4.Doc.
Sulfur. Hydrogen sulfide, sulphides, hydrosulfides. Sulfur oxides (IV) and (VI). Sulfuric and sulfuric acids and their salts. Sulfuric acid esters. Sodium thiosulfate
4.1. Sulfur
Sulfur is one of the few chemical elements that have already enjoyed a person for several millennia. It is widely spread-in nature and occurs both in free co-standing (native sulfur), so in the compound. Minerals containing sulfur can be divided into two groups - sulphides (cchedes, shine, deckures) and sulfates. The native sulfur in large quantities is found in Italy (Sicily Island) and the United States. In the CIS, the native sulfur fields are available in the Volga region, in the states of Central Asia, in the Crimea and other areas.
The minerals of the first group include lead gloss PBS, copper glitter Cu 2 S, silver shine - AG 2 S, zinc cheating - KA - ZNS, cadmium cheating - CDS, pyrite or iron count - Fes 2, Halcopyrite - Cufes 2, Cynanar - HGS.
The minerals of the second group include CASO 4 2N 2 O, Mirabilite (Glauberova Salt) - Na 2 SO 4 10N 2 O, Ki-Zerit - MgSO 4 H 2 O.
The sulfur is contained in the organisms of animals and plants, as it is included in the composition of protein molecules. Organic sulfur compounds are contained in oil.
Obtaining
1. When obtaining sulfur from natural compounds, such as sulfur sulfur, it is heated to high temperatures. The gray cchedan decomposes with the formation of iron sulfide (II) and sulfur:
2. The sulfur can be obtained by oxidation of hydrogen sulfide with a disadvantage of oxygen by reaction:
2H 2 S + O 2 \u003d 2S + 2N 2 O
3. Currently, the preparation of sulfur with carbon dioxide carbon SO 2 - by-product was spread during the smelting of metals from sulfur ores:
SO 2 + C \u003d CO 2 + S
4. The exhaust gases of metallurgical and coke oven contain a mixture of sulfur dioxide and hydrogen sulfide. This mixture is passed at high temperatures above the catalyst:
H 2 S + SO 2 \u003d 2H 2 O + 3S
^ Physical properties
The sulfur is a solid fragile substance of lemon yellow. There is practically insoluble in water, but it's well-creative in the CS 2 survironment and some other solvents.
He does not heat the heat and electric current. Sulfur forms several allotropic modifications:
1 . ^ Rhombic sulfur (most stable), crystals have the type of octahedra.
When sulfur is heated, its color and viscosity changes: first yellow is formed, and then as the temperature increases, it darkens and is being made so viscous that it does not extend from the test tube, with further heating the viscosity falls again, and at 444, 6 ° C boils.
2. ^ Monoclinic sulfur - Modification in the form of dark yellow needle crystals, is obtained with a slow cooling of molten sulfur.
3. Plastic sulfurit is formed if the sulfur heated to the boiling is pouring into cold water. It is easily stretched like rubber (see Fig. 19).
Natural sulfur consists of a mixture of four stable isotopes: 32 16 S, 33 16 S, 34 16 S, 36 16 S.
^ Chemical properties
Sulfur atom, having an incomplete external energy level, can attach two electrons and show a degree
Oxidation -2. Such a degree of sulfur oxidation exhibits in compounds with metals and hydrogen (Na 2 S, H 2 S). With the return or delaying electrons to the atom of a more electronegative element, the degree of sulfur oxidation can be +2, +4, +6.
It is relatively inert, but with an increase in temperature, its reactivity increases with the increase in temperature. 1. With sulfur metals exhibit oxidative properties. With these reactions, sulphides are formed (with gold, platinum and iridium does not react): Fe + S \u003d FES
2. With hydrogen under normal conditions of sulfur, it does not interact, and at 150-200 ° C proceeds reversible:
3. In the reactions with metals and with hydrogen sulfur behaves like a typical oxidizing agent, and in the presence of strong oxidants, rehabilitation properties.
S + 3F 2 \u003d SF 6 (IOD does not react)
4. The combustion of sulfur in oxygen flows at 280 ° C, and in air at 360 ° C. At the same time, a mixture of SO 2 and SO 3 is formed:
S + O 2 \u003d SO 2 2S + 3O 2 \u003d 2SO 3
5. When heated without air access, the sulfur is directly co-united with phosphorus, carbon, showing oxidative properties:
2p + 3s \u003d P 2 S 3 2S + C \u003d CS 2
6. When interacting with complex substances, sulfur behaves mainly as a reducing agent:
7. Sera is capable of disproportionation reactions. So, when boiling sulfur powder with alkalis, sulfites and sulphides are formed:
Application
The sulfur is widely used in industry and rural ho. About half of its production is spent for obtaining sulfuric acid. Use sulfur for volcanization of rubber: while rubber turns into rubber.
In the form of a sulfur (thin powder) sulfur used to combat vineyard and cotton diseases. Its is completed to obtain powder, matches, luminous compositions. In medicine prepared sulfur masses for the treatment of skin diseases.
4.2. Hydrogen sulfide, sulphides, hydrosulfides
Hydrogen sulfide is an analogue of water. His electronic formula
It shows that two p-electron of the appearance of the sulfur atom participate in the formation of H-S-H connections. H 2 S molecule has an angular shape, so it is polar.
^ Finding in nature
The hydrogen sulfide is found in nature in volcanic gases and in the waters of some mineral springs, such as Pyatig-Sak, Macesta. It is formed in the rotting of sulfur-containing organic substances of various animals and vegetable remains. This explains the characteristic unpleasant smell of wastewater, cesspool and garbage dumps.
