Sulfurous acid- unstable dibasic inorganic acid of medium strength. Corresponds to the oxidation state of sulfur +4. Chemical formula $\backslash mathsf(H\_2SO\_3)$.

Chemical properties

Medium strength acid:

$\backslash mathsf(H\_2SO\_3\; \backslash rightleftarrows\; H^+\; +\; HSO\_3^-)$ $\backslash mathsf(HSO\_3^-\; \backslash rightleftarrows\; H^+\; +\; SO\_3^(2-))$

Exists only in dilute aqueous solutions (not isolated in a free state):

$\backslash mathsf(SO\_2+H\_2O\; \backslash rightleftarrows\; H\_2SO\_3\; \backslash rightleftarrows\; H^++HSO\_3^-\; \backslash rightleftarrows\; 2H^+\; +\; SO\_3^(2-))$

Solutions of H 2 SO 3 always have a sharp, specific odor of SO 2 not chemically bound with water.

$\backslash mathsf(H\_2SO\_3\; +\; NaOH\; \backslash longrightarrow\; NaHSO\_3\; +\; H\_2O)$ $\backslash mathsf(H\_2SO\_3\; +\; 2NaOH\; \backslash longrightarrow\; Na\_2SO\_3\; +\; 2H\_2O)$

Like sulfur dioxide, sulfurous acid and its salts are strong reducing agents:

$\backslash mathsf(H\_2SO\_3\; +\; Br\_2\; +\; H\_2O\; \backslash longrightarrow\; H\_2SO\_4\; +\; 2HBr)$

When interacting with even stronger reducing agents, it can play the role of an oxidizing agent:

$\backslash mathsf(H\_2SO\_3\; +\; 2H\_2S\; \backslash longrightarrow\; 3S\; \backslash downarrow\; +\; 3H\_2O)$

Qualitative reaction to sulfite ions - discoloration of a solution of potassium permanganate:

$\backslash mathsf(5SO\_3^(2-)\; +\; 6H^(+)\; +\; 2MnO\_4^(-)\; \backslash longrightarrow\; 5SO\_4^(2-)\; +\; 2Mn^(2+)\; +\; 3H\_2O)$

Application

Sulfurous acid and its salts are used as reducing agents for bleaching wool, silk and other materials that cannot withstand bleaching with strong oxidizing agents (chlorine). Sulfurous acid is used in canning fruits and vegetables. Calcium hydrosulfite (sulfite liquor, Ca(HSO 3) 2) is used to process wood into so-called sulfite cellulose (a solution of calcium hydrosulfite dissolves lignin, a substance that binds cellulose fibers, as a result of which the fibers are separated from each other; wood treated in this way is used for receipt of paper).

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Literature

• Chemical Encyclopedia / Editorial Board: Knunyants I.L. and others. - M.: Soviet Encyclopedia, 1995. - T. 4 (Pol-Three). - 639 p. - ISBN 5-82270-092-4.

Excerpt characterizing sulfurous acid

Since the morning of that day, Natasha had not had a minute of freedom, and not once had time to think about what lay ahead of her.
In the damp, cold air, in the cramped and incomplete darkness of the swaying carriage, for the first time she vividly imagined what awaited her there, at the ball, in the illuminated halls - music, flowers, dancing, the sovereign, all the brilliant youth of St. Petersburg. What awaited her was so beautiful that she did not even believe that it would happen: it was so incongruous with the impression of the cold, crampedness and darkness of the carriage. She understood everything that awaited her only when, having walked along the red cloth of the entrance, she entered the entryway, took off her fur coat and walked next to Sonya in front of her mother between the flowers along the illuminated stairs. Only then did she remember how she had to behave at the ball and tried to adopt the majestic manner that she considered necessary for a girl at the ball. But fortunately for her, she felt that her eyes were running wild: she saw nothing clearly, her pulse beat a hundred times a minute, and the blood began to pound at her heart. She could not accept the manner that would make her funny, and she walked, frozen with excitement and trying with all her might to hide it. And this was the very manner that suited her most of all. In front and behind them, talking just as quietly and also in ball gowns, guests entered. The mirrors along the stairs reflected ladies in white, blue, pink dresses, with diamonds and pearls on their open arms and necks.

