Sulfuric acid boiling point. Effective methods for processing hydrogen sulfide at oil refineries (production of sulfuric acid, elemental sulfur, etc.)

Every person studied acids in chemistry lessons. One of them is called sulfuric acid and is designated HSO 4. Our article will tell you about the properties of sulfuric acid.

Physical properties of sulfuric acid

Pure sulfuric acid or monohydrate is a colorless oily liquid that solidifies into a crystalline mass at a temperature of +10°C. Sulfuric acid, intended for reactions, contains 95% H 2 SO 4 and has a density of 1.84 g/cm 3. 1 liter of such acid weighs 2 kg. The acid hardens at a temperature of -20°C. The heat of fusion is 10.5 kJ/mol at a temperature of 10.37°C.

The properties of concentrated sulfuric acid are varied. For example, when this acid is dissolved in water, it will release large number heat (19 kcal/mol) due to the formation of hydrates. These hydrates can be isolated from solution at low temperatures in solid form.

Sulfuric acid is one of the most basic products in chemical industry. It is intended for production mineral fertilizers(ammonium sulfate, superphosphate), various salts and acids, detergents and medicines, artificial fibers, dyes, explosives. Sulfuric acid also has applications in metallurgy (for example, decomposition uranium ores), for purification of petroleum products, for drying gases, and so on.

Chemical properties of sulfuric acid

The chemical properties of sulfuric acid are:

1. Interaction with metals:
   • dilute acid dissolves only those metals that are to the left of hydrogen in the voltage series, for example H 2 +1 SO 4 + Zn 0 = H 2 O + Zn +2 SO 4;
   • The oxidizing properties of sulfuric acid are great. When interacting with various metals (except Pt, Au), it can be reduced to H 2 S -2, S +4 O 2 or S 0, for example:
   • 2H 2 +6 SO 4 + 2Ag 0 = S +4 O 2 + Ag 2 +1 SO 4 + 2H 2 O;
   • 5H 2 +6 SO 4 +8Na 0 = H 2 S -2 + 4Na 2 +1 SO 4 + 4H 2 O;
2. Concentrated acid H 2 S +6 O 4 also reacts (when heated) with some non-metals, turning into sulfur compounds with a lower oxidation state, for example:
   • 2H 2 S +6 O 4 + C 0 = 2S +4 O 2 + C +4 O 2 + 2H 2 O;
   • 2H 2 S +6 O 4 + S 0 = 3S +4 O 2 + 2H 2 O;
   • 5H 2 S +6 O 4 + 2P 0 = 2H 3 P +5 O 4 + 5S +4 O 2 + 2H 2 O;
3. WITH basic oxides:
   • H 2 SO 4 + CuO = CuSO 4 + H 2 O;
4. With hydroxides:
   • Cu(OH) 2 + H 2 SO 4 = CuSO 4 + 2H 2 O;
   • 2NaOH + H 2 SO 4 = Na 2 SO 4 + 2H 2 O;
5. Interaction with salts during metabolic reactions:
   • H 2 SO 4 + BaCl 2 = 2HCl + BaSO 4;

The formation of BaSO 4 (a white precipitate insoluble in acids) is used to determine this acid and soluble sulfates.

Monohydrate is an ionizing solvent that is acidic in nature. It is very good to dissolve sulfates of many metals in it, for example:

• 2H 2 SO 4 + HNO 3 = NO 2 + + H 3 O + + 2HSO 4 - ;
• HClO 4 + H 2 SO 4 = ClO 4 - + H 3 SO 4 +.

Concentrated acid is a fairly strong oxidizing agent, especially when heated, for example 2H 2 SO 4 + Cu = SO 2 + CuSO 4 + H 2 O.

Acting as an oxidizing agent, sulfuric acid is usually reduced to SO 2 . But it can be reduced to S and even to H 2 S, for example H 2 S + H 2 SO 4 = SO 2 + 2H 2 O + S.

Monohydrate can hardly conduct electric current. Conversely, aqueous acid solutions are good conductors. Sulfuric acid strongly absorbs moisture, so it is used to dry various gases. As a desiccant, sulfuric acid acts as long as the water vapor pressure above its solution is less than its pressure in the gas that is being dried.

If you boil a dilute solution of sulfuric acid, then water will be removed from it, and the boiling point will increase to 337 ° C, for example, when they begin to distill sulfuric acid at a concentration of 98.3%. Conversely, from solutions that are more concentrated, excess sulfuric anhydride evaporates. The steam of acid boiling at a temperature of 337°C is partially decomposed into SO 3 and H 2 O, which will be combined again when cooled. The high boiling point of this acid is suitable for its use in the separation of highly volatile acids from their salts when heated.

Precautions when working with acid

When handling sulfuric acid, you must be extremely careful. When this acid gets on the skin, the skin turns white, then brownish and redness appears. The surrounding tissues swell. If this acid gets on any part of the body, it must be quickly washed off with water, and the burned area should be lubricated with a soda solution.

Now you know that sulfuric acid, the properties of which have been well studied, is simply irreplaceable for a variety of production and mineral extraction.

Sulfuric acid (H₂SO₄) is one of the strongest dibasic acids.

