Presentation of the use of hydrogen sulfide in everyday life. Chemistry lesson "Hydrogen sulfide. Sulfides" (grade 9). Water solubility

Hydrogen sulfide. Sulphides

Chemistry lesson, grade 9

The presentation was prepared by

chemistry teacher

the highest qualification category

MBOU "Veresaevskaya secondary school"

Levitskaya Ekaterina Nikolaevna

Updating basic knowledge

• Write the molecular and ionic equations for the reaction between solutions:

iron (II) sulfide and sulfuric acid

• What substance is formed as a result of the reaction?

Motivation for learning activities

Remember

what do you know about hydrogen sulfide

Hydrogen sulfide in nature, its physical properties. Obtaining hydrogen sulfide.

Sulfur hyena

Yu. Kuznetsov "Secrets of the Black Sea"

The Crimea was shaking in the twenty-eighth year,

And the sea reared up,

Emitting, to the horror of the people,

Fiery sulfur pillars.

It's all gone.

Foam walks again

But since then everything is higher

everything is denser

Twilight Sulfur Gehenna

Approaches the bottoms of ships.

Oxidizing agent or reducing agent?

H + 2 S 2-

S 2- - 2e → S 0

S 2- - 6e → S 4+

hydrogen sulfide has the properties of a reducing agent,

because sulfur included in its composition , has minimal oxidation state -2 and in this case can only donate electrons

We fill the table

Properties

Hydrogen sulfide

Formula of substance

Type of chemical bond

State of aggregation under normal conditions

Colour

Lighter or heavier than air(confirm by calculations)

Smell

Water solubility

Physiological action

Being in nature

Getting in the laboratory

Chemical properties of hydrogen sulfide

Properties of an aqueous solution of hydrogen sulfide

Qualitative reaction for sulfide ions

Combustion of hydrogen sulfide

Hydrogen sulfide burns

in the air with a blue flame, while

sulfur dioxide, or sulfur (IV) oxide and water .

And with a lack of oxygen, water vapor and sulfur .

Working in pairs:

Make the equations of these reactions by arranging the coefficients using the electronic balance method)

Hydrogen sulfide - reducing agent

Burning in air (blue flame):

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

S 2- - 6е → S 4+

O 0 2 + 4 e = 2 O 2-

Combustion with a lack of oxygen:

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

S 2- - 2е → S 0

O 0 2 + 4 e = 2 O 2-

Check yourself!

Na 2 S + CuCl 2 = CuS ↓ + 2NaCl

2 Na + + S 2- + Cu 2+ + 2Cl - = CuS ↓ +2 Na + + 2Cl -

S 2- + Cu 2+ = CuS ↓

A black precipitate is formed - CuS-copper (II) sulfide

Independent work

Complete the task

according to the textbook:

to choose

№ 2.3 p. 70)

Live and learn!

ALL:

1) Work through the material in paragraph 19

2) Fill in the remaining columns of the table

3) Problem number 4, test tasks p.70

Creative assignment .

1) Using the Internet and additional literature, prepare a message or presentation on one of the topics:

"Influence of sulfur (IV) oxide on the human body"

"Acid Rains"

"Application of sulfur oxide (IV)"

2) Make 3-5 test tasks based on the material studied.

Slide 1

Slide 2

Hydrogen sulfide, hydrogen sulphide (H2S) is a colorless gas with a pungent odor. Chemical formula H2S Rel. molecule mass 34.082 a. eat. Molar mass 34.082 g / mol Melting point -82.30 ° C Boiling point -60.28 ° C Density of the substance 1.363 g / L g / cm3 Solubility 0.25 (40 ° C) g / 100 ml pKa 6.89, 19 ± 2 State (st.w.) colorless gas CAS number 7782-79-8

Slide 3

Being in nature Occurs naturally in petroleum, natural gas, volcanic gas and in hot springs.

Slide 4

Properties Thermally unstable (at temperatures above 400 ° C it decomposes into simple substances- S and H2), a poisonous gas heavier than air with an unpleasant smell of rotten eggs. The hydrogen sulfide molecule has an angular shape, therefore it is polar (μ = 0.34 · 10-29 C · m). Unlike water molecules, hydrogen sulfide molecules do not form strong hydrogen bonds, therefore H2S is a gas. Saturated water solution H2S is hydrosulfuric acid.

Slide 5

Preparation In the laboratory, it is usually obtained by the action of dilute acids on sulfides: FeS + 2HCl = FeCl2 + H2S Or by adding water to aluminum sulfide: Al2S3 + H2O = 2Al (OH) 3 + H2S (the reaction differs in the purity of the obtained hydrogen sulfide)

Slide 6

Application Hydrogen sulfide finds limited use due to its toxicity. V analytical chemistry hydrogen sulfide and hydrogen sulfide water are used as a precipitation reagent heavy metals whose sulfides are very slightly soluble In medicine - in the composition of hydrogen sulfide baths Hydrogen sulfide is used to obtain sulfuric acid, elemental sulfur, sulfides Used in organic synthesis to obtain thiophene and mercaptans B last years the possibility of using hydrogen sulfide accumulated in the depths of the Black Sea as an energy and chemical raw material is being considered.

