Sulphuric acid. Sulfur oxides

In this article, you will find information on what sulfur oxide is. Its main properties of a chemical and physical nature, existing forms, methods of obtaining them and differences between themselves will be considered. And also the areas of application and biological role this oxide in its various forms.

What is the 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 manifested valence S, namely: SO (monoxide, sulfur monoxide), SO 2 (sulfur dioxide or sulfur dioxide) and SO 3 (trioxide or sulfur anhydride). All of the listed variations of sulfur oxides have similar chemical and physical characteristics.

General data on 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 pungent and specific odor. Reacts with aqueous solution... A fairly rare compound in the earth's atmosphere. It is unstable to the effects of temperatures, exists in dimeric form - S 2 O 2. Sometimes it is capable of reacting with oxygen to form sulfur dioxide as a result of the reaction. Does not form salt.

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

• 2S2 + O 2 = 2SO;
• 2SO2 = 2SO + O2.

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

• S 2 O 2 + H 2 O = H 2 S 2 O 3.

General data on sulfur dioxide

Sulfur oxide is another form of sulfur oxides with chemical formula SO 2. Has an unpleasant specific odor and colorless. When exposed 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, they are obtained by burning sulfur or burning its sulfides:

• 2FeS 2 + 5O 2 = 2FeO + 4SO 2.

In laboratories, as a rule, SO 2 is obtained with the help of sulfites and hydrosulfites, subjecting them to a strong acid, as well as to 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 reflected in its reducing properties, where the oxidation state of sulfur oxide increases. May exhibit oxidizing properties when exposed to a strong reducing agent. The last characteristic feature used for the production of hypophosphorous acid, or for the separation of S from the gases of the metallurgical field of activity.

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

SO 2 is a rather toxic compound. Characteristic symptoms that indicate poisoning with it are coughing, breathing problems, usually in the form of a runny nose, hoarseness, an unusual taste, and a sore throat. Inhalation of such gas can cause suffocation, impaired speech ability of the individual, vomiting, difficulty in swallowing, and acute pulmonary edema. The maximum permissible concentration of this substance in the working room is 10mg / m 3. However, the different people the body can show different sensitivity to sulfur dioxide.

General data on sulfuric anhydride

Sulfur gas, or, as it is called, sulfuric anhydride, is a higher sulfur oxide with the chemical formula SO 3. Liquid with a suffocating odor, highly volatile under standard conditions. Capable of hardening, forming mixtures crystal type of its solid modifications, at temperatures from 16.9 ° C and below.

Detailed analysis of higher oxide

When SO 2 is oxidized by air under the influence of high temperatures, 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 interaction of ozone and SO 2:

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

Oxidation of SO 2 with NO 2:

• SO 2 + NO 2 = SO 3 + NO.

Physical quality characteristics include: presence in the gas state flat structure, trigonal type and D 3 h symmetry, during the transition from gas to crystal or liquid 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 has, respectively, different melting points, degree of polymerization, and various crystalline forms. The existence of such a number of SO 3 species is due to the formation of donor-acceptor 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 = K 2 SO 4 + H 2 O;
• CaO + SO 3 = CaSO 4.

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

• SO 3 + H 2 O = H2SO 4.

Reacts with hydrogen chloride and forms chlorosulfate acid:

• SO 3 + HCl = HSO 3 Cl.

The manifestation of strong oxidizing properties is characteristic of sulfur oxide.

Sulfuric anhydride is used in the creation of sulfuric acid. A small amount of it is allocated in environment while using sulfur bombs. SO 3, forming sulfuric acid after interacting with a damp surface, destroys a variety of dangerous organisms, such as fungi.

Summing up

Sulfur oxide can be in different aggregate states from liquid to solid. It is rarely found 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 valence. Can be very toxic and cause serious health problems.

Sulfur is distributed in earth crust, among other elements 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, by 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 corrosive. This compound is also highly flammable (resembles methane with 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 suffocating pungent odor. At a temperature of minus 10 C, it turns into 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 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 meaning. 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 number 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 acid sulfuric 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 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.

