Characteristics of hydrosulphuric acid. Sulfuric acid. Properties, production, application and price of hydrosulfide acid. Reactions with salts

PART AND

GENERAL CHEMISTRY

CHEMISTRY OF THE ELEMENTS

OXYGEN. SULFUR

hydrogen sulfide

The hydrogen sulfide molecule consists of a Sulfur atom and two Hydrogen atoms connected by a polar covalent bond. Angle between bonds

SH equals 91°. The hydrogen sulfide molecule is polar.

Hydrogen sulfide - natural component volcanic and natural gases. Some mineral waters contain dissolved hydrogen sulfide, which gives them medicinal properties. Hydrogen sulfide is formed as a result of the decay of products containing proteins in their composition. In the Black Sea, at a depth of more than 40 meters, there is no life due to the saturation of the waters with hydrogen sulfide.

Physical properties of hydrogen sulfide

Hydrogen sulfide is a colorless gas with a rotten egg odor. In 1 volume of water, 3 volumes of hydrogen sulfide dissolve, and approximately 0.1 molar solution is formed. The melting point of hydrogen sulfide is -83 °C, and the boiling point is -61 °C. Hydrogen sulfide affects nervous system person, so it is necessary to work with him under a fume hood.

Chemical properties hydrogen sulfide

Hydrogen sulfide is a compound that has a structure similar to the water molecule, but compared to it is less stable. In the case of heating to high temperatures, hydrogen sulfide decomposes according to the reaction:

Combustion can occur in two various directions. In excess of oxygen, water and sulfur are formed (And

V) oxide:

Due to the lack of oxygen, incomplete combustion of hydrogen sulfide occurs. This process is used to extract sulfur on an industrial scale from gases that are formed during the roasting of ores:

Bromine and iodine reduce hydrogen sulfide to a simple sulfur substance:

Hydrogen sulfide reacts with hexafluorosulfur at elevated temperatures:

In the case of dissolution of hydrogen sulfide in water, a weak dibasic sulfide acid is formed (K a 1 \u003d 10 - 7, K a 2 \u003d 1.2 ∙ 10 - 13):

Medium salts of sulfide acid are called sulfides (for example, K 2 S is potassium sulfide. Acid salts of the corresponding acid are also known - hydrogen sulfide(KHS - potassium hydrogen sulfide). Since sulfide acid is a rather weak acid, solutions of sulfides and hydrogen sulfides undergo hydrolysis by the anion, and, accordingly, the solution medium is basic:

Alkaline sulfides and alkaline earth metals soluble in water, while other sulfides are insoluble. Many salts of sulfide acid have a characteristic color: HgS - red, Sb 2 S 3 - orange, CdS - yellow, MnS - pink, CuS - black.

Production and use of hydrogen sulfide

Hydrogen sulfide is usually produced by the action of mineral acids on metal sulfides:

Hydrogen sulfide can also be obtained from simple substances.

Hydrogen sulfide is used in the qualitative analysis of cations according to the sulfide classification. He also plays important role during the production of sulfuric acid.

Qualitative reaction to hydrogen sulfide i sulfide ion

To determine sulfide ions in a solution, any soluble lead salt is added to the test solution (most often acetate P b (CH 3 SOO) 2 or nitrate Pb(NO3) 2). If after addition a black precipitate appears in the solution, then sulfide ions were present in the test sample:

If they say that he is weak, then a disease has come, or hunger, in general, adversity. In chemistry, things are different. Consider a weak hydrogen sulfide. It is weak not because it is ready to disintegrate, to perish, but, on the contrary, because of the unwillingness to dissociate.

This is the name given to the process of dissolution in water, separation into a hydronium ion and an anion. Hydrogen sulfide dissociates by only 0.011%, moreover, in two stages. On the first of them, the degree of decomposition does not exceed 0.005%.

So, it is quite resistant, "holds the blow." However, this is by human standards. In chemistry, things are different. Let's dive into its world, continuing to study the properties of hydrogen sulfide.

Properties of hydrosulfide acid

The heroine's resilience is relative. Not wanting to completely dissolve in water, the compound decomposes under the action of oxygen. It oxidizes hydrosulfide acid. Formula it looks like this: - H 2 S. H in it -, S -. So, the latter, during oxidation, “breaks out” of the formula. The connection breaks up.

In fact, hydrosulfide acid is an aqueous solution of gas. Hydrogen sulfide is known for its rotten egg smell and toxicity. the substance does not. There are no indicator papers that have been in hydrosulphuric acid. Property this is another pointer to the weakness of the connection. Strong color litmus in tones.

Characteristics of hydrosulfide acid is reduced not only to slow dissolution in water. Other reactions with the heroine of the article also pass slowly. In relation to the human character, this is rather laziness than weakness.