When sulfur dioxide (SO 2 ) is dissolved in water, it produces a chemical compound known as sulfurous acid. The formula of this substance is written as follows: H 2 SO 3. In truth, this connection is extremely unstable, with a certain assumption it can even be argued that it does not actually exist. Nevertheless, this formula is often used for the convenience of writing equations of chemical reactions.

Sulfurous acid: basic properties

An aqueous solution of sulfur dioxide is characterized by an acidic environment. It itself has all the properties that are inherent in acids, including the neutralization reaction. Sulfurous acid is capable of forming two types of salts: hydrosulfites and ordinary sulfites. Both belong to the group of reducing agents. The first type is usually obtained when sulfurous acid is present in fairly large quantities: H 2 SO 3 + KOH -> KHSO 3 + H 2 O. Otherwise, ordinary sulfite is obtained: H 2 SO 3 + 2KOH -> K 2 SO 3 + 2H 2 O. A qualitative reaction to these salts is their interaction with a strong acid. As a result, SO 2 gas is released, which is easily distinguished by its characteristic pungent odor.

Sulfurous acid can have a bleaching effect. It is no secret that chlorine water also gives a similar effect. However, the compound in question has one important advantage: unlike chlorine, sulfurous acid does not lead to the destruction of dyes; sulfur dioxide forms colorless chemical compounds with them. This property is often used for bleaching fabrics made of silk, wool, plant material, as well as anything that is destroyed by oxidizing agents containing Cl. In the old days, this compound was even used to restore ladies' straw hats to their original appearance. H 2 SO 3 is a fairly strong reducing agent. With the access of oxygen, its solutions gradually turn into sulfuric acid. In those cases when it interacts with a stronger reducing agent (for example, hydrogen sulfide), sulfuric acid, on the contrary, exhibits oxidizing properties. The dissociation of this substance occurs in two stages. First, the hydrosulfite anion is formed, and then the second step occurs, and it turns into the sulfite anion.

Where is sulfurous acid used?

The production of this substance plays a big role in the production of all kinds of wine materials as an antiseptic; in particular, with its help it is possible to prevent the process of fermentation of the product in barrels and thereby ensure its safety. It is also used to prevent grain fermentation during the extraction of starch from it. Sulfurous acid and preparations based on it have broad antimicrobial properties, and therefore they are often used in the fruit and vegetable industry for canning. Calcium hydrosulfite, also called sulfite liquor, is used to process wood into sulfite pulp, from which paper is subsequently made. It remains to add that this compound is poisonous for humans, and therefore any laboratory work and experiments with it require caution and increased attention.

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. It is obtained by contact oxidation of sulfur dioxide (SO2).

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 volume in tons. This is why sulfuric acid is called the “blood of chemistry.” With the help of sulfuric acid, fertilizers, medicines, other acids, large quantities of fertilizers and much more are obtained.

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 large-scale release of heat.
2. H2SO4 is a strong acid.
3. Sulfuric acid is called a monohydrate - it contains 1 mole of H2O (water) per 1 mole of SO3. Due to its impressive hygroscopic properties, it is used to extract moisture from gases.
4. Boiling point – 330 °C. In this case, the acid decomposes into SO3 and water. Density – 1.84. Melting point – 10.3 °C/.
5. Concentrated sulfuric acid is a powerful oxidizing agent. To initiate a 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 with metals differently. In a dilute state, sulfuric acid is capable of oxidizing all metals that are in the voltage series before hydrogen. The exception is 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 voltage series, including silver.
7. Sulfuric acid forms two types of salts: acidic (these are hydrosulfates) and intermediate (sulfates)
8. H2SO4 reacts actively with organic substances and non-metals, and it can turn some of them into coal.
9. Sulfuric anhydrite dissolves well 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 the water in a small stream, and not vice versa. This is done to prevent the water from boiling and splashing the acid.