Obtaining
1. hydrogen sulfide can be obtained by direct sulfur compound with hydrogen when heated:
2. But it is usually obtained by the action of dilute hydrochloric or sulfuric acid on iron sulphide (III):
2HCl + Fes \u003d FECL 2 + H 2 S 2H + + Fes \u003d Fe 2+ + H 2 S This reaction is often carried out in the Cypa apparatus.
^ Physical properties
Under normal conditions, hydrogen sulfide is a colorless gas with a strong characteristic smell of rotten eggs. Very poisonous, with a go-in-hazanie binds to hemoglobin, causing paralysis that
Ko leads to death. In low concentrations less dangerous. It is necessary to work with it in exhaust cabinets or with hermetically closing devices. The allowable content of H 2 S in the industrial premises is 0.01 mg in 1 l of air.
The hydrogen sulfide is relatively soluble in water (at 20 ° C in 1 volume of water, 2.5 sulfide volume is dissolved).
The hydrogen sulfide solution in water is called hydrogen sulfide water or hydrogen sulfide acid (it detects the properties of weak acid).
^ Chemical properties
1, with strong heating, hydrogen sulfide is almost completely broken-in the formation of sulfur and hydrogen.
2. Gaseous hydrogen sulfide burns in air with a blue flame with the formation of sulfur oxide (IV) and water:
2H 2 S + 3O 2 \u003d 2SO 2 + 2N 2
With a lack of oxygen, sulfur and water is formed: 2H 2 S + O 2 \u003d 2S + 2N 2 O
3. Hydrogen sulfide is a rather strong reducing agent. This is his important chemical property can be explained so. In solution of H 2 S, it relatively easily gives electrons with air oxygen molecules:
At the same time, air oxygen oxidizes hydrogen sulfide to sulfur, which makes the hummate hydrogen sulfide water:
2H 2 S + O 2 \u003d 2S + 2H 2 O
This explains the fact that hydrogen sulfide is not accumulated in very large quantities in nature in the rotation of organic substances - air oxygen oxidizes it into a free sulfur.
4, hydrogen sulfide reacts vigorously with halogen solutions, an example:
H 2 S + I 2 \u003d 2HI + S is the selection of sulfur and discoloration of the iodine solution.
5. Various oxidizers react vigorously with hydrogen sulfide: a free sulfur is formed under the action of nitric acid.
6. The hydrogen sulfide solution has a sour response due to dissocia:
H 2 SN + + HS - HS - H + + S -2
Usually the first stage prevails. It is a very weak acid: weaker coal, which usually displaces H 2 S from sulfides.
Sulfides and hydrosulfides
Hydrogen sulfide acid, like a two-axis, forms two rows of salts:
Medium - sulphides (Na 2 S);
Sour - hydrosulfides (NaHS).
These salts can be obtained: - the interaction of hydroxides with hydrogen sulfide: 2NAOH + H 2 S \u003d Na 2 s + 2N 2
Directly interaction of sulfur with metals:
Salley exchange reaction with H 2 S or between the salts:
PB (NO 3) 2 + Na 2 S \u003d PBS + 2Nano 3
Cuso 4 + H 2 S \u003d Cus + H 2 SO 4 Cu 2+ + H 2 S \u003d Cus + 2H +
Hydrosulfides are almost all well soluble in water.
Alkaline and alkaline earth metal sulphides are also easily soluble in water, colorless.
Heavy metals sulphides are practically insoluble or low-soluble in water (FES, MNS, ZNS); Some of them do not dissolve in diluted acids (CUS, PBS, HGS).
As salts of weak acid, sulphides in aqueous solutions Sil-but hydrolyzed. For example, alkali metal sulphides when dissolved in water have an alkaline reaction:
Na 2 S + nonnahs + NaOH
All sulphides, like hydrogen sulfide, are energetic reducing agents:
3PBS -2 + 8HN +5 O 3 (RSC) \u003d 3PBS +6 O 4 + 4N 2 O + 8N +2 O
Some sulphides have a typical color: CUS and PBS - black, CDS - yellow, ZNS - white, MNS - pink, SNS - brown, Al 2 S 3 - orange. On the different solubility of sulphides and various color of many of them, qualitative analysis of cations is founded.
^ 4.3. Sulfur oxide (IV) and sulfuric acid
Sulfur (IV) oxide, or sulfur gas, under normal conditions, colorless gas with a sharp stilege smell. When cooling to -10 ° C is liquefied into a colorless liquid.
Obtaining
1. In the laboratory conditions, sulfur oxide (IV) is obtained from solts of sulfuric acid with strong acids on them:
Na 2 SO 3 + H 2 SO 4 \u003d Na 2 SO 4 + S0 2 + H 2 O 2NAHSO 3 + H 2 SO 4 \u003d Na 2 SO 4 + 2SO 2 + 2H 2 O 2HSO - 3 + 2H + \u003d 2SO 2 + 2H 2 O
2. Also, the sulfurous gas is formed when the interaction of the concentricular sulfuric acid is interacted when heated with low-active metals:
Cu + 2H 2 SO 4 \u003d Cuso 4 + SO 2 + 2N 2
Cu + 4N + + 2SO 2- 4 \u003d Cu 2+ + SO 2- 4 + SO 2 + 2H 2 O
3. Sulfur oxide (IV) is also formed when burning sulfur in air or oxygen:
4. In industrial conditions, SO 2 is obtained by firing pyrite FES 2 or sulfurous ores of non-ferrous metals (zinc decking ZNS, lead shine PBS, etc.):
4FES 2 + 11O 2 \u003d 2FE 2 O 3 + 8SO 2
Structural formula SO 2 molecule:
In the formation of bonds in the SO 2 molecule, the sulfur electron and four electron from two oxygen atoms take part. The mutual repulsion of binding electronic pairs and the non-divided e-pair of sulfur gives the molecule angular shape.