With metals, for example, a hydrogen sulfide solution reacts reluctantly. The explanation for this is the low concentration of positive hydrogen ions. Their deficiency is associated with a low degree of dissociation.

Of the metals, the heroine of the article interacts only with those that are up to H 2 in the voltage series. Such elements are capable of displacing hydrogen from solution. The interaction can lead to the formation hydrosulphuric acid salts.

It is completely insoluble in water. The response concerns sulfides. This is one of the types formed with the participation of a hydrogen sulfide compound. The second type is hydrosulfides. They are formed during the reaction with alkali and alkaline earth, soluble.

Entering into interaction with alkaline earth metals, hydrogen sulfide reacts with alkalis. The heroine of the article acts as a reducer, that is, she gives away electrons. It turns out that the properties of the connection are typical for a weak type.

The other is ambiguous. Being a solution of poisonous hydrogen sulfide, the heroine of the article is only relatively dangerous. Due to the low concentration of the original substance, it becomes a medicine. Where and how it is used, we will tell in the next chapter.

The use of hydrosulfide acid

Dissociation of hydrosulfide acid to a solution of saturation in thousandths of a percent allows the use of the compound for medicinal purposes. They, as a rule, are organized at the places where groundwater containing hydrogen sulfide comes out. The smell of rotten eggs is tolerated for the sake of getting rid of skin ailments, rehabilitation of the system, and treatment of insomnia.

Hydrogen sulfide baths improve blood flow, which means they have a beneficial effect on the entire body. Moving faster through the vessels, the blood does not stagnate, more quickly supplies the organs with the elements they need. The metabolism is accelerated, leading to the purification of toxins. On the general effect of rejuvenation.

"On the face" used in direct meaning. Cosmetologists use hydrogen sulfide solution for lifting procedures. In addition to tightening, you can get rid of cellulite and acne. Local application of the solution has fewer contraindications than baths.

Doctors notice that hydrogen sulfide baths are not taken at home and, in general, indoors. The concentration of vapors emanating from the water may exceed the permissible values.

In sanatoriums, they try to place pools in the open air. Hot springs. Therefore, swimming in them is pleasant even in winter. There are a number of hydrogen sulfide resorts, for example, near the city of Severobaikalsk.

Doctors supervising the guests recommend the heroine of the article also as a cure for ailments of the genitourinary system. True, pregnant and lactating procedures are contraindicated. But, for those who want to become a parent, hydrogen sulfide baths will not hurt.

In the west of the country, hydrogen sulfide is formed along the Black Sea shelf. True, there the compound is formed at a depth of about 150 meters, emerging as bubbles in shallow water.

If temporary procedures in a gas atmosphere are acceptable, then prolonged inhalation of hydrogen sulfide leads to the extinction of the ability to smell. This is the result of paralysis of the olfactory nerve.

How to recognize hydrosulphuric acid in the air at a low concentration, in the absence of an obvious smell? Will only help. She is also poisonous, but otherwise nothing. Wet in the reagent. In an atmosphere with a hydrogen sulfide content of at least 0.0000001%, the sheet will be covered with bloom.

Obtaining hydrosulfide acid

Since it is a solution of hydrogen sulfide, it is worth wondering how to obtain it. A popular way to use and sulfide. As the latter, natural minerals are taken. There are several sulfides in the bowels of the planet. The most famous, perhaps. Its formula: - FeS 2 .

The reaction between sulfide and violent, with active evolution of gas. Accordingly, the interaction is carried out in isolated rooms, using protective clothing and clothing.

Industrialists often go the other way. Hydrogen sulfide is a by-product of many industries. It remains only to extract the substance from industrial gases, the purification of which, anyway, is the direct responsibility of enterprises.

Then, hydrogen sulfide is dissolved in water. The liquid is heated. This makes dissociation more successful. The heroine of the article is ready for use or sale. Let's find out the prices.

Hydrosulphuric acid price

Since in everyday life the heroine of the article is needed only for water procedures, the form of selling the compound is reduced to for hydrogen sulfide baths. Example: - Means "Matsesta". It is sold in pharmacies, like other drugs of the group.

"Matsesta" is sold in packages, added to a bath with water at a temperature of 37-38 degrees Celsius. The drug is thoroughly stirred and immersed for 5-15 minutes. The pleasure costs about 300 per package, that is, one procedure.

Nobody canceled the remark about the danger of taking hydrogen sulfide baths at home. But, manufacturers are reinsured, choosing the optimal, safe concentration. With her, do not apply for 15 minutes.

For laboratory needs and industrial production, it makes no sense to pay for water with a minimum proportion of hydrogen sulfide. It is more convenient to organize the supply of liquefied gas in cylinders and do it yourself. The product is specific, demand is limited. Therefore, there are few offers, and for gas cylinders, as a rule, it is negotiable.

