Electronic and structural formula of h2so4. Sulfuric acid - chemical properties and industrial production. Interaction with water

New topic: Sulfuric acid -H 2 SO 4

1. Electronic and structural formulas of sulfuric acid

*S - sulfur is in an excited state 1S 2 2S 2 2P 6 3S 1 3P 3 3d 2

The electronic formula of the sulfuric acid molecule:

Structural formula of the sulfuric acid molecule:

1 H - -2 O -2 O

1 H - -2 O -2 O

2. Receipt:

The chemical processes for the production of sulfuric acid can be represented as the following scheme:

S + O 2 + O 2 + H 2 O

FeS 2 SO 2 SO 3 H 2 SO 4

Sulfuric acid is produced in three stages:

1 stage. Sulfur, iron pyrite or hydrogen sulfide are used as raw materials.

4 FeS 2 + 11 O 2 \u003d 2Fe 2 O 3 + 8SO 2

2 stage. Oxidation of SO 2 to SO 3 with oxygen using a catalyst V 2 O 5

2SO 2 + O 2 \u003d 2SO 3 + Q

3rd stage. Not water is used to convert SO 3 to sulfuric acid. there is a strong heating, and a concentrated solution of sulfuric acid.

SO 3 + H 2 O H 2 SO 4

The result is oleum - a solutionSO 3 in sulfuric acid.

Apparatus circuit diagram(see textbook p.105)

3.Physical properties.

a) liquid b) colorless c) heavy (vitriol) d) non-volatile

d) when dissolved in water, strong heating occurs ( so sulfuric acid must be poured intowater,Anot vice versa!)

4. Chemical properties of Sulfuric acid.

DilutedH 2 SO 4	concentratedH 2 SO 4
Has all the properties of acids	Has specific properties
1.Changes the color of the indicator: H 2 SO 4 H + + HSO 4 - HSO 4 - H + +SO 4 2- 2.Reacts with metals standing up to hydrogen: Zn + H 2 SO 4 ZnSO 4 +H 2 3. Reacts with basic and amphoteric oxides: MgO + H 2 SO 4 MgSO 4 + H 2 O 4. Interacts with bases (neutralization reaction) 2NaOH + H 2 SO 4 Na 2 SO 4 + 2H 2 O excess acid forms acidic salts NaOH + H 2 SO 4 NaHSO 4 +H 2 O 5. Reacts with dry salts, displacing other acids from them (this is the strongest and non-volatile acid): 2NaCl+H 2 SO 4 Na 2 SO 4 +2HCl 6. Reacts with salt solutions if an insoluble salt is formed: BaCl 2 +H 2 SO 4 BaSO 4 +2HCl- whitesediment qualitative reaction to an ionSO 4 2- 7. When heated, it decomposes: H 2 SO 4 H 2 O + SO 3	1. Concentrated H 2 SO 4 is the strongest oxidizing agent; when heated, it reacts with all metals (except Au and Pt). In these reactions, depending on the activity of the metal and the conditions, S, SO 2 or H 2 S are released For example: Cu+ conc 2H 2 SO 4 CuSO 4 +SO 2 +H 2 O 2.conc. H 2 SO 4 passivates iron and aluminum, therefore it can be transported in steel and aluminum tanks. 3. conc. H 2 SO 4 absorbs water well H 2 SO 4 + H 2 O H 2 SO 4 * 2H 2 O Therefore, it chars organic matter

5.Application: Sulfuric acid is one of the most important products used in various industries. Its main consumers are the production mineral fertilizers, metallurgy, cleaning of oil products. Sulfuric acid is used in the manufacture of other acids, detergents, explosives, medicines, paints, and as electrolytes for lead-acid batteries. (Textbook p.103).

6.Salts of sulfuric acid

Sulfuric acid dissociates in steps

H 2 SO 4 H + + HSO 4 -

HSO 4 - H + +SO 4 2-

therefore, it forms two types of salts - sulfates and hydrosulfates

For example: Na 2 SO 4 - sodium sulfate (medium salt)

Na HSO 4 - sodium hydrogen sulfate (acid salt)

The most widely used are:

Na 2 SO 4 * 10H 2 O - Glauber's salt (used in the production of soda, glass, in medicine and

veterinary medicine.

CaSO 4 * 2H 2 O - gypsum

CuSO 4 * 5H 2 O - copper sulfate (used in agriculture).

