicals: included in bleaches and disinfectants.

Finding sulfur in nature

Most often found in nature is native sulfur (S), but its compounds with other elements are also found: FeS2 (iron (II) sulfate, pyrite), ZnS (zinc sulfate, zinc blende), CaSO4*2H2O (gypsum), PbS (lead sulfate, lead luster) and others.

Biological role of sulfur

Sulfur is found in living organisms, especially in the proteins of nails, hair, and hooves. Total weight sulfur in the human body is about 130 grams. This substance is also found in some vitamins and hormones.

Sulfur has unique chemical and physical properties, making it an essential component of industry and indispensable in the creation of medicines.

Miass Mechanical Engineering Faculty.

Department of Machine Production Technologies.

Final abstract.

"Characteristics of a chemical element

No. 16 (Sulphur)"

Completed by: Lobzev E.A.

Checked by: Melnechenko V.G.

Plan.

1. History of the discovery of the element.

2.Distribution of the element in nature.

3.Physical properties.

4. Chemical properties.

5.Receipt.

6. Application.

History of the discovery of the element. Sulfur (English Sulfur, French Sufre, German Schwefel) in its native state, as well as in the form of sulfur compounds, has been known since ancient times. Man probably became familiar with the smell of burning sulfur, the suffocating effect of sulfur dioxide and the disgusting smell of hydrogen sulfide back in the prehistoric times. It was because of these properties that sulfur was used by priests as part of sacred incense during religious rites. Sulfur was considered the work of superhuman beings from the world of spirits or underground gods. A very long time ago, sulfur began to be used as part of various flammable mixtures for military purposes. Homer already described “sulphurous fumes” lethal action emissions of burning sulfur. Sulfur was probably part of the “Greek fire” that terrified opponents. Around the 8th century The Chinese began to use it in pyrotechnic mixtures, in particular in mixtures such as gunpowder. The flammability of sulfur, the ease with which it combines with metals to form sulfides (for example, on the surface of pieces of metal), explains why it was considered the "principle of flammability" and mandatory integral part metal ores. Presbyter Theophilus (11th century) describes the method of oxidative firing of sulfide copper ore, probably known back in ancient Egypt. During the period of Arab alchemy, the mercury-sulfur theory of the composition of metals arose, according to which sulfur was revered as an essential component (father) of all metals. Later it became one of the three principles of alchemists, and later the “principle of flammability” became the basis of the theory of phlogiston. The elemental nature of sulfur was established by Lavoisier in his combustion experiments. With the introduction of gunpowder in Europe, the development of natural sulfur mining began, as well as the development of a method for producing it from pyrites; the latter was distributed in ancient Rus'. It was first described in literature by Agricola. Origin of Lat. Sulfur unclear. It is believed that this name was borrowed from the Greeks. In the literature of the alchemical period, sulfur often appears under various secret names. In Ruland one can find, for example, the names Zarnec (explanation of “egg with fire”), Thucios (living sulfur), Terra foetida, spiritus foetens, Scorith, Pater, etc. The Old Russian name “sulfur” has been used for a very long time. It meant various flammable and foul-smelling substances, resins, physiological secretions (earwax, etc.). Apparently, this name comes from the Sanskrit sira (light yellow). The word “gray” is associated with it, that is, of an indefinite color, which, in particular, refers to resins. The second Old Russian name for sulfur - bogey (flammable sulfur) - also contains the concept of not only flammability, but also a bad odor. As philologists explain, German. Schwefel has the Sanskrit root swep (to sleep, Anglo-Saxon sweblan - to kill), which may be related to poisonous properties sulfur dioxide.(3)

Distribution of the element in nature. Sulfur is widely distributed in nature. It makes up 0.05% of the mass earth's crust. In a free state (native sulfur) it is found in large quantities in Italy (the islands of Sicily) and the USA. Deposits of native sulfur are available in the Volga region, in the states Central Asia, in Crimea and other areas.

