Superior sulfur oxide character. Sulfur oxide

colorless liquid Molar mass 80.06 g/mol Density 1.92 g/cm³ Thermal properties T. melt. 16.83°C T. kip. 44.9°C Enthalpy of formation -395.8 kJ/mol Classification Reg. CAS number Safety LD 50 510 mg/kg Toxicity Data is based on standard conditions (25 °C, 100 kPa) unless otherwise noted.

Sulfur oxide (VI) (sulfuric anhydride, sulfur trioxide, sulfuric gas) SO 3 - the highest oxide of sulfur. Under normal conditions, a highly volatile, colorless liquid with a suffocating odor. At temperatures below 16.9 ° C, it solidifies with the formation of a mixture of various crystalline modifications of solid SO 3.

Receipt

Can be obtained by thermal decomposition of sulfates:

$\backslash mathsf(Fe\_2(SO\_4)\_3\; \backslash xrightarrow(^ot)\; Fe\_2O\_3\; +\; 3SO\_3)$

or the interaction of SO 2 with ozone:

$\backslash mathsf(SO\_2\; +\; O\_3\; \backslash rightarrow\; SO\_3\; +\; O\_2)$

For the oxidation of SO 2, NO 2 is also used:

$\backslash mathsf(SO\_2\; +\; NO\_2\; \backslash rightarrow\; SO\_3\; +\; NO)$

This reaction underlies the historically first, nitrous method for the production of sulfuric acid.

Physical properties

Sulfur oxide (VI) - under normal conditions, a highly volatile, colorless liquid with a suffocating odor.

The SO 3 molecules in the gas phase have a flat trigonal structure with D 3h symmetry (OSO angle = 120°, d(S-O) = 141 pm). Upon transition to the liquid and crystalline states, a cyclic trimer and zigzag chains are formed. Type of chemical bond in a molecule: covalent polar chemical bond.

Solid SO 3 exists in α-, β-, γ- and δ-forms, with melting points of 16.8, 32.5, 62.3 and 95 ° C, respectively, and differing in the shape of crystals and the degree of polymerization of SO 3. The α-form of SO 3 consists mainly of trimer molecules. Other crystalline forms of sulfuric anhydride consist of zigzag chains: isolated at β-SO 3 , connected into flat networks at γ-SO 3 or into three-dimensional structures at δ-SO 3 . When cooled, the vapor first forms a colorless, ice-like, unstable α-form, which gradually passes in the presence of moisture into a stable β-form - white "silky" crystals, similar to asbestos. The reverse transition of the β-form to the α-form is possible only through the gaseous state of SO 3 . Both modifications "smoke" in air (droplets of H 2 SO 4 are formed) due to the high hygroscopicity of SO 3. Mutual transition to other modifications proceeds very slowly. The variety of forms of sulfur trioxide is associated with the ability of SO 3 molecules to polymerize due to the formation of donor-acceptor bonds. The polymer structures of SO 3 easily transform into each other, and solid SO 3 usually consists of a mixture of various forms, the relative content of which depends on the conditions for obtaining sulfuric anhydride.

Chemical properties

$\backslash mathsf(2KOH\; +\; SO\_3\; \backslash rightarrow\; K\_2SO\_4\; +\; H\_2O)$

and oxides:

$\backslash mathsf(CaO\; +\; SO\_3\; \backslash rightarrow\; CaSO\_4)$

SO 3 is characterized by strong oxidizing properties, usually reduced to sulfur dioxide:

$\backslash mathsf(5SO\_3\; +\; 2P\; \backslash rightarrow\; P\_2O\_5\; +\; 5SO\_2)$ $\backslash mathsf(3SO\_3\; +\; H\_2S\; \backslash rightarrow\; 4SO\_2\; +\; H\_2O)$ $\backslash mathsf(2SO\_3\; +\; 2KI\; \backslash rightarrow\; SO\_2\; +\; I\_2\; +\; K\_2SO\_4)$

When interacting with hydrogen chloride, chlorosulfonic acid is formed:

$\backslash mathsf(SO\_3\; +\; HCl\; \backslash rightarrow\; HSO\_3Cl)$

It also reacts with sulfur dichloride and chlorine to form thionyl chloride:

$\backslash mathsf(SO\_3\; +\; Cl\_2\; +\; 2SCl\_2\; \backslash rightarrow\; 3SOCl\_2)$

Application

Sulfuric anhydride is used primarily in the production of sulfuric acid.

Sulfuric anhydride is also released into the air when sulfur pellets are burned, which are used in the disinfection of premises. Upon contact with wet surfaces, sulfuric anhydride turns into sulfuric acid, which already destroys fungus and other harmful organisms.

