What two types of salts forms sulfuric acid. Chemical properties of sulfuric acid

Dioxide (dioxide) sulfur SO 2 is formed when burning sulfur in air or oxygen. It also turns out when calcining in air ("burning") of metals sulphides, such as iron polegan:

According to this reaction, sulfur dioxide is usually obtained in industry (about other industrial methods for producing SO 2 cm, 9 § 131).

Sulfur dioxide is a colorless gas ("sulfur gas") with a sharp smell of hot sulfur. It is fairly easily condensed into a colorless liquid, boiling at -10.0 ° C. When evaporation of liquid SO 2, a strong decrease in temperature (up to -50 ° C) occurs.

Sulfur dioxide is well soluble in water (about 40 volumes in 1 water volume at 20 ° C); At the same time, the reaction with water is partially occurred and formed. sulfuric acid:

Thus, sulfur dioxide is a sulfuric acid anhydride. When heated, SO 2 solubility decreases and equilibrium is shifted to the left; Gradually, the entire sulfur dioxide is again distinguished from the solution.

SO 2 molecule is constructed similarly to the ozone molecule. The kernel of the components of its atoms form an equally chaired triangle:

Here is a sulfur atom, like the central oxygen atom in the ozone molecule, is in the state of SP 2-hybridization and the OSO angle is close to 120 °. Operated perpendicular to the plane of the molecule P z -Orbital atom of the sulfur does not participate in hybridization. Due to this orbital and similarly oriented P z -Orbitali atoms of oxygen formed three centuries? -C. Her pair of electrons belongs to all three atoms of the molecule.

Sulfur dioxide is used to obtain sulfuric acid, as well as (in significantly smaller quantities) for straw, wool, silk and how disinfectant (To destroy mold fungi in basements, cellars, wine barrels, fermentation chains).

Sulfuric acid H 2 SO 3 is a very fragile connection. It is known only in aqueous solutions. When trying to highlight sulfuric acid, it disintegrates on SO 2 and water. For example, under the action of concentrated sulfuric acid on sodium sulfite instead of a sulfuric acid, sulfur dioxide is released:

Sulfuric acid solution must be protected from air access, otherwise it absorbs oxygen, slowly oxidizes in sulfuric acid:

Sulfuric acid is a good reducing agent. For example, free halogens are restored by it in halogeneous hydrogen:

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

Being a two-axis (k 1? 2 · 10 -2, k 2 \u003d 6.3 · 10 -8), sulfuric acid forms two rows of salts. The average salts are called sulfite, acidic - hydrosulfitis.

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

The sulfites of the most active metals with calcination decompose with the formation of sulphides and sulfates (self-examination reaction - self-healing):

Potassium and sodium sulfites are used to whiten some of the materials in textile industry When painting tissues, in the photo. A solution of Ca (HSO 3) 2 (this salt exists only in solution) is used to process wood into the so-called sulfite cellulose, from which the paper is then obtained.

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Raising:

Create conditions for moral and aesthetic education of students to the environment, the ability to work in pairs in the self-analysis of control cuts, tests.

Developing:

develop the ability to work in the search atmosphere, creativity, give each student the opportunity to achieve success; the ability to give self-esteem activities in the lesson;

General education:

organize students' activity for assimilation:

• knowledge
: chemical properties and methods for producing sulfur gas and sulfuric acid;
• skills
: Record equations chemical reactionscharacterizing the chemical properties of sulfuric acid and its salts in ion and redox form.

During the classes

I. Orgmant.

II. Studying a new material:

1. Build:

SO 2 (sulfur gas, sulfur oxide (IV)), molecular formula

Structural formula

2. Physical properties

1. Colorless gas with a sharp smell, poisonous.
2. It is well soluble in water (in 1 V H 2 O dissolves 40 V SO 2 with N.U.)
3. Heavier air, poisonous.

3. Receipt

1. In industry: sulfide firing.

FES 2 + O 2 → Fe 2 O 3 + SO 2

a) Make an electronic balance (OVR).

2. In laboratory conditions: the interaction of sulphites with strong acids:

Na 2 SO 3 + 2HCl → 2NACL + SO 2 + H 2 O

3. When oxidizing metals with concentrated sulfuric acid:

Cu + H 2 SO 4 (concluding) → CUSO 4 + SO 2 + H 2 O

b) make an electronic balance (OVR) .

4. Chemical properties SO 2.

1. Interaction with water

When dissolved in water, a weak and unstable sulfuric acid H 2 SO 3 (exists only in aqueous solution) is formed.

