Sulfuric acid and its chemical properties. Oxidizing properties of sulfuric acid

The industrial production of sulfuric acid began in the 15th century - then this substance was called "vitriol". Today it is a demanded substance that is widely used in industry. If at the dawn of the discovery of sulfuric acid, the entire need of mankind for this substance was several tens of liters, today the bill goes to millions of tons per year.

Pure sulfuric acid (formula H2SO4) at 100% concentration is a thick, colorless liquid. Its main property is high hygroscopicity, accompanied by high heat release. Concentrated solutions include solutions from 40% - they can dissolve palladium or silver. At a lower concentration, the substance is less active and reacts, for example, with copper or brass.

H2SO4 occurs in its pure form in nature. For example, in the Dead Lake in Sicily, sulfuric acid oozes from the bottom: in this case, pyrite from earth's crust. Also, small drops of sulfuric acid often end up in the earth's atmosphere after large volcanic eruptions, in which case H2SO4 can cause significant climate changes.

Obtaining sulfuric acid.

Despite the presence of sulfuric acid in nature, most of it is produced industrial way.

The most common today is contact method production: it reduces harm to environment and get a product that is most suitable for all consumers. Less popular is the nitrous method of production, which involves oxidation with nitric oxide.

The following substances act as raw materials in contact production:

• Sulfur;
• pyrite (sulfur pyrites);
• vanadium oxide (used as a catalyst);
• sulfides of various metals;
• hydrogen sulfide.

Before the beginning production process raw materials are being prepared, during which, first of all, pyrite is crushed in special crushing machines. This allows you to speed up the reaction due to an increase in the area of ​​​​contact of the active substances. Then pyrite is cleaned: for this, it is immersed in large containers of water, while impurities and waste rock float to the surface, after which they are removed.

The production itself can be divided into several stages:

1. Purified pyrite after grinding is loaded into the furnace, where it is fired at a temperature of up to 800 degrees. From below, air is supplied to the chamber according to the counterflow principle, due to which the perit is in a suspended state. Previously, such firing took place within a few hours, but now the process takes a few seconds. Waste in the form of iron oxide, formed during the roasting process, is removed and sent to the metallurgical enterprises. During firing, SO2 and O2 gases are released, as well as water vapour. After cleaning from the smallest particles and water vapor, oxygen and pure sulfur oxide are obtained.
2. In the second stage, an exothermic reaction takes place under pressure, in which a vanadium catalyst is involved. The reaction starts at a temperature of 420 degrees, but for greater efficiency it can be raised to 550 degrees. During the reaction, catalytic oxidation occurs and SO2 is converted to SO
3. The third production step is the absorption of SO3 in an absorption tower, resulting in the formation of H2SO4 oleum, which is filled into tanks and sent to consumers. Excess heat during production is used for heating.

About 10 million tons of H2SO4 are produced annually in Russia. At the same time, the main producers are companies that are also its main consumers. Basically, these are enterprises producing mineral fertilizers, for example, Ammophos, Balakovo Mineral Fertilizers. Since pyrite, which is the main raw material, is a waste product of enrichment enterprises, its suppliers are the Talnakh and Norilsk enrichment plants.

In the world, the leaders in the production of H2SO4 are China and the United States, annually producing 60 and 30 million tons of the substance, respectively.

The use of sulfuric acid.

The global industry annually consumes about 200 million tons of sulfuric acid for the production of many types of products. In terms of industrial use, it ranks first among all acids.

1. Fertilizer production. The main consumer of sulfuric acid (about 40%) is the production of fertilizers. That is why plants producing H2SO4 are built near plants producing fertilizers. Sometimes they are parts of the same enterprise with a common production cycle. In this production, pure acid of 100% concentration is used. For the production of a ton of superphosphate, or ammophos, most often used in agriculture, takes about 600 liters of sulfuric acid.
2. Purification of hydrocarbons. Production of gasoline, kerosene, mineral oils also does not do without sulfuric acid. This industry also consumes about 30% of all H2SO4 produced in the world, which in this case is used for purification in the oil refining process. It also treats wells during oil production and increases the octane number of fuel.
3. Metallurgy. Sulfuric acid used in metallurgy for cleaning sheet metal, wire and all kinds of blanks from rust, scale, as well as for the restoration of aluminum in the production of non-ferrous metals. Used for etching metal surfaces before coating them with nickel, chromium or copper.
4. Chemical industry. With the help of H2SO4, many organic and inorganic compounds are produced: phosphoric, hydrofluoric and other acids, aluminum sulfate, which is used in pulp and paper industry. Without it, it is impossible to produce ethyl alcohol, medicines, detergents, insecticides and other substances.

The scope of H2SO4 is truly huge and it is impossible to list all the ways of its industrial use. It is also used in water purification, dye production, as an emulsifier in the food industry, in the synthesis of explosives, and for many other purposes.

Acids are chemical compounds consisting of hydrogen atoms and acidic residues, for example, SO4, SO3, PO4, etc. They are inorganic and organic. The former include hydrochloric, phosphoric, sulfide, nitric, sulfuric acid. To the second - acetic, palmitic, formic, stearic, etc.

What is sulfuric acid

This acid consists of two hydrogen atoms and an acid residue SO4. It has the formula H2SO4.

Sulfuric acid, or, as it is also called, sulfate, refers to inorganic oxygen-containing dibasic acids. This substance is considered one of the most aggressive and chemically active. In most chemical reactions, it acts as an oxidizing agent. This acid can be used in concentrated or diluted form, in these two cases it has slightly different Chemical properties.

Physical properties

Sulfuric acid under normal conditions has a liquid state, its boiling point is approximately 279.6 degrees Celsius, the freezing point when it turns into solid crystals is about -10 degrees for one hundred percent and about -20 for 95 percent.

Pure 100% sulfate acid is an oily liquid substance odorless and colorless, which has almost twice the density than water - 1840 kg / m3.

Chemical properties of sulfate acid

Sulfuric acid reacts with metals, their oxides, hydroxides and salts. Diluted with water in various proportions, it can behave differently, so let's take a closer look at the properties of a concentrated and weak solution of sulfuric acid separately.

concentrated sulfuric acid solution

A concentrated solution is considered to be a solution that contains from 90 percent sulfate acid. Such a solution of sulfuric acid is capable of reacting even with little active metals, as well as with non-metals, hydroxides, oxides, salts. The properties of such a solution of sulfate acid are similar to those of concentrated nitrate acid.