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Literature

• Akhmetov N. S. "General and inorganic chemistry" M .: Higher school, 2001
• Karapetyants M. Kh., Drakin S. I. "General and inorganic chemistry" M .: Chemistry 1994

An excerpt characterizing Sulfur oxide (VI)

Natasha flushed. - I don't want to marry anyone. I'll tell him the same when I see him.
– That's how! Rostov said.
“Well, yes, it’s all nonsense,” Natasha continued to chat. - And why is Denisov good? she asked.
- Good.
- Well, goodbye, get dressed. Is he scary, Denisov?
- Why is it scary? Nicholas asked. - Not. Vaska is nice.
- You call him Vaska - strange. And that he is very good?
- Very good.
“Well, come and drink some tea.” Together.
And Natasha stood up on tiptoe and walked out of the room the way dancers do, but smiling the way happy 15-year-old girls smile. Having met Sonya in the living room, Rostov blushed. He didn't know how to deal with her. Yesterday they kissed in the first moment of the joy of meeting, but today they felt that it was impossible to do this; he felt that everyone, both mother and sisters, looked at him inquiringly and expected from him how he would behave with her. He kissed her hand and called her you - Sonya. But their eyes, having met, said “you” to each other and kissed tenderly. With her eyes, she asked him for forgiveness for the fact that at Natasha's embassy she dared to remind him of his promise and thanked him for his love. He thanked her with his eyes for the offer of freedom and said that one way or another, he would never stop loving her, because it was impossible not to love her.
“How strange, however,” said Vera, choosing a general moment of silence, “that Sonya and Nikolenka now met like strangers. - Vera's remark was just, like all her remarks; but, like most of her remarks, everyone became embarrassed, and not only Sonya, Nikolai and Natasha, but also the old countess, who was afraid of this love of her son for Sonya, which could deprive him of a brilliant party, also blushed like a girl. Denisov, to Rostov's surprise, in a new uniform, pomaded and perfumed, appeared in the living room as dandy as he was in battles, and so amiable with ladies and gentlemen, which Rostov did not expect to see him.

Returning to Moscow from the army, Nikolai Rostov was adopted by his family as the best son, hero and beloved Nikolushka; relatives - as a sweet, pleasant and respectful young man; acquaintances - as a handsome hussar lieutenant, a clever dancer and one of the best grooms in Moscow.
The Rostovs knew all of Moscow; the old count had enough money this year, because all the estates were remortgaged, and therefore Nikolushka, having got his own trotter and the most fashionable trousers, special ones that no one else in Moscow had, and boots, the most fashionable, with the most pointed socks and little silver spurs, had a lot of fun. Rostov, returning home, experienced a pleasant feeling after a certain period of time trying on himself for the old conditions of life. It seemed to him that he had matured and grown very much. Despair for an examination that was not consistent with the law of God, borrowing money from Gavrila for a cab, secret kisses with Sonya, he recalled all this as about childishness, from which he was now immeasurably far away. Now he is a hussar lieutenant in a silver cape, with soldier George, preparing his trotter for a run, along with well-known hunters, elderly, respectable. He has a familiar lady on the boulevard, to whom he goes in the evening. He conducted the mazurka at the ball at the Arkharovs, talked about the war with Field Marshal Kamensky, visited an English club, and was on you with one forty-year-old colonel, whom Denisov introduced him to.
His passion for the sovereign somewhat weakened in Moscow, since during this time he did not see him. But he often talked about the sovereign, about his love for him, making it feel that he still did not tell everything, that there was something else in his feeling for the sovereign that could not be understood by everyone; and wholeheartedly shared the feeling of adoration common at that time in Moscow for Emperor Alexander Pavlovich, who at that time in Moscow was given the name of an angel in the flesh.
During this short stay of Rostov in Moscow, before leaving for the army, he did not get close, but, on the contrary, parted ways with Sonya. She was very pretty, sweet, and obviously passionately in love with him; but he was in that time of his youth, when it seems that there is so much to do that there is no time to do it, and the young man is afraid to get involved - he values ​​\u200b\u200bhis freedom, which he needs for many other things. When he thought of Sonya during this new sojourn in Moscow, he said to himself: Eh! there are still many, many of these will be and are there, somewhere, still unknown to me. I still have time, when I want, to make love, but now there is no time. In addition, it seemed to him that something humiliating for his courage in women's society. He went to balls and sororities, pretending to do so against his will. Running, an English club, a revelry with Denisov, a trip there - that was another matter: it was decent for a young hussar.