SO 2 + H 2 O ↔ H 2 SO 3

2. Interaction with alkalis:

Ba (OH) 2 + SO 2 → Baso 3 ↓ (barium sulfite) + H 2 O

BA (OH) 2 + 2SO 2 (excess) → BA (HSO 3) 2 (Barium hydrosulfite)

3. Interaction S. the main oxides (Salt is formed):

SO 2 + CaO \u003d Caso 3

4. Oxidation reactions, SO 2 - reducing agent:

SO 2 + O 2 → SO 3 (catalyst - V 2 O 5)

c) make an electronic balance (OVR)

SO 2 + BR 2 + H 2 O → H 2 SO 4 + HBr

d) make an electronic balance (OVR)

SO 2 + KMNO 4 + H 2 O → K 2 SO 4 + MNSO 4 + H 2 SO 4

e) make an electronic balance (OVR)

5. Recovery Reactions, SO 2 - Oxidizer

SO 2 + C → S + CO 2 (when heated)

e) make an electronic balance (OVR)

SO 2 + H 2 S → S + H 2 O

g) make an electronic balance (OVR)

5. Chemical properties H 2 SO 3

1. Sulfuric acid dissociates stepped:

H 2 SO 3 ↔ H + + HSO 3 - (first stage, hydrosulfite is formed - anion)

HSO 3 - ↔ H + + SO 3 2- (second stage, anion sulphite is formed)

H 2 SO 3 forms two rows of salts:

Medium (sulfites)

Sour (hydrosulfite)

2. Sulfuric acid solution H 2 SO 3 has reducing properties:

H 2 SO 3 + I 2 + H 2 O \u003d H 2 SO 4 + Ni

h) make an electronic balance (OVR)

III. Self-control.

Transform the scheme:

S → H 2 S → SO 2 → Na 2 SO 3 → Baso 3 → SO 2

Equations of the ion exchange reactions write in full and short ion form.

Replies for self-test are displayed on the screen.

IV. Reflection.

Answer questions in the table "Questions to the Student" (Appendix 1).

V. Homework (differentiated)

Make tasks highlighted in red:

Equations A, B, E, F - "3"

Equations A - E - "4"

Equations A - Z - "5"

Attachment 1

Questions to the student

Date ___________________ class ______________________

Try to remember exactly what I heard in the classroom and answer the questions raised:

Definition

Anhydrous sulfuric acid It is a heavy, viscous liquid that is easily mixed with water in any proportion: the interaction is characterized by an extremely large exothermic effect (~ 880 kJ / mol with infinite dilution) and can lead to explosive boiling and spraying the mixture if the water is added to acid; Therefore, it is so important to always use the reverse order in the preparation of solutions and add acid into water, slowly and with stirring.

Some physical properties of sulfuric acid are shown in the table.

Anhydrous H 2 SO 4 - a wonderful connection with unusual high dielectric permeability and very high electrical conductivity, which is due to ion auto-separation (auto-produce) compound, as well as the reinforcement mechanism with proton transfer, ensuring the flow electric current Through a viscous liquid with a large number of hydrogen bonds.

Table 1. Physical properties of sulfuric acid.

Obtaining sulfuric acid

Sulfuric acid - the most important industrial chemical and the cheapest from produced in large volume Children in love of the world.

The concentrated sulfuric acid ("vigorous oil") was first obtained by heating the "green vitriol" FESO 4 × NH 2 O and spent in large quantities to receive Na 2 SO 4 and NaCl.

IN modern process The production of sulfuric acid is used by a catalyst consisting of vanadium oxide (V) with the addition of potassium sulfate on a carrier from silicon dioxide or kizelur. Sulfur SO 2 is becoming incineration of cleansers or under firing sulfide ore (first of all pyrite or ores, Ni and Zn) in the process of extracting these emails. SO 2 is oxidized to trioxide, and then by dissolving in water obtained sulfuric acid:

S + O 2 → SO 2 (ΔH 0 - 297 kJ / mol);

SO 2 + ½ O 2 → SO 3 (ΔH 0 - 9.8 kJ / mol);

SO 3 + H 2 O → H 2 SO 4 (ΔH 0 - 130 kJ / mol).

Chemical properties of sulfuric acid

Sulfuric acid - a strong two-axis acid. At the first stage in solutions of a low concentration, it dissociates almost aimed:

H 2 SO 4 ↔H + + HSO 4 -.

Dissociation on the second stage

HSO 4 - ↔H + + SO 4 2-

leaks to a lesser extent. The dissociation constant of sulfuric acid over the second stage, expressed through the activity of ions, k 2 \u003d 10 -2.

Like a two-axis acid, sulfuric acid forms two rows of salts: medium and sour. The average salts of sulfuric acid are called sulfates, and acidic - hydrosulfates.

Sulfuric acid greedily absorbs water pairs and therefore is often used to dry out gases. The ability to absorb water is also explained by the charring organic substancesEspecially related to the class of carbohydrates (fiber, sugar, etc.), under the action of concentrated sulfuric acid. Sulfuric acid takes away from carbohydrates hydrogen and oxygen, which form water, and carbon is distinguished in the form of coal.