Chemical properties
1. Sulfur oxide (IV) exhibits all the properties of acidic oxides:
Water interaction
Interaction with alkalis,
Interaction with the main oxides.
2. For sulfur oxide (IV), replacement properties are characterized:
S +4 O 2 + O 0 2 2S +6 O -2 3 (in the presence of a catalyst, when heated)
But in the presence of strong reducing agents SO 2 behaves like an oxidizing agent:
The redox duality of sulfur oxide (IV) is explained by the fact that the sulfur has an oxidation degree of +4 in it, and therefore it can, giving 2 electrons, oxide to S +6, and taking 4 electrons, recover to S °. The manifestation of these or other properties depends on the nature of the reacting component.
Sulfur oxide (IV) is well soluble in water (in 1 volume at 20 ° C. 40 volumes of SO 2 dissolves). At the same time, a sulfuric acid is formed only in aqueous solution:
SO 2 + H 2 Oh 2 SO 3
Reaction is reversible. In an aqueous solution of sulfur oxide (IV) and sulfuric acid are in chemical equilibrium, which can be shifted. When binding H 2 SO 3 (neutralization of acid
You) the reaction proceeds towards the formation of sulfuric acid; When removing SO 2 (purging through a nitrogen solution or heating), the reaction proceeds towards the starting materials. In the solution of sulfuric acid, there is always sulfur oxide (IV), which suits a sharp smell.
Sulnyary acid has all acid properties. In the racial work dissociates stepped:
H 2 SO 3 N + + HSO - 3 HSO - 3 N + + SO 2-3
Termically unstable, flying. Sulfuric acid, like a two-axis, forms two types of salts:
Medium - sulfites (Na 2 SO 3);
Sour - hydrosulfite (NaHSO 3).
The sulfites are formed with complete acid neutralization by alkali:
H 2 SO 3 + 2NAOH \u003d Na 2 SO 3 + 2N 2
Hydrosulphites are obtained with a shortage of alkali:
H 2 SO 3 + NaOH \u003d NaHSO 3 + H 2 O
Sulfuric acid and its salts have both oxidative and reducing properties, which is determined by the reaction partner.
1. So, under the action of oxygen, sulfites are oxidized to Sul Fatov:
2NA 2 S +4 O 3 + O 0 2 \u003d 2NA 2 S +6 O -2 4
Even easier occurs the oxidation of sulfuric acid bromine and permanganate potassium:
5H 2 S +4 O 3 + 2Kmn +7 O 4 \u003d 2H 2 S +6 o 4 + 2mn +2 s +6 o 4 + k 2 s +6 o 4 + 3n 2 o
2. In the presence of more energetic reducing agents, the sulfites exhibit oxidative properties:
Alkali metal hydro-sulfites and alkali metal sulfites dissolve from sulfur salts.
3. Since H 2 SO 3 is weak acid, with the action of the kit-lot on sulfites and hydrosulfites, SO 2 is selected. This method is usually used upon receipt of SO 2 in laboratory conditions:
NaHSO 3 + H 2 SO 4 \u003d Na 2 SO 4 + SO 2 + H 2 O
4. Water soluble sulfites are easily subjected to hydrolysis, as a result of which the concentration of OH increases in the solution:
Na 2 SO 3 + Nonnahso 3 + NaOH
Application
Sulfur oxide (IV) and sulfuric acid blew Many dyes, forming colorless connections with them. The latter can again decompose when heated or in light, in the result of what color is restored. Consequently, the whitening action SO 2 and H 2 SO 3 differs from the whirlwind of chlorine. Usually RCCID sulfur (IV) whites wool, silk and straw.
Sulfur oxide (IV) kills many microorganisms. Therefore, for the destruction of mold fungi, they emphasize raw basements, cellar, wine barrels, etc. It is also used during transport-ke and storage of fruits and berries. In large quantities of sulfur oxide IV) is used to obtain sulfuric acid.
Important use is a solution of CAHSO 3 calcium hydrosulfite solution (sulfite liquor), which are treated with wood and paper ground.
^ 4.4. Sulfur oxide (VI). Sulfuric acid
Sulfur oxide (VI) (see Table 20) - a colorless liquid, solidified at a temperature of 16.8 ° C into a solid crystalline mass. It absorbs moisture very much, forming a sulfuric acid: SO 3 + H 2 O \u003d H 2 SO 4
Table 20. Sulfur oxide properties
The dissolution of sulfur oxide (VI) in water is accompanied by the separation of a significant amount of heat.
Sulfur oxide (VI) is very well soluble in concentrated sulfuric acid. SO 3 solution in anhydrous acid is called oleum. Oleums may contain up to 70% SO 3.