Laboratory experience

Chemical properties of sulfuric acid.

Equipment: Test tubes.

Reagents: sulfuric acid, methyl orange, zinc, magnesium oxide, sodium hydroxide and phenolphthalein, sodium carbonate, barium chloride.

b) Fill in the table of observations

Physical properties of sulfuric acid:
Heavy oily liquid ("vitriol");
density 1.84 g/cm3; non-volatile, highly soluble in water - with strong heating; t°pl. = 10.3°C, bp \u003d 296 ° C, very hygroscopic, has water-removing properties (charring of paper, wood, sugar).

The heat of hydration is so great that the mixture may boil, splatter and cause burns. Therefore, it is necessary to add acid to water, and not vice versa, since when water is added to acid, lighter water will be on the surface of the acid, where all the heat released will be concentrated.

Industrial production of sulfuric acid (contact method):

1) 4FeS 2 + 11O 2 → 2Fe 2 O 3 + 8SO 2

2) 2SO 2 + O 2 V 2 O 5 → 2SO 3

3) nSO 3 + H 2 SO 4 → H 2 SO 4 nSO 3 (oleum)

Crushed purified wet pyrite (sulfur pyrite) is poured from above into the kiln for firing in " fluidized bed". From below (counterflow principle) air enriched with oxygen is passed through.
Furnace gas comes out of the furnace, the composition of which is: SO 2, O 2, water vapor (pyrite was wet) and the smallest particles of cinder (iron oxide). The gas is purified from impurities of solid particles (in a cyclone and electrostatic precipitator) and water vapor (in a drying tower).
In the contact apparatus, sulfur dioxide is oxidized using a V 2 O 5 catalyst (vanadium pentoxide) to increase the reaction rate. The process of oxidation of one oxide to another is reversible. Therefore, they select optimal conditions the course of a direct reaction high blood pressure(since the direct reaction proceeds with a decrease in the total volume) and the temperature is not higher than 500 C (since the reaction is exothermic).

In the absorption tower, sulfur oxide (VI) is absorbed by concentrated sulfuric acid.
Water absorption is not used, because sulfur oxide dissolves in water with the release of a large amount of heat, so the resulting sulfuric acid boils and turns into steam. In order to avoid the formation of sulfuric acid mist, use 98% concentrated sulfuric acid. Sulfur oxide dissolves very well in such an acid, forming oleum: H 2 SO 4 nSO 3

Chemical properties of sulfuric acid:

H 2 SO 4 is a strong dibasic acid, one of the strongest mineral acids, because of the high polarity, the H - O bond is easily broken.

1) Sulfuric acid dissociates in aqueous solution , forming a hydrogen ion and an acid residue:
H 2 SO 4 \u003d H + + HSO 4 -;
HSO 4 - \u003d H + + SO 4 2-.
Summary Equation:
H 2 SO 4 \u003d 2H + + SO 4 2-.

2) The interaction of sulfuric acid with metals:
Dilute sulfuric acid only dissolves metals in the voltage series to the left of hydrogen:
Zn 0 + H 2 +1 SO 4 (razb) → Zn +2 SO 4 + H 2

3) Sulfuric acid interactionwith basic oxides:
CuO + H 2 SO 4 → CuSO 4 + H 2 O

4) The interaction of sulfuric acid withhydroxides:
H 2 SO 4 + 2NaOH → Na 2 SO 4 + 2H 2 O
H 2 SO 4 + Cu(OH) 2 → CuSO 4 + 2H 2 O

5) Exchange reactions with salts:
BaCl 2 + H 2 SO 4 → BaSO 4 ↓ + 2HCl
The formation of a white precipitate of BaSO 4 (insoluble in acids) is used to detect sulfuric acid and soluble sulfates (qualitative reaction for sulfate ion).

Special properties of concentrated H 2 SO 4:

1) concentrated sulfuric acid is strong oxidizing agent ; when interacting with metals (except Au, Pt) recover to S +4 O 2 , S 0 or H 2 S -2 depending on the activity of the metal. Without heating, it does not react with Fe, Al, Cr - passivation. When interacting with metals with variable valence, the latter are oxidized to higher oxidation states than in the case of a dilute acid solution: Fe0→ Fe 3+ , Cr 0→ Cr 3+ , Mn 0→Mn4+,sn 0→ sn 4+

active metal

8 Al + 15 H 2 SO 4 (conc.) → 4Al 2 (SO 4) 3 + 12H 2 O + 3 H 2 S
4│2Al 0 – 6 e- → 2Al 3+ - oxidation
3│ S 6+ + 8e → S 2– restoration