Sulfur is common in the earth's crust, among other elements it occupies the sixteenth place. It occurs both in the free state and in bound form. Non-metallic properties are characteristic of this chemical element. Its Latin name is "Sulfur", denoted by the symbol S. The element is part of various ions of compounds containing oxygen and / or hydrogen, forms many substances belonging to the classes of acids, salts and several oxides, each of which can be called sulfur oxide with the addition symbols denoting valency. The oxidation states that it exhibits in various compounds are +6, +4, +2, 0, −1, −2. Sulfur oxides with various degrees of oxidation are known. The most common are sulfur dioxide and trioxide. Less well known are sulfur monoxide, as well as higher (except SO3) and lower oxides of this element.

Sulfur monoxide

An inorganic compound called sulfur oxide II, SO, in appearance this substance is a colorless gas. When in contact with water, it does not dissolve, but reacts with it. This is a very rare compound that occurs only in a rarefied gaseous environment. The SO molecule is thermodynamically unstable, it initially turns into S2O2, (called disulfur gas or sulfur peroxide). Due to the rare occurrence of sulfur monoxide in our atmosphere and the low stability of the molecule, it is difficult to fully determine the dangers of this substance. But in a condensed or more concentrated form, the oxide turns into peroxide, which is relatively toxic and caustic. This compound is also highly flammable (reminiscent of methane in this property), and when burned, sulfur dioxide is produced - a poisonous gas. Sulfur oxide 2 was found near Io (one of the Venusian atmosphere and interstellar medium. It is assumed that on Io it is produced as a result of volcanic and photochemical processes. The main photochemical reactions are as follows: O + S2 → S + SO and SO2 → SO +O.

Sulphur dioxide

Sulfur oxide IV, or sulfur dioxide (SO2), is a colorless gas with a suffocating, pungent odor. At a temperature of minus 10 C, it passes into a liquid state, and at a temperature of minus 73 C, it solidifies. At 20C, about 40 volumes of SO2 dissolve in 1 liter of water.

This sulfur oxide, dissolving in water, forms sulfurous acid, as it is its anhydride: SO2 + H2O ↔ H2SO3.

It interacts with bases and 2NaOH + SO2 → Na2SO3 + H2O and SO2 + CaO → CaSO3.

Sulfur dioxide has the properties of both an oxidizing agent and a reducing agent. It is oxidized by atmospheric oxygen to sulfuric anhydride in the presence of a catalyst: SO2 + O2 → 2SO3. With strong reducing agents, such as hydrogen sulfide, it plays the role of an oxidizing agent: H2S + SO2 → S + H2O.

Sulfur dioxide is mainly used in industry to produce sulfuric acid. Sulfur dioxide is obtained by burning sulfur or iron pyrite: 11O2 + 4FeS2 → 2Fe2O3 + 8SO2.

Sulfuric anhydride

Sulfur oxide VI, or sulfur trioxide (SO3) is an intermediate product and has no independent value. It is a colorless liquid in appearance. It boils at a temperature of 45 C, and below 17 C it turns into a white crystalline mass. This sulfur (with the oxidation state of the sulfur atom + 6) is extremely hygroscopic. With water, it forms sulfuric acid: SO3 + H2O ↔ H2SO4. Dissolving in water, it releases a large amount of heat, and if a large amount of oxide is added at once, not gradually, then an explosion can occur. Sulfur trioxide dissolves well in concentrated sulfuric acid to form oleum. The content of SO3 in oleum reaches 60%. This sulfur compound is characterized by all the properties

Higher and lower oxides of sulfur

Sulfurs are a group of chemical compounds with the formula SO3 + x, where x can be 0 or 1. The monomeric oxide SO4 contains a peroxo group (O-O) and is characterized, like the oxide SO3, by the oxidation state of sulfur +6. This sulfur oxide can be produced at low temperatures (below 78 K) by reaction of SO3 and or by photolysis of SO3 mixed with ozone.

Lower sulfur oxides are a group of chemical compounds, which include:

• SO (sulfur oxide and its dimer S2O2);
• sulfur monoxides SnO (are cyclic compounds consisting of rings formed by sulfur atoms, while n can be from 5 to 10);
• S7O2;
• polymer oxides of sulfur.

Interest in lower sulfur oxides has increased. This is due to the need to study their content in the terrestrial and extraterrestrial atmospheres.

The +4 oxidation state for sulfur is quite stable and manifests itself in SHal 4 tetrahalides, SOHal 2 oxodihalides, SO 2 dioxide, and their corresponding anions. We will get acquainted with the properties of sulfur dioxide and sulfurous acid.