Concentrated sulfuric acid, especially hot, is an energetic oxidizer. It oxidizes Hi and HBr (but not HCl) to free halogen, coal - to CO 2, sulfur - to SO 2. These reactions are expressed by equations:

8HI + H 2 SO 4 \u003d 4i 2 + H 2 S + 4H 2 O;

2HR + H 2 SO 4 \u003d br 2 + SO 2 + 2H 2 O;

C + 2H 2 SO 4 \u003d CO 2 + 2SO 2 + 2H 2 O;

S + 2H 2 SO 4 \u003d 3SO 2 + 2H 2 O.

The interaction of sulfuric acid with metals proceeds differently depending on its concentration. Diluted sulfuric acid oxidizes its hydrogen ion. Therefore, it interacts only with those metals that stand in a row of voltages only to hydrogen, for example:

Zn + H 2 SO 4 \u003d ZNSO 4 + H 2.

However, the lead is dissolved in dilute acid, since the resulting salt PBSO 4 is insoluble.

Concentrated sulfuric acid is an oxidizing agent due to sulfur (VI). It oxidizes metals in a row of voltages to silver inclusive. Products of its recovery can be different depending on the activity of metal and on the conditions (the concentration of the acid, temperature). When interacting with low-active metals, for example, copper, acid is restored to SO 2:

Cu + 2H 2 SO 4 \u003d Cuso 4 + SO 2 + 2H 2 O.

When interacting with more active metals, recovery products can be both dioxide and free sulfur and hydrogen sulfide. For example, when interacting with the zinc may be reactions:

Zn + 2H 2 SO 4 \u003d ZNSO 4 + SO 2 + 2H 2 O;

3ZN + 4H 2 SO 4 \u003d 3ZNSO 4 + S ↓ + 4H 2 O;

4ZN + 5H 2 SO 4 \u003d 4ZNSO 4 + H 2 S + 4H 2 O.

Sulfuric acid use

The use of sulfuric acid varies from country to country and from a decade to decade. So, for example, in the US, the main area of \u200b\u200bconsumption H 2 SO 4 - the production of fertilizers (70%), followed by chemical production, metallurgy, oil purification (~ 5% in each area). In the UK, the distribution of consumption by industry is different: only 30% produced by H 2 SO 4 is used in the production of fertilizers, but 18% is in paints, pigments and semi-product production of dyes, 16% for chemical production, 12% on obtaining soap and detergents, 10% for the production of natural and artificial fibers and 2.5% is used in metallurgy.

Examples of solving problems

Example 1.

Russian University of Friendship Peoples

Faculty of Foreign Languages \u200b\u200band General Education Disciplines

Sulfur. Its use in medicine.

Performed

student group SV-53

Head of Chemistry Seminars

Chemistry departments

Professor V.F. Zakharov

Moscow, 2002.

Finding sulfur in nature.

The physical properties of sulfur.

Chemical properties of sulfur and its connections.

1) Properties of a simple substance.

Oxide properties:

sulfur oxide (IV);

sulfur oxide (VI).

Properties of acids and their salts:

sulfuric acid and her salt;

hydrogen sulfide and sulphides;

sulfuric acid and her salt.

Use of sulfur in medicine.

General characteristics of the subgroup of oxygen

The oxygen subgroup includes five elements: oxygen, sulfur, selenium, televour and polonium (polonium - radioactive element). These are P-elementsVI Group of Periodic System D.I. Mendeleeva. They have a group name - chalcoge, which means "forming ores".

Properties of elements of the subgroup of oxygen

At the atoms of chalcogen, the same structure of the external energy level - NS 2 NP 4. This explains the similarity of their chemical properties. All chalcoge in compounds with hydrogen and metals exhibit oxidation -2, and in compounds with oxygen and other active non-metals - usually +4 and +6. For oxygen, as well as for fluorine, the degree of oxidation equal to the number of the group is not typical. It shows the degree of oxidation is usually -2 and in compounds with fluorine +2.

Hydrogen compounds of the elements of the subgroup of oxygen meet the formula H. 2 R.(R.- Symbol of element ): H. 2 O., H. 2 S., H. 2 SE, H. 2 TE. They are called chalnovodors. When dissolving them, acids are formed in water (the formulas the same). The power of these acids increases with increasing ordinal number item that is explained by a decrease in communication energy in a number of compounds H. 2 R.. Water dissociating on ions H. + and IS HE - is an amphoter electrolyte.

Sulfur, selenium and teleurur form the same forms of compounds with oxygen type Ro. 2 and Ro. 3 . They correspond to acids like H. 2 Ro. 3 and H. 2 Ro. 4 . With the growth of the sequence number of the element, the power of these acids decreases. All of them exhibit oxidative properties, and acid acids H. 2 Ro. 3 Also restoration.