If we talk about physical properties, then sulfuric acid looks like a thick, transparent, odorless, oily liquid. Depending on the concentration, sulfuric acid has a variety of various properties and areas of application:

• metal processing;
• ore processing;
• production of mineral fertilizers;
• chemical synthesis.

History of the discovery of sulfuric acid

Contact sulfuric acid has a concentration of 92 to 94 percent:

2SO₂ + O₂ = 2SO₂;

H₂O + SO₃ = H₂SO₄.

Physical and physicochemical properties of sulfuric acid

H₂SO₄ mixes with water and SO₃ in all proportions.

In aqueous solutions, Н₂SO₄ forms hydrates like Н₂SO₄·nH₂O

The boiling point of sulfuric acid depends on the degree of concentration of the solution and reaches a maximum at a concentration greater than 98 percent.

Caustic compound oleum is a solution of SO₃ in sulfuric acid.

As the concentration of sulfur trioxide in oleum increases, the boiling point decreases.

Chemical properties of sulfuric acid

When heated, concentrated sulfuric acid is a powerful oxidizing agent that can oxidize many metals. The only exceptions are some metals:

• gold (Au);
• platinum (Pt);
• iridium (Ir);
• rhodium (Rh);
• tantalum (Ta).

By oxidizing metals, concentrated sulfuric acid can be reduced to H₂S, S and SO₂.

Active metal:

8Al + 15H₂SO₄(conc.) → 4Al₂(SO₄)₃ + 12H₂O + 3H₂S

Medium activity metal:

2Cr + 4 H₂SO₄(conc.)→ Cr₂(SO₄)₃ + 4 H₂O + S

Low-active metal:

2Bi + 6H₂SO₄(conc.) → Bi₂(SO₄)₃ + 6H₂O + 3SO₂

Iron does not react with cold concentrated sulfuric acid because it is covered with an oxide film. This process is called passivation.

Reaction of sulfuric acid and H₂O

When H₂SO₄ is mixed with water, an exothermic process occurs: such a large amount of heat is released that the solution can even boil. Conducting chemical experiments, you should always add sulfuric acid to water little by little, and not vice versa.

Sulfuric acid is a strong dehydrogenating agent. Concentrated sulfuric acid displaces water from various compounds. It is often used as a desiccant.

Reaction of sulfuric acid and sugar

The greed of sulfuric acid for water can be demonstrated in a classic experiment - mixing concentrated H₂SO₄ and, which is an organic compound (carbohydrate). To extract water from a substance, sulfuric acid breaks down the molecules.

To carry out the experiment, add a few drops of water to the sugar and mix. Then carefully pour in sulfuric acid. After a short period of time, a violent reaction can be observed with the formation of coal and the release of sulfur dioxide and.

Sulfuric acid and sugar cube:

Remember that working with sulfuric acid is very dangerous. Sulfuric acid is a caustic substance that instantly leaves severe burns on the skin.

you'll find safe sugar experiments you can do at home.

Reaction of sulfuric acid and zinc

This reaction is quite popular and is one of the most common laboratory methods obtaining hydrogen. If zinc granules are added to dilute sulfuric acid, the metal will dissolve and release gas:

Zn + H₂SO₄ → ZnSO₄ + H₂.

Dilute sulfuric acid reacts with metals that are to the left of hydrogen in the activity series:

Me + H₂SO₄(dil.) → salt + H₂

Reaction of sulfuric acid with barium ions

A qualitative reaction to and its salts is the reaction with barium ions. It is widespread in quantitative analysis, in particular gravimetry:

H₂SO₄ + BaCl₂ → BaSO₄ + 2HCl

ZnSO₄ + BaCl₂ → BaSO₄ + ZnCl₂

Attention! Do not try to repeat these experiments yourself!

sulfuric acid, sulfuric acid formula
Sulfuric acid H2SO4 is a strong dibasic acid, corresponding to highest degree sulfur oxidation (+6). Under normal conditions, concentrated sulfuric acid is a heavy, oily liquid, colorless and odorless, with a sour “copper” taste. In technology, sulfuric acid is a mixture of both water and sulfuric anhydride SO3. If the molar ratio of SO3:H2O< 1, то это водный раствор серной кислоты, если >1 - solution of SO3 in sulfuric acid (oleum).

• 1 Title
• 2 Physical and physical chemical properties
  • 2.1 Oleum
• 3 Chemical properties
• 4 Application
• 5 Toxic effect
• 6 Historical information
• 7 Additional information
• 8 Preparation of sulfuric acid
  • 8.1 First method
  • 8.2 Second method
• 9 Standards
• 10 Notes
• 11 Literature
• 12 Links

Name

IN XVIII-XIX centuries sulfur for gunpowder was produced from sulfur pyrite (pyrite) in vitriol factories. Sulfuric acid at that time was called " oil of vitriol"(usually it was a crystalline hydrate, with a consistency reminiscent of oil), this is obviously the origin of the name of its salts (or rather crystalline hydrates) - vitriol.