1) For the reaction with the hydroxide formed by some element of the 1 (A) - group, weighing 4.08 g, 1.46 g of hydrochloric acid is required. This element: rubidium; To

aliy; lithium; sodium;
2) The sum of the coefficients in the equation for the reaction of higher sulfur hydroxide with potassium hydroxide is: 4; 6; 5; 8;

1.Lithium hydroxide reacts with; 1) calcium hydroxide 2) hydrochloric acid 3) magnesium oxide 4) barium 2. most pronounced

non-metallic properties of a simple substance:

1) chlorine 2) sulfur 3) silicon 4) calcium

3.the group number in the periodic table is:

1) the highest valence of the atom 2) the number of electrons in the atom 3) the number of protons in the nucleus 4) the number of electronic layers

4. higher nitrogen hydroxide reacts with:

1) calcium hydroxide 2) hydrochloric acid 3) barium sulfate 4) silicon oxide

5. the most pronounced metallic properties of a simple substance: 1) sodium 2) magnesium 3) calcium 4) potassium

For all reactions, it will be necessary to write a complete and concise ionic equation. 1. Potassium → potassium hydroxide → potassium sulfate →

barium sulfate

2. Phosphorus → phosphorus (III) oxide → phosphorus (V) oxide → phosphoric acid → calcium phosphate

3. Zinc → zinc chloride → zinc hydroxide → zinc oxide

4. Sulfur → sulfur dioxide → higher sulfur oxide → sulfuric acid → aluminum sulfate.

5. Lithium → lithium hydroxide → lithium chloride → silver chloride

6. Nitrogen → nitric oxide (II) → nitric oxide (IV) → nitric acid → sodium nitrate

7.Sulfur → calcium sulfide → calcium oxide → calcium carbonate → carbon dioxide

8. Carbon dioxide→ sodium carbonate → calcium carbonate → calcium oxide

9. Iron → iron (II) oxide → iron (III) oxide → iron (III) sulfate

10. Barium → barium oxide → barium chloride → barium sulfate

1) Copper is a simple substance in the expression: A) the wire is made of copper B) copper is part of copper oxide C) copper is part of malachite D) m