Interaction with metals

During the chemical reaction of a concentrated solution of sulfate acid with metals located to the right of hydrogen in the electrochemical series of metal voltages (that is, with not the most active), the following substances are formed: sulfate of the metal with which the interaction takes place, water and sulfur dioxide. The metals, as a result of interaction with which the listed substances are formed, include copper (cuprum), mercury, bismuth, silver (argentum), platinum and gold (aurum).

Interaction with inactive metals

With metals that are to the left of hydrogen in the voltage series, concentrated sulfuric acid behaves a little differently. As a result of such a chemical reaction, the following substances are formed: sulfate of a certain metal, hydrogen sulfide or pure sulfur and water. The metals with which such a reaction takes place also include iron (ferum), magnesium, manganese, beryllium, lithium, barium, calcium and all the others that are in the series of voltages to the left of hydrogen, except for aluminum, chromium, nickel and titanium - with them concentrated sulfate acid does not react.

Interaction with non-metals

This substance is a strong oxidizing agent, therefore it is able to participate in redox chemical reactions with non-metals, such as, for example, carbon (carbon) and sulfur. As a result of such reactions, water is necessarily released. When this substance is added to carbon, carbon dioxide and sulfur dioxide are also released. And if you add acid to sulfur, you get only sulfur dioxide and water. In such a chemical reaction, sulfate acid plays the role of an oxidizing agent.

Interaction with organic substances

Carbonization can be distinguished among the reactions of sulfuric acid with organic substances. Such a process occurs when a given substance collides with paper, sugar, fibers, wood, etc. In this case, carbon is released in any case. The carbon formed during the reaction can partially interact with sulfuric acid in excess. The photo shows the reaction of sugar with a solution of sulfate acid of medium concentration.

Reactions with salts

Also, a concentrated solution of H2SO4 reacts with dry salts. In this case, a standard exchange reaction occurs, in which metal sulfate is formed, which was present in the structure of the salt, and an acid with a residue that was in the composition of the salt. However, concentrated sulfuric acid does not react with salt solutions.

Interaction with other substances

Also, this substance can react with metal oxides and their hydroxides, in these cases exchange reactions occur, in the first metal sulfate and water are released, in the second - the same.

Chemical properties of a weak solution of sulfate acid

Dilute sulfuric acid reacts with many substances and has the same properties as all acids. It, unlike concentrated, interacts only with active metals, that is, those that are to the left of hydrogen in a series of voltages. In this case, the same substitution reaction occurs, as in the case of any acid. This releases hydrogen. Also, such an acid solution interacts with salt solutions, as a result of which an exchange reaction occurs, already discussed above, with oxides - just like concentrated, with hydroxides - also the same. In addition to ordinary sulfates, there are also hydrosulfates, which are the product of the interaction of hydroxide and sulfuric acid.

How to know if a solution contains sulfuric acid or sulfates

To determine whether these substances are present in a solution, a special qualitative reaction for sulfate ions is used, which allows you to find out. It consists in adding barium or its compounds to the solution. As a result, a precipitate may form white color(barium sulfate), indicating the presence of sulfates or sulfuric acid.

How is sulfuric acid produced?

The most common method of industrial production of this substance is its extraction from iron pyrite. This process occurs in three stages, each of which is a certain chemical reaction. Let's consider them. First, oxygen is added to pyrite, resulting in the formation of ferum oxide and sulfur dioxide, which is used for further reactions. This interaction occurs at high temperature. This is followed by a step in which, by adding oxygen in the presence of a catalyst, which is vanadium oxide, sulfur trioxide is obtained. Now, at the last stage, water is added to the resulting substance, and sulfate acid is obtained. This is the most common process for the industrial extraction of sulfate acid, it is used most often because pyrite is the most accessible raw material suitable for the synthesis of the substance described in this article. Sulfuric acid obtained using such a process is used in various industries - both in the chemical industry and in many others, for example, in oil refining, ore dressing, etc. It is also often used in the manufacturing technology of many synthetic fibers .

DEFINITION

anhydrous sulfuric acid is a heavy viscous liquid, which is easily miscible with water in any proportion: the interaction is characterized by an exceptionally large exothermic effect (~880 kJ / mol at infinite dilution) and can lead to explosive boiling and splashing of the mixture if water is added to the acid; That's why it's so important to always use reverse order in the preparation of solutions and add the acid to the water, slowly and with stirring.

Some physical properties of sulfuric acid are given in the table.

Anhydrous H 2 SO 4 is a remarkable compound with an unusually high dielectric constant and very high electrical conductivity, which is due to the ionic autodissociation (autoprotolysis) of the compound, as well as the proton transfer relay conduction mechanism that ensures the flow electric current through a viscous liquid a large number hydrogen bonds.

Table 1. Physical properties sulfuric acid.

Getting sulfuric acid

Sulfuric acid is the most important industrial chemical and the cheapest produced in large volume acids in any country of the world.

Concentrated sulfuric acid (“vitriol oil”) was first obtained by heating “green vitriol” FeSO 4 × nH 2 O and spent in in large numbers to obtain Na 2 SO 4 and NaCl.

The modern process for producing sulfuric acid uses a catalyst consisting of vanadium(V) oxide with the addition of potassium sulfate on a carrier of silicon dioxide or diatomaceous earth. Sulfur dioxide SO 2 is obtained by burning pure sulfur or by roasting sulfide ore (primarily pyrite or ores of Cu, Ni and Zn) in the process of extracting these metals. Then SO 2 is oxidized to trioxide, and then sulfuric acid is obtained by dissolving in water:

S + O 2 → SO 2 (ΔH 0 - 297 kJ / mol);

SO 2 + ½ O 2 → SO 3 (ΔH 0 - 9.8 kJ / mol);

SO 3 + H 2 O → H 2 SO 4 (ΔH 0 - 130 kJ / mol).

Chemical properties of sulfuric acid

Sulfuric acid is a strong dibasic acid. In the first stage, in solutions of low concentration, it dissociates almost completely:

H 2 SO 4 ↔H + + HSO 4 -.