4Mg+ 5H 2 SO 4 → 4MgSO 4 + H 2 S + 4H 2 O

Medium activity metal

2Cr + 4 H 2 SO 4 (conc.) → Cr 2 (SO 4) 3 + 4 H 2 O + S
1│ 2Cr 0 - 6e → 2Cr 3+ - oxidation
1│ S 6+ + 6e → S 0 - restoration

Metal inactive

2Bi + 6H 2 SO 4 (conc.) → Bi 2 (SO 4) 3 + 6H 2 O + 3 SO2
1│ 2Bi 0 - 6e → 2Bi 3+ - oxidation
3│ S 6+ + 2e →S 4+ - recovery

2Ag + 2H 2 SO 4 → Ag 2 SO 4 + SO 2 + 2H 2 O

2) Concentrated sulfuric acid oxidizes some non-metals, as a rule, to the maximum oxidation state, it itself is reduced toS+4O2:

C + 2H 2 SO 4 (conc) → CO 2 + 2SO 2 + 2H 2 O

S+ 2H 2 SO 4 (conc) → 3SO 2 + 2H 2 O

2P+ 5H 2 SO 4 (conc) → 5SO 2 + 2H 3 PO 4 + 2H 2 O

3) Oxidation of complex substances:
Sulfuric acid oxidizes HI and HBr to free halogens:
2 KBr + 2H 2 SO 4 \u003d K 2 SO 4 + SO 2 + Br 2 + 2H 2 O
2 KI + 2H 2 SO 4 \u003d K 2 SO 4 + SO 2 + I 2 + 2H 2 O
Concentrated sulfuric acid cannot oxidize chloride ions to free chlorine, which makes it possible to obtain HCl by the exchange reaction:
NaCl + H 2 SO 4 (conc.) = NaHSO 4 + Hcl

Sulfuric acid removes chemically bound water from organic compounds containing hydroxyl groups. Dehydration of ethyl alcohol in the presence of concentrated sulfuric acid leads to the production of ethylene:
C 2 H 5 OH \u003d C 2 H 4 + H 2 O.

Charring of sugar, cellulose, starch and other carbohydrates upon contact with sulfuric acid is also explained by their dehydration:
C 6 H 12 O 6 + 12H 2 SO 4 \u003d 18H 2 O + 12SO 2 + 6CO 2.

Undiluted sulfuric acid is a covalent compound.

In a molecule, sulfuric acid is tetrahedrally surrounded by four oxygen atoms, two of which are part of the hydroxyl groups. The S–O bonds are double, and the S–OH bonds are single.

Colorless, ice-like crystals have a layered structure: each H 2 SO 4 molecule is connected to four neighboring strong hydrogen bonds, forming a single spatial framework.

The structure of liquid sulfuric acid is similar to the structure of solid one, only the integrity of the spatial frame is broken.

Physical properties of sulfuric acid

Under normal conditions, sulfuric acid is 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 SO 3: H 2 O is less than 1, then this is an aqueous solution of sulfuric acid, if more than 1, it is a solution of SO 3 in sulfuric acid.

100% H 2 SO 4 crystallizes at 10.45 °C; T bp = 296.2 °C; density 1.98 g/cm 3 . H 2 SO 4 mixes with H 2 O and SO 3 in any ratio to form hydrates, the heat of hydration is so great that the mixture can boil, splatter and cause burns. Therefore, it is necessary to add acid to water, and not vice versa, since when water is added to acid, lighter water will be on the surface of the acid, where all the heat released will be concentrated.

When aqueous solutions of sulfuric acid containing up to 70% H 2 SO 4 are heated and boiled, only water vapor is released into the vapor phase. Sulfuric acid vapors also appear above more concentrated solutions.

In terms of structural features and anomalies, liquid sulfuric acid is similar to water. Here is the same system of hydrogen bonds, almost the same spatial framework.

Chemical properties of sulfuric acid

Sulfuric acid is one of the strongest mineral acids; due to its high polarity, the H-O bond is easily broken.

Sulfuric acid dissociates in aqueous solution , forming a hydrogen ion and an acid residue:

H 2 SO 4 \u003d H + + HSO 4 -;

HSO 4 - \u003d H + + SO 4 2-.