unit is a part of bronze 2) In the periods of the periodic system, the charge of the nuclei does not change: A) the mass of the atom B) the number of energy levels C) the total number of electrons D) the number of electrons at the external energy level 3) Formulas of higher oxides of sulfur, nitrogen, chlorine , respectively: A) SO3, N2O5, Cl2O7 B) SO2, N2O5, Cl2O7 C) SO3, N2O3, ClO2 D) SO2, NO2, Cl2O5 4) The ionic type of bond and crystal lattice has: A) sodium fluoride B) water C) silver D) bromine 5) Formulas of soluble base and amphoteric hydroxide, respectively: A) BaO, Cu (OH) 2 B) Ba (OH) 2, Al (OH) 3 C) Zn (OH) 2, Ca (OH) 2 D ) Fe (OH) 3, KOH 6) Coefficient before the oxygen formula in the thermal decomposition of potassium permanganate: A) 1 B) 2 C) 3 D) 4 7) Interaction of hydrochloric acid and copper (II) oxide refers to the reactions: A) decomposition B) compounds C) substitution D) exchange 8) The amount of heat released during the combustion of 2 g of coal (thermochemical reaction equation C + O2 = CO2 + 393 kJ) is equal to: A ) 24 kJ B) 32.75 kJ C) 65.5 kJ D) 393 kJ 9) At elevated temperatures, oxygen reacts with all substances of the group: A) CuO, H2, Fe B) P, H2, Mg C) Cu, H2 , Au D) S, CH4, H2O 10) Both with hydrogen and oxygen at elevated temperatures reacts: A) copper oxide (II) B) gold C) sulfur D) nitric acid 11) Diluted sulfuric acid can react with: A ) Mg and Cu (OH) 2 B) CO2 and NaOH C) FeO and H2S D) P and CuCl2 12) Sulfur (IV) oxide does not react with: A) O2 B) HCl C) H2O D) NaOH 13) Formulas of substances "X" and "Y" in the scheme of transformations of CaO x Ca (OH) 2 y CaCl2 A) X - H2; Y is HCl B) X is H2O; Y is HCl B) X is H2; Y - Cl2 D) X - H2O; Y - Cl2 14) Mass fraction sulfur in sulfur oxide (IV) is equal to: a) 20% b) 25% c) 33% d) 50% 15) A solution containing 19.6 g of sulfuric acid was neutralized with an excess of magnesium oxide. The amount of the substance of the formed salt is: a) 0.2 mol b) 2 mol c) 0.1 mol d) 1 mol 16) The number of completely filled energy levels in the sodium atom: A) 2 B) 3 C) 4 D) 5 17 ) The ratio of the chemical activity of the elements in a pair is correctly indicated: A) Li  Na B) Na  K C) Li  K D) Na  Li 18) Metallic properties in the series Li  Na  K  Cs A) increase B) decrease C ) do not change D) change periodically 19) The electronic formula of the external energy level of the bromine atom: A) 2s22p5 B) 3s13p6 C) 4s14p7 D) 4s24p5 20) The electronic formula 1s22s22p63s23p5 has an atom: A) iodine B) bromine C) chlorine D) fluorine 21 ) Metallic properties chemical elements in the row I  Br  Cl  F A) increase B) decrease C) change periodically D) do not change 22) Formula of a substance with a covalent non-polar bond: A) SO3 B) Br2 C) H2O D) NaCl 23) Crystal lattice of solid oxide carbon (IV): A) ionic B) atomic C) molecular D) metallic 24) Substance with ionic bond: A) sulfur oxide (VI) B) chlorine C) hydrogen sulfide D) sodium chloride 25) Number 2, 8, 5 corresponds to the distribution of electrons over the energy levels of the atom: A) aluminum B) nitrogen C) phosphorus D) chlorine 26) The electronic formula of the external energy level 2s22p4 corresponds to the atom: a) sulfur B) carbon C) silicon D) oxygen 27) Four electrons on the external energy level has an atom: A) helium B) beryllium C) carbon D) oxygen

Characteristic of sulfur: 1) The position of the element in the Periodic table D. And Characteristic of sulfur: 1) The position of the element in the Periodic table

D.I. Mendeleev and the structure of its atoms 2) The nature of a simple substance (metal, non-metal) 3) Comparison of the properties of a simple substance with the properties of simple substances formed by neighboring elements in a subgroup 4) Comparison of the properties of a simple substance with the properties of simple substances formed by neighboring elements elements 5) The composition of the higher oxide, its character (basic, acidic, amphoteric) 6) The composition of the higher hydroxide by its character (oxygen-containing acid, base, amphoteric hydroxide) 7) the composition of the volatile hydrogen compound (for non-metals)

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 oxidants, 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 interact:

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

Pure sulfuric anhydride practical does not have. 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 characteristic properties 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. it qualitative response per sulfate ion.

Oxidizing - reducing properties

In dilute H 2 SO 4, H + ions are oxidizing agents, and in concentrated H 2 SO 4, sulfate ions are SO 4 2+. 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 are 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, in 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 finds a variety of uses in the most different areas 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 relationship to heating is special.

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

CuSO 4 = CuO + SO 3

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

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 Security 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. 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, 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 gaseous state of SO 3. 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 .: graduate School, 2001
• Karapetyants M. Kh., Drakin S. I. "General and inorganic chemistry" Moscow: Chemistry 1994

Excerpt Characterizing Sulfur (VI) Oxide

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“How strange, however,” said Vera, choosing a general moment of silence, “that Sonya and Nikolenka have now met on you and as strangers. - Vera's remark was correct, like all her remarks; but like 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, 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 in Moscow had, and boots, the most fashionable, with the most sharp socks and small 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 unrestrained from the law of God, borrowing money from Gavrila for a cab, 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 mantle, 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, making it felt 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 still have time, when I want, to make love, and now I have 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. Running, an English club, carousing with Denisov, a trip there - that was another matter: it was decent for a young hussar.