Slide 7

Toxicology Very toxic. At high concentrations, a single inhalation can cause instant death. At low concentrations, adaptation to the unpleasant smell of "rotten eggs" occurs rather quickly, and it ceases to be felt. A sweetish metallic taste develops in the mouth. At high concentration, it is odorless.

Presentation on the topic "Hydrogen sulfide" in chemistry in powerpoint format. The presentation tells about the colorless gas hydrogen sulfide, its properties, production, use and toxicity. Author of the presentation: Sergey Zorin, Serik Shakenov, Dmitry Yugay, Artyom Ohay, 9th grade students.

Fragments from the presentation

Hydrogen sulfide, hydrogen sulphide (H2S) is a colorless gas with a pungent odor.

• Chemical formula - H2S
• Rel. molecule mass - 34.082 a. eat.
• Molar mass - 34.082 g / mol
• Melting point - -82.30 ° C
• Evaporating temperature - -60.28 ° C
• The density of the substance is 1.363 g / l g / cm3
• Solubility - 0.25 (40 ° C) g / 100 ml
• pKa - 6.89, 19 ± 2
• Condition (st.usl) - colorless gas
• CAS number - 7782-79-8

Being in nature

It occurs naturally in petroleum, natural gas, volcanic gas and in hot springs.

Properties

It is thermally unstable (at temperatures above 400 ° C it decomposes into simple substances - S and H2), a poisonous gas is heavier than air with an unpleasant smell of rotten eggs. The hydrogen sulfide molecule has an angular shape, therefore it is polar (μ = 0.34 · 10-29 C · m). Unlike water molecules, hydrogen sulfide molecules do not form strong hydrogen bonds, therefore H2S is a gas. A saturated aqueous solution of H2S is hydrosulfuric acid.

Receiving

• In the laboratory, it is usually obtained by the action of dilute acids on sulfides: FeS + 2HCl = FeCl2 + H2S
• Or when adding water to aluminum sulfide: Al2S3 + H2O = 2Al (OH) 3 + H2S (the reaction differs in the purity of the obtained hydrogen sulfide)

Application

• Due to its toxicity, hydrogen sulfide is of limited use.
• In analytical chemistry, hydrogen sulfide and hydrogen sulfide water are used as a reagent for the precipitation of heavy metals, the sulfides of which are very slightly soluble.
• In medicine - as part of hydrogen sulfide baths
• Hydrogen sulfide is used to produce sulfuric acid, elemental sulfur, sulfides
• Used in organic synthesis to obtain thiophene and mercaptans
• In recent years, the possibility of using hydrogen sulfide accumulated in the depths of the Black Sea as an energy and chemical raw material has been considered.

Toxicology

• Very toxic. At high concentrations, a single inhalation can cause instant death. At low concentrations, adaptation to the unpleasant smell of "rotten eggs" occurs rather quickly, and it ceases to be felt. There is a sweetish metallic taste in the mouth
• At high concentration, it is odorless.

Hydrogen sulfide in nature It is a part of volcanic gases. Formed when proteins decay. Found in mineral springs (Matsesta, Pyatigorsk, Caucasus).

Hydrogen sulfide, hydrogen sulphide (H 2 S) is a colorless gas with a pungent odor. Chemical formula H 2 S Rel. molecule weight 34.082 e. m. Molar mass 34.082 g / mol Melting point -82. 30 ° C Boiling point -60. 28 ° C Density of the substance 1.363 g / l g / cm 3 Solubility 0.25 (40 ° C) g / 100 ml State (st.conv.) Colorless gas

Physical properties Gas, colorless, with the smell of rotten eggs, poisonous (odorless in large concentrations), heavier than air, soluble in water (in 1 V H 2 O dissolves 2, 4 V H 2 S at normal conditions); t ° pl = -86 ° C; t ° bale = -60 ° С. Poisonous! Able to interact with iron included in the hemoglobin of the blood. Work with hydrogen sulphide in a fume cupboard and sealed devices!

Effect of hydrogen sulfide on the body Very toxic. Even one breath of pure hydrogen sulfide leads to loss of consciousness due to paralysis of the respiratory center. Its insidiousness lies in the fact that after a slight poisoning, its smell ceases to be felt. From hydrogen sulfide released during the eruption of Vesuvius, he died in 79 BC. NS. natural scientist Pliny the Elder.

