Higher sulfur oxide and its character. Sulfur oxides

In redox processes, sulfur dioxide can be both an oxidizing agent and a reducing agent, because the atom in this compound has an intermediate oxidation state of +4.

As an oxidizing agent, SO 2 reacts with stronger reducing agents, for example:

SO 2 + 2H 2 S = 3S ↓ + 2H 2 O

As a reducing agent, SO 2 reacts with stronger oxidizing agents, for example, in the presence of a catalyst, with, etc .:

2SO 2 + O 2 = 2SO 3

SO 2 + Cl 2 + 2H 2 O = H 2 SO 3 + 2HCl

Receiving

1) Sulfur dioxide is formed when sulfur is burned:

2) In industry, it is obtained by roasting pyrite:

3) In the laboratory, sulfur dioxide can be obtained:

Cu + 2H 2 SO 4 = CuSO 4 + SO 2 + 2H 2 O

Application

Sulfur dioxide is widely used in the textile industry for bleaching various products. In addition, it is used in agriculture to destroy harmful microorganisms in greenhouses and cellars. Large quantities of SO 2 are used to produce sulfuric acid.

Sulfur oxide (VI) – SO 3 (sulfuric anhydride)

Sulfuric anhydride SO 3 is a colorless liquid that, at temperatures below 17 ° C, turns into a white crystalline mass. Absorbs moisture very well (hygroscopic).

Chemical properties

Acid-base properties

How does a typical acidic oxide sulfuric anhydride react:

SO 3 + CaO = CaSO 4

c) with water:

SO 3 + H 2 O = H 2 SO 4

A special property of SO 3 is its ability to dissolve well in sulfuric acid. A solution of SO 3 in sulfuric acid is called oleum.

Oleum formation: H 2 SO 4 + n SO 3 = H 2 SO 4 ∙ n SO 3

Redox properties

Sulfur oxide (VI) is characterized by strong oxidizing properties (usually reduced to SO 2):

3SO 3 + H 2 S = 4SO 2 + H 2 O

Receiving and using

Sulfuric anhydride is formed during the oxidation of sulfur dioxide:

2SO 2 + O 2 = 2SO 3

In its pure form, sulfuric anhydride has no practical value. It is obtained as an intermediate product in the production of sulfuric acid.

H 2 SO 4

Sulfuric acid was first mentioned by Arab and European alchemists. It was obtained by calcining iron sulfate in air (FeSO 4 ∙ 7H 2 O): 2FeSO 4 = Fe 2 O 3 + SO 3 + SO 2 or a mixture with: 6KNO 3 + 5S = 3K 2 SO 4 + 2SO 3 + 3N 2, and the evolved vapors of sulfuric anhydride condensed. By absorbing moisture, they turned into oleum. Depending on the method of preparation, H 2 SO 4 was called vitriol oil or sulfuric oil. In 1595 the alchemist Andreas Libavius ​​established the identity of both substances.

For a long time, vitriol oil was not widely used. Interest in him greatly increased after in the XVIII century. the process of obtaining indigo carmine, a stable blue dye, was discovered. The first sulfuric acid factory was founded near London in 1736. The process was carried out in lead chambers, at the bottom of which water was poured. In the upper part of the chamber, a molten mixture of saltpeter and sulfur was burned, then air was introduced into it. The procedure was repeated until an acid of the required concentration was formed at the bottom of the container.

In the XIX century. the method was improved: instead of nitrate, they began to use nitric acid (it gives, when decomposed in the chamber). To return nitrous gases to the system, special towers were designed, which gave the name to the whole process - the tower process. Plants operating according to the tower method exist in our time.

Sulfuric acid is a heavy oily liquid, colorless and odorless, hygroscopic; well soluble in water. When concentrated sulfuric acid is dissolved in water, a large amount of heat is released, so it must be carefully poured into the water (and not vice versa!) And the solution must be stirred.

A solution of sulfuric acid in water with an H 2 SO 4 content of less than 70% is usually called dilute sulfuric acid, and a solution of more than 70% is called concentrated sulfuric acid.

Chemical properties

Acid-base properties

Diluted sulfuric acid exhibits all the characteristic properties of strong acids. She reacts:

H 2 SO 4 + NaOH = Na 2 SO 4 + 2H 2 O

H 2 SO 4 + BaCl 2 = BaSO 4 ↓ + 2HCl

The process of interaction of Ba 2+ ions with sulfate ions SO 4 2+ leads to the formation of a white insoluble precipitate BaSO 4. This qualitative reaction to sulfate ion.