The properties of simple substances are naturally changed: non-metallic and metal properties increase with an increase in the charge of the kernel. So, oxygen and televar - non-metals, but the latter has a metal glitter and conducts electric current.

Finding sulfur in nature

The sulfur is widespread in nature. It is 0.05% of the mass earth crust. In a free state (native sulfur) in large quantities Italy is found in Italy (Sicily Island) and the United States. The native sulfur field is available in the Kuibyshev region (Volga region), in the states of Central Asia, in the Crimea and other areas.

The sulfur is often found in the form of connections with other elements. The most important natural compounds are metals sulphides: Fes. 2 - iron pram, or pyrite; HGS. - Cynanar, etc., as well as sulfuric acid salts (crystallohydrates): Caso. 4 ּ 2 H. 2 O. - Gypsum, Na. 2 SO. 4 ּ 10 H. 2 O.- Glauberova Salt, MgSO. 4 ּ 7 H. 2 O.- Bitter salt, etc.

Physical properties of sulfur

Natural sulfur consists of a mixture of four stable isotopes:
,
,
.

Sulfur forms several allotropic modifications. Stable at room temperature rhombic sulfurit is a yellow powder, poorly soluble in water, but a well-soluble in the servo carbon, aniline and some other solvents. Poor spends warmth and electricity. When crystallization from chloroform Chcl 3 or from Serougoland CS. 2 it stands out in the form of transparent octahedral crystals. Rhombic sulfur consists of cyclic molecules S. 8 having a shape of the crown. At 113 0 of the chair melts, turning into a yellow lightweight fluid. With further heating, the melt thickens, as long polymer chains are formed in it. And if you heat sulfur up to 444.6 0 s, it boats. Pouring boiling sulfur thin-rod in cold water, you can get it plastic sulfur -rubber-like modification consisting of polymer chains. Drop-yellow needle crystals are formed with slow cooling of the melt monoclinic sulfur.(T pl \u003d 119 0 C). Like rhombic gray, this modification consists of molecules S. 8 . At room temperature, the plastic and monoclinic sulfur is unstable and spontaneously turn into a rhombic sulfur powder.

Chemical properties of sulfur and its connections

Properties of a simple substance.

A sulfur atom, having an incomplete external energy level, can attach two electrons and show the degree of oxidation -2. Such a degree of sulfur oxidation exhibits in compounds with metals and hydrogen (for example, Na. 2 S.and H. 2 S.). With the return or delaying electrons to the atom of a more electroneary element, the degree of sulfur oxidation can be +2, +4 and +6.

The sulfur easily forms connections with many elements. When combustion of it in air or in oxygen, sulfur oxide (IV) is formed SO. 2 and partly sulfur oxide (VI) SO. 3 :

S + O. 2 \u003d So. 3

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

These are the most important sulfur oxides.

When the sulfur is heated directly connected to hydrogen, halogens (except iodine), phosphorus, coal, as well as with all metals, except gold, platinum and iridium. For example:

S + H. 2 \u003d H. 2 S.

3S + 2P \u003d P 2 S. 3

S + CL. 2 \u003d SCL. 2

2S + C \u003d CS 2

S. + FE. = Fes.

As follows from examples, in reactions with metals and some non-metals of sulfur is an oxidizing agent, in reactions with more active non-metals, such as oxygen, chlorine, with a reducing agent.

Properties of oxide

Sulfur oxide (IV)

Sulphur dioxide SO. 2 - Colorless gas with a stiven sharp odor. When it is dissolved in water (at 0 ° C 1, the volume of water dissolves more than 70 volumes SO. 2 ) sulfuric acid is formed H. 2 SO. 3 which is known only in solutions.

In laboratory conditions for obtaining SO. 2 Act on solid sodium sulfite with concentrated sulfuric acid:

Na. 2 SO. 3 + 2h. 2 SO. 4 \u003d 2Nahso. 4 + So. 2 + H. 2 O.

In industry SO. 2 obtained when firing sulfide ores, for example, pyrite:

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

or when burning sulfur. Sulfur gas is a semi-product in the production of sulfuric acid. It is also used (together with sodium hydrosulfitis NaHSO 3 and calciumCA (HSO 3) 2) to release cellulose from wood. This gas is emphasized trees and shrubs to destroy the pests of agriculture.

Chemical reactions typical for SO. 2 can be divided into 3 groups:

Reactions flowing without changing the degree of oxidation, for example:

SO. 2 + CA (OH) 2 \u003d Caso. 3  + H. 2 O.

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

Reactions flowing down with a decrease in the degree of sulfur oxidation, for example:

SO. 2 + 2h. 2 S \u003d 3S + 2H 2 O.