Obtaining hydrogen sulfide in the laboratory 1) H 2 + S → H 2 S 2) Fe. S 2 + 2 HCl → H 2 S + Fe. Cl 2 iron (II) sulfide

1) Combustion of hydrogen sulfide. Complete combustion (with excess O 2) 2 H 2 S-2 + 3 O 2 → 2 S + 4 O 2 + 2 H 2 O Incomplete combustion (lack of O 2) 2 H 2 S-2 + O 2 → 2 S 0 + 2 H 2 O

2) Reducing properties (with halogens, salts, oxygen, acids). H 2 S-2 + Br 2 → S 0 + 2 HBr H 2 S-2 + 2 Fe. Cl 3 → 2 Fe. Cl 2 + S 0 + 2 HCl

3) Interaction with water. A solution of H 2 S in water is a weak dibasic acid ( hydrosulfuric acid) Dissociation occurs in two stages: I st. H 2 S⇄ H + + HS- (hydrosulfide - ion) II st. HS- ⇄ H + + S 2 - (sulfide ion) Average salts (sulfides): Na 2 S - sodium sulfide Average salts (sulfides): Ca. S - calcium sulfide Acid salts (hydrosulfides): Na. HS - sodium hydrosulfide Ca (HS) 2 - calcium hydrosulfide

4) Acidic properties. Interacts with bases: H 2 S + 2 Na. OH h. → Na 2 S + 2 H 2 O sodium sulfide H 2 S g. + Na. OH → Na. HS + H 2 O sodium hydrosulfide

5) Qualitative reaction to hydrogen sulfide acid and sulfides. H 2 S + Pb (NO 3) 2 → Pb. S ↓ + 2 HNO 3 Pb 2+ + S 2 - → Pb. S ↓ black H 2 S + Cu (NO 3) 2 → Cu. S ↓ + 2 HNO 3 Cu 2+ + S 2 - → Cu. S ↓ black

Many sulfides are colored and insoluble in water: Pb. S - black, Cd. S - yellow, Zn. S - white, Mn. S - pink, Cu. S - black, Ni. S - black.

Application of hydrogen sulfide Due to its toxicity, hydrogen sulfide finds limited application. Ø In medicine - as part of natural and artificial hydrogen sulfide baths (normalizes the functioning of the heart and nervous system, blood pressure, is used for skin diseases. Ø Hydrogen sulfide is used to obtain sulfuric acid, sulfur, sulfides.

Lesson “Hydrogen sulfide. Sulfides "

(Grade 9)

Lesson objectives:

Educational:

– 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 effect of hydrogen sulfide on environment and human health.

Developing:

Be able to apply the knowledge gained to explain a variety of chemical phenomena and properties of substances.

Be able to apply additional material from information sources, computer technology

Use the acquired knowledge and skills in practical activities and Everyday life: a) environmentally sound behavior in the environment; b) assessing the impact of chemical pollution of the environment on the body person.

Educational:

– Respect for the environment and health of students.

- Educating the ability to work in pairs in introspection of control slices, tests.

Lesson Objectives:

Promote the development of chemical literacy in students.

Interdisciplinary connections: The relationship of chemistry with other sciences: biology, geography, mathematics, medicine and literature.

Lesson type: studying a new topic.

Elements of pedagogical technologies: differentiated learning, problem learning, ICT, gaming technologies.

Methods:

reproductive, partially exploratory.

verbal (story, conversation), independent work of students.

Equipment and facilities:

multimedia screen

Personal Computer

reagents for qualitative response per sulfide anion

textbook

During the classes

I Organizing time(2 minutes.)

Receiving a report from the attendant;

Greetings

Hello guys! Today we have guests at the lesson. Don't worry, work as usual.

II Repetition of previously studied material. Homework check

(10 min.)

?

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

We learned that sulfur is a simple substance, studied its physical and chemical properties, allotropic modifications, the finding of sulfur in nature.

At home, it was necessary to consider the proposed reactions in the light of ideas about redox processes.

Did everyone complete the written assignment?

Differentiated writing (5-7 min.)

Assistants distribute tasks according to options.

Students answer questions for differentiated writing.

Mutual review of work performance with simultaneous presentation of answers on the slide.

Who worked with level B and C - raise your hands.

Slide number 1

III Learning new material (30 min.)

Mystery

I am everywhere - but little by little,

I blacken the silver spoon.

When the egg is spoiled

I am immediately there too

I suppress my appetite

And it is very poisonous.

And also remember the lines from A.S. Pushkin, written in 1832 in the poem "And then we went - and fear embraced me":

“... Then I heard (oh, miracle!) A bad smell,

As if a rotten egg broke ... "

?

What kind of connection does Pushkin mention in a passage of this verse?

How did you guess that this is hydrogen sulfide?

And what is still unknown to you about the properties of hydrogen sulfide?