Oxidizing - reducing properties

In dilute H 2 SO 4, the oxidizing agents are H + ions, and in concentrated H 2 SO 4 sulfate ions are oxidizing agents. SO 4 2+ ions are stronger oxidizing agents than Н + ions (see diagram).

V dilute sulfuric acid metals that are in the electrochemical series of voltages are dissolved to hydrogen... In this case, metal sulfates are formed and released:

Zn + H 2 SO 4 = ZnSO 4 + H 2

Metals that are in the electrochemical series of voltages after hydrogen do not react with dilute sulfuric acid:

Cu + H 2 SO 4 ≠

Concentrated sulfuric acid is a strong oxidizing agent, especially when heated. It oxidizes many and some organic substances.

When concentrated sulfuric acid interacts with metals that are in the electrochemical series of voltages after hydrogen (Cu, Ag, Hg), metal sulfates are formed, as well as the product of sulfuric acid reduction - SO 2.

Reaction of sulfuric acid with zinc

With more active metals (Zn, Al, Mg), concentrated sulfuric acid can be reduced to free. For example, during the interaction of sulfuric acid with, depending on the concentration of the acid, various products of sulfuric acid reduction - SO 2, S, H 2 S - can simultaneously be formed:

Zn + 2H 2 SO 4 = ZnSO 4 + SO 2 + 2H 2 O

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

4Zn + 5H 2 SO 4 = 4ZnSO 4 + H 2 S + 4H 2 O

In the cold, concentrated sulfuric acid passivates some metals, for example, and therefore it is transported in iron tanks:

Fe + H 2 SO 4 ≠

Concentrated sulfuric acid oxidizes some non-metals (, etc.), reducing to sulfur oxide (IV) SO 2:

S + 2H 2 SO 4 = 3SO 2 + 2H 2 O

C + 2H 2 SO 4 = 2SO 2 + CO 2 + 2H 2 O

Receiving and using

In industry, sulfuric acid is obtained by the contact method. The production process takes place in three stages:

1. Obtaining SO 2 by roasting pyrite:

4FeS 2 + 11O 2 = 2Fe 2 O 3 + 8SO 2

1. Oxidation of SO 2 to SO 3 in the presence of a catalyst - vanadium (V) oxide:

2SO 2 + O 2 = 2SO 3

1. Dissolution of SO 3 in sulfuric acid:

H 2 SO 4 + n SO 3 = H 2 SO 4 ∙ n SO 3

The resulting oleum is transported in iron tanks. Sulfuric acid of the desired concentration is obtained from oleum by adding it to water. This can be expressed by the diagram:

H 2 SO 4 ∙ n SO 3 + H 2 O = H 2 SO 4

Sulfuric acid is widely used in various areas of the national economy. It is used for drying gases, in the production of other acids, for the production of fertilizers, various dyes and medicines.

Sulfuric acid salts

Most sulfates are readily soluble in water (slightly soluble CaSO 4, even less PbSO 4 and practically insoluble BaSO 4). Some sulfates containing water of crystallization are called vitriol:

CuSO 4 ∙ 5H 2 O copper sulfate

FeSO 4 ∙ 7H 2 O ferrous sulfate

Everybody has sulfuric acid salts. Their attitude to heating is special.

Sulfates of active metals (,) do not decompose even at 1000 о С, and others (Cu, Al, Fe) - decompose upon slight heating into metal oxide and SO 3:

CuSO 4 = CuO + SO 3

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* in the recording image there is a photograph of copper sulfate

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

1.11.1. Sulfur (IV) oxide Molecular structure so2

The structure of the SO 2 molecule is similar to that of the ozone molecule. The sulfur atom is in a state of sp 2 -hybridization, the orbital arrangement is a regular triangle, the molecular shape is angular. There is a lone electron pair on the sulfur atom. 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 multiplicity of the S - O bond is 2, that is, 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, the melting point is -75 ° C, and the boiling point is -10 ° C. Let's well dissolve in water, at 20 ° С 40 volumes of sulfur dioxide dissolve in 1 volume of water. Toxic gas.

Chemical properties of sulfur (IV) oxide

Sulfur dioxide is highly reactive. Sulfur dioxide is an acidic oxide. It is fairly well soluble in water to form hydrates. It also partially interacts with water, forming weak sulfurous acid, which is not isolated in its individual form:

SO 2 + H 2 O = H 2 SO 3 = H + + HSO 3 - = 2H + + SO 3 2-.