Summary Equation:

H 2 SO 4 \u003d 2H + + SO 4 2-.

Shows the properties of acids , reacts with metals, metal oxides, bases and salts.

Dilute sulfuric acid does not exhibit oxidizing properties; when it interacts with metals, hydrogen and a salt containing the metal in the lowest oxidation state are released. In the cold, acid is inert to metals such as iron, aluminum, and even barium.

The concentrated acid has oxidizing properties. Possible interaction products simple substances with concentrated sulfuric acid are given in the table. The dependence of the reduction product on the concentration of the acid and the degree of activity of the metal is shown: the more active the metal, the deeper it reduces the sulfate ion of sulfuric acid.

Interaction with oxides:

CaO + H 2 SO 4 \u003d CaSO 4 \u003d H 2 O.

Interaction with bases:

2NaOH + H 2 SO 4 \u003d Na 2 SO 4 + 2H 2 O.

Interaction with salts:

Na 2 CO 3 + H 2 SO 4 = Na 2 SO 4 + CO 2 + H 2 O.

Oxidizing properties

Sulfuric acid oxidizes HI and HBr to free halogens:

H 2 SO 4 + 2HI \u003d I 2 + 2H 2 O + SO 2.

Sulfuric acid removes chemically bound water from organic compounds containing hydroxyl groups. Dehydration of ethyl alcohol in the presence of concentrated sulfuric acid leads to the production of ethylene:

C 2 H 5 OH \u003d C 2 H 4 + H 2 O.

Charring of sugar, cellulose, starch and other carbohydrates upon contact with sulfuric acid is also explained by their dehydration:

C 6 H 12 O 6 + 12H 2 SO 4 \u003d 18H 2 O + 12SO 2 + 6CO 2.

Target: To get acquainted with the structure, physical and chemical properties, the use of sulfuric acid.

Educational tasks: Consider the physical and Chemical properties(common with other acids and specific) sulfuric acid, obtaining, show the great importance of sulfuric acid and its salts in the national economy.

Educational tasks: To continue the formation of a dialectical-materialistic understanding of nature among students.

Development tasks: Development of general educational skills and abilities, work with a textbook and additional literature, rules for working on a desktop, the ability to systematize and generalize, establish cause-and-effect relationships, express one’s thoughts conclusively and competently, draw conclusions, draw diagrams, sketch.

During the classes

1. Repetition of the past.

Frontal class survey. Compare the properties of crystalline and plastic sulfur. Explain the essence of allotropy.

2. Learning new material.

After carefully listening to the tale, we will explain at the end of the lesson why sulfuric acid behaved strangely with water, wood and a golden ring.

Sounds like an audio recording.

The Adventures of Sulfuric Acid.

In one chemical kingdom lived a sorceress, her name was sulfuric acid. It didn't look so bad, it was a colorless liquid, viscous like oil, odorless. Sulfuric acid I wanted to be famous, so I went on a trip.

She had already been walking for 5 hours, and since the day was too hot, she was very thirsty. And suddenly she saw a well. "Water!" acid exclaimed, and running up to the well, she touched the water. The water hissed terribly. With a cry, the frightened sorceress rushed away. Of course, the young acid did not know that when mixed sulfuric acid water releases a large amount of heat.

"If water comes into contact with sulfuric acid, then the water, not having time to mix with the acid, can boil and throw out splashes sulfuric acid. This entry appeared in the diary of a young traveler, and then entered the textbooks.

Since the acid did not quench their thirst, then, a sprawling tree, decided to lie down and rest in the shade. But she didn't succeed either. As soon as Sulfuric acid touched the tree, it began to char. Not knowing the reason for this, the frightened acid ran away.

Soon she came to the city and decided to go to the first store that came across her way. They turned out to be jewelry. Approaching the shop windows, the acid saw many beautiful rings. Sulfuric acid I decided to try one ring. Asking the seller for a gold ring, the traveler put it on her long beautiful finger. The sorceress really liked the ring and she decided to buy it. That's what she could boast to her friends!

Leaving the city, the acid went home. On the way, the thought did not leave her, why did water and wood behave so strangely when touched with her, but nothing happened to this golden thing? “Yes, because gold is in sulfuric acid does not oxidize. These were the last words written by acid in his diary.

Teacher's explanation.

Electronic and structural formulas of sulfuric acid.