In this way, SO. 2 It may exhibit both oxidative and restorative properties.

Sulfur oxide (VI)

Sulfurian anhydride SO. 3 At room temperature, it is a colorless easily bat (T kip \u003d 44.8.0 ° C, T pl \u003d 16.8 0 c), which over time passes into asbestoside modification consisting of shiny silky crystals. The fibers of the sulfuric anhydride are stable only in a sealed vessel. Absorbing air moisture, they turn into a thick colorless liquid - oleum (from lat.oleum- "oil"). Although formally oleum can be considered as a solution SO. 3 in H. 2 SO. 4 In fact, it is a mixture of various pirosal acids: H. 2 S. 2 O. 7 ,H. 2 S. 3 O. 10 etc. With water SO. 3 It interacts very vigorously: while it is distinguished so much heat that the resulting the smallest droplets of sulfuric acid create fog. It is necessary to work with this substance extremely careful.

Sulfur oxide (VI) is obtained by oxidation SO. 2 Oxygen only in the presence of a catalyst:

2so. 2 + O. 2  2so. 3 + Q.

The need to use the catalyst in this reversible reaction is due to the fact that a good output SO. 3 (i.e., the balance of equilibrium to the right) can only be obtained when the temperature decreases, but at low temperatures, the reaction rate is very much.

Sulfur oxide (VI) is vigorously connected to water, forming a sulfuric acid:

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

Properties of acids and their salts

Sulfuric acid and her salt

Sulfur oxide (IV) is well soluble in water (in 1 the volume of water at 20 0 s dissolves 40 volumes of SO 2). At the same time, an existing sulfuric acid existing in aqueous solution:

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

Connection reaction SO. 2 With water reversible. In an aqueous solution of sulfur oxide (IV) and sulfuric acid are in chemical equilibrium, which can be shifted. When binding N. 2 SO. 3 alkali (neutralization of acid) The reaction proceeds towards the formation of sulfuric acid; When deleting SO. 2 (purging through a solution of nitrogen 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 N. 2 S.O. 3 dissociates stepped:

N. 2 S.ABOUT 3  H. + + HSO. 4 –

HSO. 3 -  H. + + So. 3 2-

As a two-axis acid, it forms two rows of salts - sulphites and hydrosulfites. The sulfites are formed with complete acid neutralization by alkali:

N. 2 SO. 3 + 2 N.aON \u003d.N.butHS.ABOUT 4 + 2N 2 ABOUT

The hydrosulfites are obtained by deficiency of alkali (compared to the amount necessary for complete neutralization of the acid):

N. 2 SO. 3 + N.аон \u003d nans.O. 3 + N. 2 ABOUT

As well as sulfur oxide (IV), sulfuric acid and its salts are strong reducing agents. At the same time, the degree of oxidation of sulfur increases. So, N. 2 S.ABOUT 3 It is easily oxidized in sulfuric acid even air oxygen:

2N 2 SO. 3 + O. 2 \u003d 2N 2 SO. 4

Therefore, long stored solutions of sulfuric acid always contain sulfuric acid.

Even easier occurs the oxidation of sulfuric acid bromine and permanganate potassium:

N. 2 S.ABOUT 3 + B.r. 2 + N. 2 O \u003d N. 2 SO. 4 + 2NVR

5N 2 S.0 3 + 2kmn.ABOUT 4 \u003d 2N 2 SO. 4 + 2mnSO. 4 + K. 2 S.ABOUT 4 + 2N 2 ABOUT

Sulfur oxide (IV) and sulfuric acid discolor many dyes, forming the colorless connections. The latter can again decompose when heated into the light, as a result of which the color is restored. Consequently whitening action SO. 2 and N. 2 SO. 4 It differs from the whirlwind of chlorine. Usually, sulfur oxide (IV) whites wool, silk and straw (chlorine water these materials are destroyed).

Important application It finds a solution of calcium hydrosulfite CA.(HSO. 3 ) 2 (sulfite liquor), which are treated with wood fibers and paper mass.

Hydrogen sulfide and sulphides

Hydrogen sulfide N. 2 S. - Colorless gas with smell of rotten eggs. It is well soluble in water (at 20 ° C in 1 volume of water, 2.5 sulfide volumes are dissolved). The case of hydrogen sulfide in water is called hydrogen sulfide water or hydrogen suture acid (it detects the properties of weak acid).

Hydrogen sulfide - very poisonous gas affecting nervous system. Therefore, it is necessary to work with it in exhaust cabinets or with hermetically closing devices. Permissible content H 2 SV production rooms is 0.01 mg in 1 l of air.

Hydrogen sulfide occurs in nature in volcanic gases and in the waters of some mineral sources, for example, Pyatigorsk; Matsesta. It is formed with the rotting of sulfur-containing organic substances of various plant and animal residues. This explains characteristic nasty smell Wastewater, cesspool and garbage dumps.

