Obtaining sulfuric acid reaction. Sulfuric acid salts and their uses

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Nurturing:

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

Developing:

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

General education:

organize the activities of students for assimilation:

• knowledge
: Chemical properties and methods for producing sulfur dioxide and sulfurous acid;
• skills
: write down the equations of chemical reactions that characterize the chemical properties of sulfurous acid and its salts in ionic and redox form.

During the classes

I. Organizational moment.

II. Learning new material:

1. Structure:

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

Structural formula

2. Physical properties

1. A colorless gas with a pungent odor, poisonous.
2. Highly soluble in water (40 V SO 2 dissolves in 1 V H 2 O at N.O.)
3. Heavier than air, poisonous.

3. Receipt

1. In industry: sulphide roasting.

FeS 2 + O 2 → Fe 2 O 3 + SO 2

a) Draw up an electronic balance sheet (OVR).

2. In laboratory conditions: the interaction of sulfites 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 (conc) → CuSO 4 + SO 2 + H 2 O

b) Compile an electronic balance (OVR) .

4. Chemical properties of SO 2

1. Interaction with water

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

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 with basic 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) Draw up an electronic balance (OVR)

SO 2 + Br 2 + H 2 O → H 2 SO 4 + HBr

d) Draw up an electronic balance (OVR)

SO 2 + KMnO 4 + H 2 O → K 2 SO 4 + MnSO 4 + H 2 SO 4

e) Compile an electronic balance sheet (OVR)

5. Recovery reactions, SO 2 - oxidizing agent

SO 2 + C → S + CO 2 (when heated)

f) Compile an electronic balance sheet (OVR)

SO 2 + H 2 S → S + H 2 O

g) Compile an electronic balance (OVR)

5. Chemical properties of H 2 SO 3

1. Sulfurous acid dissociates in steps:

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

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

H 2 SO 3 forms two series of salts:

Medium (sulfites)

Acidic (hydrosulfites)

2. A solution of sulfurous acid H 2 SO 3 has reducing properties:

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

h) Compile an electronic balance (OVR)

III. Self control.

Carry out the transformations according to the scheme:

S → H 2 S → SO 2 → Na 2 SO 3 → BaSO 3 → SO 2

Write the equations for ion exchange reactions in full and short ionic form.

The self-test answers are displayed on the screen.

IV. Reflection.

Answer the questions in the table “Questions to the student” (Appendix 1).

v. Homework(differentiated)

Make tasks highlighted in red:

Equations a, c, e, g - “3”

Equations a – e – “4”

Equations a – h – “5”

Appendix 1

Questions to the student

Date ___________________ Class ______________________

Try to remember exactly what you heard in the lesson and answer the questions:

H2SO3, a weak dibasic acid. It is not isolated in a free form, it exists in aqueous solutions. Salts of sulfurous acid sulfites ... Large encyclopedic Dictionary

SULFURIC ACID- (H2SO3) weak dibasic acid. Exists only in aqueous solutions. Salts S. to. sulfites. Used in pulp and paper Food Industry. See also Acids and anhydrides... Russian encyclopedia of labor protection

sulfurous acid- - [A.S. Goldberg. English Russian Energy Dictionary. 2006] Topics energy in general EN sulfurous acid … Technical Translator's Handbook

H2SO3, a weak dibasic acid. It is not isolated in a free form, it exists in aqueous solutions. Salts of sulfuric acid sulfites. * * * SULFURIC ACID SULFURIC ACID, H2SO3, a weak diacid. Not isolated in free form, ... ... encyclopedic Dictionary

sulfurous acid- sulfito rūgštis statusas T sritis chemija formulė H₂SO₃ atitikmenys: angl. sulfurous acid. sulfurous acid ryšiai: sinonimas - vandenilio trioksosulfatas (2–) ... Chemijos terminų aiskinamasis žodynas

H2SO3, a weak dibasic acid corresponding to the +4 oxidation state of sulfur. Known only in dilute aqueous solutions. Dissociation constants: K1 = 1.6 10 2, K2 = 1.0 10 7 (18°C). Gives two series of salts: normal sulfites and acidic ... ... Great Soviet Encyclopedia

H2SO3, a weak dibasic acid. It is not isolated in free form, it exists in water. rah. Salts S. to. sulfites ... Natural science. encyclopedic Dictionary

See Sulfur... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

SULFURIC ACID- H2SO3, a weak dibasic acid. It is not isolated in a free form, it exists in aqueous solutions. Salts of sulfurous acid sulfites ... Big Encyclopedic Dictionary