Concentrated and diluted sulfuric acids

Concentrated solutions of sulfuric acid include solutions from 40% that can dissolve silver or palladium.

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

Preparation of sulfuric acid

The production of sulfuric acid on an industrial scale began in the 15th century, but at that time it was called “oil of vitriol.” If earlier humanity consumed only a few tens of liters of sulfuric acid, then in the 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. Nitrose method
3. Other methods

Let's talk in detail about each of them.

Contact production method

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

• The result is a product that satisfies the needs of the maximum number of consumers.
• During production, environmental damage is reduced.

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

• pyrite (sulfur pyrite);
• sulfur;
• vanadium oxide (this substance acts as a catalyst);
• hydrogen sulfide;
• sulfides of various metals.

Before starting the production process, raw materials are pre-prepared. To begin with, in special crushing plants, the pyrite is crushed, which allows, by increasing the contact area of ​​the active substances, to speed up the reaction. Pyrite undergoes purification: it is lowered into large containers of water, during which waste rock and all sorts of impurities float to the surface. At the end of the process they are removed.

The production part is divided into several stages:

1. After crushing, the 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 into the chamber from below, and this ensures that the pyrite is in a suspended state. Today, this process takes a few seconds, but previously it took several hours to fire. During the roasting process, waste appears in the form of iron oxide, which is removed and subsequently transferred to the metallurgical industry. During firing, water vapor, O2 and SO2 gases are released. When purification from water vapor and tiny impurities is completed, pure sulfur oxide and oxygen are obtained.
2. In the second stage, an exothermic reaction occurs under pressure using a vanadium catalyst. The reaction starts when the temperature reaches 420 °C, but it can be increased to 550 °C 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: absorption of SO3 in an absorption tower, during which 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 consumer.

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, which use the released steam to generate additional electricity.

Nitrous method for producing sulfuric acid

Despite the advantages of the contact production method, 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, the starting material, both in the contact and nitrose methods, is sulfur dioxide. It is obtained specifically for these purposes by burning sulfur or roasting sulfur metals.

Processing sulfur dioxide into sulfurous acid involves 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 react directly with oxygen, therefore, with the nitrous method, sulfur dioxide is oxidized using nitrogen oxides. Higher oxides of nitrogen (we are talking about nitrogen dioxide NO2, nitrogen trioxide NO3) during this process are reduced to nitrogen oxide NO, which is subsequently oxidized again 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:

• The result is 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.
• Possibility of SO2 recycling at 100%.
• Simplicity of hardware design.

Main Russian sulfuric acid plants

The annual production of H2SO4 in our country is in the six-digit range - about 10 million tons. The leading producers of sulfuric acid in Russia are companies that are, in addition, its main consumers. We are talking about companies whose field of activity is the production of mineral fertilizers. For example, “Balakovo mineral fertilizers”, “Ammophos”.

In Crimea, in Armyansk, the largest titanium dioxide producer in Eastern Europe, Crimean Titan, operates. In addition, the plant produces sulfuric acid, mineral fertilizers, iron sulfate, etc.

Many factories produce various types of sulfuric acid. 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 PA, etc.

Sulfuric acid of special purity is produced by OHC Shchekinoazot, Component-Reaktiv.

Spent sulfuric acid can be purchased at the ZSS and HaloPolymer Kirovo-Chepetsk plants.

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 of enrichment enterprises, its suppliers are the Norilsk and Talnakh enrichment factories.