Dissociation on the second stage

HSO 4 - ↔H + + SO 4 2-

proceeds to a lesser extent. The dissociation constant of sulfuric acid in the second stage, expressed in terms of ion activity, K 2 = 10 -2.

As a dibasic acid, sulfuric acid forms two series of salts: medium and acidic. Medium salts of sulfuric acid are called sulfates, and acid salts are called hydrosulfates.

Sulfuric acid greedily absorbs water vapor and is therefore often used to dry gases. The ability to absorb water also explains the charring of many organic substances, especially those belonging to the class of carbohydrates (fiber, sugar, etc.), when exposed to concentrated sulfuric acid. Sulfuric acid removes hydrogen and oxygen from carbohydrates, which form water, and carbon is released in the form of coal.

Concentrated sulfuric acid, especially hot, is a vigorous oxidizing agent. It oxidizes HI and HBr (but not HCl) to free halogens, coal to CO 2 , sulfur to SO 2 . These reactions are expressed by the equations:

8HI + H 2 SO 4 \u003d 4I 2 + H 2 S + 4H 2 O;

2HBr + H 2 SO 4 \u003d Br 2 + SO 2 + 2H 2 O;

C + 2H 2 SO 4 \u003d CO 2 + 2SO 2 + 2H 2 O;

S + 2H 2 SO 4 \u003d 3SO 2 + 2H 2 O.

The interaction of sulfuric acid with metals proceeds differently depending on its concentration. Dilute sulfuric acid oxidizes with its hydrogen ion. Therefore, it interacts only with those metals that are in the series of voltages only up to hydrogen, for example:

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

However, lead does not dissolve in dilute acid because the resulting PbSO 4 salt is insoluble.

Concentrated sulfuric acid is an oxidizing agent due to sulfur (VI). It oxidizes metals in the voltage series up to and including silver. The products of its reduction can be different depending on the activity of the metal and on the conditions (acid concentration, temperature). When interacting with low-active metals, such as copper, the acid is reduced to SO 2:

Cu + 2H 2 SO 4 \u003d CuSO 4 + SO 2 + 2H 2 O.

When interacting with more active metals, reduction products can be both dioxide and free sulfur and hydrogen sulfide. For example, when interacting with zinc, reactions can occur:

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

3Zn + 4H 2 SO 4 = 3ZnSO 4 + S↓ + 4H 2 O;

4Zn + 5H 2 SO 4 \u003d 4ZnSO 4 + H 2 S + 4H 2 O.

The use of sulfuric acid

The use of sulfuric acid varies from country to country and from decade to decade. So, for example, in the USA, the main area of ​​H 2 SO 4 consumption is the production of fertilizers (70%), followed by chemical production, metallurgy, oil refining (~5% in each area). In the UK, the distribution of consumption by industry is different: only 30% of H 2 SO 4 produced is used in the production of fertilizers, but 18% goes to paints, pigments and dye intermediates, 16% to chemical production, 12% to soap and detergents, 10 % for the production of natural and artificial fibers and 2.5% is used in metallurgy.

Examples of problem solving

EXAMPLE 1

Exercise	Determine the mass of sulfuric acid that can be obtained from one ton of pyrite if the yield of sulfur oxide (IV) in the roasting reaction is 90%, and sulfur oxide (VI) in the catalytic oxidation of sulfur (IV) is 95% of the theoretical.
Decision	Let us write the reaction equation for pyrite firing: 4FeS 2 + 11O 2 \u003d 2Fe 2 O 3 + 8SO 2. Calculate the amount of pyrite substance: n(FeS 2) = m(FeS 2) / M(FeS 2); M (FeS 2) \u003d Ar (Fe) + 2 × Ar (S) \u003d 56 + 2 × 32 \u003d 120 g / mol; n (FeS 2) \u003d 1000 kg / 120 \u003d 8.33 kmol. Since in the reaction equation the coefficient for sulfur dioxide is twice as large as the coefficient for FeS 2, the theoretically possible amount of sulfur oxide (IV) substance is: n (SO 2) theor \u003d 2 × n (FeS 2) \u003d 2 × 8.33 \u003d 16.66 kmol. And practically the amount of mole of sulfur oxide (IV) obtained is: n (SO 2) pract \u003d η × n (SO 2) theor \u003d 0.9 × 16.66 \u003d 15 kmol. Let's write the reaction equation for the oxidation of sulfur oxide (IV) to sulfur oxide (VI): 2SO 2 + O 2 \u003d 2SO 3. The theoretically possible amount of sulfur oxide substance (VI) is: n(SO 3) theor \u003d n (SO 2) pract \u003d 15 kmol. And practically the amount of mole of sulfur oxide (VI) obtained is: n(SO 3) pract \u003d η × n (SO 3) theor \u003d 0.5 × 15 \u003d 14.25 kmol. We write the reaction equation for the production of sulfuric acid: SO 3 + H 2 O \u003d H 2 SO 4. Find the amount of sulfuric acid substance: n (H 2 SO 4) \u003d n (SO 3) pract \u003d 14.25 kmol. The reaction yield is 100%. The mass of sulfuric acid is: m (H 2 SO 4) \u003d n (H 2 SO 4) × M (H 2 SO 4); M(H 2 SO 4) = 2×Ar(H) + Ar(S) + 4×Ar(O) = 2×1 + 32 + 4×16 = 98 g/mol; m (H 2 SO 4) \u003d 14.25 × 98 \u003d 1397 kg.
Answer	The mass of sulfuric acid is 1397 kg

Sulfuric acid, H2SO4, a strong dibasic acid corresponding to the highest oxidation state of sulfur (+6). Under normal conditions - a heavy oily liquid, colorless and odorless. In engineering, sulfuric acid is called its mixtures with both water and sulfuric anhydride. If the molar ratio of SO3: H2O is less than 1, then this is an aqueous solution of sulfuric acid, if more than 1, it is a solution of SO3 in sulfuric acid.

Natural deposits of native sulfur are relatively small. The total sulfur content in the earth's crust is 0.1%. Sulfur is found in oil, coal, combustible and flue gases. Sulfur is most often found in nature in the form of compounds with zinc, copper and other metals. It should be noted that the share of pyrites and sulfur in the total balance of sulfuric acid raw materials is gradually decreasing, and the share of sulfur extracted from various wastes is gradually increasing. The possibilities for obtaining sulfuric acid from waste are very significant. The use of waste gases from non-ferrous metallurgy makes it possible to obtain, without special costs, in sulfuric acid systems for the roasting of sulfur-containing raw materials.