SULFURIC ACID- (H2SO3) weak dibasic acid. Exists only in aqueous solutions. Salts S. to. sulfites. Used in the pulp and paper and food industries. See also Acids and anhydrides... Russian encyclopedia of labor protection

sulfurous acid- - [A.S. Goldberg. English Russian Energy Dictionary. 2006] Topics energy in general EN sulfurous acid … Technical Translator's Handbook

sulfurous acid- H2SO3, a weak dibasic acid. It is not isolated in a free form, it exists in aqueous solutions. Salts of sulfuric acid sulfites. * * * SULFURIC ACID SULFURIC ACID, H2SO3, a weak diacid. Not isolated in free form, ... ... encyclopedic Dictionary

sulfurous acid- sulfito rūgštis statusas T sritis chemija formulė H₂SO₃ atitikmenys: angl. sulfurous acid. sulfurous acid ryšiai: sinonimas - vandenilio trioksosulfatas (2–) ... Chemijos terminų aiskinamasis žodynas

sulfurous acid- H2SO3, a weak dibasic acid corresponding to the oxidation state of sulfur +4. Known only in dilute aqueous solutions. Dissociation constants: K1 = 1.6 10 2, K2 = 1.0 10 7 (18°C). Gives two series of salts: normal sulfites and acidic ... ... Great Soviet Encyclopedia

SULFURIC ACID- H2SO3, a weak dibasic acid. It is not isolated in free form, it exists in water. rah. Salts S. to. sulfites ... Natural science. encyclopedic Dictionary

sulfurous acid- see Sulfur... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

Sulfur oxide (IV) is highly soluble in water (40 volumes of SO2 dissolve in 1 volume of water at 200C). In this case, sulfurous acid exists only in an aqueous solution:

SO2 + H2O = H2SO3

The reaction of SO2 with water is reversible. In an aqueous solution, sulfur oxide (IV) and sulfurous acid are in chemical equilibrium, which can be displaced. When H2SO3 is bound with alkali (neutralization of the acid), the reaction proceeds towards the formation of sulfurous acid; when removing SO2 (blowing through a nitrogen solution or heating), the reaction proceeds towards the starting materials. Sulfuric acid solution always contains sulfur oxide (IV), which gives it a pungent odor.

Sulfurous acid has all the properties of acids. In solution, H2SO3 dissociates in steps:

Н2SO3 H+ + HSO4 –

HSO3 -H++ SO3 2-

As a dibasic acid, it forms two series of salts - sulfites and hydrosulfites. Sulfites are formed when an acid is completely neutralized with an alkali:

H2SO3 + 2NaOH \u003d NaHSO4 + 2H2O

Hydrosulfites are obtained with a lack of alkali (compared to the amount needed to completely neutralize the acid):

H2SO3 + NaOH = NaHSO3 + H2O

Like sulfur oxide (IV), sulfurous acid and its salts are strong reducing agents. At the same time, the degree of oxidation of sulfur increases. So, H2SO3 is easily oxidized to sulfuric acid even the oxygen in the air

2H2SO3+O2= 2H2SO4

Therefore, sulfuric acid solutions that have been stored for a long time always contain sulfuric acid.

The oxidation of sulfurous acid with bromine and potassium permanganate proceeds even more easily:

H2SO3 + Br2 + H2O = H2SO4 + 2HBr

5H2S03+ 2KmnO4= 2H2SO4+ 2MnSO4+ K2SO4+ 2H2O

Sulfur oxide (IV) and sulfurous acid decolorize many dyes, forming colorless compounds with them. The latter can decompose again when heated or in the light, as a result of which the color is restored. Therefore, the bleaching effect of SO2 and H2SO4 is different from that of chlorine. Usually, wool, silk and straw are whitened with sulfur (IV) oxide (these materials are destroyed by chlorine water).

Important application finds a solution of calcium hydrosulfite Ca (HSO3) 2 (sulfite lye), which is used to treat wood fibers and paper pulp.

Hydrogen sulfide and sulfides

Hydrogen sulfide H2S is a colorless gas with the smell of rotten eggs. It is highly soluble in water (at 20 °C, 2.5 volumes of hydrogen sulfide dissolve in 1 volume of water). A solution of hydrogen sulfide in water is called hydrogen sulfide water or hydrosulfide acid (it exhibits the properties of a weak acid).

Hydrogen sulfide is a highly toxic gas nervous system. Therefore, it is necessary to work with it in fume hoods or with hermetically sealed devices. Permissible content of H2Sv industrial premises is 0.01 mg per 1 liter of air.

Hydrogen sulfide occurs naturally in volcanic gases and in the waters of some mineral springs, such as Pyatigorsk; Matsesta. It is formed during the decay of sulfur-containing organic substances of various plant and animal residues. This explains the characteristic bad smell Wastewater, cesspools and garbage dumps.

Hydrogen sulfide can be obtained by directly combining sulfur with hydrogen when heated:

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

2HCl + FeS = FeCl2 + H2S

This reaction is often carried out in a Kipp apparatus.