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

When gaseous sulfur dioxide 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 = 2NaHSO 3.

Redox duality is characteristic of sulfur dioxide, for example, while exhibiting reducing properties, it discolors bromine water:

SO 2 + Br 2 + 2H 2 O = H 2 SO 4 + 2HBr

and potassium permanganate solution:

5SO 2 + 2KMnO 4 + 2H 2 O = 2KНSO 4 + 2MnSO 4 + H 2 SO 4.

oxidized by oxygen to sulfuric anhydride:

2SO 2 + O 2 = 2SO 3.

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

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

SO 2 + 2H 2 = S + 2H 2 O.

Obtaining sulfur oxide (IV)

Burning sulfur in air

S + O 2 = SO 2.

Oxidation of sulfides

4FeS 2 + 11O 2 = 2Fe 2 O 3 + 8SO 2.

The action of strong acids on metal sulfites

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

1.11.2. Sulfurous acid and its salts

When sulfur dioxide dissolves in water, a weak sulfurous acid is formed, the bulk of dissolved SO 2 is in the form of a hydrated form of SO 2 · H 2 O, upon cooling, crystalline hydrate is also released, only a small part of the molecules of sulfurous acid dissociates into sulfite and hydrosulfite ions. In the free state, no acid is released.

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

colorless liquid Molar mass 80.06 g / mol Density 1.92 g / cm³ Thermal properties T. float. 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 are based on standard conditions (25 ° C, 100 kPa) unless otherwise noted.

Sulfur oxide (VI) (sulfur anhydride, sulfur trioxide, gray gas) SO 3 - higher sulfur oxide. Under normal conditions, it is 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.

Receiving

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 forms the basis of the historically first, nitrous method for producing 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 planar trigonal structure with D 3h symmetry (OSO angle = 120 °, d (S-O) = 141 pm). During the transition to the liquid and crystalline states, a cyclic trimer and zigzag chains are formed. The type of chemical bond in the molecule: covalent polar chemical bond.

Solid SO 3 exists in α-, β-, γ- and δ-forms, with melting points, respectively, 16.8, 32.5, 62.3 and 95 ° C and differing in the shape of crystals and the degree of polymerization of SO 3. The α-form of SO 3 consists predominantly of trimer molecules. Other crystalline forms of sulfuric anhydride consist of zigzag chains: isolated in β-SO 3, connected in flat networks in γ-SO 3 or in spatial structures in δ-SO 3. When cooled, the steam first forms a colorless, ice-like, unstable α-form, which gradually transforms 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 SO 3 gaseous state. Both modifications "smoke" in air (H 2 SO 4 droplets are formed) due to the high hygroscopicity of SO 3. Mutual transition to other modifications is very slow. 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. Polymeric structures of SO 3 readily 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 interacts 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 mainly in the production of sulfuric acid.

Sulfuric anhydride is also released into the air during the combustion of sulfur bombs used in the decontamination of premises. On contact with damp surfaces, sulfuric anhydride turns into sulfuric acid, which already destroys fungi 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" Moscow: Chemistry 1994

Excerpt Characterizing Sulfur (VI) Oxide

Natasha flushed. - I do not want to marry anyone. I'll tell him the same when I see him.
- Here's how! - said Rostov.
“Well, yes, it's all nonsense,” Natasha continued to chatter. - And what is Denisov good? She asked.
- Good.
- Well, goodbye, get dressed. Is he scary, Denisov?
- Why scary? - asked Nicolas. - Not. Vaska is glorious.
- You call him Vaska - it's strange. Is he very good?
- Very good.
- Well, come and drink tea as soon as possible. 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 drawing-room, Rostov blushed. He didn't know how to deal with her. Yesterday they kissed in the first minute of the joy of meeting, but today they felt that it was impossible to do this; he felt that everyone, both his mother and sisters, looked at him inquiringly and was expected of him how he would behave with her. He kissed her hand and called her you - Sonya. But their eyes, meeting, said "you" to each other and kissed tenderly. With her glance, she asked for forgiveness from him for the fact that at Natasha's embassy she dared to remind him of his promise and thanked him for his love. With his glance, he thanked her for the offer of freedom and said that either way or another, he would never stop loving her, because one cannot but love her.
“How strange, however,” Vera said, choosing a general moment of silence, “that Sonya and Nikolenka now met on you and as strangers. - Vera's remark was correct, like all her remarks; but as with most of her remarks, everyone felt awkward, and not only Sonya, Nikolai and Natasha, but also the old countess, who was afraid of this son's love for Sonya, which could deprive him of his brilliant part, also blushed like a girl. Denisov, to Rostov's surprise, in a new uniform, pomaded and perfumed, appeared in the drawing-room as dandy as he was in battles, and so amiable to ladies and gentlemen that Rostov had never expected to see him.

