Physical properties of hydrogen sulfide acid. Properties, production, application and price of hydrosulfide acid

LESSON #26

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

Chemistry: 9th grade

Lesson objectives:

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

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

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

– Students' caring attitude towards the environment and their health.

- Developing the ability to work in pairs during self-analysis of control sections and tests.

Lesson type: learning a new topic.

Equipment and facilities: multimedia screen, Personal Computer, textbook

During the classes

I Organizational moment (2 min.)

Greetings

Hello guys!

II Repetition of previously studied material. Checking homework

(10 min.)

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

Slide No. 1

III Learning new material (30 min.)

1. Being in nature

Slide No. 4

Hydrogen sulfide is quite common in nature.

Hydrogen sulfide occurs wherever decomposition and rotting of plant and, especially, animal remains occurs under the influence of microorganisms.

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

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

Hydrogen sulfide is found in volcanic gases.

It is maintained in a dissolved state in the waters of the Black Sea.

Effect of hydrogen sulfide on the body:

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

There are many cases of poisoning with harmful gases when the victims were workers repairing pipelines. This gas is heavier, so it accumulates in holes and wells, from where it is not so easy to get out quickly

Hydrogen sulfide H2S- Under normal conditions, a colorless gas with an unpleasant odor (rotten eggs), slightly heavier than air. When inhaled, hydrogen sulfide binds to hemoglobin in the blood and interferes with the transfer of oxygen, making it very poisonous.

Hydrogen sulfide is formed during the rotting 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 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 the S−2 sulfur atoms.

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

2H2S+O2=2H2O+2S↓

2H2S+3O2=2H2O+2SO2

Hydrogen sulfide 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

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

H2S+CuCl2=CuS↓+2HCl.

2. Production of hydrogen sulfide (see textbook)

Slide No. 5

Hydrogen sulfide is obtained:

In 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

Interaction of aluminum sulfide with water (the purest hydrogen sulfide)

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

When heating a mixture of paraffin and sulfur

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

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

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

And now we will have a little physical education.

3 Structure of hydrogen sulfide

Slide No. 6

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

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

What physical properties do you assume based on the structure (MCR)?

This:

Slide No. 7

Gas;

With 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 are dissolved 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 included in 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) N 2 S+ O2 (disadvantage)→ S + H 2 OFor all six schemes

2) N 2 S+ O2 (excess) → SO 2 +H 2 Omake an electrical balance

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

4) N 2 S+Cl 2 → S + HClel . balance !

5) N 2 S+FeCl 3 →FeCl 2 + HCl + S

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

Hydrogen sulfide acid is a solution of hydrogen sulfide in water. This acid is dibasic, oxygen-free, 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 dissociates into ions stepwise:

(make up dissociation equations!)

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

N 2 S+ Ca →

3) interacts with basic oxides:

N 2 S+ MgO →

4) interacts with alkalis, forming acid salts (hydrosulfides) and middle salts (sulfides): H 2 S+ KON →

N 2 S+ 2 KON →

5) interacts with salts (if ↓):

N 2 S+CuSO 4 →

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

Na 2 S + Pb( NO 3 ) 2 →

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

Dissociation occurs in two stages:

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

II H.S. - ↔ H + + S 2- (in the second step, dissociation practically does not occur)

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

Na2S – sodium sulfide;

CaS – calcium sulfide;

NaHS – sodium hydrosulfide;

Ca(HS)2 – calcium hydrosulfide.

Write down chemical reactions with basic oxides and salts at home.

Suggest a reaction to detect sulfide anionS 2-

Conduct a laboratory experiment to confirm

Write the UCR 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 when stored for a long time 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 beneficial or harmful?

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 reagents for the precipitation of heavy metals, the sulfides of which are very poorly 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, and sulfides.

- Colored sulfides 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 tanning.

- In recent years, the possibility of using hydrogen sulfide accumulated in the depths of the Black Sea as energy (hydrogen sulfide energy) and chemical raw materials has been considered

Is everything now clear about the mystery of hydrogen sulfide?

Student statements

Why doesn't hydrogen sulfide accumulate in large quantities in nature?

(it is oxidized by atmospheric oxygen to elemental sulfur)

6 Final part (3 min.)

ASSIGNMENT TASKS

Task No. 1
Write the reaction equations that can be used to carry out the following transformations:
Cu →CuS →H 2 S → SO 2

Task No. 2
Write down equations for the redox reactions of complete and incomplete combustion of hydrogen sulfide. Arrange the coefficients using the electronic balance method, indicate the oxidizing agent and reducing agent for each reaction, as well as the processes of oxidation and reduction.