Physical and chemical properties of sulfuric acid

100% H2SO4 (SO3 x H2O) is called monohydrate. The compound does not smoke, in a concentrated form it does not destroy ferrous metals, while being one of the strongest acids;

• the substance has a detrimental effect on plant and animal tissues, taking away water from them, as a result of which they are charred.
• crystallizes at 10.45 "C;
• tkip 296.2 "C;
• density 1.9203 g/cm3;
• heat capacity 1.62 J/g.

Sulfuric acid mixes with H2O and SO3 in any ratio, forming compounds:

• H2SO4 x 4 H2O (tmelt - 28.36 "C),
• H2SO4 x 3 H2O (tmelt - 36.31 "C),
• H2SO4 x 2 H2O (tmelt - 39.60 "C),
• H2SO4 x H2O (tmelt - 8.48 "C),
• H2SO4 x SO3 (H2S2O7 - disulfuric or pyrosulfuric acid, mp 35.15 "C) - oleum,
• H2SO x 2 SO3 (H2S3O10 - trisulfuric acid, mp 1.20 "C).

When aqueous solutions of sulfuric acid containing up to 70% H2SO4 are heated and boiled, only water vapor is released into the vapor phase. Sulfuric acid vapors also appear above more concentrated solutions. A solution of 98.3% H2SO4 (azeotropic mixture) is completely distilled at boiling (336.5 "C). Sulfuric acid containing more than 98.3% H2SO4 releases SO3 vapor when heated.
Concentrated sulfuric acid is a strong oxidizing agent. It oxidizes HI and HBr to free halogens. When heated, it oxidizes all metals except Au and platinum metals (with the exception of Pd). In the cold, concentrated sulfuric acid passivates many metals, including Pb, Cr, Ni, steel, cast iron. Dilute sulfuric acid reacts with all metals (except Pb) that precede hydrogen in the voltage series, for example: Zn + H2SO4 = ZnSO4 + H2.

how strong acid H2SO4 displaces weaker acids from their salts, such as boric acid from borax:

Na2B4O7 + H2SO4 + 5 H2O = Na2SO4 + 4 H2BO3,

and when heated, it displaces more volatile acids, for example:

NaNO3 + H2SO4 = NaHSO4 + HNO3.

Sulfuric acid takes away chemically bound water from organic compounds containing hydroxyl groups - OH. Dehydration of ethyl alcohol in the presence of concentrated sulfuric acid leads to the production of ethylene or diethyl ether. Charring of sugar, cellulose, starch and other carbohydrates upon contact with sulfuric acid is also explained by their dehydration. As a dibasic, sulfuric acid forms two types of salts: sulfates and hydrosulfates.

Freezing point of sulfuric acid:
concentration, %	freezing temperature, "C
74,7	-20
76,4	-20
78,1	-20
79,5	-7,5
80,1	-8,5
81,5	-0,2
83,5	1,6
84,3	8,5
85,7	4,6
87,9	-9
90,4	-20
92,1	-35
95,6	-20

Raw materials for the production of sulfuric acid

The raw materials for the production of sulfuric acid can be: sulfur, sulfur pyrite FeS2, exhaust gases from oxidative roasting of sulfide ores Zn, Cu, Pb and other metals containing SO2. In Russia, the main amount of sulfuric acid is obtained from sulfur pyrites. FeS2 is burned in furnaces where it is in a fluidized bed state. This is achieved by rapidly blowing air through a layer of finely ground pyrites. The resulting gas mixture contains SO2, O2, N2, impurities of SO3, vapors of H2O, As2O3, SiO2 and others, and carries a lot of cinder dust, from which gases are cleaned in electrostatic precipitators.

Methods for producing sulfuric acid

Sulfuric acid is obtained from SO2 in two ways: nitrous (tower) and contact.

nitrous method

The processing of SO2 into sulfuric acid by the nitrous method is carried out in production towers - cylindrical tanks (15 m or more high) filled with a packing of ceramic rings. From above, towards the gas flow, "nitrose" is sprayed - dilute sulfuric acid containing nitrosyl sulfuric acid NOOSO3H, obtained by the reaction:

N2O3 + 2 H2SO4 = 2 NOOSO3H + H2O.

Oxidation of SO2 by nitrogen oxides occurs in solution after its absorption by nitrose. Nitrose is hydrolyzed by water:

NOOSO3H + H2O = H2SO4 + HNO2.

Sulfur dioxide entering the towers forms sulfurous acid with water:

SO2 + H2O = H2SO3.

The interaction of HNO2 and H2SO3 leads to the production of sulfuric acid:

2 HNO2 + H2SO3 = H2SO4 + 2 NO + H2O.

The liberated NO is converted in the oxidation tower into N2O3 (more precisely, into a mixture of NO + NO2). From there, the gases enter the absorption towers, where sulfuric acid is supplied to meet them from above. Nitrose is formed, which is pumped into the production towers. Thus, the continuity of production and the cycle of nitrogen oxides are ensured. Their inevitable losses with exhaust gases are replenished by the addition of HNO3.

Sulfuric acid obtained by the nitrous method has an insufficiently high concentration and contains harmful impurities (for example, As). Its production is accompanied by the release of nitrogen oxides into the atmosphere ("fox tail", so named for the color of NO2).

contact way

The principle of the contact method for the production of sulfuric acid was discovered in 1831 by P. Philips (Great Britain). The first catalyst was platinum. At the end of the 19th - beginning of the 20th centuries. acceleration of the oxidation of SO2 to SO3 by vanadium anhydride V2O5 was discovered. The studies of the Soviet scientists A. E. Adadurov, G. K. Boreskov, and F. N. Yushkevich played a particularly important role in the study of the action of vanadium catalysts and their selection.