Returning to Moscow from the army, Nikolai Rostov was accepted by his family as the best son, hero and beloved Nikolushka; family - like a sweet, pleasant and respectful young man; acquaintances - as a handsome hussar lieutenant, a dexterous dancer and one of the best suitors in Moscow.
The Rostovs met all of Moscow; this year the old count had enough money, because all the estates were re-mortgaged, and therefore Nikolushka, having started his own trotter and the most fashionable leggings, special, which no one else had in Moscow, and boots, the most fashionable, with the most sharp 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 to the old conditions of life. It seemed to him that he had matured and grown very much. Despair for an examination that was not kept from the law of God, borrowing money from Gavrila for a cab driver, secret kisses with Sonya, he recalled all this as childishness, from which he was immeasurably far away now. Now he is a hussar lieutenant in a silver mentic, with the soldier George, preparing his trotter for a run, together with famous hunters, elderly, respectable ones. He has a lady friend on the boulevard, to whom he goes in the evening. He conducted a mazurka at the Arkharovs' ball, talked about the war with Field Marshal Kamensky, visited an English club, and was in touch with a 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, giving him the feeling that he was not yet telling everything, that there was something else in his feelings for the sovereign, which could not be understood by everyone; and with all his heart he shared the feeling of adoration that was common in Moscow at that time for the emperor Alexander Pavlovich, who was given the name of an angel in the flesh in Moscow at that time.
During this short stay of Rostov in Moscow, before leaving for the army, he did not become close, but on the contrary parted with Sonya. She was very pretty, sweet, and obviously passionately in love with him; but he was in that period of youth when it seems so much to do that there is no time to do it, and the young man is afraid to get involved - he values ​​his freedom, which he needs for many other things. When he thought about Sonya during this new stay in Moscow, he said to himself: Eh! there are many more, many of them will be and are there, somewhere, unknown to me. I’ll still have time, when I want, to make love, but now there’s no time. In addition, it seemed to him that something humiliating for his courage in female society. He went to balls and to the sorority, pretending to do so against his will. Bega, an English club, a binge with Denisov, a trip there - that was another matter: it was decent for a young hussar.

Sulfur is distributed in the earth's crust, among other elements it takes the sixteenth place. It is found both in a free state and in a bound form. Non-metallic properties are characteristic of this chemical element. Its Latin name "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 +6, +4, +2, 0, −1, −2. Sulfur oxides with various oxidation states are known. The most common are sulfur dioxide and sulfur trioxide. Less 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. On contact with water, it does not dissolve, but reacts with it. This is a very rare compound that is found only in a rarefied gas environment. The SO molecule is thermodynamically unstable, transforms initially 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 hazards of this substance. But in condensed or more concentrated form, the oxide turns into peroxide, which is relatively toxic and caustic. This compound is also highly flammable (resembles methane by this property), and when burned, sulfur dioxide, a poisonous gas, is obtained. Sulfur oxide 2 was discovered near Io (one of the atmosphere of Venus and in the interstellar medium. It is assumed that it is produced on Io 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 pungent, suffocating odor. At a temperature of minus 10 C it turns 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, since it is its anhydride: SO2 + H2O ↔ H2SO3.

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

Sulfur dioxide is characterized by 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 used in industry mainly for the production of sulfuric acid. Sulfur dioxide is produced 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 significance. 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 you add not gradually, but immediately a large amount of oxide, then an explosion can occur. Sulfur trioxide dissolves well in concentrated sulfuric acid to form oleum. The SO3 content in oleum reaches 60%. This sulfur compound has all the properties

Higher and lower sulfur oxides

Sulfur is 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 obtained at low temperatures (below 78 K) as a result of the reaction of SO3 and or photolysis of SO3 in a mixture with ozone.

Lower sulfur oxides are a group of chemical compounds that include:

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

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