Since sulfur is in the 3rd period of the periodic system, the octet rule (eight electronic structure) is not respected and a sulfur atom can acquire up to twelve electrons. The electronic and structural formulas of sulfuric acid are as follows:

(The six electrons of sulfur are marked with an asterisk)

Receipt.

Sulfuric acid is formed by the interaction of sulfur oxide (5) with water (SO 3 + H 2 O -> H 2 SO 4).

physical properties.

Sulfuric acid is a colorless, heavy, non-volatile liquid. When dissolved in water, a very strong heating occurs. remember, that do not pour water into concentrated sulfuric acid!

Concentrated sulfuric acid absorbs water vapor from the air. This can be seen if an open vessel with concentrated sulfuric acid is balanced on a scale: after a while, the cup with the vessel will sink.

Chemical properties.

Dilute sulfuric acid has properties common to all acids. In addition, sulfuric acid has specific properties.

Chemical properties of sulfuric - Application .

Demonstration by the teacher of an entertaining experience.

Brief safety briefing.

Eskimo (Charcoal from sugar)

Equipment	Experience plan	Conclusion
Powdered sugar. concentrated sulfuric acid. Two chemical glasses of 100-150 ml. Glass rod. Scales.	Pour 30 g of powdered sugar into a beaker. Use a beaker to measure out 12 ml of concentrated sulfuric acid. Mix sugar and acid in a glass with a glass rod into a mushy mass (remove the glass rod and put it in a glass of water). After some time, the mixture darkens, warms up, and soon a porous coal mass begins to crawl out of the glass - popsicle	Carbonization of sugar with sulfuric acid (concentrated) is explained by the oxidizing properties of this acid. The reducing agent is carbon. The process is exothermic. 2H 2 SO 4 + C 12 O 11 + H22 -> 11C + 2SO 2 + 13H 2 O + CO 2

Students fill out a table with an entertaining experience in a notebook.

Students' reasoning about why Sulfuric acid behaved so strangely with water, wood and gold.

Application.

Due to its properties (the ability to absorb water, oxidizing properties, non-volatility), sulfuric acid is widely used in the national economy. It belongs to the main products of the chemical industry.

1. receiving dyes;
2. obtaining mineral fertilizers;
3. cleaning of oil products;
4. electrolytic production of copper;
5. electrolyte in batteries;
6. receiving explosives;
7. receiving dyes;
8. obtaining artificial silk;
9. receiving glucose;
10. obtaining salts;
11. obtaining acids.

Salts of sulfuric acid are widely used, for example

Na 2 SO 4 * 10H 2 O– sodium sulfate crystalline hydrate (Glauber's salt)- used in the production of soda, glass, in medicine and veterinary medicine.

CaSO4*2H2O- hydrated calcium sulfate (natural gypsum)- used to obtain semi-aqueous gypsum, which is necessary in construction, and in medicine - for applying plaster bandages.

CuSO4*5H2O– hydrated copper sulfate (2) (copper sulfate)- used in the fight against pests and plant diseases.

The work of students with the extra-textual component of the textbook.

This is interesting

…in the Gulf of Kara-Bogaz-Gol, the water contains 30% of Glauber's salt at a temperature of +5 ° C, this salt precipitates as a white precipitate, like snow, and with the onset of warm weather, the salt dissolves again. Since Glauber's salt appears and disappears in this bay, it was named mirabilite, which means "wonderful salt".

3. Questions to consolidate the educational material, written on the board.

1. In winter, a vessel with concentrated sulfuric acid is sometimes placed between the window frames. What is the purpose of doing this, why can't the vessel be filled with acid to the top?
2. Why is sulfuric acid called the "bread" of chemistry?

Homework and instructions for its implementation.

Where appropriate, write equations in ionic form.

Conclusion on the lesson, setting and commenting marks.

References.

1. Rudzitis G.E. Feldman F.G., Chemistry: A textbook for grades 7-11 of an evening (shift) secondary school at 2 hours. Part 1-3 edition - M .: Education, 1987.
2. Chemistry at school No. 6, 1991.
3. Strempler Genrikh Ivanovich, Chemistry at leisure: Book. for students Wednesdays. and old. age /Fig. ed. with the participation of V.N. Rastopchiny.- F .: Ch. ed. KSE, 1990.