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

Scope of application of sulfuric acid

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

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

• Sulfuric acid is used in enormous volumes for the production of mineral fertilizers, and this consumes about 40% of the total tonnage. For this reason, factories that produce H2SO4 are built next to factories that produce fertilizers. These are ammonium sulfate, superphosphate, etc. During their production, sulfuric acid is taken in its pure form (100% concentration). To produce a ton of ammophos or superphosphate you will need 600 liters of H2SO4. These fertilizers are in most cases used in agriculture.
• H2SO4 is used to produce explosives.
• Purification of petroleum products. To obtain kerosene, gasoline and mineral oils, purification of hydrocarbons is required, which occurs using sulfuric acid. In the process of refining oil to purify 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 in metallurgy is used to remove scale and rust from wire and sheet metal, as well as to restore aluminum in the production of non-ferrous metals. Before coating metal surfaces with copper, chromium or nickel, the surface is etched with sulfuric acid.
• In the production of medicines.
• In the production of paints.
• In the chemical industry. H2SO4 is used in the production of detergents, ethylene, insecticides, etc., and without it these processes are impossible.
• For the production of other known acids, organic and inorganic compounds used for industrial purposes.

Salts of sulfuric acid and their use

The most important salts of sulfuric acid:

• 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, and 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. When gypsum is heated to a temperature of 150 - 170 °C, partial dehydration occurs, resulting in burnt gypsum, known to us as alabaster. By mixing alabaster with water to the consistency of a batter, 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 casting molds are made from it. In plastering work, alabaster is indispensable as a binding material. Patients in trauma departments are given special fixing hard bandages - they are made on the basis of alabaster.
• Iron sulfate FeSO4 · 7H2O is used to prepare ink, impregnate wood, and also in agricultural activities to kill pests.
• Alum KCr(SO4)2 · 12H2O, KAl(SO4)2 · 12H2O, etc. are used in the production of paints and the leather industry (leather tanning).
• Many of you know copper sulfate CuSO4 · 5H2O firsthand. This is an active assistant in agriculture in the fight against plant diseases and pests - grain is treated with an aqueous solution of CuSO4 · 5H2O and sprayed on plants. It is also used to prepare some mineral paints. And in everyday life it is used to remove mold from walls.
• Aluminum sulfate – it is used in the pulp and paper industry.

Sulfuric acid in diluted form is used as an electrolyte in lead 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 (you can also find other formulas of oleum).

Amazing fact! Oleum is more chemically active 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 scope of use of the “queen of acids” is truly large-scale, and it is difficult to talk about all the ways it is used in industry. It is also used as an emulsifier in the food industry, for water purification, in the synthesis of explosives and many other purposes.

The history of sulfuric acid

Who among us has not at least once heard of copper sulfate? So, it was studied in ancient times, and in some works of the beginning of the new era, scientists discussed the origin of vitriol and their properties. Vitriol was studied by the Greek physician Dioscorides and the Roman nature explorer Pliny the Elder, and in their works they wrote about the experiments they carried out. For medical purposes, various vitriol substances were used by the ancient physician Ibn Sina. How vitriol was used in metallurgy was discussed in the works of the alchemists of Ancient Greece Zosimas of Panopolis.

The first way to obtain sulfuric acid is the process of heating potassium alum, and there is information about this in the alchemical literature of the 13th century. At that time, the composition of alum and the essence of the process were unknown to alchemists, but already in the 15th century, the chemical synthesis of sulfuric acid began to be deliberately studied. 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 "oil of vitriol", but then the name changed to vitriol acid.

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

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

Vitriol acid appeared in Rus' 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 durable large leaded chambers, which were cheaper than glass containers.

This method held its position in industry for almost 200 years, and 65% sulfuric acid was obtained in 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 of, for example, dyes.

At the beginning of the 19th century, new methods were discovered for oxidizing sulfur dioxide into 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 been 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 is called the nitrous method for producing sulfuric acid.

The British acetic acid merchant Peregrine Philips patented an economical process for the production of sulfur oxide (VI) and concentrated sulfuric acid only in 1831, and it is this method that is familiar to the world today as a contact method for its production.