So, the topic of the lesson today is hydrogen sulfide(I open the board) .

We write in the notebook the topic “Hydrogen sulfide. Sulphides ».

Slide number 2

Lesson Objectives: Slide number 3

To study the composition, structure and properties, methods of obtaining hydrogen sulfide and sulfides;

Trace the causal relationship between the structure, properties and use of substances;

Consider the impact of hydrogen sulfide on the environment and human health;

To consolidate the ability to compose UHR and consider them from the point of view of redox processes;

Promote the development of student literacy.

An outline for the discussion of this topic on the board.

As we study the topic, we will take notes.

1. Being in nature

Slide number 4

Hydrogen sulfide is quite common in nature. And where exactly, he will tell us(student speech)

Hydrogen sulfide is found everywhere where decomposition and putrefaction 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, release elemental sulfur, a product of hydrogen sulfide oxidation.

In our country, hydrogen sulfide is found in the Caucasus in sulfur mineral springs. Near Mineralnye Vody there is a unique in Russia and in the world unique chemical composition a hydrogen sulfide source that restored health to many people. (The resorts of Pyatigorsk, Essentuki, Matsestinsky springs are known.

The sources are used to treat diseases of the musculoskeletal system, cardiovascular system, and skin diseases. Hydrogen sulfide irritates the nerve endings of the skin, dilating small blood vessels, improving blood circulation in tissues, i.e. produces their food. It also normalizes blood pressure, nervous system, improves heart function.

Hydrogen sulfide is found in volcanic gases.

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

2. Obtaining hydrogen sulfide (see the tutorial)

Slide number 5

Hydrogen sulfide is obtained:

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

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

Flowing 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 an experiment was demonstrated at a lecture: the melting of 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 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 will spend a little physical education.

3 Structure of hydrogen sulfide

Slide number 6

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

?

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

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

It:Slide number 7

Gas;

Low melting point (-82 0 C) and boiling point (-60 0 WITH);

Colorless;

With the smell of rotten eggs and a sweetish taste;

Let's slightly dissolve in water (it dissolves well in alcohol);

(2.4 volumes of hydrogen sulfide are dissolved in 1 volume of water)

(This solution is called hydrogen sulphide water or hydrogen sulphide acid)

Heavier than air;

POISONOUS!

Even one inhalation 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 blood hemoglobin.

?

Slide No. 8

There is a problem : is hydrogen sulfide useful or harmful?

Hydrogen sulfide is poisonous, but hydrogen sulfide medicinal sources exist.

We must solve this problem by the end of the lesson.

4 Chemical properties of hydrogen sulfide

Slide number 9

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)

What properties does hydrogen sulfide exhibit in these reactions?

Parsing

When dissolved in water, hydrosulfuric acid is formed.

?

Characterize this acidSlide number 10

Weak;

Two-base;

Oxygen-free.

Dissociation takes place in two stages:

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

IIHs - ↔ H + + S 2- (practically no dissociation proceeds in the second stage)

?

What salts does hydrosulfuric acid form?

medium (sulfides) -Na 2 S

acidic (hydrosulfides) -NaHS

?

Hydrogen sulfide acid has the general properties of acids. Which ones?

Interaction with bases, basic oxides, salts

Let us write down the UHR of the interaction of hydrogen sulfide acid with sodium hydroxide.

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

H 2 S ( hut ) + 2NaOH → NaHS + 2H 2 OSlide №11

CCR with basic oxides and salts to record at home.

?

Suggest a reaction to detect the sulfide anionS 2-

Conduct laboratory experiments to confirm.Slide number 12

Write down the CCR in molecular and ionic form.

Many sulfides are water insoluble and colored:

- PbS- black color;Slide number 13

- 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 hydrogen sulfide acid are used in analytical chemistry to precipitate heavy metals.

?

Let's get back to our problem.

Is hydrogen sulfide useful or harmful?

5 Application of hydrogen sulfide

Slide number 14

Due to its toxicity, hydrogen sulfide is of limited use.

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 slightly soluble.

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

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

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

Sulphides of potassium, strontium and barium are used in tanning to remove wool from hides before dressing.

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

?

Is everything now clear about the hydrogen sulfide riddle?

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.)

Slide number 15

What did we learn new for ourselves in the lesson?

What can be practically applied in life?

Student responses

Homework: §11, exercise. 2, 3 p. 34

Creative task (optional) : Whydo artistic paintings by old masters darken over time and lose their original brightness? How do restorers update these paintings?

Air 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 art 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 decay of proteins; in the atmosphere of industrial regions, etc.) turn intoPbS... Lead white is a pigment that is lead carbonate (II). It reacts with hydrogen sulfide in the polluted atmosphere to form 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,

in this case, lead sulfate is formed (II), the compound is white.

In this way, blackened oil paintings are restored.