SECTION II. INORGANIC CHEMISTRY

9.3. ElementsVIAgroups

9.3.7. Hydrogen sulfide (hydrogen sulfide). Hydrogen sulfide (sulfide) acid. Sulphides 2

Hydrogen sulfide and hydrosulfide acid Hydrogen sulfide or hydrogen sulfide H 2 S , is a volatile compound of Sulfur with Hydrogen. In a hydrogen sulfide molecule, the sulfur atom forms two covalent polar bonds with two hydrogen atoms. The bond angle is 92.1°. Solution H 2 S in water is called hydrosulphuric acid.

The prevalence of hydrogen sulfide in nature

In nature, hydrogen sulfide is found in the composition of natural and volcanic gases, is found in the water of some mineral springs, and is also formed during the decomposition of organic substances (plant and animal residues), and therefore is found in small amounts in the air.

Huge reserves of hydrogen sulfide accumulated in the depths of the Black Sea: its layer starts from a depth of 150-200 m and reaches the bottom (maximum depth - 2210 m). The concentration of hydrogen sulfide at a depth of 150 m - 0.19 mg/l sea water, at a depth of 200 m - 0.83 mg / l, and at a depth of 2000 m it reaches 9.60 mg / l. Thus, with the exception of some specific micro-organisms, there are almost no living beings.

Physical properties and physiological action of hydrogen sulfide

Hydrogen sulfide - a colorless gas with a sharp unpleasant smell of rotten eggs - water dissolves up to 2.5 liters of H 2 S. Hydrogen sulfide is very toxic. The presence in the air of a volume fraction of 0.1% causes poisoning. Hydrogen sulfide binds hemoglobin, forming with an ion Fe2+ , which is part of it, a small-sized compound - ferrum (II) sulfide.

Extraction of hydrogen sulfide

In the laboratory, to extract hydrogen sulfide, a reaction is used between the sulfide of a metal element and perchloric acid or dilute sulfuric acid:

In industry, hydrogen sulfide is produced by passing hydrogen over molten sulfur:

Chemical properties of hydrogen sulfide and sulfide acid

hydrogen sulfide

1. Hydrogen sulfide burns with a bluish flame:

With a lack of oxygen, sulfur is formed:

2. Hydrogen sulfide is classified as a strong reducing agent - it can be oxidized to sulfur, sulfur (I V ) oxide or sulfuric acid:

3. Hydrogen sulfide interacts with oxidizing acids:

4. Reacts with both strong and weak oxidants:

The use of hydrogen sulfide

1. In the chemical industry for the production of sulfuric acid, elemental sulfur, sulfides.

2. In the organic synthesis of sulfur-containing substances (thiols 3).

3. As a reagent in analytical chemistry for the detection of ions of heavy metal elements (Ag + , Pb 2+ , С u 2+).

4. In the future, it is possible to use the giant reserves of hydrogen sulfide contained in the Black Sea for the needs of hydrogen sulfide energy and the chemical industry.

5. In medicine natural springs and artificial baths containing hydrogen sulfide are used to combat skin diseases.

Sulfonic acid

A solution of hydrogen sulfide in water is hydrogen sulfide water, or hydrogen sulfide (sulfide) acid is a weak dibasic acid. It is weaker than sulfite acid H 2 SO 3 . It dissociates in two stages (after the II degree - to a small extent):

Sulfonic acid exhibits general properties acids. It reacts with basic oxides, bases, forming medium and acidic salts, as well as with some salts and metals:

Salts of hydrosulphuric acid

Hydrosulphuric acid forms two series of salts: medium - sulfides (K 2 S, CaS) - and acidic - hydrogen sulfide(KHS, Ca(HS ) 2). Water-soluble sulfides of alkali and alkaline earth metal elements, as well as ammonium sulfide(NH4)2S. Some sulfides have a characteristic color: black - PbS and CuS, yellow - CdS, white - ZnS, MgS, pink - MnS.

Chemical properties of sulfides

1. Water-soluble sulfides slowly hydrolyze, that is, they are decomposed by water:

As a result of complete hydrolysis in solution, some sulfides cannot be obtained:

2. Sulfides react with some other salts:

These two reactions are qualitative for the detection of the sulfide ion S 2- , because the formation of characteristic black precipitates is observed - CuS and PbS.

3. Sulfides are decomposed by strong acids:

4. Sulfides, when interacting with oxidizing agents, exhibit restorative properties:

______________________________________________________________

1 The reaction is used to bind spilled mercury (demercurization). The floor area where the mercury thermometer has broken should be sprinkled with sulfur powder. Cinnabar is a non-poisonous compound. It does not evaporate (at room temperature) and can be easily collected.