Physical and physico-chemical properties

Very strong acid, at 18°C ​​pKa (1) = −2.8, pKa (2) = 1.92 (K₂ 1.2 10−2); bond lengths in the molecule S=O 0.143 nm, S-OH 0.154 nm, HOSOH angle 104°, OSO 119°; boils, forming an azeotropic mixture (98.3% H2SO4 and 1.7% H2O with a boiling point of 338.8 ° C). Sulfuric acid corresponding to 100% H2SO4 content has the following composition (%): H2SO4 99.5, HSO4− - 0.18, H3SO4+ - 0.14, H3O+ - 0.09, H2S2O7 - 0.04, HS2O7⁻ - 0.05. Miscible with water and SO3, in all proportions. In aqueous solutions, sulfuric acid almost completely dissociates into H3O+, HSO3+, and 2HSO₄−. Forms H2SO4 nH2O hydrates, where n = 1, 2, 3, 4 and 6.5.

Oleum

Solutions of sulfuric anhydride SO3 in sulfuric acid are called oleum, they form two compounds H2SO4 SO3 and H2SO4 2SO3.

Oleum also contains pyrosulfuric acids, obtained by the reactions:

The boiling point of aqueous solutions of sulfuric acid increases with increasing its concentration and reaches a maximum at a content of 98.3% H2SO4.

The boiling point of oleum decreases with increasing SO3 content. With increasing concentration of aqueous solutions of sulfuric acid total pressure vapor above the solutions decreases and reaches a minimum at a content of 98.3% H2SO4. As the concentration of SO3 in oleum increases, the total vapor pressure above it increases. Steam pressure above aqueous solutions sulfuric acid and oleum can be calculated using the equation:

the values ​​of the coefficients A and depend on the concentration of sulfuric acid. Vapor over aqueous solutions of sulfuric acid consists of a mixture of water vapor, H2SO4 and SO3, and the composition of the vapor differs from the composition of the liquid at all concentrations of sulfuric acid, except for the corresponding azeotropic mixture.

With increasing temperature, dissociation increases:

Equation for the temperature dependence of the equilibrium constant:

At normal pressure, degree of dissociation: 10⁻⁵ (373 K), 2.5 (473 K), 27.1 (573 K), 69.1 (673 K).

The density of 100% sulfuric acid can be determined by the equation:

With increasing concentration of sulfuric acid solutions, their heat capacity decreases and reaches a minimum for 100% sulfuric acid; the heat capacity of oleum increases with increasing SO3 content.

With increasing concentration and decreasing temperature, thermal conductivity λ decreases:

where C is the concentration of sulfuric acid, in%.

Oleum H2SO4·SO3 has the maximum viscosity; with increasing temperature, η decreases. Electrical resistance sulfuric acid is minimal at a concentration of SO3 and 92% H2SO4 and maximum at a concentration of 84 and 99.8% H2SO4. For oleum, the minimum ρ is at a concentration of 10% SO3. With increasing temperature, ρ of sulfuric acid increases. Permittivity 100% sulfuric acid 101 (298.15 K), 122 (281.15 K); cryoscopic constant 6.12, ebullioscopic constant 5.33; the diffusion coefficient of sulfuric acid vapor in air varies depending on temperature; D = 1.67·10⁻⁵T3/2 cm²/s.

Chemical properties

Sulfuric acid in concentrated form when heated is a fairly strong oxidizing agent; oxidizes HI and partially HBr to free halogens, carbon to CO2, sulfur to SO2, oxidizes many metals (Cu, Hg, with the exception of gold and platinum). In this case, concentrated sulfuric acid is reduced to SO2, for example:

The most powerful reducing agents reduce concentrated sulfuric acid to S and H2S. Concentrated sulfuric acid absorbs water vapor, so it is used for drying gases, liquids and solids, for example, in desiccators. However, concentrated H2SO4 is partially reduced by hydrogen, which is why it cannot be used for drying. Splitting off water from organic compounds and leaving behind black carbon (charcoal), concentrated sulfuric acid causes charring of wood, sugar and other substances.

Dilute H2SO4 interacts with all metals located in the electrochemical voltage series to the left of hydrogen with its release, for example:

The oxidizing properties of dilute H2SO4 are uncharacteristic. Sulfuric acid forms two series of salts: medium - sulfates and acidic - hydrosulfates, as well as esters. Peroxomonosulfuric (or Caro acid) H2SO5 and peroxodisulfuric H2S2O8 acids are known.

Sulfuric acid also reacts with basic oxides, forming sulfate and water:

In metalworking plants, a solution of sulfuric acid is used to remove a layer of metal oxide from the surface of metal products that are subjected to high heat during the manufacturing process. Thus, iron oxide is removed from the surface of sheet iron by the action of a heated solution of sulfuric acid:

A qualitative reaction to sulfuric acid and its soluble salts is their interaction with soluble barium salts, which results in the formation of a white precipitate of barium sulfate, insoluble in water and acids, for example:

Application

Sulfuric acid is used:

• in ore processing, especially during mining rare elements, incl. uranium, iridium, zirconium, osmium, etc.;
• in the production of mineral fertilizers;
• as an electrolyte in lead acid batteries;
• to obtain various mineral acids and salts;
• in the production of chemical fibers, dyes, smoke-forming and explosives;
• in the oil, metalworking, textile, leather and other industries;
• V food industry- registered as food additives E513(emulsifier);
• in industrial organic synthesis in reactions:
  • dehydration (production of diethyl ether, esters);
  • hydration (ethanol from ethylene);
  • sulfonation (synthetic detergents and intermediate products in the production of dyes);
  • alkylation (production of isooctane, polyethylene glycol, caprolactam), etc.
  • For the restoration of resins in filters in the production of distilled water.