Obtaining
1. Sulfur oxide (VI) is obtained by oxidation of the sulfur gas oxygen-house in the presence of catalysts at a temperature of 450 ° C (see Obtaining sulfuric acid):
2SO 2 + O 2 \u003d 2SO 3
2. Another method of oxidation SO 2 to SO 3 is the use of nitrogen oxide as oxidizing agent (IV):
The resulting oxide of nitrogen (II) when interacting with an oxygen-house of air easily and quickly turns into nitrogen oxide (IV): 2NO + O 2 \u003d 2NO 2
Which can be used again in SO 2 oxidation. Next, NO 2 acts as an oxygen carrier. This method of oxidation SO 2 to SO 3 is called nitrogen. SO 3 molecule has a triangle shape, in the center of which
There is a sulfur atom:
Such a structure is due to the mutual repulsion of the tie electronic pairs. On their formation, the sulfur atom provided six external electrons.
Chemical properties
1. SO 3 - typical acidic oxide.
2. Sulfur oxide (VI) has the properties of a strong oxidant.
Application
Sulfur oxide (VI) is used to produce sulfuric acid. The most important is the contact method for obtaining
Sulfuric acid. By this method, it is possible to obtain H 2 SO 4 of any concentration, as well as oleum. The process consists of three stages: obtaining SO 2; oxidation SO 2 in SO 3; Obtaining H 2 SO 4.
SO 2 is obtained by firing pyrite fes 2 in special furnaces: 4fes 2 + 11o 2 \u003d 2Fe 2 O 3 + 8SO 2
To accelerate the firing, the pyrite is pre-crushed, and for a more complete burnout of sulfur, much larger air (oxygen) is introduced than the reaction is administered. The gas coming out of the firing furnace consists of sulfur oxide (IV), oxygen, nitrogen, arsenic compounds (from the impurities in the cchedan) and water vapor. It is called the roasting gas.
The fuggling gas is undergoing careful cleaning, as even a small content of arsenic compounds, as well as dust and moisture poisoning the catalyst. From the compounds of arsenic and from dust, the gas is cleaned, passing it through special electro-filters and a flushing tower; Moisture is absorbed by the concentric bathroom with sulfuric acid in the drying tower. The purified gas containing oxygen is heated in the heat exchanger to 450 ° C and enters the contact unit. Inside the contact apparatus there are lattice shelves filled with a catalyst.
Previously, fine metal platinum was used as a catalyst. Subsequently, it was replaced by vanadium compounds - vanadium oxide (V) V 2 O 5 or Sul Fat Vanadil Voso 4, which are cheaper than platinum and more slowly poison.
SO 2 oxidation reaction in SO 3 reversible:
2SO 2 + O 2 2SO 3
An increase in the oxygen content in the firing gas increases the yield of sulfur oxide (VI): at a temperature of 450 ° C, it usually reaches 95% and higher.
The resulting sulfur oxide (Vi) is further fed by the method of pro-tivotok to the absorbing tower, where it is absorbed by the converged sulfuric acid. As it is saturated, anhydrous sulfuric acid is turned into, and then oleum. In the future, oleum is diluted to 98% sulfuric acid and supplied in countershells.
Structural formula of sulfuric acid:
^ Physical properties
Sulfuric acid - severe colorless oily liquid bone crystallizing at + 10.4 ° C, almost twice ( \u003d 1.83 g / cm 3) heavier than water does not smell, non-volatile. Extremely gig-Roscopic. It absorbs moisture with the release of a large amount of heat, so it is impossible to put water to concentrated sulfuric acid - the acid splash will occur. For
The databases need sulfuric acid to pour into small portions to water.
Anhydrous sulfuric acid dissolves up to 70% sulfur oxide (VI). When heated, SO 3 is cleaved up until it is formed with a solution with a mass fraction of H 2 SO 4 98.3%. Anhydrous H 2 SO 4 almost does not conduct an electric current.
^ Chemical properties
1. With water mixed in any ratios and forms hydrates of various composition:
H 2 SO 4 H 2 O, H 2 SO 4 2N 2 O, H 2 SO 4 3N 2 O, H 2 SO 4 4N 2 O, H 2 SO 4 6,5N 2 O
2. Concentrated sulfuric acid charred organic substances - sugar, paper, wood, fiber, from them water elements:
From 12 H 22 O 11 + H 2 SO 4 \u003d 12C + H 2 SO 4 11N 2 O
The resulting coal partially enters into interaction with acid:
A drying of gases is based on the absorption of water with sulfuric acid.
As a strong non-volatile acid H 2 SO 4 displaces other sour salts from dry salts:
Nano 3 + H 2 SO 4 \u003d NaHSO 4 + HNO 3
However, if you add, H 2 SO 4 to salts, then the displacement of acids does not occur.
H 2 SO 4 - strong dibasic acid: H 2 SO 4 N + + HSO - 4 HSO - 4 H + + SO 2-4
It has all the properties of non-volatile strong acids.
Diluted sulfuric acid is characterized by all properties of non-oxidant acids. Namely: interacts with metal, which stand in an electrochemical row of metal stresses to hydrogen:
The interaction with metals is due to the restoration of hydrogen ions.
6. Concentrated sulfuric acid is an energetic oxidant. When heating heats up most of the metal, including those standing in the electrochemical series of voltage after hydrogen, does not respond only with platinum and ash-volume. Depending on the activity of the metal as the recovery products, S -2, S ° and s +4 can be.
On cold, concentrated sulfuric acid does not interact with such strong metals as aluminum, iron, chrome. This is explained by the passivation of metals. This feature is widely used when transporting it in the iron container.
However, when heated:
Thus, concentrated sulfuric acid is interconnected with metals due to the reduction of acid formation atoms.
The high-quality reaction to SO 2-4 sulfate ion is the formation of a white crystalline precipitate Baso 4, insoluble in water and acids:
SO 2- 4 + Ba +2 baso 4
Application
Sulfuric acid is an essential product of the main chemical industry engaged in the production of non-
Organic acids, alkalis, salts, mineral fertilizers and chlorine.