Hydrogen sulfide can be obtained by direct sulfur compound with hydrogen when heated:

S. + N. 2 = H. 2 S.

But it is usually obtained by the action of dilute hydrochloric or sulfuric acid on the iron sulphide (II):

2NSL + FES \u003dF.eUl. 2 + N. 2 S.

This reaction is often carried out in the Cyprus apparatus.

H 2 S-less durable compound than water. This is due to large size The sulfur atom compared to the oxygen atom. Therefore, the connection of the N-0 is shorter and stronger communication n-s. With strong heating, hydrogen sulfide is almost completely decomposed on sulfur and hydrogen:

N. 2 S. = S. + N. 2

Gaseous H 2 Sports on air Blue flame with sulfur oxide (IV) and water:

2N 2 S. + 3 O. 2 = 2 SO. 2 + 2N 2 ABOUT

With a lack of oxygen, sulfur and water are formed:

2N 2 S. + O. 2 = 2 S. + 2N 2 ABOUT

This reaction is used to obtain sulfur hydrogen sulfide on an industrial scale.

Hydrogen sulfide is a rather strong reducing agent. This important chemical property can be explained so. In solution N. 2 S.comparatively easily gives electrons with air oxygen molecules:

N. 2 S - 2.e.- \u003d S + 2H + 2

O. 2 + 4 e.- \u003d 2O. 2- 1

In this case, H 2 is saming air oxygen to sulfur, which makes humid hydrogen sulfide water. Total reaction equation:

2 N. 2 S + O. 2 \u003d 2S + 2N. 2 O.

This explains the fact that hydrogen sulfide does not accumulate in very large quantities in nature in the rotation of organic substances - air oxygen oxidizes it in a free sulfur.

Energetically reacts hydrogen sulfide with halogen solutions. For example:

N. 2 S + I. 2 \u003d 2hi + s

The sulfur is released and the discoloration of the iodine solution.

Hydrogen sulfide acid as a two-axis forms two rows of salts - medium (sulfides) and acidic (hydrosulfides). For example, NA 2 S. - sodium sulphide, Nan.S.- Sodium hydrosulfide. Hydrosulfides are almost all well soluble in water. Alkaline and alkaline earth metal sulphides are also soluble in water, and the remaining metals are practically insoluble or a little soluble; Some of them do not dissolve in dilute acids. Therefore, such sulphides can be easily obtained, passing hydrogen sulfide through the salt of the corresponding metal, for example:

FROMuso 4 + N. 2 S \u003d CUS + H 2 SO. 4

Some sulphides have a characteristic color: CUS.and RbS. - black, FROMds.- Yellow ZNS.- white, MNS.- Pink, SNS.- brown, SB. 2 S. 3 - orange, etc. On the different solubility of sulphides and various color of many of them, qualitative analysis of the cations is founded.

Sulfuric acid and her salt

Sulfuric acid - severe colorless oily liquid. Extremely hygroscopic. It absorbs moisture with the release of a large amount of heat, so it is impossible to pour water to concentrated acid - acid splashing will occur. For dilution it is necessary to pour sulfuric acid with small amounts to water.

Anhydrous sulfuric acid dissolves up to 70% sulfur oxide (VI). At normal temperature, it is not flying and does not smell. When heated smacks SO. 3 As long as the solution is formed containing 98.3% N. 2 SO. 4 . Anhydrous H. 2 SO. 4 Almost does not conduct an electric current.

Concentrated sulfuric acid charred organic substances - sugar, paper, wood, fiber, etc. Elements of water take away from them. At the same time, hydrates of sulfuric acid are formed. Sugar charred can be expressed by the equation

FROM 12 N. 22 ABOUT 11 + n.N. 2 SO. 4 \u003d 12C + N 2 SO. 4 ּ n.N. 2 ABOUT

The resulting coal partially enters into interaction with acid:

C + 2N 2 SO. 4 \u003d S 2 + 2 SO. 2 + 2N 2 ABOUT

Therefore, the acid that goes on sale has a brown color from the randomly falling dust and organic substances charred in it.

On the absorption (from the test) of the water with sulfuric acid. Gas dryer is based.

As a strong non-volatile acid N. 2 SO. 4 Ops other acids from dry salts. For example:

NAnose + N. 2 SO. 4 \u003d NanSO. 4 + N.No. 3

However, if N. 2 S.ABOUT 4 It is added to salts solutions, then the displacement of acids does not occur.