Modern sulfuric acid plants are built to work according to the contact method. Vanadium oxides with additions of SiO2, Al2O3, K2O, CaO, BaO in various proportions are used as the basis of the catalyst. All vanadium contact masses show their activity only at a temperature not lower than ~ 420 ° C. In the contact apparatus, the gas usually passes 4 or 5 layers of the contact mass. In the production of sulfuric acid by the contact method, the roasting gas is preliminarily purified from impurities that poison the catalyst. dust residues are removed in washing towers irrigated with sulfuric acid.Fog is removed from sulfuric acid (formed from SO3 and H2O present in the gas mixture) in wet electrostatic precipitators.H2O vapor is absorbed by concentrated sulfuric acid in drying towers.The SO2-air mixture then passes through the catalyst ( contact mass) and oxidized to SO3:

SO2 + 1/2 O2 = SO3.

SO3 + H2O = H2SO4.

Depending on the amount of water entering the process, a solution of sulfuric acid in water or oleum is obtained.
About 80% of the world's H2SO4 is now produced by this method.

The use of sulfuric acid

Sulfuric acid can be used to purify petroleum products from sulfurous, unsaturated organic compounds.

In metallurgy, sulfuric acid is used to remove scale from wire, as well as sheets before tinning and galvanizing (diluted), for pickling various metal surfaces before coating them with chromium, copper, nickel, etc. Complex ores are also decomposed with sulfuric acid (in particular, uranium).

In organic synthesis, concentrated sulfuric acid is a necessary component of nitrating mixtures, as well as a sulphurizing agent in the production of many dyes and medicinal substances.

Sulfuric acid is widely used for the production of fertilizers, ethyl alcohol, artificial fibers, caprolactam, titanium dioxide, aniline dyes and a number of others. chemical compounds.

Spent sulfuric acid (waste) is used in chemical, metallurgical, woodworking and other industries. Battery sulfuric acid is used in the production of lead-acid current sources.

Sulfuric acid (H2SO4) is one of the most caustic acids and dangerous reagents, known to man especially in concentrated form. Chemically pure sulfuric acid is a heavy toxic liquid of oily consistency, odorless and colorless. Obtained by oxidation sour gas(SO2) contact way.

At a temperature of + 10.5 °C, sulfuric acid turns into a frozen glassy crystalline mass, greedily, like a sponge, absorbing moisture from the environment. In industry and chemistry, sulfuric acid is one of the main chemical compounds and occupies a leading position in terms of production in tons. That is why sulfuric acid is called the "blood of chemistry". Sulfuric acid is used to make fertilizers medications, other acids, large , fertilizers and much more.

Basic physical and chemical properties of sulfuric acid

1. Sulfuric acid in its pure form (formula H2SO4), at a concentration of 100%, is a colorless thick liquid. The most important property of H2SO4 is its high hygroscopicity - the ability to remove water from the air. This process is accompanied by a massive release of heat.
2. H2SO4 is a strong acid.
3. Sulfuric acid is called monohydrate - it contains 1 mol of H2O (water) per 1 mol of SO3. Because of its impressive hygroscopic properties, it is used to extract moisture from gases.
4. Boiling point - 330 ° C. In this case, the acid is decomposed into SO3 and water. Density - 1.84. Melting point - 10.3 ° C /.
5. Concentrated sulfuric acid is a powerful oxidizing agent. To start the redox reaction, the acid must be heated. The result of the reaction is SO2. S+2H2SO4=3SO2+2H2O
6. Depending on the concentration, sulfuric acid reacts differently with metals. In a dilute state, sulfuric acid is capable of oxidizing all metals that are in the series of voltages to hydrogen. An exception is made as the most resistant to oxidation. Dilute sulfuric acid reacts with salts, bases, amphoteric and basic oxides. Concentrated sulfuric acid is capable of oxidizing all metals in the series of voltages, and silver too.
7. Sulfuric acid forms two types of salts: acidic (hydrosulfates) and medium (sulfates)
8. H2SO4 enters into an active reaction with organic substances and non-metals, and it can turn some of them into coal.
9. Sulfuric anhydrite is perfectly soluble in H2SO4, and in this case oleum is formed - a solution of SO3 in sulfuric acid. Outwardly, it looks like this: fuming sulfuric acid, releasing sulfuric anhydrite.
10. Sulfuric acid in aqueous solutions is a strong dibasic acid, and when it is added to water, a huge amount of heat is released. When preparing dilute solutions of H2SO4 from concentrated ones, it is necessary to add a heavier acid to water in a small stream, and not vice versa. This is done to avoid boiling water and splashing acid.

Concentrated and dilute sulfuric acids

Concentrated solutions of sulfuric acid include solutions from 40%, capable of dissolving silver or palladium.

Dilute sulfuric acid includes solutions whose concentration is less than 40%. These are not such active solutions, but they are able to react with brass and copper.

Getting sulfuric acid

The production of sulfuric acid on an industrial scale was launched in the 15th century, but at that time it was called "vitriol". If earlier humanity consumed only a few tens of liters of sulfuric acid, then in modern world the calculation goes to millions of tons per year.

The production of sulfuric acid is carried out industrially, and there are three of them:

1. contact method.
2. nitrous method
3. Other Methods

Let's talk in detail about each of them.

contact production method

The contact method of production is the most common, and it performs the following tasks:

• It turns out a product that satisfies the needs of the maximum number of consumers.
• During production, harm to the environment is reduced.

In the contact method, the following substances are used as raw materials:

• pyrite (sulfur pyrites);
• sulfur;
• vanadium oxide (this substance causes the role of a catalyst);
• hydrogen sulfide;
• sulfides of various metals.

Before starting the production process, raw materials are pre-prepared. To begin with, pyrite is subjected to grinding in special crushing plants, which allows, due to an increase in the area of ​​​​contact of the active substances, to accelerate the reaction. Pyrite undergoes purification: it is lowered into large containers of water, during which waste rock and all kinds of impurities float to the surface. They are removed at the end of the process.

The production part is divided into several stages:

1. After crushing, pyrite is cleaned and sent to the furnace - where it is fired at temperatures up to 800 ° C. According to the principle of counterflow, air is supplied to the chamber from below, and this ensures that the pyrite is in a suspended state. Today, this process takes a few seconds, but earlier it took several hours to fire. During the roasting process, waste in the form of iron oxide appears, which is removed and subsequently transferred to enterprises. metallurgical industry. During firing, water vapor, O2 and SO2 gases are released. When the purification from water vapor and the smallest impurities is completed, pure sulfur oxide and oxygen are obtained.
2. In the second stage, an exothermic reaction takes place under pressure using a vanadium catalyst. The start of the reaction starts when the temperature reaches 420 °C, but it can be increased to 550 °C in order to increase efficiency. During the reaction, catalytic oxidation occurs and SO2 becomes SO.
3. The essence of the third stage of production is as follows: the absorption of SO3 in the absorption tower, during which the oleum H2SO4 is formed. In this form, H2SO4 is poured into special containers (it does not react with steel) and is ready to meet the end user.

