Lesson No. 9th grade date: _____

Lesson topic. Hydrogen chloride: preparation and properties.

Lesson type: combined lesson.

The purpose of the lesson: consider methods of production and properties of hydrogen chloride; teach to correlate the areas of application of hydrogen chloride with its properties.

Lesson objectives:

Educational: introduce students to the chemical formula and structure of the hydrogen chloride molecule, physical and chemical properties, production and use of hydrogen chloride.

Methods and techniques:

Equipment: textbook “Chemistry 9th grade” Rudzitis G.E., Feldman F.G.; periodic table of chemical elements D.I. Mendeleev; cards with individual tasks, handouts.

DURING THE CLASSES

Organizing time.

Checking homework.

Frontal conversation.

- Tell us about the physical properties of chlorine (chlorine is a gas, yellow-green in color, has a pungent, suffocating odor. Poisonous for all living organisms. 2.5 times heavier than air. Boils at a temperature of +15 ºС).

How does the chemical activity of halogens change from fluorine to iodine? (fluorine is chemically the most active, and iodine is the least active).

How does the displacement activity of halogens change in solutions of their salts? (more active halogens displace less active halogens from their compounds).

What simple substances does chlorine react with? (with metals and hydrogen).

Describe the interaction of chlorine with water, revealing the essence of the reaction (Cl 2 + H 2 O = HCl + HClO. An exchange reaction results in the formation of two acids: hydrochloric and hypochlorous; OVR).

- Tell us about possible cases of the reaction of chlorine with hydrogen, the mechanism and essence of the reaction (chlorine reacts with hydrogen in the light, as well as when heated; it explodes when irradiated, forming hydrogen chloride).

How does hydrogen chloride dissolve in water and what is its solution? (dissolves very well in water, hydrochloric acid is formed).

Written homework. (This is done on the board by students, while students are doing tasks at the board, the teacher conducts a frontal conversation with the class).

Individual task.

MnO 2 ) with muric acid."

This gas is chlorine. When chlorine interacts with hydrogen, hydrogen chloride is formed, an aqueous solution of “muric acid” - hydrochloric acid. When the mineral pyrolusite is heated with hydrochloric acid, chlorine is formed according to the reaction:

4HCl + MnO 2 = MnCl 2 + Cl 2 + 2H 2 O

Learning new material.

The chemical formula of hydrogen chloride isHCl. The chemical bond is polar covalent.

In industry, hydrogen chloride is produced by reacting chlorine with hydrogen.

Cl 2 + H 2 = 2 HCl

In the laboratory it is prepared by heating sodium chloride with concentrated sulfuric acid. Under such conditions, in the absence of water, hydrogen chloride gas is released, which is then dissolved in water to form hydrochloric acid.

2NaCl + H 2 SO 4 = Na 2 SO 4 + 2HCl (cm. rice. 13 §14).

Hydrogen chloride is a colorless gas, slightly heavier than air, with a pungent odor, and smokes in moist air. The most characteristic property of hydrogen chloride is its high solubility in water (at 0 ºС, about 500 volumes of gas dissolve in one volume of water).

Is it possible to obtain hydrogen chloride using a solution of table salt? (no, because all substances in solution are strong electrolytes).

Chemical properties: Hydrogen chloride does not react with metals or basic oxides (unlike hydrochloric acid). Remember that hydrochloric acid and hydrogen chloride are not the same substance, although they are described by the same formula. These substances have different physical and chemical properties.

Solving problematic issues.

It has been established that river waters near volcanoes contain hydrochloric acid. Make an assumption about the origin of this phenomenon (hydrogen chloride is one of the components of poisonous volcanic gases).

Questions - tips: what is gastric juice? Remember the composition of gastric juice? What is the role of hydrochloric acid in digestion? For what digestive disorders is a highly diluted solution of hydrochloric acid prescribed?

Homework . Learn the material § 14, complete No. 1-2 p. 55.

Individual task.