Superphosphate production 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 dangerous chemicals, and upon contact with the skin causes severe burns. In addition, it can cause chemical poisoning in humans. If certain rules are not followed during transportation, sulfuric acid, due to its explosiveness, can cause a lot of harm to both people and the environment.

Sulfuric acid is classified as hazard class 8 and must be transported by specially trained and trained professionals. An important condition for the delivery of sulfuric acid is compliance with specially developed Rules for the Transportation of Dangerous Goods.

Transportation by road is carried out in accordance with the following rules:

1. For transportation, special containers are made from a special steel alloy that does not react with sulfuric acid or titanium. Such containers do not oxidize. Dangerous sulfuric acid is transported in special sulfuric acid chemical tanks. They differ in design and are selected for transportation depending on the type of sulfuric acid.
2. When transporting fuming acid, specialized isothermal thermos tanks are taken, in which the required temperature regime is maintained to preserve the chemical properties of the acid.
3. If ordinary acid is transported, then a sulfuric acid tank is selected.
4. Transportation of sulfuric acid by road, such types as fuming, anhydrous, concentrated, for batteries, and glover, is carried out in special containers: tanks, barrels, containers.
5. The transportation of dangerous goods can only be carried out by drivers who have an ADR certificate.
6. Travel time has no restrictions, since during transportation you must strictly adhere to the permissible speed.
7. During transportation, a special route is built, which should pass places of large crowds of people 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 upon direct contact with the skin, but upon inhalation of its vapors, when sulfur dioxide is released. Hazardous effects include:

• Respiratory system;
• Skin;
• Mucous membranes.

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

Important! As you know, severe burns occur when acid comes into contact with the skin. Poisoning by sulfuric acid vapors is no less dangerous. The 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 skin, a severe burn appears that does not heal well. If the burn is significant 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, “experiencing” the toxic effects of acid in everyday life is problematic. Most often, acid poisoning occurs due to neglect of industrial safety precautions when working with the solution.

Mass poisoning with sulfuric acid vapor may occur due to technical problems at work or negligence, and a massive release into the atmosphere occurs. To prevent such situations, special services operate whose task is to monitor the functioning of production where dangerous acid is used.

What symptoms are observed during sulfuric acid intoxication?

If the acid was ingested:

• Pain in the area of ​​the digestive organs.
• Nausea and vomiting.
• Abnormal bowel movements as a result of severe intestinal disorders.
• Heavy secretion of saliva.
• Due to toxic effects on the kidneys, the urine becomes reddish.
• Swelling of the larynx and throat. Wheezing and hoarseness occur. This can be fatal from suffocation.
• Brown spots appear on the gums.
• The skin turns blue.

When the skin is burned, there can be all the complications inherent in a burn disease.

In case of vapor poisoning, the following picture is observed:

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

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

First aid and therapeutic procedures for sulfuric acid injury

Proceed as follows when in contact with sulfuric acid:

• First of all, call an ambulance. If liquid gets inside, rinse the stomach with warm water. After this, you will need to drink 100 grams of sunflower or olive oil in small sips. 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, you need to rinse them with running water and then drip them with a solution of dicaine and novocaine.
• If acid gets on the skin, rinse the burned area well under running water and apply a bandage with soda. You need to rinse for about 10-15 minutes.
• In case of vapor poisoning, you need to go out into fresh air, and also rinse the affected mucous membranes with water as soon as possible.

In a hospital setting, treatment will depend on the area of ​​the burn and the degree of poisoning. Pain relief is carried out only with novocaine. To avoid the development of infection in the affected area, the patient is given a course of antibiotic therapy.

In case of gastric bleeding, plasma or blood transfusion is administered. The source of bleeding can be eliminated surgically.