According to a variety of use, sulfuric acid occupies a perica among the acids. Its largest is spent to obtain phosphate and nitrogen fertilizers. Being non-taxes, sulfuric acid is used to obtain other kitty-lot - hydrochloric, fluoride, phosphoric and acetic.
It goes a lot to clean oil products - gasoline, kero-blue, lubricating oils - from harmful impurities. In the machine-based sulfuric acid, the surface of the metal from oxides before coating (nickelocation, chromium, etc.) is purified. Sulfuric acid is used in the production of explosives, source fibers, dyes, plastics and many others. It is used to fill batteries.
Sulfuric acid salts are important.
^ Sodium sulfateNa 2 SO 4 is crystallized from aqueous solutions in the form of hydrate Na 2 SO 4 10N 2 o, which is called Glaubero Salt. It is used in medicine as a laxative. Anhydrous sodium sulfate is used in the production of soda and glass.
^ Ammonium sulfate(NH 4) 2 SO 4 - nitrogen fertilizer.
Sulfate potassiumK 2 SO 4 - potash fertilizer.
Calcium sulfate SSO 4 is found in nature in the form of mine-la Gypsum Caso 4 2N 2 O. When heated to 150 ° C, it loses part of the water and moves into 2Caso 4 H 2 O composition, called liner plaster, or alabaster. Alebaster when kneading with water into a tough mass after a while again hard-devasts, turning into Caso 4 2N 2 O. Gypsum is widely used in construction business (plaster).
^ Magnesium sulfateMgSO 4 is contained in seawater, lifting her bitter taste. Crystal hydrate, called bitter salt, is used as a laxative.
Vitrios- Technical name of FE, Cu, Zn, Ni, CO metal sulfate crystalline (dehydrated sodes dehydrated salts). Copper KunerCUSO 4 5N 2 O is a poisonous substance of blue. It is sprayed with a diluted solution and rolling the seeds before sowing. inkstoneFESO 4 7N 2 O - light green substance. Used to combat pests of plants, cooking ink, mineral paints, etc. Zinci-vigorZNSO 4 7N 2 O is used in the production of mineral paints, in cross-printing, medicine.
^ 4.5. Sulfuric acid esters. Sodium thiosulfate
Surround essentials include dialkyl sulfates (RO 2) SO 2. These are high-boiling liquids; lower soluble in water; In the presence of alkalisms, alcohol and sulfuric acid salts are formed. Lower dialkyl sulfates are alkylating agents.
Diethyl sulfate(C 2 H 5) 2 SO 4. The melting point is -26 ° C, the boiling point of 210 ° C, soluble in alcohols, insoluble in water. Obtained by the interaction of sulfuric acid with ethanol. Yav is a leading agent in organic synthesis. It penetrates through the skin.
Dimethyl sulfate(CH 3) 2 SO 4. Melting point -26.8 ° C, Boiling point 188.5 ° C. Soluble in alcohols, bad in water. Reacts with ammonia in the absence of a solubular-body (with an explosion); Some aromatic co-unity sulphists, such as the ethers of phenols. It is obtained by the interaction of 60% oleum with methanol at 150 ° C, is a methylating agent in organic synthesis. Carcinogen, striking eyes, skin, respiratory organs.
^ Sodium thiosulfate Na 2 S 2 O 3
Tyoseric acid salt in which two sulfur atoms have different oxidation degrees: +6 and -2. The crystalline substance is well soluble in water. Released in the form of crystal hydrogen radium Na 2 S 2 O 3 5H 2 O, in use called hyposulfite. The interaction of sodium sulfite with gray at boiling:
Na 2 SO 3 + S \u003d Na 2 S 2 O 3
Like thioseric acid, is a strong reducing agent, it is easily oxidized by chlorine to sulfuric acid:
Na 2 S 2 O 3 + 4Cl 2 + 5N 2 O \u003d 2H 2 SO 4 + 2NACL + 6NSL
This reaction was based on the use of sodium thiosulfate to absorb chlorine (in the first anti-masks).
A somewhat different occurs oxidation of sodium thiosulfate weak oxidizers. In this case, the salts of tetrationic acid are formed, for example:
2NA 2 S 2 O 3 + i 2 \u003d Na 2 S 4 O 6 + 2NAI
Sodium thiosulfate is a by-product in NaHSO 3 production, sulfur dyes, when cleaning industrial gases from sulfur. It is used to remove traces of chlorine after whitening tissues, to extract silver from ores; It is fixed in photograph, reagent in iodometry, antidote in poisoning with arsenic, mercury, anti-inflammatory means.
Sulfur oxide (sulfur gas, sulfur dioxide, angidride sulfur) is a colorless gas having a sharp characteristic smell in normal conditions (similar to the smell of a fitting match). Liquets under pressure at room temperature. Sulfurous gas soluble in water, while unstable sulfuric acid is formed. This substance is also dissolved in sulfuric acid and ethanol. This is one of the main components that are part of volcanic gases.
Sulphur dioxide
The preparation of sulfur dioxide SO2 is an industrial method is to burn sulfur or sulphide roasting (used mainly pyrite).
4fes2 (pyrite) + 11O2 \u003d 2Fe2O3 + 8SO2 (sulfur gas).