Structural formula

True, empirical, or gross formula: H2SO4

Chemical composition of sulfuric acid

Molecular weight: 98.076

Sulfuric acid H 2 SO 4 is a strong dibasic acid, corresponding to the highest oxidation state of sulfur (+6). Under normal conditions, concentrated sulfuric acid is a heavy oily liquid, colorless and odorless, with a sour "coppery" taste. In technology, sulfuric acid is called its mixtures with both water and sulfuric anhydride SO 3. If the molar ratio of SO 3: H 2 O is less than 1, then this is an aqueous solution of sulfuric acid, if more than 1 - a solution of SO 3 in sulfuric acid (oleum).

Name

In the XVIII-XIX centuries, sulfur for gunpowder was produced from sulfur pyrites (pyrite) at vitriol plants. Sulfuric acid at that time was called "vitriol oil" (as a rule it was a crystalline hydrate, resembling oil in consistency), the origin of the name of its salts (or rather, crystalline hydrates) - vitriol, is obviously from here.

Getting sulfuric acid

Industrial (contact) method

In industry, sulfuric acid is produced by the oxidation of sulfur dioxide (sulphurous gas produced during the combustion of sulfur or sulfur pyrite) to trioxide (sulfuric anhydride), followed by the interaction of SO 3 with water. The sulfuric acid obtained by this method is also called contact (concentration 92-94%).

Nitrous (tower) method

Previously, sulfuric acid was obtained exclusively by the nitrous method in special towers, and the acid was called tower acid (75% concentration). The essence of this method is the oxidation of sulfur dioxide with nitrogen dioxide in the presence of water.

Another way

In those rare cases when hydrogen sulfide (H 2 S) displaces sulfate (SO 4 -) from salt (with metals Cu, Ag, Pb, Hg), sulfuric acid is a by-product. Sulfides of these metals have the highest strength, as well as a distinctive black color.

Physical and physico-chemical properties

A very strong acid, at 18 o C pK a (1) \u003d -2.8, pK a (2) \u003d 1.92 (K z 1.2 10 -2); bond lengths in the molecule S=O 0.143 nm, S-OH 0.154 nm, angle HOSOH 104°, OSO 119°; boils, forming an azeotropic mixture (98.3% H 2 SO 4 and 1.7% H 2 O with a boiling point of 338.8 ° C). Sulfuric acid, corresponding to 100% H 2 SO 4 content, has a composition (%): H 2 SO 4 99.5, HSO 4 - - 0.18, H 3 SO 4 + - 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 3 O + , HSO 3 + , and 2HSO 4 - . Forms hydrates H 2 SO 4 nH 2 O, where n = 1, 2, 3, 4 and 6.5.

Oleum

Solutions of sulfuric anhydride 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 acids. The boiling point of aqueous solutions of sulfuric acid increases with an increase in its concentration and reaches a maximum at a content of 98.3% H 2 SO 4 . The boiling point of oleum decreases with increasing SO 3 content. With an increase in the concentration of aqueous solutions of sulfuric acid, the total vapor pressure over the solutions decreases and at a content of 98.3% H 2 SO 4 reaches a minimum. With an increase in the concentration of SO 3 in oleum, the total vapor pressure above it increases. The vapor pressure over aqueous solutions of sulfuric acid and oleum can be calculated by the equation:

log p=A-B/T+2.126

the values ​​of the coefficients A and B depend on the concentration of sulfuric acid. Steam over aqueous solutions of sulfuric acid consists of 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. As the temperature rises, dissociation increases. The oleum H 2 SO 4 ·SO 3 has the maximum viscosity; with increasing temperature, η decreases. The electrical resistance of sulfuric acid is minimal at a concentration of SO 3 and 92% H 2 SO 4 and maximum at a concentration of 84 and 99.8% H 2 SO 4 . For oleum, the minimum ρ is at a concentration of 10% SO 3 . As the temperature rises, the ρ of sulfuric acid increases. Dielectric constant of 100% sulfuric acid 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 varies with 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. Oxidizes many metals (exceptions: Au, Pt, Ir, Rh, Ta.). In this case, concentrated sulfuric acid is reduced to SO 2 . In the cold in concentrated sulfuric acid, Fe, Al, Cr, Co, Ni, Ba are passivated and the reactions do not proceed. With the strongest reducing agents, concentrated sulfuric acid is reduced to S and H 2 S. Concentrated sulfuric acid absorbs water vapor, so it is used to dry gases, liquids, and solids, for example, in desiccators. However, concentrated H 2 SO 4 is partially reduced by hydrogen, which is why it cannot be used for drying it. Splitting water from organic compounds and leaving black carbon (coal) at the same time, concentrated sulfuric acid leads to the carbonization of wood, sugar and other substances. Diluted H 2 SO 4 interacts with all metals that are in the electrochemical series of voltages to the left of hydrogen with its release. Oxidizing properties for dilute H 2 SO 4 are uncharacteristic. Sulfuric acid forms two series of salts: medium - sulfates and acidic - hydrosulfates, as well as esters. Peroxomonosulfuric (or Caro's acid) H 2 SO 5 and peroxodisulfuric H 2 S 2 O 8 acids are known. Sulfuric acid also reacts with basic oxides to form sulfate and water. In metalworking plants, a sulfuric acid solution is used to remove a layer of metal oxide from the surface of metal products that are subjected to strong heating during the manufacturing process. So, 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 forms a white precipitate of barium sulfate, insoluble in water and acids, for example.