1. Sulfuric acid occurs in nature in its 100% pure form. For example, in Italy, Sicily, in the Dead Sea, you can see a unique phenomenon - sulfuric acid seeps straight from the bottom! What happens is this: 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 near 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 cause negative environmental consequences and cause serious climate change.
3. Sulfuric acid is an active absorbent of water, so it is used as a gas desiccant. In the old days, to prevent indoor windows from fogging up, this acid was poured into jars and placed between the glass of window openings.
4. Sulfuric acid is the main cause of acid rain. The main cause of acid rain is air pollution from sulfur dioxide, which when dissolved in water forms sulfuric acid. Sulfur dioxide, in turn, is released when fossil fuels are burned. In acid rain studied in recent years, the content of nitric acid has increased. The reason for this phenomenon is the reduction of sulfur dioxide emissions. Despite this fact, the main cause of acid rain remains sulfuric acid.

We offer you a video selection of interesting experiments with sulfuric acid.

Let's 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. Then the most interesting thing happens. The mass begins to grow rapidly and climb outside the flask. The output is a proud substance, similar to porous charcoal, 3-4 times larger than the original volume.

The author of the video suggests comparing the reaction of Coca-Cola with hydrochloric acid and sulfuric acid. When Coca-Cola is mixed 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 comes into contact with toilet paper. Toilet paper is made of cellulose. When acid hits the cellulose molecule, it instantly breaks down releasing free carbon. Similar charring can be observed when acid comes into contact with wood.

I add a small piece of potassium to a flask with concentrated acid. In the first second, smoke is released, after which the metal instantly flares up, ignites and explodes, breaking into pieces.

In the following experiment, when sulfuric acid hits a match, it ignites. In the second part of the experiment, aluminum foil with acetone and a match inside is immersed. The foil is instantly heated, releasing a huge amount of smoke and completely dissolving it.

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

We strongly advise against carrying out all of the above experiments at home. Sulfuric acid is a very aggressive and toxic substance. Such experiments must be carried out in special rooms equipped with forced ventilation. The gases released in reactions with sulfuric acid are very toxic and can cause damage to the respiratory tract and poisoning of the body. In addition, similar experiments are carried out using personal protective equipment for the skin and respiratory system. Take care of yourself!

Sulfur dioxide SO2 is formed when sulfur is burned in air or oxygen. It is also obtained by calcining metal sulfides, such as iron pyrites, in air (“burning”):

From this reaction, sulfur dioxide is usually obtained industrially (about other industrial methods for producing SO 2 cm, 9 § 131).

Sulfur dioxide is a colorless gas (“sulfur dioxide”) with a pungent odor of hot sulfur. It condenses quite easily into a colorless liquid, boiling at -10.0°C. When liquid SO 2 evaporates, a strong drop in temperature occurs (down to -50°C).

Sulfur dioxide is highly soluble in water (about 40 volumes in 1 volume of water at 20°C); in this case, a partial reaction with water occurs and sulfurous acid is formed:

Thus, sulfur dioxide is an anhydride of sulfurous acid. When heated, the solubility of SO 2 decreases and the equilibrium shifts to the left; gradually all the sulfur dioxide is released from the solution again.

The SO 2 molecule is structured similarly to the ozone molecule. The nuclei of its constituent atoms form an isosceles triangle:

Here the sulfur atom, like the central oxygen atom in the ozone molecule, is in a state of sp 2 hybridization and the OSO angle is close to 120°. The p z orbital of the sulfur atom, oriented perpendicular to the plane of the molecule, does not participate in hybridization. Due to this orbital and similarly oriented p z orbitals of oxygen atoms, a three-center α bond is formed; the pair of electrons that carry it out belongs to all three atoms of the molecule.

Sulfur dioxide is used to produce sulfuric acid, and also (in much smaller quantities) for bleaching straw, wool, silk and as a disinfectant (to destroy mold in basements, cellars, wine barrels, fermentation tanks).