1.11.1. Sulfur oxide (IV) The structure of the so2 molecule

The structure of the SO 2 molecule is similar to the structure of the ozone molecule. The sulfur atom is in a state of sp 2 hybridization, the shape of the orbitals is a regular triangle, the shape of the molecule is angular. The sulfur atom has an unshared electron pair. The S-O bond length is 0.143 nm, the bond angle is 119.5°.

The structure corresponds to the following resonant structures:

Unlike ozone, the S–O bond multiplicity is 2, i.e., the first resonance structure makes the main contribution. The molecule is characterized by high thermal stability.

Physical properties

Under normal conditions, sulfur dioxide or sulfur dioxide is a colorless gas with a pungent suffocating odor, melting point -75 °C, boiling point -10 °C. Let's well dissolve in water, at 20 °C in 1 volume of water 40 volumes of sulfur dioxide are dissolved. Toxic gas.

Chemical properties of sulfur oxide (IV)

Sulfur dioxide is highly reactive. Sulfur dioxide is an acid oxide. It is quite soluble in water with the formation of hydrates. It also partially interacts with water, forming a weak sulfurous acid, which is not isolated individually:

SO 2 + H 2 O \u003d H 2 SO 3 \u003d H + + HSO 3 - \u003d 2H + + SO 3 2-.

As a result of dissociation, protons are formed, so the solution has an acidic environment.

When sulfur dioxide gas is passed through a sodium hydroxide solution, sodium sulfite is formed. Sodium sulfite reacts with excess sulfur dioxide to form sodium hydrosulfite:

2NaOH + SO 2 = Na 2 SO 3 + H 2 O;

Na 2 SO 3 + SO 2 \u003d 2NaHSO 3.

Sulfur dioxide is characterized by redox duality, for example, it, showing reducing properties, discolors bromine water:

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

and potassium permanganate solution:

5SO 2 + 2KMnO 4 + 2H 2 O \u003d 2KНSO 4 + 2MnSO 4 + H 2 SO 4.

oxidized by oxygen to sulfuric anhydride:

2SO 2 + O 2 \u003d 2SO 3.

It exhibits oxidizing properties when interacting with strong reducing agents, for example:

SO 2 + 2CO \u003d S + 2CO 2 (at 500 ° C, in the presence of Al 2 O 3);

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

Production of sulfur oxide (IV)

Burning sulfur in air

S + O 2 \u003d SO 2.

Sulfide oxidation

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

The action of strong acids on metal sulfites

Na 2 SO 3 + 2H 2 SO 4 \u003d 2NaHSO 4 + H 2 O + SO 2.

1.11.2. Sulfuric acid and its salts

When sulfur dioxide is dissolved in water, weak sulfurous acid is formed, the bulk of the dissolved SO 2 is in the form of a hydrated form of SO 2 H 2 O, a crystalline hydrate is also released upon cooling, only a small part of the sulfurous acid molecules dissociates into sulfite and hydrosulfite ions. In the free state, the acid is not isolated.

Being dibasic, it forms two types of salts: medium - sulfites and acidic - hydrosulfites. Only alkali metal sulfites and hydrosulfites of alkali and alkaline earth metals dissolve in water.

In this article you will find information about what sulfur oxide is. Its main properties of a chemical and physical nature, existing forms, methods for their preparation and differences among themselves will be considered. And also the fields of application and the biological role of this oxide in its various forms will be mentioned.

What is a substance

Sulfur oxide is a compound of simple substances, sulfur and oxygen. There are three forms of sulfur oxides, differing from each other in the degree of valence S manifested, namely: SO (monoxide, sulfur monoxide), SO 2 (sulfur dioxide or sulfur dioxide) and SO 3 (sulfur trioxide or anhydride). All listed variations of sulfur oxides have similar chemical and physical characteristics.

General information about sulfur monoxide

Divalent sulfur monoxide, or otherwise sulfur monoxide, is an inorganic substance consisting of two simple elements - sulfur and oxygen. Formula - SO. Under normal conditions, it is a colorless gas, but with a sharp and specific odor. Reacts with an aqueous solution. A rather rare compound in the earth's atmosphere. It is unstable to the influence of temperatures, exists in a dimeric form - S 2 O 2. Sometimes it is capable, interacting with oxygen, as a result of the reaction to form sulfur dioxide. Salt does not form.

Sulfur oxide (2) is usually obtained by burning sulfur or decomposing its anhydride:

• 2S2+O2 = 2SO;
• 2SO2 = 2SO+O2.

The substance dissolves in water. As a result, sulfur oxide forms thiosulfuric acid:

• S 2 O 2 + H 2 O \u003d H 2 S 2 O 3.