World production of sulfuric acid is approx. 160 million tons per year. The largest consumer of sulfuric acid is the production of mineral fertilizers. P₂O₅ phosphorus fertilizers consume 2.2-3.4 times more mass of sulfuric acid, and (NH₄)₂SO₄ sulfuric acid consumes 75% of the mass of consumed (NH₄)₂SO₄. Therefore, they tend to build sulfuric acid plants in conjunction with factories for the production of mineral fertilizers.

Toxic effect

Sulfuric acid and oleum are very corrosive substances. They affect the skin, mucous membranes, respiratory tract(cause chemical burns). When inhaling vapors of these substances, they cause difficulty breathing, coughing, and often laryngitis, tracheitis, bronchitis, etc. The maximum permissible concentration of sulfuric acid aerosol in the air of the working area is 1.0 mg/m³, in atmospheric air 0.3 mg/m³ (maximum one-time) and 0.1 mg/m³ (average daily). The damaging concentration of sulfuric acid vapor is 0.008 mg/l (exposure 60 min), lethal 0.18 mg/l (60 min). Hazard class II. An aerosol of sulfuric acid can form in the atmosphere as a result of emissions from chemical and metallurgical industries containing S oxides and fall in the form of acid rain.

Historical information

Sulfuric acid has been known since ancient times, occurring in nature in free form, for example, in the form of lakes near volcanoes. Perhaps the first mention of acid gases produced by the calcination of alum or iron sulfate of the “green stone” is found in writings attributed to the Arab alchemist Jabir ibn Hayyan.

In the 9th century, the Persian alchemist Ar-Razi, calcining a mixture of iron and copper sulfate(FeSO4 7H2O and CuSO4 5H2O), also obtained a solution of sulfuric acid. This method was perfected by the European alchemist Albert Magnus, who lived in the 13th century.

Scheme for obtaining sulfuric acid from iron sulfate - thermal decomposition iron (II) sulfate followed by cooling the mixture

Dalton sulfuric acid molecule

1. 2FeSO4+7H2O→Fe2O3+SO2+H2O+O2
2. SO2+H2O+1/2O2 ⇆ H2SO4

The works of the alchemist Valentin (13th century) describe a method for producing sulfuric acid by absorbing gas (sulfuric anhydride) released by burning a mixture of sulfur and nitrate powders with water. Subsequently, this method formed the basis of the so-called. “chamber” method, carried out in small chambers lined with lead, which does not dissolve in sulfuric acid. In the USSR, this method existed until 1955.

Alchemists of the 15th century also knew a method for producing sulfuric acid from pyrite - sulfur pyrite, a cheaper and more common raw material than sulfur. Sulfuric acid has been produced this way for 300 years. small quantities in glass retorts. Subsequently, in connection with the development of catalysis, this method replaced the chamber method for the synthesis of sulfuric acid. Currently, sulfuric acid is produced by the catalytic oxidation (on V2O5) of sulfur oxide (IV) to sulfur oxide (VI), and subsequent dissolution of sulfur oxide (VI) in 70% sulfuric acid to form oleum.

In Russia, the production of sulfuric acid was first organized in 1805 near Moscow in the Zvenigorod district. In 1913, Russia ranked 13th in the world in sulfuric acid production.

More information

Tiny droplets of sulfuric acid can form in medium and upper layers atmosphere as a result of the reaction of water vapor and volcanic ash, containing large amounts of sulfur. The resulting suspension, due to the high albedo of sulfuric acid clouds, makes access difficult sun rays to the surface of the planet. Therefore (and also as a result of the large number tiny particles volcanic ash in the upper atmosphere, also making access difficult sunlight to the planet) after particularly strong volcanic eruptions significant climate changes may occur. For example, as a result of the eruption of the Ksudach volcano (Kamchatka Peninsula, 1907) increased concentration dust remained in the atmosphere for about 2 years, and characteristic noctilucent clouds of sulfuric acid were observed even in Paris. The explosion of Mount Pinatubo in 1991, which released 3 107 tons of sulfur into the atmosphere, resulted in 1992 and 1993 being significantly colder than 1991 and 1994.

Preparation of sulfuric acid

First way

Second way

In those rare cases when hydrogen sulfide (H2S) displaces sulfate (SO4-) from a salt (with metals Cu, Ag, Pb, Hg), the by-product is sulfuric acid

Sulfides of these metals have the highest strength, as well as a distinctive black color.

Standards

• Technical sulfuric acid GOST 2184-77
• Battery sulfuric acid. Specifications GOST 667-73
• Sulfuric acid of special purity. Technical specifications GOST 1422-78
• Reagents. Sulfuric acid. Technical specifications GOST 4204-77