Under the laboratory conditions, sulfur gas can be obtained by exposure to strong acids on hydrosulfite and sulfite. At the same time, the resulting sulfuric acid immediately disintegrates into water and sulfur gas. For example:
Na2SO3 + H2SO4 (sulfuric acid) \u003d Na2SO4 + H2SO3 (sulfuric acid).
H2SO3 (sulfuric acid) \u003d H2O (water) + SO2 (sulfur gas).
The third method of obtaining sulfuric anhydride consists in the effects of concentrated sulfuric acid when heated to low-effective metals. For example: Cu (copper) + 2H2SO4 (sulfuric acid) \u003d CusO4 (copper sulfate) + SO2 (sulfur dioxide) + 2H2O (water).
Chemical properties of sulfur dioxide
The formula of sulfur gas - SO3. This substance refers to acid oxides.
1. Sulfur dioxide dissolves in water, and sulfuric acid is formed. Under normal conditions, this reaction is reversible.
SO2 (sulfur dioxide) + H2O (water) \u003d H2SO3 (sulfuric acid).
2. With alkalis, sulfur dioxide forms sulfites. For example: 2NAOH (sodium hydroxide) + SO2 (sulfur gas) \u003d \u200b\u200bNa2SO3 (sodium sulfite) + H2O (water).
3. The chemical activity of sulfur gas is large enough. The most expressed replacement properties of sulfur anhydride. In such reactions, the degree of sulfur oxidation increases. For example: 1) SO2 (sulfur dioxide) + BR2 (bromine) + 2H2O (water) \u003d H2SO4 (sulfuric acid) + 2HBR (bromomic); 2) 2SO2 (sulfur dioxide) + o2 (oxygen) \u003d 2SO3 (sulfite); 3) 5SO2 (sulfur dioxide) + 2kmnO4 (potassium permanganate) + 2H2O (water) \u003d 2H2SO4 (sulfuric acid) + 2mnsO4 (manganese sulfate) + K2SO4 (potassium sulfate).
The latter reaction is an example of a high-quality reaction to SO2 and SO3. The purple solution is discoloration).
4. Under the presence of strong reducing agents, the sulfuric anhydride can show oxidative properties. For example, in order to remove sulfur from exhaust gases in the metallurgical industry, the reduction of sulfur dioxide of carbon (CO) is used: SO2 (sulfur dioxide) + 2CO (carbon oxide) \u003d 2CO2 + S (sulfur).
Also, the oxidative properties of this substance are used in order to obtain a phosphine xyloth: PH3 (phosphine) + SO2 (sulfur gas) \u003d \u200b\u200bH3PO2 (phosphoric acid) + s (sulfur).
Where sulfur gas is used
Mostly sulfur dioxide is used to obtain a sulfuric acid. It is also used as in the production of low alcohol drinks (wine and other beverages of the average price category). Thanks to the property of this gas, killing various microorganisms, they emphasize warehouses and vegetable stores. In addition, sulfur oxide is used for whitening wool, silk, straw (those materials that cannot be whiten by chlorine). In the laboratories, sulfur gas is used as a solvent and in order to obtain different solo sulfuric acids.
Physiological impact
Sulfurous gas has strong toxic properties. The symptoms of poisoning are cough, runny nose, voice hoarseness, a kind of taste in the mouth, a strong throat. When inhalation of sulfur dioxide in high concentrations, it is difficult to swallowing and suffocation, a speech disorder, nausea and vomiting, it is possible to develop acute edema of the lungs.
MPC sulfur gas:
- indoors - 10 mg / m³;
- The average daily maximum-one in atmospheric air - 0.05 mg / m³.
Sensitivity to sulfur dioxide among individuals, plants and animals are different. For example, among the trees most stable oak and birch, and the least - spruce and pine.
Sulfur oxide (IV) has acidic properties that manifest themselves in reactions with substances that manifest basic properties. Acid properties are manifested when interacting with water. At the same time, a solution of sulfuric acid is formed:
The degree of oxidation of sulfur in the sulfur gas (+4) determines the recovery and oxidative properties of sulfur gas:
re-Tel: S + 4 - 2E \u003d\u003e S + 6
oK-TEL: S + 4 + 4E \u003d\u003e S0
Recovery properties are manifested in reactions with strong oxidizing agents: oxygen, halogens, nitric acid, potassium permanganate and others. For example:
2SO2 + O2 \u003d 2SO3
S + 4 - 2E \u003d\u003e S + 6 2
O20 + 4E \u003d\u003e 2O-2 1
With strong reducing agents, gas exhibits oxidative properties. For example, if you mix sulfur gas and hydrogen sulfide, they interact under normal conditions:
2H2S + SO2 \u003d 3S + 2H2O
S-2 - 2E \u003d\u003e S0 2
S + 4 + 4E \u003d\u003e S0 1
Sulfuric acid exists only in solution. It is unstable and decomposed on sulfur gas and water. Surnery acid does not relate to strong acids. It is an acid of medium power and dissociates stepped. When adding to sulfuric acid, Salt is formed. Sulfuric acid gives two rows of salts: medium - sulphites and sour - hydrosulfitis.
Sulfur oxide (VI)
Sulfur trioxide manifests acid properties. It thoroughly reacts with water, while there is a large amount of heat. This reaction is used to obtain the most important product of the chemical industry - sulfuric acid.
SO3 + H2O \u003d H2SO4
Since sulfur trioxide has the highest oxidation, then sulfur oxide (VI) exhibits oxidative properties. For example, it oxidizes halides, non-metals with low electronegativity:
2SO3 + C \u003d 2SO2 + CO2
S + 6 + 2E \u003d\u003e S + 4 2
C0 - 4E \u003d\u003e C + 4 2
Sulfuric acid reacts three types: acid-primary, ion exchange, redox. It also actively interacts with organic substances.