General data on sour gas

Sulfur oxide is another form of sulfur oxides with the chemical formula SO 2 . Has an unpleasant specific smell and has no color. When subjected to pressure, it can ignite at room temperature. When dissolved in water, it forms unstable sulfurous acid. It can dissolve in ethanol and sulfuric acid solutions. It is a component of volcanic gas.

In industry, it is obtained by burning sulfur or roasting its sulfides:

• 2FeS 2 + 5O 2 \u003d 2FeO + 4SO 2.

In laboratories, as a rule, SO 2 is obtained using sulfites and hydrosulfites, exposing them to a strong acid, as well as to the action of metals with a low degree of activity concentrated H 2 SO 4 .

Like other sulfur oxides, SO 2 is an acidic oxide. Interacting with alkalis, forming various sulfites, it reacts with water, creating sulfuric acid.

SO 2 is extremely active, and this is clearly expressed in its reducing properties, where the oxidizing degree of sulfur oxide increases. May exhibit oxidizing properties when attacked by a strong reducing agent. The latter characteristic is used for the production of hypophosphorous acid, or for the separation of S from the gases of the metallurgical field.

Sulfur oxide (4) is widely used by humans to produce sulfurous acid or its salts - this is its main area of ​​application. And also he participates in the processes of winemaking and acts there as a preservative (E220), sometimes they pickle vegetable stores and warehouses, as it destroys microorganisms. Materials that cannot be bleached with chlorine are treated with sulfur oxide.

SO 2 is a rather toxic compound. Typical symptoms indicating poisoning with it are coughing, the appearance of breathing problems, usually in the form of a runny nose, hoarseness, the appearance of an unusual aftertaste and a scratchy throat. Inhalation of such a gas can cause suffocation, impaired speech ability of the individual, vomiting, difficulty in swallowing, as well as acute pulmonary edema. The maximum allowable concentration of this substance in the working room is 10 mg/m 3 . However, different people may have different sensitivity to sulfur dioxide.

General information about sulfuric anhydride

Sulfuric gas, or, as it is called, sulfuric anhydride, is the highest sulfur oxide with the chemical formula SO 3 . Liquid with a suffocating odor, highly volatile under standard conditions. Able to solidify, forming mixtures of crystalline type from its solid modifications, at temperatures from 16.9 ° C and below.

Detailed analysis of the higher oxide

When SO 2 is oxidized with air under the influence of high temperatures, a necessary condition is the presence of a catalyst, for example V 2 O 5 , Fe 2 O 3 , NaVO 3 or Pt.

Thermal decomposition of sulfates or the interaction of ozone and SO 2:

• Fe 2 (SO 4) 3 \u003d Fe 2 O 3 + 3SO 3;
• SO 2 + O 3 \u003d SO 3 + O 2.

Oxidation of SO 2 with NO 2:

• SO 2 + NO 2 \u003d SO 3 + NO.

The physical qualitative characteristics include: the presence of a flat structure, trigonal type and D 3 h symmetry in the gas state, during the transition from gas to a crystal or liquid it forms a trimer of a cyclic nature and a zigzag chain, has a covalent polar bond.

In solid form, SO 3 occurs in alpha, beta, gamma and sigma forms, and it has, respectively, a different melting point, degree of polymerization and a variety of crystal forms. The existence of such a number of SO 3 species is due to the formation of donor-acceptor type bonds.

The properties of sulfur anhydride include many of its qualities, the main ones are:

Ability to interact with bases and oxides:

• 2KHO + SO 3 \u003d K 2 SO 4 + H 2 O;
• CaO + SO 3 \u003d CaSO 4.

Higher sulfur oxide SO 3 has a sufficiently high activity and creates sulfuric acid by interacting with water:

• SO 3 + H 2 O \u003d H2SO 4.

It enters into reactions with hydrogen chloride and forms chlorosulfate acid:

• SO 3 + HCl \u003d HSO 3 Cl.

Sulfur oxide is characterized by the manifestation of strong oxidizing properties.

Sulfuric anhydride finds its use in the production of sulfuric acid. A small amount of it is released into the environment during the use of sulfur checkers. SO 3 , forming sulfuric acid after interaction with a wet surface, destroys a variety of dangerous organisms, such as fungi.

Summing up

Sulfur oxide can be in different states of aggregation, ranging from liquid to solid form. It is rare in nature, and there are quite a few ways to obtain it in industry, as well as areas where it can be used. The oxide itself has three forms in which it exhibits varying degrees of valency. Can be very toxic and cause serious health problems.