Notes

1. Ushakova N. N., Figurnovsky N. A. Vasily Mikhailovich Severgin: (1765-1826) / Ed. I. I. Shafranovsky. M.: Nauka, 1981. P. 59.
2. 1 2 3 Khodakov Yu.V., Epshtein D.A., Gloriozov P.A. § 91. Chemical properties of sulfuric acid // Inorganic chemistry: Textbook for grades 7-8 high school. - 18th ed. - M.: Education, 1987. - P. 209-211. - 240 s. - 1,630,000 copies.
3. Khodakov Yu.V., Epshtein D.A., Gloriozov P.A. § 92. Qualitative reaction on sulfuric acid and its salts // Inorganic chemistry: Textbook for grades 7-8 of secondary school. - 18th ed. - M.: Education, 1987. - P. 212. - 240 p. - 1,630,000 copies.
4. ballet artistic director's face Bolshoi Theater Sulfuric acid was splashed on Sergei Filin
5. Epstein, 1979, p. 40
6. Epstein, 1979, p. 41
7. see article “Volcanoes and climate” (Russian)
8. Russian Archipelago - Is humanity to blame for global change climate? (Russian)

Literature

• Handbook of sulfuric acid, ed. K. M. Malina, 2nd ed., M., 1971
• Epshtein D. A. General chemical technology. - M.: Chemistry, 1979. - 312 p.

Links

• Article “Sulfuric acid” (Chemical Encyclopedia)
• Density and pH value of sulfuric acid at t=20 °C

sulfuric acid, sulfuric acid Wikipedia, sulfuric acid hydrolysis, sulfuric acid its effect 1, sulfuric acid hazard class, buy sulfuric acid in Ukraine, sulfuric acid application, sulfuric acid corrodes, sulfuric acid with water, sulfuric acid formula

Sulfuric Acid Information About

Sulfur trioxide typically appears as a colorless liquid. It can also exist in the form of ice, fibrous crystals or gas. When sulfur trioxide is exposed to air, it begins to release white smoke. It is a constituent element of such a chemical active substance as concentrated sulfuric acid. It is a clear, colorless, oily and very aggressive liquid. It is used in the production of fertilizers, explosives, other acids, in the petroleum industry, in lead-acid batteries in cars.

Concentrated sulfuric acid: properties

Sulfuric acid is highly soluble in water, has a corrosive effect on metals and fabrics, and upon contact chars wood and most other materials. organic matter. As a result of long-term exposure to low concentrations of a substance or short-term exposure to high concentrations, adverse consequences for health from inhalation.

Concentrated sulfuric acid is used to make fertilizers and other chemicals, in oil refining, in iron and steel production, and for many other purposes. Because she has enough high temperature boiling, it can be used to release more volatile acids from their salts. Concentrated sulfuric acid has a strong hygroscopic property. It is sometimes used as a drying agent for dehydration (removing water chemical method) many compounds, such as carbohydrates.

Sulfuric acid reactions

Concentrated sulfuric acid reacts with sugar in an unusual way, leaving behind a brittle, spongy black mass of carbon. A similar reaction is observed when exposed to leather, cellulose and other plant and animal fibers. When concentrated acid is mixed with water, it releases a large amount of heat, enough to cause instant boiling. To dilute, it should be added slowly to cold water with constant stirring to limit heat buildup. Sulfuric acid reacts with liquid, forming hydrates with pronounced properties.

Physical characteristics

A colorless and odorless liquid in a diluted solution has a sour taste. Sulfuric acid is extremely aggressive when exposed to the skin and all tissues of the body, causing severe burns upon direct contact. In its pure form, H 2 SO4 is not a conductor of electricity, but the situation changes in the opposite side with the addition of water.

Some properties are that the molecular weight is 98.08. The boiling point is 327 degrees Celsius, the melting point is -2 degrees Celsius. Sulfuric acid is a strong mineral acid and one of the main products of the chemical industry due to its wide commercial applications. It forms naturally from the oxidation of sulfide materials such as iron sulfide.

The chemical properties of sulfuric acid (H 2 SO4) are manifested in various chemical reactions:

1. When interacting with alkalis, two series of salts are formed, including sulfates.
2. Reacts with carbonates and bicarbonates to form salts and carbon dioxide(CO 2).
3. It affects metals differently, depending on the temperature and degree of dilution. Cold and dilute releases hydrogen, hot and concentrated releases SO 2 emissions.
4. A solution of H 2 SO4 (concentrated sulfuric acid) decomposes into sulfur trioxide (SO 3) and water (H 2 O) when boiled. Chemical properties also include the role of a strong oxidizing agent.

Fire danger

Sulfuric acid has a high reactivity to ignition of finely dispersed combustible materials upon contact. When heated, highly toxic gases begin to be released. It is explosive and incompatible with a huge amount substances. At elevated temperatures and pressures, quite aggressive chemical changes and deformations. May react violently with water and other liquids, causing splashing.

Health Hazard

Sulfuric acid corrodes all body tissues. Inhalation of vapors may cause serious lung damage. Damage to the mucous membrane of the eyes can lead to complete loss of vision. Contact with skin may cause severe necrosis. Even a few drops can be fatal if the acid gains access to the trachea. Chronic exposure can cause tracheobronchitis, stomatitis, conjunctivitis, gastritis. Gastric perforation and peritonitis may occur, accompanied by circulatory collapse. Sulfuric acid is very caustic and should be handled with extreme care. Signs and symptoms of exposure can be severe and include drooling, extreme thirst, difficulty swallowing, pain, shock and burns. Vomit is usually the color of ground coffee. Acute inhalation exposure may result in sneezing, hoarseness, choking, laryngitis, shortness of breath, airway irritation and chest pain. Bleeding from the nose and gums, pulmonary edema, chronic bronchitis and pneumonia may also occur. Skin exposure may result in severe painful burns and dermatitis.