Application

Sulfuric acid is used:

• in the processing of ores, especially in the extraction of rare elements, including uranium, iridium, zirconium, osmium, etc.;
• in the production of mineral fertilizers;
• as an electrolyte in lead batteries;
• to obtain various mineral acids and salts;
• in the production of chemical fibers, dyes, smoke-forming and explosive substances;
• in the oil, metalworking, textile, leather and other industries;
• V Food Industry- registered as food additive E513 (emulsifier);
• in industrial organic synthesis in reactions:
• dehydration (obtaining diethyl ether, esters);
• hydration (ethanol from ethylene);
• sulfonation (synthetic detergents and intermediates in the production of dyes);
• alkylation (obtaining isooctane, polyethylene glycol, caprolactam), etc.
• For the recovery of resins in filters in the production of distilled water.

World production of sulfuric acid approx. 160 million tons per year. The largest consumer of sulfuric acid is the production of mineral fertilizers. For P 2 O 5 phosphate fertilizers, 2.2-3.4 times more sulfuric acid is consumed by mass, and for (NH 4) 2 SO 4 sulfuric acid 75% of the mass of consumed (NH 4) 2 SO 4. Therefore, sulfuric acid plants tend to be built in conjunction with plants for the production of mineral fertilizers.

Historical information

Sulfuric acid has been known since antiquity, occurring naturally in free form, for example, in the form of lakes near volcanoes. Perhaps the first mention of acid gases obtained by calcining alum or iron sulfate "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 blue vitriol(FeSO 4 7H 2 O and CuSO 4 5H 2 O), also received a solution of sulfuric acid. This method was perfected by the European alchemist Albert Magnus, who lived in the 13th century. Scheme for the production of sulfuric acid from ferrous sulfate - thermal decomposition of iron (II) sulfate, followed by cooling the mixture. The works of the alchemist Valentine (XIII century) describe a method for producing sulfuric acid by absorbing gas (sulphuric anhydride) released by burning a mixture of sulfur and saltpeter 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, such a method existed until 1955. Alchemists of the 15th century also knew a method for obtaining sulfuric acid from pyrite - sulfur pyrite, a cheaper and more common raw material than sulfur. Sulfuric acid was produced in this way for 300 years, in small quantities in glass retorts. Subsequently, due to the development of catalysis, this method replaced the chamber method for the synthesis of sulfuric acid. Currently, sulfuric acid is produced by catalytic oxidation (on V 2 O 5) 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 the production of sulfuric acid.

additional information

The smallest 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 quantities sulfur. The resulting suspension, due to the high albedo of sulfuric acid clouds, makes it difficult to access sun rays to the surface of the planet. Therefore (and also as a result of a large number of tiny particles of volcanic ash in the upper atmosphere, which also make it difficult to access sunlight to the planet) after particularly strong volcanic eruptions, significant climate changes can occur. For example, as a result of the eruption of the Ksudach volcano (Kamchatka Peninsula, 1907), an increased concentration of dust in the atmosphere persisted for about 2 years, and characteristic silvery clouds of sulfuric acid were observed even in Paris. The explosion of the Pinatubo volcano in 1991, which sent 3 10 7 tons of sulfur into the atmosphere, led to the fact that 1992 and 1993 were much colder than 1991 and 1994.

Standards

• Sulfuric acid technical GOST 2184-77
• Sulfuric acid battery. Specifications GOST 667-73
• Sulfuric acid of special purity. Specifications GOST 1422-78
• Reagents. Sulfuric acid. Specifications GOST 4204-77