Sulfurous acid H 2 SO 3 is a very fragile compound. It is known only in aqueous solutions. When trying to isolate sulfurous acid, it breaks down into SO 2 and water. For example, when concentrated sulfuric acid acts on sodium sulfite, sulfur dioxide is released instead of sulfurous acid:

The sulfurous acid solution must be protected from access to air, otherwise it, absorbing oxygen from the air, slowly oxidizes into sulfuric acid:

Sulfurous acid is a good reducing agent. For example, it reduces free halogens into hydrogen halides:

However, when interacting with strong reducing agents, sulfurous acid can play the role of an oxidizing agent. So, its reaction with hydrogen sulfide mainly proceeds according to the equation:

Being dibasic (K 1 ? 2·10 -2, K 2 = 6.3·10 -8), sulfurous acid forms two series of salts. Its average salts are called sulfites, acidic ones - hydrosulfites.

Like acid, sulfites and hydrosulfites are reducing agents. When they are oxidized, salts of sulfuric acid are obtained.

When calcined, sulfites of the most active metals decompose to form sulfides and sulfates (self-oxidation - self-healing reaction):

Potassium and sodium sulfites are used for bleaching certain materials, in the textile industry for dyeing fabrics, and in photography. A solution of Ca(HSO 3)2 (this salt exists only in solution) is used to process wood into the so-called sulfite pulp, from which paper is then obtained.

Sulfur compounds (1U). Sulfurous acid

In tetrahalides SHal 4, oxohalides SOI Ial 2 and dioxide S0 2, sulfurous acid 1I 2 S0 3, sulfur exhibits an oxidation state of +4. In all these compounds, as well as in their corresponding anionic complexes, the sulfur atom has an unshared pair of electrons. Based on the number of a-bonding and non-bonding electrons, the shape of the molecules of these compounds changes from a distorted tetrahedron (SHal 4) to an angular shape (S0 9) through a trigonal pyramid shape (SOHal 2 and SO3). S(IV) compounds have acidic properties, which manifests themselves in reactions with water:

Sulfur oxide(1U) S0 2, or sulfur dioxide, is formed by burning sulfur in air or oxygen, as well as by calcining sulfides, such as pyrite:

Pyrite oxidation underlies the industrial method for producing S0 2. The S0 2 molecule is constructed similarly to the Oe molecule and has the structure of an isosceles triangle with a sulfur atom at the vertex. The S-O bond length is 0.143 nm, and the bond angle is 119.5°:

The sulfur atom is in the 5/? 2-hybridization. The p-orbital is oriented perpendicular to the plane of the molecule and is not involved in hybridization (Fig. 25.2). Due to this and other similarly oriented p-orbitals of oxygen atoms, a three-center n-bond is formed.

Rice. 25.2.

Under normal conditions, sulfur oxide (1U) is a colorless gas with a characteristic pungent odor. Let's dissolve well in water. Aqueous solutions have an acidic reaction, since S0 2, interacting with water, forms sulfurous acid H 2 S0 3. The reaction is reversible:

A characteristic feature of S0 2 is its redox duality. This is explained by the fact that in SO. ; sulfur has an oxidation state of +4, and therefore it can, by donating two electrons, be oxidized to S(VI), and by receiving four electrons, reduced to S. The manifestation of these and other properties depends on the nature of the reacting component. Thus, with strong oxidizing agents, S0 2 behaves as a typical reducing agent. For example, halogens are reduced to the corresponding hydrogen halides, and S(IV) usually transforms into S(VI):

In the presence of strong reducing agents, S0 2 behaves as an oxidizing agent:

It is also characterized by a disproportionation reaction:

SQ is an acidic oxide, easily soluble in water (1 volume of H 2 0 dissolves 40 volumes of S0 2). An aqueous solution of SOv is acidic and is called sulfurous acid. Typically, the bulk of S0 2 dissolved in water is in solution in the hydrated form of S0 2 azH 2 0, and only a small part of S0 2 interacts with water according to the scheme

Sulfurous acid, as a dibasic acid, forms two types of salts: medium - sulfites (Na 2 S0 3) and acidic - hydrosulfites (NaHS0 3). H 2 S0 3 exists in two tautomeric forms (Fig. 25.3).