2 Polysulfides - Sulfur compounds with the general formula X 2 S n , whose structure contains chains of atoms - S-S(n-2)-S - where, depending on the component X, n may vary: in hydrogen polysulfides H2Sn (oily liquid depending on the sulfur content from yellow to red) n varies from 2 to 23, in ammonium polysulfides ( NH 4) 2 S n - 2 to 9, alkali metals Me 2 S n - from 2 to 8. They are used in the leather industry to remove hair from the skin), in the production of dyes, polysulfide rubbers, in analytical chemistry.

3 Thiols (or mercaptans) have a strong unpleasant odor. In particular, egantiol C2H5SH added to natural gas (methane is odorless) before it enters the domestic gas pipeline to detect gas leaks from the system.

This is the name given to the process of dissolution in water, separation into hydronium ion and anion. Hydrogen sulfide dissociates by only 0.011%, moreover, in two stages. On the first of them, the degree of decomposition does not exceed 0.005%.

So, it is quite resistant, "holds the blow." However, this is by human standards. In chemistry, things are different. Let's dive into her world by continuing to study the properties of hydrogen sulfide.

Properties of hydrosulfide acid

The use of hydrosulfide acid

"On the face" is used in the literal sense. Cosmetologists use hydrogen sulfide solution for lifting procedures. In addition to tightening, you can get rid of cellulite and acne. Local application of the solution has fewer contraindications than baths.

Doctors notice that hydrogen sulfide baths are not taken at home and, in general, indoors. The concentration of vapors emanating from water may exceed the permissible values.

In the west of the country, hydrogen sulfide is formed along the Black Sea shelf. True, there the compound is formed at a depth of about 150 meters, emerging as bubbles in shallow water.

Obtaining hydrosulfide acid

The reaction between sulfide and violent, with active evolution of gas. Accordingly, the interaction is carried out in isolated rooms, using protective clothing and clothing.

Then, hydrogen sulfide is dissolved in water. The liquid is heated. This makes dissociation more successful. The heroine of the article is ready for use or sale. Let's find out the prices.

Hydrosulphuric acid price

Since in everyday life the heroine of the article is needed only for water procedures, the form of selling the compound is reduced to hydrogen sulfide baths. Example: - Means "Matsesta". It is sold in pharmacies, like other drugs of the group.

FeS + 2HCl \u003d FeCl 2 + H 2 S

Reaction of aluminum sulfide with cold water

Al 2 S 3 + 6H 2 O \u003d 2Al (OH) 3 + 3H 2 S

Direct synthesis from elements occurs when hydrogen is passed over molten sulfur:

H 2 + S = H 2 S.

Heating a mixture of paraffin and sulfur.

1.9. Hydrosulfuric acid and its salts

Hydrosulfuric acid has all the properties of weak acids. It reacts with metals, metal oxides, bases.

As a dibasic acid, it forms two types of salts - sulfides and hydrosulfides . Hydrosulfides are highly soluble in water, sulfides of alkali and alkaline earth metals as well, sulfides of heavy metals are practically insoluble.

Sulfides of alkali and alkaline earth metals are not colored, the rest have a characteristic color, for example, sulfides of copper (II), nickel and lead are black, cadmium, indium, tin are yellow, antimony is orange.

Ionic alkali metal sulfides M 2 S have a fluorite type structure, where each sulfur atom is surrounded by a cube of 8 metal atoms and each metal atom is surrounded by a tetrahedron of 4 sulfur atoms. MS type sulfides are characteristic of alkaline earth metals and have a sodium chloride type structure, where each metal and sulfur atom is surrounded by an octahedron of atoms of a different sort. When the covalent nature of the metal-sulfur bond is strengthened, structures with lower coordination numbers are realized.

Non-ferrous metal sulfides are found in nature as minerals and ores and serve as raw materials for the production of metals.

Getting sulfides

Direct interaction of simple substances when heated in an inert atmosphere

Recovery of solid salts of oxo acids

BaSO 4 + 4C = BaS + 4CO (at 1000°C)

SrSO 3 + 2NH 3 \u003d SrS + N 2 + 3H 2 O (at 800 ° C)

CaCO 3 + H 2 S + H 2 \u003d CaS + CO + 2H 2 O (at 900 ° C)

Slightly soluble metal sulfides are precipitated from their solutions by the action of hydrogen sulfide or ammonium sulfide

Mn(NO 3) 2 + H 2 S \u003d MnS ↓ + 2HNO 3

Pb (NO 3) 2 + (NH 4) 2 S \u003d PbS ↓ + 2NH 4 NO 3

Chemical properties of sulfides

Soluble sulfides in water are highly hydrolyzed, have an alkaline environment:

Na 2 S + H 2 O \u003d NaHS + NaOH;

S 2- + H 2 O \u003d HS - + OH -.