Task No. 3
Write down the equation for the chemical reaction of hydrogen sulfide with a solution of lead (II) nitrate in molecular, total and short ionic form. Note the signs of this reaction, is the reaction reversible?

Task No. 4
Hydrogen sulfide was passed through an 18% solution of copper (II) sulfate weighing 200 g. Calculate the mass of the precipitate formed as a result of this reaction.

Task No. 5
Determine the volume of hydrogen sulfide (NS) formed by the interaction of hydrochloric acid with a 25% solution of iron (II) sulfide weighing 2 kg? What new did we learn in the lesson?

What can be practically applied in life?

Student answers

Homework: §11, ex. 2, 3 page 34

PART AND

GENERAL CHEMISTRY

CHEMISTRY OF 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

Due to 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 the simple substance sulfur:

Hydrogen sulfide reacts with hexafluorsulfur at elevated temperatures:

When hydrogen sulfide is dissolved in water, a weak dibasic sulfide acid is formed (K a 1 = 10 - 7, K a 2 = 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 sulfides(K.H.S. - potassium hydrogen sulfide). Since sulfidic acid is a rather weak acid, solutions of sulfides and hydrogen sulfides undergo hydrolysis at the anion, and accordingly the solution environment is basic:

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

Extraction and application 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. It also plays an important role in the sulfuric acid production process.

Qualitative reaction to hydrogen sulfide i sulfide ion

To determine sulfide ions in a solution, add any soluble Lead salt to the test solution (most often P b acetate (CH 3 COO) 2 or nitrate Pb (NO 3) 2). If after addition a black precipitate appears in the solution, then the test sample contained sulfide ions:

If they say that he is weak, it means that illness or hunger has come, in general, adversity. In chemistry everything is different. Let's consider weak hydrogen sulfide. It is weak not because it is ready to fall apart or die, but, on the contrary, because of its unwillingness to dissociate.

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%, and in two stages. In the first of them, the degree of decay does not exceed 0.005%.

So, it is quite resistant, “takes a hit.” However, this is by human standards. In chemistry everything is different. Let's dive into its world by continuing to study the properties of hydrogen sulfide.

Properties of hydrogen sulfide acid

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

In fact, hydrosulfide acid is an aqueous solution of gas. Hydrogen sulfide is known to smell like rotten eggs and is toxic. the substance does not. Nor do indicator papers that have been in hydrosulfide acid. Property this is another indicator of a weak connection. Strong ones color litmus in tones.

Characteristics of hydrogen sulfide acid comes down not only to slow dissolution in water. Other reactions with the heroine of the article also take place slowly. In relation to human character, this is rather laziness than weakness.

For example, hydrogen sulfide solution reacts reluctantly with metals. 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 H2 in the voltage series. Such elements are capable of displacing hydrogen from solution. Interaction can lead to the formation hydrosulfide salts.

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

When interacting with alkaline earth metals, hydrogen sulfide also reacts with alkalis. The heroine of the article acts as a reducing agent, that is, she donates electrons. It turns out that the properties of the connection are typical for the weak type.

Ambiguously different. 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. We will tell you where and how it is used in the next chapter.

Application of hydrogen sulfide acid

Dissociation of hydrosulfide acid to a solution with a saturation of thousandths of a percent allows the compound to be used for medicinal purposes. They are usually organized at places where groundwater containing hydrogen sulfide emerges. 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 and more quickly supplies the organs with the elements they need. Metabolism accelerates, leading to cleansing of toxins. For the overall effect of rejuvenation.

“On the face” is used in its literal 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 note that baths with hydrogen sulfide are not taken at home or, in general, in enclosed spaces. The concentration of vapors emanating from water may exceed the permissible limits.

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

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

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

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

How to recognize hydrogen sulfide acid in the air at low concentrations, in the absence of obvious odor? It will only help. She is also poisonous, but there is no other way. It is moistened in the reagent. In an atmosphere containing at least 0.0000001% hydrogen sulfide, the leaf will become coated.

Preparation of hydrogen sulfide acid

Since it is a solution of hydrogen sulfide, it is worth asking about its production. The method of using sulfide is also popular. Natural minerals are used as the latter. There are several sulfides in the interior of the planet. The most famous is perhaps. Its formula: - FeS 2.