During production, as we said above, a lot of thermal energy is generated, which is used for heating purposes. Many sulfuric acid plants install steam turbines that use the exhaust steam to generate additional electricity.

Nitrous process for the production of sulfuric acid

Despite the advantages of the contact method of production, which produces more concentrated and pure sulfuric acid and oleum, quite a lot of H2SO4 is produced by the nitrous method. In particular, at superphosphate plants.

For the production of H2SO4, sulfur dioxide acts as the initial substance, both in the contact and in the nitrous method. It is obtained specifically for these purposes by burning sulfur or roasting sulfurous metals.

The conversion of sulfur dioxide into sulfurous acid consists in the oxidation of sulfur dioxide and the addition of water. The formula looks like this:
SO2 + 1|2 O2 + H2O = H2SO4

But sulfur dioxide does not directly react with oxygen, therefore, with the nitrous method, the oxidation of sulfur dioxide is carried out using nitrogen oxides. Higher oxides of nitrogen (we are talking about nitrogen dioxide NO2, nitrogen trioxide NO3) at this process are reduced to nitric oxide NO, which is subsequently again oxidized by oxygen to higher oxides.

The production of sulfuric acid by the nitrous method is technically formalized in two ways:

• Chamber.
• Tower.

The nitrous method has a number of advantages and disadvantages.

Disadvantages of the nitrous method:

• It turns out 75% sulfuric acid.
• Product quality is low.
• Incomplete return of nitrogen oxides (addition of HNO3). Their emissions are harmful.
• The acid contains iron, nitrogen oxides and other impurities.

Advantages of the nitrous method:

• The cost of the process is lower.
• The possibility of processing SO2 at 100%.
• Simplicity of hardware design.

Major Russian Sulfuric Acid Plants

The annual production of H2SO4 in our country is calculated in six figures - about 10 million tons. The leading producers of sulfuric acid in Russia are companies that are, in addition, its main consumers. It's about about companies whose field of activity is the issuance mineral fertilizers. For example, "Balakovo mineral fertilizers", "Ammophos".

In the Crimea, in Armyansk, the largest producer of titanium dioxide operates in the territory of Eastern Europe Crimean Titan. In addition, the plant is engaged in the production of sulfuric acid, mineral fertilizers, iron sulphate etc.

sulfuric acid various kinds produced by many factories. For example, battery sulfuric acid is produced by: Karabashmed, FKP Biysk Oleum Plant, Svyatogor, Slavia, Severkhimprom, etc.

Oleum is produced by UCC Shchekinoazot, FKP Biysk Oleum Plant, Ural Mining and Metallurgical Company, Kirishinefteorgsintez Production Association, etc.

Sulfuric acid of high purity is produced by UCC Shchekinoazot, Component-Reaktiv.

Spent sulfuric acid can be bought at the plants ZSS, HaloPolymer Kirovo-Chepetsk.

Manufacturers of technical sulfuric acid are Promsintez, Khiprom, Svyatogor, Apatit, Karabashmed, Slavia, Lukoil-Permnefteorgsintez, Chelyabinsk Zinc Plant, Electrozinc, etc.

Due to the fact that pyrite is the main raw material in the production of H2SO4, and this is a waste product of enrichment enterprises, its suppliers are the Norilsk and Talnakh enrichment plants.

The leading world positions in the production of H2SO4 are occupied by the USA and China, which account for 30 million tons and 60 million tons, respectively.

Scope of sulfuric acid

The world annually consumes about 200 million tons of H2SO4, from which a wide range of products is produced. Sulfuric acid rightfully holds the palm among other acids in terms of industrial use.

As you already know, sulfuric acid is one of the essential products chemical industry, so the scope of sulfuric acid is quite wide. The main uses of H2SO4 are as follows:

• Sulfuric acid is used in huge volumes for the production of mineral fertilizers, and it takes about 40% of the total tonnage. For this reason, plants producing H2SO4 are being built next to fertilizer plants. These are ammonium sulfate, superphosphate, etc. In their production, sulfuric acid is taken in its pure form (100% concentration). It will take 600 liters of H2SO4 to produce a ton of ammophos or superphosphate. These fertilizers are mostly used in agriculture.
• H2SO4 is used to make explosives.
• Purification of petroleum products. To obtain kerosene, gasoline, mineral oils, hydrocarbon purification is required, which occurs with the use of sulfuric acid. In the process of refining oil for the purification of hydrocarbons, this industry "takes" as much as 30% of the world's tonnage of H2SO4. In addition, the octane number of fuel is increased with sulfuric acid and wells are treated during oil production.
• in the metallurgical industry. Sulfuric acid is used in metallurgy to remove scale and rust from wire, sheet metal, as well as to reduce aluminum in the production of non-ferrous metals. Before covering metal surfaces copper, chromium or nickel, the surface is etched with sulfuric acid.
• In the manufacture of medicines.
• in the production of paints.
• in the chemical industry. H2SO4 is used in the production of detergents, ethyl detergent, insecticides, etc., and these processes are impossible without it.
• To obtain other known acids, organic and inorganic compounds used for industrial purposes.