They are oxidized by air oxygen, depending on the conditions, the formation of oxides, sulfates and metals is possible:

2CuS + 3O 2 \u003d 2CuO + 2SO 2;

CaS + 2O 2 \u003d CaSO 4;

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

Sulfides, especially those soluble in water, are strong reducing agents:

2KMnO 4 + 3K 2 S + 4H 2 O = 3S + 2MnO 2 + 8KOH.

1.10. Toxicity of hydrogen sulfide

Hydrogen sulfide ignites in air at about 300°C. Its mixtures with air are explosive, containing from 4 to 45% H 2 S. The toxicity of hydrogen sulfide is often underestimated and work with it is carried out without observing sufficient precautions. Meanwhile, already 0.1% H 2 S in the air quickly causes severe poisoning. When hydrogen sulfide is inhaled in significant concentrations, fainting or even death from respiratory paralysis can occur instantly (if the victim was not removed from the poisoned atmosphere in a timely manner). The first symptom of acute poisoning is loss of smell. Subsequently, there are headache, dizziness and nausea. Sometimes after a while, sudden fainting occurs. The antidote is, first of all, clean air. Severely poisoned with hydrogen sulfide give oxygen to inhale. Sometimes you have to apply artificial respiration. Chronic poisoning with small amounts of H 2 S causes a general deterioration in well-being, emaciation, headaches, etc. The maximum permissible concentration of H 2 S in the air of industrial premises is 0.01 mg/l.

LESSON #26

Topic: “Hydrogen sulfide. Hydrosulfuric acid and its salts »

Chemistry: Grade 9

Lesson Objectives:

– Consider the composition, structure and properties of hydrogen sulfide.

- Learn to write reaction equations that characterize the properties of hydrogen sulfide and qualitative reactions to sulfides.

– Consider the impact of hydrogen sulfide on the environment and human health.

– Careful attitude of students to environment and your health.

- Cultivating the ability to work in pairs during self-analysis of control sections, tests.

Lesson type: learning a new topic.

Equipment and facilities: multimedia screen, Personal Computer, textbook

During the classes

I Organizing time(2 minutes.)

Greetings

Hello guys!

II Repetition of previously learned material. Checking homework

(10 min.)

Let's remember what we learned in the last lesson.

Slide #1

III Learning new material (30 min.)

1. Being in nature

Slide #4

Hydrogen sulfide is quite common in nature.

Hydrogen sulfide is found wherever there is decomposition and decay of plant and, especially, animal remains, under the action of microorganisms.

Some photosynthetic bacteria, such as green sulfur bacteria, for which hydrogen sulfide is a nutrient, release elemental sulfur, a product of the oxidation of hydrogen sulfide.

In our country, hydrogen sulfide is found in the Caucasus in sulfur mineral springs. close Mineralnye Vody there is the only hydrogen sulfide source in Russia and in the world, unique in its chemical composition, which has restored health to many people. (The resorts of Pyatigorsk, Essentuki are well-known

Hydrogen sulfide is found in volcanic gases.

In a dissolved state, it is maintained in the waters of the Black Sea.

The effect of hydrogen sulfide on the body:

Hydrogen sulfide not onlysmells bad, it is also extremely poisonous. When this gas is inhaled in large quantities, paralysis of the respiratory nerves quickly sets in, and then the person ceases to smell - this is the mortal danger of hydrogen sulfide.

There are many cases of poisoning with harmful gas when workers were injured while repairing pipelines. This gas is heavier, so it accumulates in pits, wells, where it is not so easy to get out quickly.

hydrogen sulfide H2S- at normal conditions colorless gas with an unpleasant odor (rotten eggs), slightly heavier than air. When inhaled, hydrogen sulfide binds to hemoglobin in the blood and prevents the transfer of oxygen, therefore it is very toxic.

Hydrogen sulfide is formed during the decay of protein products. It is contained in volcanic gases, is constantly released at the bottom of the Black Sea and accumulates in the lower layers of the water. Included in some mineral waters.

Hydrogen sulfide dissolves moderately in water - at room temperature, approximately 2.5 volumes of hydrogen sulfide dissolve in 1 volume of water.

In redox reactions, hydrogen sulfide exhibits strong reducing properties due to S−2 sulfur atoms.

It burns easily in oxygen or air to form sulfur or sulfur oxide (IV):

2H2S+O2=2H2O+2S↓

2H2S+3O2=2H2O+2SO2

Hydrosulphuric acid

A solution of hydrogen sulfide in water is calledhydrogen sulfide acid . It is a weak dibasic acid. It is characterized by the general properties of acids: H2S + 2KOH = K2S + 2H2O

Hydrosulfuric acid enters into exchange reactions with some salts if insoluble sulfides are formed:

H2S+CuCl2=CuS↓+2HCl.