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

Industrialists often go the other way. Hydrogen sulfide is a by-product of many industries. All that remains is 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 price tags.

Hydrosulfide acid price

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

“Matsesta” is sold in bags and added to a bath of 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.

The remark about the dangers of taking hydrogen sulfide baths at home has not been canceled. But manufacturers play it safe by selecting the optimal, safe concentration. With it, do not apply it within 15 minutes.

For laboratory needs and industrial production, it makes no sense to pay for water with a minimal 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 gas cylinders are usually negotiable.

SECTION II. INORGANIC CHEMISTRY

9.3. ElementsVIAgroups

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

Hydrogen sulfide and hydrogen sulfide 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 H2S in water is called hydrosulfide acid.

Prevalence of hydrogen sulfide in nature

In nature, hydrogen sulfide is found in natural and volcanic gases, is contained 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 quantities 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). Hydrogen sulfide concentration at a depth of 150 m - 0.19 mg/l of 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 microorganisms, there are almost no living creatures there.

Physical properties and physiological effects of hydrogen sulfide

Hydrogen sulfide is a colorless gas with a sharp, unpleasant odor of rotten eggs - hich water dissolves up to 2.5 liters of H 2 S. Hydrogen sulfide is very poisonous. The presence of a volume fraction of 0.1% in the air causes poisoning. Hydrogen sulfide binds hemoglobin, forming with the ion Fe 2+ , included in its composition, is a low-purity compound - ferrum(II) sulfide.

Hydrogen sulfide production

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

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:

When there is a lack of oxygen, sulfur is formed:

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

3. Hydrogen sulfide interacts with oxidizing acids:

4. Reacts with both strong and weak oxidizing agents:

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+, C u 2+).

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

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

Sulfide acid

A solution of hydrogen sulfide in water - hydrogen sulfide water, or hydrogen sulfide (sulfide) acid - a weak dibasic acid. It is weaker than sulfite acid H 2 SO 3. Dissociates in two steps (beyond degree II - to a slight extent):

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

Salts of hydrosulfide acid

Hydrogen sulfide acid forms two series of salts: medium - sulfides (K 2 S, CaS) - and acidic - hydrogensulfides(KHS, Ca(HS ) 2). Water-soluble sulfides of alkali and alkaline earth metal elements, as well as ammonium sulfide(NH 4) 2 S. 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 decompose with 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 sulfide ion S 2- , because the formation of characteristic black deposits is observed - CuS and PbS.

3. Sulfides are decomposed by strong acids:

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

______________________________________________________________

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

2 Polysulfides are Sulfur compounds with the general formula X 2 S n , the structure of which contains chains of atoms - S - S (n -2) - S -, where, depending on the component X, n may vary: in Hydrogen polysulfides H2Sn (liquid polysulfides, depending on the Sulfur content, from yellow to red) n varies from 2 to 23, in ammonium polysulfides ( NH 4) 2 S n - from 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, and in analytical chemistry.

3 Thiols (or mercaptans) have a strong unpleasant odor. In particular, eganthiol C2H5SH added to natural gas (methane has no odor) before it is supplied to the domestic gas pipeline to detect gas leaks from the system.

Sulfur is one of the substances known to mankind from time immemorial. Even the ancient Greeks and Romans found various uses for it. Pieces of native sulfur were used to perform the ritual of expelling evil spirits. So, according to legend, Odysseus, returning to his home after long wanderings, first ordered it to be fumigated with sulfur. There are many references to this substance in the Bible.

In the Middle Ages, sulfur occupied an important place in the arsenal of alchemists. As they believed, all metals consist of mercury and sulfur: the less sulfur, the more noble. Practical interest in this substance in Europe increased in the 13th – 14th centuries, after the advent of gunpowder and firearms. The main supplier of sulfur was Italy.

Today, sulfur is used as a raw material for the production of sulfuric acid, gunpowder, in the vulcanization of rubber, in organic synthesis, and also for controlling agricultural pests. Sulfur powder is used in medicine as an external disinfectant.