Sulfur often occurs in compounds with other elements. Its most important natural compounds are metal sulfides: FeS 2- iron pyrite, or pyrite; ZnS- zinc blende; PbS- lead shine; HgS- cinnabar, etc., as well as sulfuric acid salts (crystalline hydrates): CaSO 4 × 2H 2 O- plaster, Na2SO4 × 10H2O- Glauber's salt, МgSO 4 × 7H2O- bitter salt, etc.(2)

Physical properties. Sulfur is a hard, brittle, yellow substance. It is practically insoluble in water, but dissolves well in carbon disulfide, aniline and some other solvents. Conducts heat and electricity poorly. Sulfur forms several allotropic modifications - sulfur rhombic, monoclinic, plastic. The most stable modification is rhombic sulfur; all other modifications spontaneously transform into it after some time.

At 444.6 °C, sulfur boils, forming dark brown vapors. If they are quickly cooled, a fine powder consisting of tiny sulfur crystals is obtained, called sulfur color.

Chemical properties. Sulfur can donate its electrons when interacting with stronger oxidizing agents:

In these reactions, sulfur is the reducing agent. It must be emphasized that sulfur oxide(VI) can only be formed in the presence Pt or V2O5 and high blood pressure .

Hydrogen sulfide . When sulfur is heated with hydrogen, a reversible reaction occurs:
with a very low yield of hydrogen sulfide H 2 S. Usually H 2 S is obtained by the action of dilute acids
Hydrogen sulfide - typical reducing agent. It burns in oxygen. A solution of hydrogen sulfide in water is a very weak hydrosulfide acid, which dissociates stepwise and mainly in the first step:

Hydrogen sulfide acid, like hydrogen sulfide, is a typical reducing agent.

but also weaker ones, for example, sulfurous acid H 2 SO 3:

Some sulfides have a characteristic color: CuS And PbS- black, CdS- yellow, ZnS- white, MnS- pink, SnS- brown, Sb 2 S 3- orange, etc. Qualitative analysis of cations is based on the different solubility of sulfides and the different colors of many of them. (4)

Sulfur (IV) oxide. Sulfur (IV) oxide, or sulfur dioxide, under normal conditions is a colorless gas with a pungent, suffocating odor. When cooled to -10° C, it liquefies into a colorless liquid. In liquid form, it is stored in steel cylinders.

SO 2 is formed when sulfur is burned in oxygen or when sulfides are roasted. It is highly soluble in water (40 volumes in 1 volume of water at 20 °C).

Sulfur oxide (VI).SO 3 - sulfuric acid anhydride - a substance with t pl = 16.8 °C and t bp = 44.8 °C. Sulfur oxide (VI), or sulfur trioxide, is a colorless liquid that solidifies at temperatures below 17° C into a solid crystalline mass. Sulfur oxide (VI) has all the properties of acidic oxides. It is an intermediate product in the production of sulfuric acid.

Sulfur oxide (VI) is obtained by oxidation of SO 2 with oxygen only in the presence of a catalyst:

The need to use a catalyst in this reversible reaction is due to the fact that good way out SO 3 (i.e., a shift of equilibrium to the right) can only be obtained by lowering the temperature, but with low temperatures The reaction rate drops very significantly.

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 diluted 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 various salts metals 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 set fire to 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 removed if for a long time keep the moist contaminated area in the “vapor” of burning sulfur.

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 main problem is the transformation of sO2 into 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

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(iv) oxide can also be prepared relatively easily by dropping concentrated sulfuric acid into concentrated solution sodium sulfite na2so3. In this case, sulfuric acid, being stronger, will displace the weak acid from its salts.

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, reactors are used ceramic base. But more Sulfuric acid is now produced using the contact method.

Contact method

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:

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 during humid air. Collect so2 in an empty flask and, shaking vigorously, mix with a small amount water. We will obtain sulfuric acid - we will prove its presence, as in the previous method.

You can also place the glass wool and the 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.

Methods for producing sulfuric acid from anhydrite will 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:

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. In this case, 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.

Get high temperature we can also if we wrap the porcelain tube as tightly as possible with a 750-1000 W heating coil (see picture). 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 obtain 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, used as a lightweight, heat and sound barrier building material(Heraclitus plates).