2. Obtaining hydrogen sulfide (see textbook)

Slide #5

Hydrogen sulfide is obtained:

Under laboratory conditions, during the interaction of iron sulfide (II) with hydrochloric acidH 2 SO 4

FeS + H 2 SO 4 = FeSO 4 + H 2 S

Passing hydrogen over molten sulfur

H 2 + S = H 2 S

The interaction of aluminum sulfide with water (the purest hydrogen sulfide)

Al 2 S 3 + 6H 2 O = 2Al(OH) 3 ↓+3H 2 S

When a mixture of paraffin and sulfur is heated

C 20 H 42 + 21 S = 21 H 2 S + 20 C

Once, at a lecture, they demonstrated an experiment: the melting of sulfur in a test tube. Suddenly, everyone smelled a disgusting smell. The lecture was cancelled. Everything turned out to be simple: pieces of paraffin from the cork cap of the bottle in which sulfur powder was stored got into a test tube with sulfur. When this mixture was heated, hydrogen sulfide was released.

If the heating is stopped, the reaction stops and hydrogen sulfide is not released. This fact is convenient to use in educational laboratories.

And now we're going to do a little exercise.

3 The structure of hydrogen sulfide

Slide #6

Let's look at the structure of hydrogen sulfide (type chemical bond, type of crystal lattice).

You know that the properties of substances depend on the composition and structure.

Which physical properties you assume based on the structure (MKR)?

This:

Slide number 7

Gas;

With a low melting point (-82 0 C) and boiling point (-60 0 WITH);

Colorless;

With the smell of rotten eggs and a sweetish taste;

Slightly soluble in water (highly soluble in alcohol);

(2.4 volumes of hydrogen sulfide dissolve in 1 volume of water)

(This solution is called hydrogen sulfide water or hydrosulfide acid)

Heavier than air;

POISONOUS!

Even one breath of pure hydrogen sulfide leads to loss of consciousness due to paralysis of the respiratory center. Hydrogen sulfide is able to interact with iron ions that are part of the hemoglobin of the blood.

Chemical properties of hydrogen sulfide : in hydrogen sulfide (H 2 S) sulfur is in its lowest oxidation state (-2), and, therefore, exhibits strong reducing properties:

1) H 2 S+O2 (deficiency)→S+H 2 OFor all six schemes

2) H 2 S+O2 (excess) → SO 2 + H 2 Odraw up an electrical balance

3) H 2 S + HNO 3(conc.) → S + NO 2 + H 2 Oand equalize them using the method

4) H 2 S+Cl 2 → S + HClemail . balance !

5) H 2 S + FeCl 3 → FeCl 2 + HCl + S

6) H 2 S+KMnO 4 + H 2 SO 4 →S+MnSO 4 + K 2 SO 4 + H 2 O

Hydrogen sulfide is a solution of hydrogen sulfide in water. This acid is dibasic, anoxic, weak, volatile.

Chemical properties of hydrosulfide acid:

a) burns with a bluish flame (at a temperature of 250 0 – 300 0 WITH)

2 H 2 S -2 + 3 O 2 0 = 2 S +4 O 2 + 2 H 2 O

(brief analysis of OVR)

b) with a lack of oxygen

2 H 2 S + O 2 = 2 S 0 ↓+ 2 H 2 O

(reducing agent)

1) in an aqueous solution, it dissociates into ions in steps:

(make dissociation equations!)

2) interacts with metals in the activity series up to hydrogen:

H 2 S+ Ca →

3) interacts with basic oxides:

H 2 S+ MgO →

4) interacts with alkalis, forming acidic salts (hydrosulfides) and medium salts (sulfides): H 2 S+ KOH →

H 2 S+ 2 CON →

5) interacts with salts (if ↓):

H 2 S+CuSO 4 →

A qualitative reaction to hydrosulfide acid and its soluble salts (sulfides) is the interaction with soluble lead salts, with the formation of a black precipitate:

Na 2 S + Pb( NO 3 ) 2 →

Add the equations of chemical reactions, name the reaction products, for the last (qualitative reaction) make ionic equations!

Dissociation takes place in two stages:

IH 2 S → H + + HS - (hydrosulfide ion is formed)

II HS - ↔ H + + S 2- (on the second stage, dissociation practically does not occur)

Hydrosulfuric acid forms two series of salts - medium (sulfides) and acidic (hydrosulfides):

Na2S is sodium sulfide;

CaS, calcium sulfide;

NaHS, sodium hydrosulfide;

Ca(HS)2 is calcium hydrosulfide.