Interaction of sulfur with simple substances

Sulfur reacts like oxidizer :

2Na + S = Na 2 S

How reducing agent :

Interaction of sulfur with complex substances

a) sulfur does not dissolve in water and is not even wetted by water;

b) how the reducing agent sulfur interacts with ( , ) when heated:

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

S + 2HNO3 = H2SO4 + 2NO

S + 6HNO 3 = H 2 SO 4 + 6NO 2 + 2H 2 O

c) exhibiting the properties of both an oxidizing agent and a reducing agent, sulfur enters into disproportionation reactions (self-oxidation-self-reduction) with solutions when heated:

3S + 6NaOH = 2Na2S + Na2SO3 + 3H2O

Hydrogen sulfide and hydrogen sulfide acid

a) H 2 S + CaO = CaS + H 2 O

b) H 2 S + NaOH = NaHS + H 2 O

c) CuSO 4 + H 2 S = CuS↓ + H 2 SO 4

d) Ca + H 2 S = CaS + H 2

A qualitative reaction to hydrosulfide acid and its soluble salts (i.e., to the sulfide ion S 2-) is their interaction with soluble salts. In this case, a black precipitate of lead (II) sulfide PbS is released:

Na 2 S + Pb(NO 3) 2 = PbS↓ + 2NaNO 3

Redox properties

In redox reactions, both gaseous hydrogen sulfide and hydrogen sulfide acid exhibit strong reducing properties, since the sulfur atom in H2S has the lowest oxidation state - 2, and therefore can only be oxidized. It oxidizes easily:

You can download abstracts on other topics

Hydrogen sulfide (H 2 S) - very carcinogenic, toxic gas. It has a sharp, characteristic smell of rotten eggs.

Obtaining hydrogen sulfide.

1. In the laboratory H 2 S obtained by reaction between sulfides and dilute acids:

FeS + 2 HCl = FeCl 2 + H 2 S,

2. Interaction Al 2 S 3 with cold water (the resulting hydrogen sulfide is purer than with the first production method):

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

Chemical properties of hydrogen sulfide.

Hydrogen sulfide H2S - a covalent compound that does not form hydrogen bonds like a molecule H 2 O. (The difference is that the sulfur atom is larger and more electronegative than the oxygen atom. Therefore, the charge density of sulfur is lower. And due to the lack of hydrogen bonds, the boiling point H 2 S higher than that of oxygen. Also H 2 S poorly soluble in water, which also indicates the absence of hydrogen bonds).

H 2 S + Br 2 = S + 2HBr,

2. Hydrogen sulfide H 2 S- a very weak acid, dissociates stepwise in solution:

H 2 S ⇆ H + + H.S. - ,

H.S. - ⇆ H + + S 2- ,

3. Interacts with strong oxidizing agents:

H 2 S + 4Cl 2 + 4H 2 O = H 2 SO 4 + 8HCl,

2 H 2 S + H 2 SO 3 = 3 S + 3 H 2 O,

2 FeCl 3 + H 2 S = 2 FeCl 2 + S + 2 HCl,

4. Reacts with bases, basic oxides and salts, while forming acidic and moderate salts (hydrosulfides and sulfides):

Pb(NO 3) 2 + 2S = PbS↓ + 2HNO 3.

This reaction is used to detect hydrogen sulfide or sulfide ions. PbS- black sediment.

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 no.); t °pl. = -86°C ; t °b. = -60°C.

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 occurs, and then the person ceases to smell - this is the mortal danger of hydrogen sulfide.

There are many cases of poisoning with harmful gases when the victims were workers repairing pipelines. This gas is heavier, so it accumulates in holes and wells, from where 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)

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

Na 2 S– sodium sulfide;

CaS– calcium sulfide;

NaHS– sodium hydrosulfide;

Ca( H.S.) 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 differently:

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

4) Hydrogen sulfide is oxidized:

in case of shortage O 2

2 H 2 S -2 + O 2 → 2 S 0 + 2 H 2 O

with excess O 2

2H 2 S -2 + 3O 2 → 2S +4 O 2 + 2H 2 O

5) Silver turns black when in 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 enamel 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 that contain lead white. One of the main reasons for the darkening of artistic paintings by old masters was the use of lead white, which over several centuries, interacting with traces of hydrogen sulfide in the air (formed in small quantities during the rotting of proteins; in the atmosphere of industrial regions, etc.) turns into PbS. Lead white is a pigment that is lead carbonate ( II). It reacts with hydrogen sulfide contained in the polluted atmosphere, forming lead sulfide ( II), black connection:

PbCO 3 + H 2 S = PbS↓ + CO 2 + H 2 O

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

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

this produces lead sulfate ( II), the connection is white.

This is how blackened oil paintings are restored.

7) Restoration:

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

Sulfides

Preparation of sulfides

1) Many sulfides are prepared by heating the 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 their 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 located in the voltage series 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

ASSIGNMENT TASKS