Sulfuric acid salts and their uses

The most important salts of sulfuric acid are:

• Glauber's salt Na2SO4 10H2O (crystalline sodium sulfate). The scope of its application is quite capacious: the production of glass, soda, in veterinary medicine and medicine.
• Barium sulfate BaSO4 is used in the production of rubber, paper, white mineral paint. In addition, it is indispensable in medicine for fluoroscopy of the stomach. It is used to make "barium porridge" for this procedure.
• Calcium sulfate CaSO4. In nature, it can be found in the form of gypsum CaSO4 2H2O and anhydrite CaSO4. Gypsum CaSO4 2H2O and calcium sulfate are used in medicine and construction. With gypsum, when heated to a temperature of 150 - 170 ° C, partial dehydration occurs, as a result of which burnt gypsum, known to us as alabaster, is obtained. Kneading alabaster with water to a consistency liquid dough, the mass quickly hardens and turns into a kind of stone. It is this property of alabaster that is actively used in construction work: casts and molds are made from it. In plastering work, alabaster is indispensable as a binder. Patients of trauma departments are given special fixing solid bandages - they are made on the basis of alabaster.
• Ferrous vitriol FeSO4 7H2O is used for the preparation of ink, impregnation of wood, and also in agricultural activities for the destruction of pests.
• Alum KCr(SO4)2 12H2O, KAl(SO4)2 12H2O, etc. are used in the production of paints and the leather industry (tanning).
• Many of you know copper sulfate CuSO4 5H2O firsthand. It is an active assistant in agriculture in the fight against plant diseases and pests - an aqueous solution of CuSO4 5H2O is used to pickle grain and spray plants. It is also used to prepare some mineral paints. And in everyday life it is used to remove mold from the walls.
• Aluminum sulfate - it is used in the pulp and paper industry.

Sulfuric acid in dilute form is used as an electrolyte in lead-acid batteries. In addition, it is used to produce detergents and fertilizers. But in most cases, it comes in the form of oleum - this is a solution of SO3 in H2SO4 (other oleum formulas can also be found).

Amazing fact! Oleum is more reactive than concentrated sulfuric acid, but despite this, it does not react with steel! It is for this reason that it is easier to transport than sulfuric acid itself.

The sphere of use of the “queen of acids” is truly large-scale, and it is difficult to tell about all the ways in which it is used in industry. It is also used as an emulsifier in the food industry, for water treatment, in the synthesis of explosives, and for many other purposes.

History of sulfuric acid

Who among us has never heard of blue vitriol? So, it was studied in antiquity, and in some works the beginnings new era scientists discussed the origin of vitriol and their properties. Vitriol was studied by the Greek physician Dioscorides, the Roman explorer of nature Pliny the Elder, and in their writings they wrote about the ongoing experiments. For medical purposes, various vitriol substances were used by the ancient healer Ibn Sina. How vitriol was used in metallurgy was mentioned in the works of the alchemists of Ancient Greece Zosima from Panopolis.

The first method of obtaining sulfuric acid is the process of heating potassium alum, and there is information about this in the alchemical literature of the XIII century. At that time, the composition of alum and the essence of the process were not known to alchemists, but already in the 15th century, they began to engage in the chemical synthesis of sulfuric acid purposefully. The process was as follows: alchemists treated a mixture of sulfur and antimony (III) sulfide Sb2S3 by heating with nitric acid.

In medieval times in Europe, sulfuric acid was called "vitriol oil", but then the name changed to vitriol.

In the 17th century, Johann Glauber, as a result of burning potassium nitrate and native sulfur in the presence of water vapor received sulfuric acid. As a result of the oxidation of sulfur with nitrate, sulfur oxide was obtained, which reacted with water vapor, and as a result, an oily liquid was obtained. It was vitriol oil, and this name for sulfuric acid exists to this day.

The pharmacist from London, Ward Joshua, in the thirties of the 18th century used this reaction to industrial production sulfuric acid, but in the Middle Ages its consumption was limited to a few tens of kilograms. The scope of use was narrow: for alchemical experiments, purification of precious metals and in the pharmaceutical business. Concentrated sulfuric acid was used in small quantities in the manufacture of special matches that contained bertolet salt.

In Russia, vitriol appeared only in the 17th century.

In Birmingham, England, John Roebuck adapted the above method for producing sulfuric acid in 1746 and launched production. At the same time, he used strong large lead-lined chambers, which were cheaper than glass containers.

In industry, this method held positions for almost 200 years, and 65% sulfuric acid was obtained in the chambers.

After a while, the English Glover and the French chemist Gay-Lussac improved the process itself, and sulfuric acid began to be obtained with a concentration of 78%. But such an acid was not suitable for the production, for example, of dyes.

In the early 19th century, new methods were discovered for oxidizing sulfur dioxide to sulfuric anhydride.

Initially, this was done using nitrogen oxides, and then platinum was used as a catalyst. These two methods of oxidizing sulfur dioxide have further improved. The oxidation of sulfur dioxide on platinum and other catalysts became known as the contact method. And the oxidation of this gas with nitrogen oxides was called the nitrous method for producing sulfuric acid.

It was not until 1831 that the British acetic acid dealer Peregrine Philips patented an economical process for the production of sulfur oxide (VI) and concentrated sulfuric acid, and it is he who is today known to the world as a contact method for obtaining it.

The production of superphosphate began in 1864.

In the eighties of the nineteenth century in Europe, the production of sulfuric acid reached 1 million tons. The main producers were Germany and England, producing 72% of the total volume of sulfuric acid in the world.

Transportation of sulfuric acid is a labor-intensive and responsible undertaking.

Sulfuric acid belongs to the class of hazardous chemicals, and upon contact with the skin causes severe burns. In addition, it can cause chemical poisoning of a person. If during transportation are not observed certain rules, then sulfuric acid, due to its explosiveness, can cause a lot of harm to both people and the environment.

Sulfuric acid has been assigned a hazard class 8 and transportation must be carried out by specially trained and trained professionals. An important condition for the delivery of sulfuric acid is compliance with specially developed Rules for the transport of dangerous goods.

Shipping by car carried out according to the following rules:

1. For transportation, special containers are made of a special steel alloy that does not react with sulfuric acid or titanium. Such containers do not oxidize. Hazardous sulfuric acid is transported in special sulfuric acid chemical tanks. They differ in design and are selected during transportation depending on the type of sulfuric acid.
2. When transporting fuming acid, specialized isothermal thermos tanks are taken, in which the necessary temperature regime is maintained to preserve the chemical properties of the acid.
3. If ordinary acid is being transported, then a sulfuric acid tank is selected.
4. Transportation of sulfuric acid by road, such as fuming, anhydrous, concentrated, for batteries, glover, is carried out in special containers: tanks, barrels, containers.
5. Transportation of dangerous goods can only be carried out by drivers who have an ADR certificate in their hands.
6. Travel time has no restrictions, since during transportation it is necessary to strictly adhere to the permissible speed.
7. During transportation, a special route is built, which should run, bypassing crowded places and production facilities.
8. Transport must have special markings and danger signs.