Acid-basic reactions
Sulfuric acid exhibits acidic properties in reactions with bases and main oxides. These reactions are better carried out with diluted sulfuric acid. Since sulfuric acid is a biennial, it can form both the average salts (sulfates) and acidic (hydrosulfates).
Ion exchange reactions
For sulfuric acid, ion exchange reactions are characterized. At the same time, it interacts with solutions of salts, forming a precipitate, weak acid or highlighting gas. These reactions are carried out with greater speed, if you take 45% or even more diluted sulfuric acid. The separation of gas occurs in reactions with unstable acid salts, disintegrating with the formation of gases (coal, sulfurous, hydrogen sulfide) or to form volatile acids, such as salt.
Redox reactions
The most brightly sulfuric acid shows its properties in redox reactions, since it has the highest degree of oxidation +6. The oxidative properties of sulfuric acid can be detected in the reaction, for example, with copper.
In the sulfuric acid molecule, two oxidant elements: a sulfur atom with C.O. +6 and hydrogen ions H +. Copper cannot be oxidized with hydrogen into the degree of oxidation +1, but sulfur can. This is the cause of oxidation with sulfuric acid of such an inactive metal as copper.
Sulfur oxide (IV) and sulfuric acid
Sulfur (IV) oxide, or sulfur gas, under normal conditions, colorless gas with a sharp stilege smell. When cooling to -10 ° C is liquefied into a colorless liquid.
Obtaining
1. In the laboratory conditions, sulfur oxide (IV) is obtained from solts of sulfuric acid with strong acids on them:
Na 2 SO 3 + H 2 SO 4 \u003d Na 2 SO 4 + S0 2 + H 2 O 2NAHSO 3 + H 2 SO 4 \u003d Na 2 SO 4 + 2SO 2 + 2H 2 O 2HSO - 3 + 2H + \u003d 2SO 2 + 2H 2 O.
2. Also, the sulfuric gas is formed in the interaction of concentrated sulfuric acid when heated with low-active metals:
Cu + 2H 2 SO 4 \u003d Cuso 4 + SO 2 + 2N 2
Cu + 4N + + 2SO 2- 4 \u003d Cu 2+ + SO 2- 4 + SO 2 + 2H 2 O
3. Sulfur oxide (IV) is also formed when burning sulfur in air or oxygen:
4. In industrial conditions, SO 2 is obtained by firing pyrite FES 2 or sulfurous ores of non-ferrous metals (zinc decking ZNS, lead shine PBS, etc.):
4FES 2 + 11O 2 \u003d 2FE 2 O 3 + 8SO 2
Structural formula SO 2 molecule:
Four electrons of sulfur and four electrons from two oxygen atoms take part in the formation of bonds in the SO 2 molecule. The mutual repulsion of the binding electronic pairs and the mean-free saws of sulfur gives the molecule angular shape.
Chemical properties
1. Sulfur oxide (IV) exhibits all the properties of acidic oxides:
Water interaction
Interaction with alkalis,
Interaction with the main oxides.
2. For sulfur oxide (IV), replacement properties are characterized:
S +4 O 2 + O 0 2 "2S +6 O -2 3 (in the presence of a catalyst, when heated)
But in the presence of strong reducing agents SO 2 behaves like an oxidizing agent:
The redox duality of sulfur oxide (IV) is explained by the fact that the sulfur has an oxidation degree of +4 in it, and therefore it can, giving 2 electrons, oxide to S +6, and taking 4 electrons, recover to S °. The manifestation of these or other properties depends on the nature of the reacting component.
Sulfur oxide (IV) is well soluble in water (in 1 volume at 20 ° C. 40 volumes of SO 2 dissolves). At the same time, an existing sulfuric acid existing in aqueous solution:
SO 2 + H 2 O "H 2 SO 3
Reaction is reversible. In an aqueous solution of sulfur oxide (IV) and sulfuric acid are in chemical equilibrium, which can be shifted. When binding H 2 SO 3 (neutralization of acid
you) the reaction proceeds towards the formation of sulfuric acid; When SO 2 is removed (purging through a nitrogen solution or heating), the reaction proceeds towards the starting materials. In the solution of sulfuric acid, there is always sulfur oxide (IV), which gives it a sharp smell.
Sulnyary acid has all acid properties. In solution dissociates stepped:
H 2 SO 3 "H + + HSO - 3 HSO - 3" H + + SO 2-3
Termically unstable, flying. Sulfuric acid, like a two-axis, forms two types of salts:
Medium - sulfites (Na 2 SO 3);
Sour - hydrosulfite (NaHSO 3).
The sulfites are formed with complete acid neutralization by alkali:
H 2 SO 3 + 2NAOH \u003d Na 2 SO 3 + 2N 2
Hydrosulphites are obtained with a shortage of alkali:
H 2 SO 3 + NaOH \u003d NaHSO 3 + H 2 O
Sulfuric acid and its salts have both oxidative and reducing properties, which is determined by the nature of the reaction partner.
1. So, under the action of oxygen, sulfites are oxidized to sulfates:
2NA 2 S +4 O 3 + O 0 2 \u003d 2NA 2 S +6 O -2 4
Even easier occurs the oxidation of sulfuric acid bromine and permanganate potassium:
5H 2 S +4 O 3 + 2Kmn +7 O 4 \u003d 2H 2 S +6 o 4 + 2mn +2 s +6 o 4 + k 2 s +6 o 4 + 3n 2 o
2. In the presence of more energetic reducing agents, the sulfites exhibit oxidative properties:
Alkali metal solutions and alkali metal sulfites dissolve from solts of sulfuric acid.