Very important chemical properties of sulfuric acid - its ratio to metals. Diluted and concentrated sulfuric acid reacts with them differently. Dilutedsulfuric acid oxidizes only metals in a row of voltage to the left of hydrogen, due to ions H. + , eg:

Zn + H. 2 SO. 4 ( rSC ) \u003d ZNSO. 4 + H. 2

Concentratedsulfuric acid at normal temperature with many metals does not react. Therefore, anhydrous sulfuric acid can be stored in iron containers and transported in steel tanks. However, when heated concentrated N. 2 SO. 4 interacts with almost all metals (except Rt., BUTu.and some others), as well as with non-metals. At the same time, it acts as an oxidizing agent, it is usually restored to SO. 2 . Hydrogen in this case does not stand out, but water is formed. For example:

FROMu + 2.N. 2 SO. 4 = FROMuso 4 + So. 2  + 2 N. 2 O.

2Ag + 2h. 2 SO. 4 \u003d AG. 2 SO. 4 + So. 2  + 2h. 2 O.

C + 2H 2 SO. 4 + \u003d Co. 2  + 2SO. 2  + 2h. 2 O.

2p + 5h. 2 SO. 4 \u003d 2h. 3 PO 4 + 5SO. 2 

Sulfuric acid has all the properties of acids.

Sulfuric acid, being a two-way, forms two rows of salts: medium, called sulfates, and acidic, called hydrosulfates. Sulfates are formed at full neutralization of acid alkali (1 mol of acid accounts for 2 praying alkalis), and hydrosulfates - with a shortage of alkali (1 mol of acid - 1 mol alkali):

N. 2 SO. 4 + 2 N.butOh. \u003d NA 2 SO. 4 + 2N 2 ABOUT

N. 2 SO. 4 + Naoh. = N.butHSO. 4 + N. 2 ABOUT

Many sulfuric acid salts are of great practical importance.

Most sulfuric acid salts are soluble in water. Sololi. SASO. 4 and RbSO. 4 little soluble in water, and V.SO. 4 Practically insoluble both in water and in acids. This property allows you to use any soluble barium salt, for example Youl. 2 as a reagent for sulfuric acid and her salt (more precisely, ion SO. 4 2- ):

H. 2 SO. 4 + BACL 2 \u003d Baso. 4  + 2hcl.

NASO. 4 + BACL 2 \u003d Baso. 4  + 2NACL

At the same time, white insoluble in water and acid precipitate of barium sulfate is falling.

Sulfuric acid is an essential product of the main chemical industry, which is engaged in the production of inorganic acids, alkalis, salts, mineral fertilizers and chlorine.

According to a variety of use, sulfuric acid ranks first among the acids. The greatest number It is consumed to obtain phosphate and nitrogen fertilizers. Being non-teaching acid, sulfuric acid is used to obtain other acids - salt, fluid, phosphoric, acetic, etc. Many of it goes for cleaning petroleum products - gasoline, kerosene and lubricating oils - from harmful impurities. In engineering with sulfuric acid, the surface of the metal is purified from oxides before coating (nickelock, chromium, etc.). Sulfuric acid is used in the production of explosives, artificial fibers, dyes, plastics and many others. It is used to fill batteries. In agriculture, it is used to combat weeds (herbicide).

This determines the value of sulfuric acid in our folk economy.

Use of sulfur in medicine

Sulfurdepuratum - fine powder lemon yellow color - used in enterobiosis as an anti-zhilant. It is also a light laxative, part of the complex powder of a licorice root. Sterile 1-2% sulfur solution purified in peach oil (sulfosine) is sometimes used for pyrogenic therapy during syphilis.

In addition, sulfur compounds, both organic and inorganic, find wide application in medicine. Sulfur atoms are part of many drugs of various action. Since they are not covered by their attention, it is not possible, limited to several examples.

Sulfur (IV) oxide (IV) is well soluble in water (in 1 water volume with 200 ° C, 40 volumes of SO2 are dissolved). At the same time, an existing sulfuric acid existing in aqueous solution:

SO2 + H2O \u003d H2SO3

The reaction of the SO2C connection with water is reversible. In an aqueous solution of sulfur oxide (IV) and sulfuric acid are in chemical equilibrium, which can be shifted. When binding to 2SO3choching (neutralization of acid), the reaction proceeds towards the formation of sulfuric acid; By removing SO2 (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 the solution of H2SO3Dissorates stepwise:

H2SO3 H + + HSO4 -

HSO3 -H ++ SO3 2-

As a two-axis acid, it forms two rows of salts - sulphites and hydrosulfites. The sulfites are formed with complete acid neutralization by alkali:

H2SO3 + 2None \u003d NHSO4 + 2N2O

The hydrosulfites are obtained by deficiency of alkali (compared to the amount necessary for complete neutralization of the acid):

H2SO3 + NAON \u003d NANSO3 + H2O

As well as sulfur oxide (IV), sulfuric acid and its salts are strong reducing agents. At the same time, the degree of oxidation of sulfur increases. So, H2SO3 light oxidizes in sulfuric acid even air oxygen:

2N2SO3 + O2 \u003d 2N2SO4

Therefore, long stored solutions of sulfuric acid always contain sulfuric acid.