Dangerous properties of sulfuric acid for humans

Sulfuric acid poses an increased danger to the human body. Its toxic effect occurs not only by direct contact with the skin, but by inhalation of its vapors, when sulfur dioxide is released. The hazard applies to:

• respiratory system;
• Integuments;
• Mucous membranes.

Intoxication of the body can be enhanced by arsenic, which is often part of sulfuric acid.

Important! As you know, when acid comes into contact with the skin, severe burns occur. No less dangerous is poisoning with sulfuric acid vapors. A safe dose of sulfuric acid in the air is only 0.3 mg per 1 square meter.

If sulfuric acid gets on the mucous membranes or on the skin, a severe burn appears, which does not heal well. If the burn is impressive in scale, the victim develops a burn disease, which can even lead to death if qualified medical care is not provided in a timely manner.

Important! For an adult, the lethal dose of sulfuric acid is only 0.18 cm per 1 liter.

Of course, "experience for yourself" the toxic effect of acid in ordinary life problematic. Most often, acid poisoning occurs due to neglect of industrial safety when working with a solution.

Mass poisoning with sulfuric acid vapor can occur due to technical problems in production or negligence, and a massive release into the atmosphere occurs. To prevent such situations, special services are working, the task of which is to control the functioning of production where hazardous acid is used.

What are the symptoms of sulfuric acid intoxication?

If the acid was ingested:

• Pain in the region of the digestive organs.
• Nausea and vomiting.
• Violation of the stool, as a result of severe intestinal disorders.
• Strong secretion of saliva.
• Due to the toxic effects on the kidneys, the urine becomes reddish.
• Swelling of the larynx and throat. There are wheezing, hoarseness. This can lead to death from suffocation.
• Brown spots appear on the gums.
• The skin turns blue.

With a burn skin there may be all the complications inherent in burn disease.

When poisoning in pairs, the following picture is observed:

• Burn of the mucous membrane of the eyes.
• Nose bleed.
• Burns of the mucous membranes of the respiratory tract. In this case, the victim experiences a strong pain symptom.
• Swelling of the larynx with symptoms of suffocation (lack of oxygen, skin turns blue).
• If the poisoning is severe, then there may be nausea and vomiting.

It is important to know! Acid poisoning after ingestion is much more dangerous than intoxication from inhalation of vapors.

First aid and therapeutic procedures for damage by sulfuric acid

Proceed as follows when in contact with sulfuric acid:

• Call an ambulance first. If the liquid got inside, then do a gastric lavage with warm water. After that, in small sips you will need to drink 100 grams of sunflower or olive oil. In addition, you should swallow a piece of ice, drink milk or burnt magnesia. This must be done to reduce the concentration of sulfuric acid and alleviate the human condition.
• If acid gets into your eyes, rinse them out. running water, and then drip with a solution of dicaine and novocaine.
• If acid gets on the skin, the burned area should be washed well under running water and bandaged with soda. Rinse for about 10-15 minutes.
• In case of vapor poisoning, you need to go to Fresh air, and also rinse, as far as possible, the affected mucous membranes with water.

In a hospital setting, treatment will depend on the area of ​​the burn and the degree of poisoning. Anesthesia is carried out only with novocaine. In order to avoid the development of an infection in the affected area, a course of antibiotic therapy is selected for the patient.

In gastric bleeding, plasma is injected or blood is transfused. The source of bleeding can be removed surgically.

1. Sulfuric acid in its pure 100% form is found in nature. For example, in Italy, Sicily in the Dead Sea, you can see a unique phenomenon - sulfuric acid seeps right from the bottom! And here's what happens: pyrite from the earth's crust serves in this case as a raw material for its formation. This place is also called the Lake of Death, and even insects are afraid to fly up to it!
2. After large volcanic eruptions, droplets of sulfuric acid can often be found in the earth's atmosphere, and in such cases, the "culprit" can bring negative consequences for the environment and cause serious climate change.
3. Sulfuric acid is an active water absorber, so it is used as a gas dryer. AT old days so that the windows do not fog up in the rooms, this acid was poured into jars and placed between the panes of the window openings.
4. Sulfuric acid is the main cause of acid rain. main reason acid rain is air pollution with sulfur dioxide, and when dissolved in water, it forms sulfuric acid. In turn, sulfur dioxide is emitted when fossil fuels are burned. In acid rain studied for last years, increased content nitric acid. The reason for this phenomenon is the reduction of sulfur dioxide emissions. Despite this fact, sulfuric acid remains the main cause of acid rain.

We offer you a video compilation interesting experiences with sulfuric acid.

Consider the reaction of sulfuric acid when it is poured into sugar. In the first seconds of sulfuric acid entering the flask with sugar, the mixture darkens. After a few seconds, the substance turns black. The most interesting thing happens next. The mass begins to grow rapidly and climb out of the flask. At the output we get a proud substance, it looks like porous charcoal, exceeding the initial volume by 3-4 times.

The author of the video suggests comparing the reaction of Coca-Cola with hydrochloric acid and sulfuric acid. When mixing Coca-Cola with hydrochloric acid, no visual changes are observed, but when mixed with sulfuric acid, Coca-Cola begins to boil.

An interesting interaction can be observed when sulfuric acid gets on toilet paper. Toilet paper is made up of cellulose. When acid enters, cellulose molecules instantly break down with the release of free carbon. Similar charring can be observed when acid gets on the wood.

Add to a flask with concentrated acid small piece potassium. In the first second, smoke is released, after which the metal instantly flares up, lights up and explodes, cutting into pieces.

In the next experiment, when sulfuric acid hits a match, it flares up. In the second part of the experiment, aluminum foil is immersed with acetone and a match inside. There is an instantaneous heating of the foil with the release of a huge amount of smoke and its complete dissolution.

An interesting effect is observed when adding baking soda into sulfuric acid. Soda instantly turns yellow. The reaction proceeds with rapid boiling and an increase in volume.

We categorically do not advise to carry out all the above experiments at home. Sulfuric acid is a very corrosive and toxic substance. Similar experiments should be carried out in special rooms that are equipped forced ventilation. The gases released in reactions with sulfuric acid are highly toxic and can cause damage to the respiratory tract and poison the body. In addition, similar experiments are carried out in the means personal protection skin and respiratory organs. Take care of yourself!