First aid

1. Place victims on fresh air. Employees emergency services should avoid exposure to sulfuric acid.
2. Assess vital signs, including pulse and respiratory rate. If a pulse is not detected, perform resuscitation measures depending on the additional injuries received. If breathing is difficult, provide respiratory support.
3. Remove soiled clothing as soon as possible.
4. In case of contact with eyes, rinse warm water for at least 15 minutes, on skin - wash with soap and water.
5. If you inhale toxic fumes, rinse your mouth a large number water, drinking and inducing vomiting yourself is prohibited.
6. Transport victims to a medical facility.

SULFURIC ACID H2SO4, molecular weight 98.082; colorless odorless oily liquid. A very strong dibasic acid, at 18°C ​​pK a 1 - 2.8, K 2 1.2 10 -2, pK a 2 l.92; bond lengths in the molecule S=O 0.143 nm, S-OH 0.154 nm, HOSOH angle 104°, OSO 119°; boils with various, forming an azeotropic mixture (98.3% H 2 SO 4 and 1.7% H 2 O with a boiling point of 338.8 ° C; see also Table 1). SULFURIC ACID, corresponding to 100% content of H 2 SO 4, has the composition (%): H 2 SO 4 99.5, 0.18, 0.14, H 3 O + 0.09, H 2 S 2 O 7 0.04, HS 2 O 7 0.05. Miscible with water and SO 3 in all proportions. In aqueous solutions, SULFURIC ACID almost completely dissociates into H +, and. Forms hydrates H 2 SO 4 nH 2 O, where n = 1, 2, 3, 4 and 6.5.

Solutions of SO 3 in SULFURIC ACID are called oleum; they form two compounds H 2 SO 4 SO 3 and H 2 SO 4 2SO 3. Oleum also contains pyrosulfuric acid, obtained by the reaction: H 2 SO 4 + + SO 3 : H 2 S 2 O 7.

The boiling point of aqueous solutions of SULFURIC ACID increases with increasing its concentration and reaches a maximum at a content of 98.3% H 2 SO 4 (Table 2). The boiling point of oleum decreases with increasing SO3 content. As the concentration of aqueous solutions of SULFURIC ACID increases, the total vapor pressure above the solutions decreases and reaches a minimum at a content of 98.3% H 2 SO 4. As the concentration of SO 3 in oleum increases, the total vapor pressure above it increases. The vapor pressure above aqueous solutions of SULFURIC ACID and oleum can be calculated by the equation: logp(Pa) = A - B/T+ 2.126, the values ​​of coefficient A and B depend on the concentration of SULFURIC ACID. Steam above aqueous solutions of SULFURIC ACID consists from a mixture of water vapor, H 2 SO 4 and SO 3, while the composition of the vapor differs from the composition of the liquid at all concentrations of SULFURIC ACID, except for the corresponding azeotropic mixture.

With increasing temperature, the dissociation of H 2 SO 4 H 2 O + SO 3 - Q increases, the equation for the temperature dependence of the equilibrium constant is lnK p = 14.74965 - 6.71464ln(298/T) - 8, 10161 10 4 T 2 -9643.04 /T-9.4577 10 -3 T+2.19062 x 10 -6 T 2 . At normal pressure, the degree of dissociation is: 10 -5 (373 K), 2.5 (473 K), 27.1 (573 K), 69.1 (673 K). The density of 100% SULFURIC ACID can be determined by the equation: d = 1.8517 - - 1.1 10 -3 t + 2 10 -6 t 2 g/cm 3 . With increasing concentration of SULFURIC ACID solutions, their heat capacity decreases and reaches a minimum for 100% SULFURIC ACID; the heat capacity of oleum increases with increasing SO 3 content.

With increasing concentration and decreasing temperature, thermal conductivity l decreases: l = 0.518 + 0.0016t - (0.25 + + t/1293) C/100, where C is the concentration of SULFURIC ACID, in%. Max. The viscosity of oleum H 2 SO 4 SO 3 decreases with increasing temperature. Electric the resistance of SULFURIC ACID to. is minimal at a concentration of 30 and 92% H 2 SO 4 and maximum at a concentration of 84 and 99.8% H 2 SO 4. For oleum min. r at a concentration of 10% SO 3 . With increasing temperature r SULFURIC ACID increases. Dielectric permeability 100% SULFURIC ACID k. 101 (298.15 K), 122 (281.15 K); cryoscopic constant 6.12, ebulioscopic. constant 5.33; the diffusion coefficient of SULFURIC ACID vapor in air changes with temperature; D = 1.67 10 -5 T 3/2 cm 2 /s.

SULFURIC ACID is a fairly strong oxidizing agent, especially when heated; oxidizes HI and partially HBr to free halogens, carbon to CO 2, S to SO 2, oxidizes many metals (Cu, Hg, etc.). In this case, SULFURIC ACID is reduced to SO 2, and with the most powerful reducing agents, to S and H 2 S. Conc. H 2 SO 4 is partially reduced by H 2, which is why it cannot be used for drying. Razb. H 2 SO 4 interaction with all metals located in the electrochemical voltage series to the left of hydrogen, with the release of H 2. Oxidize. properties for dilute H 2 SO 4 are uncharacteristic. SULFURIC ACID gives two series of salts: medium sulfates and acidic hydrosulfates (see Inorganic sulfates), as well as ethers (see Organic sulfates). Peroxomonosulfuric (Caro acid) H 2 SO 5 and peroxodisulfuric H 2 S 2 O 8 acids are known (see Sulfur).