H2S is a weaker compound than water. This is due big size sulfur atom compared to oxygen atom. Therefore, the H-0 bond is shorter and stronger H-S connections. With strong heating, hydrogen sulfide almost completely decomposes into sulfur and hydrogen:

Gaseous H2S burns in air with a blue flame to form sulfur oxide (IV) and water:

2H2S+ 3O2= 2SO2+ 2H2O

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

2H2S+O2= 2S+ 2H2O

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

Hydrogen sulfide is a fairly strong reducing agent. This important chemical property can be explained as follows. In H2S solution, it is relatively easy to donate electrons to air oxygen molecules:

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

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

In this case, H2S is oxidized by atmospheric oxygen to sulfur, which makes hydrogen sulfide water cloudy. Overall reaction equation:

2H2S + O2 = 2S + 2H2O

This also explains the fact that hydrogen sulfide does not accumulate in very large quantities in nature, when organic matter decays, atmospheric oxygen oxidizes it into free sulfur.

Hydrogen sulfide reacts vigorously with halogen solutions. For example:

H2S + I2 = 2HI + S

Sulfur is released and the iodine solution becomes discolored.

Hydrosulfuric acid as a dibasic acid forms two series of salts - medium (sulfides) and acidic (hydrosulfides). For example, Na2S is sodium sulfide, NaHS is sodium hydrosulfide. Almost all hydrosulfides are highly soluble in water. Sulfides of alkali and alkaline earth metals are also soluble in water, while other metals are practically insoluble or slightly soluble; some of them do not dissolve in dilute acids. Therefore, such sulfides can be easily obtained by passing hydrogen sulfide through salts of the corresponding metal, for example:

CuSO4 + H2S = CuS + H2SO4

Some sulfides have a characteristic color: CuS and PbS - black, CdS - yellow, ZnS - white, MnS - pink, SnS - brown, Sb2S3 - orange, etc. On different solubility of sulfides and various colors many of them are based qualitative analysis cations.

TICKET #39

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

Sulfuric acid H2SO4 is a strong dibasic acid, corresponding to the highest oxidation state of sulfur (+6). At normal conditions concentrated sulfuric acid is a heavy oily liquid, colorless and odorless, with a sour "copper" taste. In engineering, sulfuric acid is called its mixtures with both water and sulfuric anhydride SO3. If the molar ratio of SO3: H2O< 1, то это water solution sulfuric acid, if> 1 - a solution of SO3 in sulfuric acid (oleum).

Sulfuric acid H 2 SO 4 is one of the strong dibasic acids. In a dilute state, it oxidizes almost all metals except gold and platinum. Reacts violently with non-metals and organic matter, turning some of them into coal. When preparing a solution of sulfuric acid, it should always be added to water, and not vice versa, to avoid splashing acid and boiling water. At 10 °C it hardens, forming a transparent vitreous mass. When heated, 100% sulfuric acid easily loses sulfuric anhydride (sulfur trioxide SO 3) until its concentration is 98%. It is in this state that it is usually used in laboratories. In a concentrated (anhydrous) state, sulfuric acid is a colorless, fuming in air (due to vapors), oily liquid with a characteristic odor (boiling point = 338 ° C). She is very strong oxidizing agent. This substance has all the properties of acids:

Chemical properties of sulfuric acid

H 2 SO 4 + Fe → FeSO 4 + H 2;

2H 2 SO 4 + Cu → CuSO 4 + SO 2 + 2H 2 O - in this case, the acid is concentrated.

H 2 SO 4 + CuO → CuSO 4 + H 2 O

The resulting solution of blue color- CuSO 4 - a solution of copper sulfate. Sulfuric acid is also called vitriol oil, since vitriol is formed during reactions with metals and their oxides. For example, in a chemical reaction with iron (Fe), a light green solution of ferrous sulfate is formed.

Chemical reaction with bases and alkalis (or neutralization reaction)

H 2 SO 4 + 2NaOH → Na 2 SO 4 + 2H 2 O

sulfurous acid(or more correctly, a solution of sulfur dioxide in water) forms two types of salts: sulfites and hydrosulfites. These salts are reducing agents.

H 2 SO 4 + NaOH → NaHSO 3 + H 2 O - this reaction proceeds with an excess sulfurous acid

H 2 SO 4 + 2NaOH → Na 2 SO 3 + 2H 2 O - and this reaction proceeds with an excess of sodium hydroxide

sulfurous acid has a whitening effect. Everyone knows that chlorine water has a similar effect. But the difference lies in the fact that, unlike chlorine, sulfur dioxide does not destroy dyes, but forms uncolored dyes with them. chemical compounds!

In addition to the main properties of acids sulfurous acid capable of discoloring a solution of potassium permanganate according to the following equation:

5H 2 SO 3 + 2KMnO 4 → 2 H 2 SO 4 + 2MnSO 4 + K 2 SO 4 + H 2 O

In this reaction, a pale pink solution is formed, consisting of potassium and manganese sulfates. The color is due to manganese sulfate.

sulfurous acid able to decolorize bromine

H 2 SO 3 + Br 2 + H 2 O → H 2 SO 4 + 2HBr

In this reaction, a solution is formed, consisting immediately of 2 strong acids: sulfuric and bromine.

If you store sulfurous acid in the presence of air, then this solution is oxidized and turns into sulfuric acid.

2H 2 SO 3 + O 2 → 2H 2 SO 2