Rice. 25.3.Structure of tautomeric forms of H 2 S0 3

Since sulfur in sulfurous acid has an oxidation state of +4, it exhibits, like S0 2, the properties of both an oxidizing agent and a reducing agent, as already mentioned, therefore sulfurous acid in oxidation-reduction reactions completely duplicates the properties of S0 9.

Salts H 2 S0 3 (sulfites) have the properties of both oxidizing and reducing agents. Thus, the SO 2 ion easily transforms into the SO 2 ion, exhibiting strong reducing properties, therefore, in solutions, sulfites are gradually oxidized by molecular oxygen, turning into sulfuric acid salts:

In the presence of strong reducing agents, sulfites behave as oxidizing agents. With strong heating, sulfites of the most active metals decompose at 600°C to form salts H 2 SO^ and H 2 S, i.e. disproportion occurs:

Of the salts of sulfurous acid, only salts of 5-elements of group I are dissolved, as well as hydrosulfites of the Me 2+ (HS0 3) 2 type.

Since H 2 S0 3 is a weak acid, when acids act on sulfites and hydrosulfites, S0 2 is released, which is usually used to obtain S0 2 in the laboratory:

Water-soluble sulfites easily undergo hydrolysis, as a result of which the concentration of OH ions in the solution increases:

When S0 2 is passed through aqueous solutions of hydrosulfites, pyrosulfites are formed:

If a solution of Na 2 S0 3 is boiled with sulfur powder, then sodium thiosulfate is formed. In thiosulfates, sulfur atoms are in two different oxidation states - +6 and -2:

The resulting thiosulfate ion corresponds to the acid H 2 S 2 0 3, called thiosulfuric acid. The free acid is unstable under normal conditions and easily decomposes:

The properties of thiosulfates are due to the presence of and in them, and

the presence of S determines the reducing properties of the S 2 0 3 _ ion:

Weaker oxidizing agents oxidize sodium thiosulfate to tetrathionic acid salts. An example is the interaction with iodine:

This reaction is widely used in analytical chemistry, as it is the basis of one of the most important methods of volumetric analysis, called iodometry.

Alkali metal thiosulfates are produced industrially on a large scale. Among them, the most important is sodium thiosulfate Na 2 S 2 0 3, which is used in medicine as an antidote for poisoning with halogens and cyanides. The action of this drug is based on its property of releasing sulfur, which, for example, with cyanide ions CN forms the less toxic thiocyanate ion SCN:

The drug can also be used for poisoning with compounds As, Pb, Hg, since non-toxic sulfides are formed. Na 2 S 2 0 3 is used for allergic diseases, arthritis, neuralgia. A characteristic reaction for Na 2 S 2 0 3 is its interaction with AgN0 3: a white precipitate of Ag is formed. ; S. ; 0 3, which over time under the influence of light and moisture turns black with the release of Ag 2 S:

These reactions are used for the qualitative detection of thiosulfate ion.

Thionyl chloride SOCl 2 is obtained by reacting S0 2 with PC1 5:

The SOCl 2 molecule has a pyramidal structure (Fig. 25.4). Bonds with sulfur are formed due to a set of orbitals, which can be very approximately considered as $/? 3-hybrid. One of them is occupied by a lone pair of electrons, so SOCl 2 can exhibit the properties of a weak Lewis base.

Rice. 25.4.

S()C1 2 - colorless, fuming liquid with a pungent odor, hydrolyzes in the presence of traces of moisture:

Volatile compounds formed during the reaction are easily removed. Therefore, SOCl 2 is often used to obtain anhydrous chlorides:

SOCl 2 is widely used as a chlorinating agent in organic syntheses.