3. Since H 2 SO 3 is a weak acid, under the action of acids to sulfites and hydrosulfites, SO 2 is selected. This method is commonly used in obtaining SO 2 in laboratory conditions:
NaHSO 3 + H 2 SO 4 \u003d Na 2 SO 4 + SO 2 + H 2 O
4. Water soluble sulfites are easily subjected to hydrolysis, as a result of which the concentration of OH increases in the solution:
Na 2 SO 3 + Nahso 3 + NaOH
Application
Sulfur oxide (IV) and sulfuric acid blew Many dyes, forming colorless connections with them. The latter can again decompose when heated or in light, resulting in coloring is restored. Consequently, the whitening effect SO 2 and H 2 SO 3 differs from the whirlwind of chlorine. Usually RCCID sulfur (IV) whites wool, silk and straw.
Sulfur oxide (IV) kills many microorganisms. Therefore, for the destruction of mold fungi, they emphasize raw basements, cellar, wine barrels, etc. It is also used when transporting and storing fruits and berries. In large quantities of sulfur oxide IV) is used to obtain sulfuric acid.
Important use is a solution of CAHSO 3 calcium hydrosulfite solution (sulfite liquor), which are treated with wood and paper ground.
The sulfur is common in the earth's crust, among other elements is the sixteenth place. It is found both in free state and in the associated form. Non-metallic properties are characteristic of this chemical element. Its Latin name "Sulfur" is denoted by symbol S. The element is part of various ions of compounds containing oxygen and / or hydrogen, forms many substances related to acid classes, salts and several oxides, each of which can be called sulfur oxide with adding Symbols denoting valence. The degree of oxidation, which it exists in different compounds +6, +4, +2, 0, -1, -2. Sulfur oxides are known with varying degrees of oxidation. The most common is dioxide and sulfur trioxide. Small monoxide, as well as the highest (except SO3) and lower oxides of this element are less well known.
Sulfur monoxide
Inorganic compound, called sulfur oxide II, SO, in appearance This substance is a colorless gas. When contacting 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, turns initially in S2O2, (called Disulfur gas or sulfur peroxide). Due to the rare appearance of sulfur monoxide in our atmosphere and 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 is converted into peroxide, which is relatively toxic and caustic. This compound is also easily flammable (reminds of this property of methane), the sulfur dioxide is obtained during combustion. Sulfur 2 oxide was discovered about IO (one of the Venus atmosphere and in the interstellar medium. It is assumed that it is obtained as a result of volcanic and photochemical processes. The main photochemical reactions look like this: O + S2 → S + SO and SO2 → SO + O.
Sulphur dioxide
Sulfur IV oxide, or sulfur dioxide (SO2) is a colorless gas with a stiven sharp odor. At a temperature of minus 10 s, it goes into a liquid state, and at a temperature of minus 73 s hardens. At 20 ° C in 1 liter of water, about 40 volumes of SO2 dissolve.
This sulfur oxide, dissolving in water, forms sulfuric acid, as it is its anhydride: SO2 + H2O ↔ H2SO3.
It interacts with the bases and 2NAOH + SO2 → Na2SO3 + H2O and SO2 + Cao → Caso3.
For sulfur gas, properties and oxidizing agent, and reducing agent are characteristic. It is oxidized by air oxygen to sulfur anhydride in the presence of a catalyst: SO2 + O2 → 2SO3. With strong reducing agents, such as hydrogen sulfide, plays the role of the oxidant: H2S + SO2 → S + H2O.
Sulfur gas in industry is used mainly to obtain sulfuric acid. The sulfur dioxide is obtained by burning sulfur or iron cchedan: 11O2 + 4FES2 → 2FE2O3 + 8SO2.
Sulfurian anhydride
Sulfur oxide VI, or sulfur trioxide (SO3) is an intermediate product and independent value does not have. In appearance, this is a colorless liquid. It boils at a temperature of 45 s, and below 17 C turns into a white crystalline mass. This sulfur (with the degree of oxidation of the sulfur atom + 6) is extremely hygroscopicity. With water, it forms a sulfuric acid: SO3 + H2O ↔ H2SO4. Dissolving in water, highlights a large amount of heat and, if you add not gradually, and immediately a large amount of oxide, then an explosion may occur. The sulfur trioxide is well dissolved in concentrated acid sulfur with the formation of oleum. The SO3 content in oleum reaches 60%. For this sulfur connection is characterized by all properties.
Higher and lower sulfur oxides
The sulfur is a group of chemical compounds with the SO3 + X formula, where X can be 0 or 1. The monomeric oxide SO4 contains a peroxagroup (O - O) and is characterized by both SO3 oxidized, the degree of sulfur oxidation +6. This sulfur oxide can be obtained at low temperatures (below 78 K) as a result of the SO3 reaction and the SO3 photolisis in the ozone mixture.
The lower sulfur oxides are a group of chemical compounds in which:
- SO (sulfur oxide and its dimer S2O2);
- sNO sulfur monoxides (are cyclic compounds consisting of rings formed by sulfur atoms, while N can be from 5 to 10);
- S7O2;
- polymeric sulfur oxides.
Interest in the lower sulfur oxides increased. This is due to the need to study their content in the ground and extraterrestrial atmosphere.
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