Receipt. The raw materials for the production of sulfuric acid are: S, metal sulfides, H 2 S, waste gases of thermal power plants, sulfates of Fe, Ca, etc. Basic. stages of obtaining SULFURIC ACID: 1) roasting of raw materials to produce SO 2; 2) oxidation of SO 2 to SO 3 (conversion); 3) SO 3 absorption. In industry, two methods are used for the production of SULFURIC ACID, differing in the method of SO 2 oxidation - contact using solid catalysts (contacts) and nitrous - with nitrogen oxides. To obtain sulfuric acid by contact method, modern factories use vanadium catalysts, which have replaced Pt and Fe oxides. Pure V 2 O 5 has a weak catalytic activity, which increases sharply in the presence of salts alkali metals, and K salts have the most influence. The promoting role of alkali metals is due to the formation of low-melting pyrosulfonadates (3K 2 S 2 O 7 V 2 O 5, 2 K 2 S 2 O 7 V 2 O 5 and K 2 S 2 O 7 V 2 O 5, decomposing at 315-330, 365-380 and 400-405 °C, respectively). The active component under catalysis conditions is in a molten state.

The scheme for the oxidation of SO 2 to SO 3 can be represented as follows:

At the first stage, equilibrium is achieved, the second stage is slow and determines the speed of the process.

The production of SULFURIC ACID from sulfur using the method of double contact and double absorption (Fig. 1) consists of the following stages. The air, after cleaning from dust, is supplied by a gas blower to the drying tower, where it is dried with 93-98% SULFURIC ACID to a moisture content of 0.01% by volume. The dried air enters the sulfur furnace after pre-heating. heating in one of the heat exchangers of the contact unit. The furnace burns sulfur supplied by nozzles: S + O 2 : SO 2 + + 297.028 kJ. Gas containing 10-14% by volume SO 2 is cooled in the boiler and, after diluting with air to a SO 2 content of 9-10% by volume at 420 ° C, enters the contact apparatus for the first stage of conversion, which takes place on three layers of catalyst (SO 2 + V 2 O 2 :: SO 3 + 96.296 kJ), after which the gas is cooled in heat exchangers. Then the gas containing 8.5-9.5% SO 3 at 200 ° C enters the first stage of absorption into the absorber irrigated with oleum and 98% SULFURIC ACID: SO 3 + H 2 O : H 2 SO 4 + + 130.56 kJ. Next, the gas is purified from splashes of SULFURIC ACID, heated to 420 °C and enters the second stage of conversion, which takes place on two layers of catalyst. Before the second stage of absorption, the gas is cooled in the economizer and supplied to the second stage absorber, irrigated with 98% SULFURIC ACID, and then, after cleaning from splashes, is released into the atmosphere.

Rice. 1. Scheme for the production of sulfuric acid from sulfur: 1-sulfur furnace; 2-recovery boiler; 3 - economizer; 4-start firebox; 5, 6 - heat exchangers of the starting furnace; 7-pin device; 8-heat exchangers; 9-oleum absorber; 10-drying tower; 11 and 12 are the first and second monohydrate absorbers, respectively; 13-acid collectors.

Fig.2. Scheme for the production of sulfuric acid from pyrites: 1-plate feeder; 2-oven; 3-recovery boiler; 4-cyclones; 5-electric precipitators; 6-washing towers; 7-wet electrostatic precipitators; 8-exhaust tower; 9-drying tower; 10-splash trap; 11-first monohydrate absorber; 12-heat exchange-wiki; 13 - contact device; 14-oleum absorber; 15-second monohydrate absorber; 16-refrigerators; 17 collections.

Rice. 3. Scheme for the production of sulfuric acid by the nitrose method: 1 - denitrate. tower; 2, 3 - first and second products. towers; 4-oxid. tower; 5, 6, 7-absorb. towers; 8 - electric precipitators.

The production of SULFURIC ACID from metal sulfides (Fig. 2) is much more complicated and consists of the following operations. FeS 2 is fired in a fluidized bed furnace using air blast: 4FeS 2 + 11O 2: 2Fe 2 O 3 + 8SO 2 + 13476 kJ. The roasting gas with a SO 2 content of 13-14%, having a temperature of 900 °C, enters the boiler, where it is cooled to 450 °C. Dust removal is carried out in a cyclone and an electric precipitator. Next, the gas passes through two washing towers, irrigated with 40% and 10% SULFURIC ACID. At the same time, the gas is finally cleaned of dust, fluorine and arsenic. To purify the gas from the aerosol SULFURIC ACID formed in the washing towers, two stages of wet electrostatic precipitators are provided. After drying in a drying tower, before which the gas is diluted to a content of 9% SO 2, it is supplied by a gas blower to the first stage of conversion (3 layers of catalyst). In heat exchangers, the gas is heated to 420 °C thanks to the heat of the gas coming from the first stage of conversion. SO 2, oxidized by 92-95% in SO 3, goes to the first stage of absorption into oleum and monohydrate absorbers, where it is freed from SO 3. Next, the gas containing SO 2 ~ 0.5% enters the second stage of conversion, which occurs on one or two layers of catalyst. The gas is preheated in another group of heat exchangers to 420 °C due to the heat of the gases coming from the second stage of catalysis. After SO 3 is separated in the second absorption stage, the gas is released into the atmosphere.