Even easier occurs the oxidation of sulfuric acid bromine and permanganate potassium:

H2SO3 + BR2 + H2O \u003d H2SO4 + 2NVR

5N2S03 + 2KMNO4 \u003d 2N2SO4 + 2MNSO4 + K2SO4 + 2N2O

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 effects2 IN2SO4 is from the whirlwind of chlorine. Usually, sulfur oxide (IV) whites wool, silk and straw (chlorine water these materials are destroyed).

Important use The Ca (HSO3) 2 hydrosulfite solution (sulfite), which is treated with wood fibers and paper mass.

Hydrogen sulfide and sulphides

Hydrogen sulfide H2S is a colorless gas with a smell of rotten eggs. It is well soluble in water (at 20 ° C in 1 volume of water, 2.5 volume of hydrogen sulfide is dissolved). The hydrogen sulfide solution in water is called hydrogen sulfide water or hydrogen sulfide acid (it detects the properties of weak acid).

Hydrogen sulfide is a very poisonous gas that affects the nervous system. Therefore, it is necessary to work with it in exhaust cabinets or with hermetically closing devices. The permissible H2SV content of industrial premises is 0.01 mg in 1 l of air.

Hydrogen sulfide occurs in nature in volcanic gases and in the waters of some mineral sources, for example, Pyatigorsk; Matsesta. It is formed with the rotting of sulfur-containing organic substances of various plant and animal residues. This explains the characteristic unpleasant odor. wastewater, cesspool and garbage dumps.

Hydrogen sulfide can be obtained by direct sulfur compound with hydrogen when heated:

But it is usually obtained by the action of dilute hydrochloric or sulfuric acid on the iron sulphide (II):

2NSL + FES \u003d FESL2 + H2S

This reaction is often carried out in the Cyprus apparatus.

H2S-less durable compound than water. This is due to the large size of the sulfur atom compared to the oxygen atom. Therefore, the connection of the N-0 is shorter and the stronger communication of H-s. With strong heating, hydrogen sulfide is almost completely decomposed on sulfur and hydrogen:

Gaseous H2SHing on air Blue flame with sulfur oxide (IV) and water formation:

2N2S + 3O2 \u003d 2SO2 + 2N2O

With a lack of oxygen, sulfur and water are formed:

2N2S + O2 \u003d 2S + 2N2O

This reaction is used to obtain sulfur hydrogen sulfide on an industrial scale.

Hydrogen sulfide is a rather strong reducing agent. This important chemical property can be explained so. In the solution of H2Scusively easily gives electrons with air oxygen molecules:

H2S - 2E- \u003d S + 2H + 2

O2 + 4E- \u003d 2O 2- 1

In this case, H2Soisses air oxygen to sulfur, which makes muddy hydrogen sulfide water. Total reaction equation:

2N2S + O2 \u003d 2S + 2N2O

This explains the fact that hydrogen sulfide does not accumulate in very large quantities in nature in the rotation of organic substances - air oxygen oxidizes it in a free sulfur.

Energetically reacts hydrogen sulfide with halogen solutions. For example:

H2S + I2 \u003d 2HI + S

The sulfur is released and the discoloration of the iodine solution.

Hydrogen sulfide acid as a two-axis forms two rows of salts - medium (sulfides) and acidic (hydrosulfides). For example, Na2S - sodium sulphide, NanS-hydrosulfide sodium. Hydrosulfides are almost all well soluble in water. Alkaline and alkaline earth metal sulphides are also soluble in water, and the remaining metals are practically insoluble or a little soluble; Some of them do not dissolve in dilute acids. Therefore, such sulphides can be easily obtained, passing hydrogen sulfide through the salt of the corresponding metal, for example:

CUSO4 + H2S \u003d CUS + H2SO4

Some sulphides have a characteristic color: CUSIRBS - black, cds-yellow, ZNS-white, MNS-pink, SNS-brown, SB2S3-orange, etc., on the different solubility of sulphides and various colors many of them are based qualitative analysis cations.

Ticket number 39.

Sulfuric acid. Getting. Physical and chemical properties. The value of sulfuric acid.

Sulfuric acid H2SO4 is a strong two-axis acid that meets the highest degree of sulfur oxidation (+6). For conventional conditions Concentrated sulfuric acid is a heavy oily liquid without color and smell, with sour "copper" taste. In the technique of sulfuric acid, it is a mixture of its mixtures with both water and SO3 sulfuric anhydride. If the molar ratio SO3: H2O< 1, то это water solution Sulfuric acid, if\u003e 1 - SO3 solution in sulfuric acid (oleum).