Record UChR with basic oxides and salts at home.

Suggest a reaction to detect the sulfide anionS 2-

Conduct a lab test to confirm

Write down UChR in molecular and ionic form.

Many sulfides are insoluble in water and are colored:

- PbS- black color;

- CuS- black color;

- AgS- black color (silver items turn black during long-term storage in the presence of hydrogen sulfide in the air);

- ZnS- White color;

- MgS- pink color.

Hydrogen sulfide and hydrosulfide acid are used in analytical chemistry to precipitate heavy metals.

Let's get back to our problem.

Is hydrogen sulfide good or bad?

5 Use of hydrogen sulfide

Hydrogen sulfide is of limited use due to its toxicity.

- In analytical chemistry, hydrogen sulfide and hydrogen sulfide water are used as precipitation reagents heavy metals, whose sulfides are very slightly soluble.

- In medicine - as part of natural and artificial hydrogen sulfide baths, as well as in some mineral waters.

- Hydrogen sulfide is used to produce sulfuric acid, elemental sulfur, sulfides.

- Colored sulphides serve as the basis for the manufacture of paints. They are also used in analytical chemistry.

- Potassium, strontium and barium sulfides are used in tanning to remove wool from hides before dressing them.

- IN last years the possibility of using hydrogen sulfide accumulated in the depths of the Black Sea as an energy (hydrogen sulfide energy) and chemical raw materials is being considered

Is everything now clear about the mystery of hydrogen sulfide?

Student statements

Why does hydrogen sulfide not accumulate in large quantities in nature?

(it is oxidized by atmospheric oxygen to elemental sulfur)

6 Final part (3 min.)

TASKS FOR REINFORCEMENT

Task number 1
Write the reaction equations that can be used to carry out the following transformations:
Cu→CuS→H 2 S→SO 2

Task number 2
Make the equations of redox reactions of complete and incomplete combustion of hydrogen sulfide. Arrange the coefficients using the electron balance method, indicate the oxidizing agent and reducing agent for each reaction, as well as the oxidation and reduction processes.

Task number 3
Write down the equation chemical reaction hydrogen sulfide with a solution of lead (II) nitrate in molecular, full and short ionic form. Mark the signs of this reaction, is the reaction reversible?

Task number 4
Hydrogen sulfide was passed through an 18% solution of copper (II) sulfate weighing 200 g. Calculate the mass of the precipitate resulting from this reaction.

Task number 5
Determine the volume of hydrogen sulfide (n.o.) formed during the interaction of hydrochloric acid with a 25% solution of iron (II) sulfide weighing 2 kg? What did we learn new for ourselves in the lesson?

What can be practically applied in life?

Student responses

Homework: §11, ex. 2, 3 page 34

Physical Properties

Gas, colorless, with the smell of rotten eggs, poisonous, soluble in water (in 1 V H 2 O dissolves 3 V H 2 S at n.o.); t °pl. = -86° C ; t °bp = -60°С.

The effect of hydrogen sulfide on the body:

Hydrogen sulfide not only smells bad, it is also extremely toxic. When this gas is inhaled in large quantities, paralysis of the respiratory nerves quickly sets in, and then the person ceases to smell - this is the mortal danger of hydrogen sulfide.

There are many cases of poisoning with harmful gas when workers were injured while repairing pipelines. This gas is heavier, so it accumulates in pits, wells, from which it is not so easy to get out quickly.

Receipt

1) H 2 + S → H 2 S (at t)

2) FeS + 2 HCl → FeCl 2 + H 2 S

Chemical properties

1) Solution H 2 S in water it is a weak dibasic acid.

Dissociation occurs in two stages:

H 2 S → H + + HS - (first stage, hydrosulfide ion is formed)

HS - → 2 H + + S 2- (second stage)

Hydrosulfuric acid forms two series of salts - medium (sulfides) and acidic (hydrosulfides):

Na 2 S- sodium sulfide;

CaS– calcium sulfide;

NaHS– sodium hydrosulfide;

Ca( HS) 2 – calcium hydrosulfide.

2) Interacts with bases:

H 2 S + 2 NaOH (excess) → Na 2 S + 2 H 2 O

H 2 S (excess) + NaOH → Na H S + H 2 O

3) H 2 S exhibits very strong restorative properties:

H 2 S -2 + Br 2 → S 0 + 2HBr

H 2 S -2 + 2FeCl 3 → 2FeCl 2 + S 0 + 2HCl

H 2 S -2 + 4Cl 2 + 4H 2 O → H 2 S +6 O 4 + 8HCl

3H 2 S -2 + 8HNO 3 (conc) → 3H 2 S +6 O 4 + 8NO + 4H 2 O

H 2 S -2 + H 2 S +6 O 4 (conc) → S 0 + S +4 O 2 + 2H 2 O

(when heated, the reaction proceeds in a different way:

H 2 S -2 + 3H 2 S +6 O 4 (conc) → 4S +4 O 2 + 4H 2 O

4) Hydrogen sulfide is oxidized:

with a lack O 2

2 H 2 S -2 + O 2 → 2 S 0 + 2 H 2 O

with an excess of O 2

2H 2 S -2 + 3O 2 → 2S +4 O 2 + 2H 2 O

5) Silver turns black on contact with hydrogen sulfide:

4 Ag + 2 H 2 S + O 2 → 2 Ag 2 S ↓ + 2 H 2 O

Darkened objects can be restored to shine. To do this, they are boiled in an enameled bowl with a solution of soda and aluminum foil. Aluminum reduces silver to metal, and the soda solution retains sulfur ions.

6) Qualitative reaction to hydrogen sulfide and soluble sulfides - formation of a dark brown (almost black) precipitate PbS:

H 2 S + Pb(NO 3) 2 → PbS↓ + 2HNO 3

Na 2 S + Pb(NO 3) 2 → PbS↓ + 2NaNO 3

Pb 2+ + S 2- → PbS ↓

Atmospheric pollution causes blackening of the surface of paintings painted with oil paints, which include white lead. One of the main reasons for the darkening of the artistic paintings of the old masters was the use of white lead, which, over several centuries, interacting with traces of hydrogen sulfide in the air (formed in small quantities during the decay of proteins; in the atmosphere of industrial regions, etc.) turns into PbS. White lead is a pigment that is lead carbonate ( II). It reacts with hydrogen sulfide found in the polluted atmosphere to form lead sulfide ( II), black compound:

PbCO 3 + H 2 S = PbS↓ + CO 2 + H 2 O

When processing lead sulfide ( II) hydrogen peroxide reaction occurs:

PbS + 4 H 2 O 2 = PbSO 4 + 4 H 2 O,

this forms lead sulfate ( II), a white compound.

Thus, blackened oil paintings are restored.

7) Restoration:

PbS + 4 H 2 O 2 → PbSO 4 (white) + 4 H 2 O

Sulfides

Getting sulfides

1) Many sulfides are obtained by heating a metal with sulfur:

Hg + S → HgS

2) Soluble sulfides are obtained by the action of hydrogen sulfide on alkalis:

H 2 S + 2 KOH → K 2 S + 2 H 2 O

3) Insoluble sulfides are obtained by exchange reactions:

CdCl 2 + Na 2 S → 2NaCl + CdS↓

Pb(NO 3) 2 + Na 2 S → 2NaNO 3 + PbS↓

ZnSO 4 + Na 2 S → Na 2 SO 4 + ZnS↓

MnSO 4 + Na 2 S → Na 2 SO 4 + MnS↓

2SbCl 3 + 3Na 2 S → 6NaCl + Sb 2 S 3 ↓

SnCl 2 + Na 2 S → 2NaCl + SnS↓

Chemical properties of sulfides

1) Soluble sulfides are highly hydrolyzed, as a result of which they aqueous solutions have an alkaline reaction:

K 2 S + H 2 O → KHS + KOH

S 2- + H 2 O → HS - + OH -

2) Sulfides of metals that are in the series of voltages to the left of iron (inclusive) are soluble in strong acids:

ZnS + H 2 SO 4 → ZnSO 4 + H 2 S

3) Insoluble sulfides can be converted into a soluble state by the action of concentrated HNO 3 :

FeS 2 + 8HNO 3 → Fe(NO 3) 3 + 2H 2 SO 4 + 5NO + 2H 2 O

TASKS FOR REINFORCEMENT

Task number 1
Write the reaction equations that can be used to carry out the following transformations:
Cu→ CuS→ H 2 S→ SO2

Task number 2
Make the equations of redox reactions of complete and incomplete combustion of hydrogen sulfide. Arrange the coefficients using the electron balance method, indicate the oxidizing agent and reducing agent for each reaction, as well as the oxidation and reduction processes.

Task number 3
Write the equation for the chemical reaction of hydrogen sulfide with a solution of lead (II) nitrate in molecular, full and short ionic form. Mark the signs of this reaction, is the reaction reversible?

Task number 4

Hydrogen sulfide was passed through an 18% solution of copper (II) sulfate weighing 200 g. Calculate the mass of the precipitate resulting from this reaction.

Task number 5
Determine the volume of hydrogen sulfide (n.o.) formed during the interaction of hydrochloric acid with a 25% solution of iron (II) sulfide weighing 2 kg?

1.9. Hydrosulfuric acid and its salts

Getting sulfides

Chemical properties of sulfides

1.10. Toxicity of hydrogen sulfide

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