The degree of conversion of SO 2 to SO 3 at contact method 99.7%, SO 3 absorption rate 99.97%. The production of SULFURIC ACID is carried out in one stage of catalysis, and the degree of conversion of SO 2 to SO 3 does not exceed 98.5%. Before being released into the atmosphere, the gas is purified from remaining SO 2 (see Gas purification). The productivity of modern installations is 1500-3100 t/day.

The essence of the nitrose method (Fig. 3) is that the roasting gas, after cooling and cleaning from dust, is treated with the so-called nitrose-C. to., in which sol. nitrogen oxides. SO 2 is absorbed by nitrose and then oxidized: SO 2 + N 2 O 3 + H 2 O : H 2 SO 4 + NO. The resulting NO is poorly soluble in nitrose and is released from it, and then partially oxidized by oxygen in the gas phase to NO 2. The mixture of NO and NO 2 is again absorbed by SULFURIC ACID. etc. Nitrogen oxides are not consumed in the nitrous process and are returned to production. cycle, due to their incomplete absorption by SULFURIC ACID, they are partially carried away by exhaust gases. Advantages of the nitrose method: simplicity of equipment design, lower cost (10-15% lower than the contact method), possibility of 100% recycling of SO 2.

The hardware design of the nitrous tower process is simple: SO 2 is processed in 7-8 ceramic-lined towers. nozzle, one of the towers (hollow) is an adjustable oxidizer. volume. The towers have acid collectors, refrigerators, and pumps that supply acid to pressure tanks above the towers. A tail fan is installed in front of the last two towers. An electric precipitator is used to purify the gas from the aerosol SULFURIC ACID. The nitrogen oxides required for the process are obtained from HNO 3 . To reduce the emission of nitrogen oxides into the atmosphere and 100% recycling of SO 2, a nitrous-free SO 2 processing cycle is installed between the production and absorption zones in combination with the water-acid method of deep capture of nitrogen oxides. The disadvantage of the nitrous method is the low quality of the product: the concentration of SULFURIC ACID is 75%, the presence of nitrogen oxides, Fe and other impurities.

To reduce the possibility of crystallization of SULFURIC ACID during transportation and storage, standards have been established for commercial grades of SULFURIC ACID, the concentration of which corresponds most low temperatures crystallization. Contents SULFURIC ACID in tech. grades (%): tower (nitrous) 75, contact 92.5-98.0, oleum 104.5, high-percentage oleum 114.6, battery 92-94. SULFURIC ACID is stored in steel tanks with a volume of up to 5000 m 3, their total capacity in the warehouse is designed for ten-day production. Oleum and SULFURIC ACID are transported in steel railway tanks. Conc. and battery SULFURIC ACID are transported in tanks made of acid-resistant steel. Tanks for transporting oleum are covered with thermal insulation and the oleum is heated before filling.

SULFURIC ACID is determined colorimetrically and photometrically, in the form of a suspension of BaSO 4 - phototurbidimetrically, as well as coulometrically. method.

Application. SULFURIC ACID is used in the production of mineral fertilizers, as an electrolyte in lead batteries, for the production of various mineral acids and salts, chemical fibers, dyes, smoke-forming substances and explosives, in the oil, metalworking, textile, leather and other industries. It is used in industry. organic synthesis in dehydration reactions (production of diethyl ether, esters), hydration (ethanol from ethylene), sulfonation (synthetic detergents and intermediate products in the production of dyes), alkylation (production of isooctane, polyethylene glycol, capro-lactam), etc. The most major consumer SULFURIC ACID - production of mineral fertilizers. For 1 t of P 2 O 5 phosphorus fertilizers, 2.2-3.4 t of SULFURIC ACID is consumed, and for 1 t of (NH 4) 2 SO 4 -0.75 t of SULFURIC ACID is consumed. Therefore, they tend to build sulfuric acid plants in a complex with factories for the production of mineral fertilizers. World production of SULFURIC ACID in 1987 reached 152 million tons.

SULFURIC ACID and oleum are extremely aggressive substances that affect the respiratory tract, skin, mucous membranes, causing difficulty breathing, coughing, often laryngitis, tracheitis, bronchitis, etc. MPC of aerosol SULPHURIC ACID in the air of the working area 1, 0 mg/m3, at atm. air 0.3 mg/m 3 (max. one-time) and 0.1 mg/m 3 (daily average). The damaging concentration of SULFURIC ACID vapors is 0.008 mg/l (exposure 60 min), lethal 0.18 mg/l (60 min). Hazard class 2. Aerosol SULFURIC ACID can be formed in the atmosphere as a result of chemical and metallurgical emissions. industries containing S oxides and fall out in the form of acid rain.

Literature: Handbook of sulfuric acid, ed. K. M. Malina, 2nd ed., M., 1971; Amelin A.G., Sulfuric acid technology, 2nd ed., M., 1983; Vasiliev B. T., Otvagina M. I., Sulfuric acid technology, M., 1985. Yu.V. Filatov.

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