Analyze the text, identify the substances and write down the equations for the reactions described:

“During the First World War (1915), poison gas was used for the first time near the city of Ypres in western Flanders. This gas attack claimed the lives of 5 thousand soldiers and disabled about 15 thousand. The interaction of this gas with hydrogen can occur explosively; an aqueous solution of the product of this reaction was previously called “muric acid.” One of the discoverers of poisonous gas was the Swedish chemist and pharmacist Karl Scheele, who obtained it by heating the mineral pyrolusite ( MnO 2 ) with muric acid."

Solving problematic issues.

It is known that hydrogen chloride and hydrochloric acid are toxic substances that have a toxic effect on the human body. At the same time, for some stomach diseases, doctors prescribe hydrochloric acid as a medicine.

Problematic question: “What explains the actions of a doctor who prescribes a toxic substance to a patient as a medicine?”

Solving problematic issues.

It has been established that river waters near volcanoes contain hydrochloric acid. Make a guess about the origin of this phenomenon.

It is known that hydrogen chloride and hydrochloric acid are toxic substances that have a toxic effect on the human body. At the same time, for some stomach diseases, doctors prescribe hydrochloric acid as a medicine.

Problematic question: “What explains the actions of a doctor who prescribes a toxic substance to a patient as a medicine?”

Solving problematic issues.

It has been established that river waters near volcanoes contain hydrochloric acid. Make a guess about the origin of this phenomenon.

It is known that hydrogen chloride and hydrochloric acid are toxic substances that have a toxic effect on the human body. At the same time, for some stomach diseases, doctors prescribe hydrochloric acid as a medicine.

Problematic question: “What explains the actions of a doctor who prescribes a toxic substance to a patient as a medicine?”

Solving problematic issues.

It has been established that river waters near volcanoes contain hydrochloric acid. Make a guess about the origin of this phenomenon.

It is known that hydrogen chloride and hydrochloric acid are toxic substances that have a toxic effect on the human body. At the same time, for some stomach diseases, doctors prescribe hydrochloric acid as a medicine.

Problematic question: “What explains the actions of a doctor who prescribes a toxic substance to a patient as a medicine?”

Lesson No. 9th grade date: _____

Lesson topic. Hydrochloric acid and its salts.

Lesson type: combined lesson.

The purpose of the lesson: generalize knowledge about the properties of hydrochloric acid, introduce qualitative reactions to halide ions.

Lesson objectives:

Educational: consider the empirical formula of hydrochloric acid and chlorides, study the meaning of qualitative reactions, conduct a chemical experiment to recognize the most important inorganic substances, recognize chlorides, draw up equations of reactions characteristic of hydrochloric acid.

Educational: show the unity of the material world.

Developmental: acquiring independent work skills.

Methods and techniques: frontal conversation, individual, independent work.

Equipment: textbook “Chemistry 9th grade” Rudzitis G.E., Feldman F.G.; periodic table of chemical elements D.I. Mendeleev; cards with individual tasks, handouts, a set of reagents: hydrochloric acid solution, zinc, silver nitrate.

DURING THE CLASSES

Organizing time.

Preparation for the perception of new material.

Safety instructions when working with acids.

Questions on the topic studied.

Prove that hydrochloric acid contains hydrogen (reaction of hydrochloric acid with zinc; observation of gas).

Zn + 2 HCl = ZnCl 2 + H 2

Prove that hydrochloric acid contains chlorine (carrying out a qualitative reaction on hydrochloric acid and its salts - a reaction with silver nitrateAgNO 3 ; observation of the precipitation of a white precipitate of silver chloride).

AgNO 3 + HCl = AgCl↓ + HNO 3

How to carry out the transformation reflected in the diagram:

CuO → CuCl 2 → AgCl

CuO + 2HCl = CuCl 2 +H 2 O

CuCl 2 + 2AgNO 3 = 2AgCl↓ + Cu(NO 3 ) 2

Learning new material.

Conducting a research assignment.

Describe the physical properties of hydrochloric acid using your observations and textbook data, p. 56 (colorless liquid with a pungent odor).

Read the textbook article p. 56 about methods for producing hydrochloric acid in the laboratory and industry.

2. Study of the chemical properties of hydrochloric acid.

Drawing up a diagram reflecting the chemical properties of hydrochloric acid, common with other acids, and specific properties.

Completing task No. 2 p.58.

Salts of hydrochloric acid.

NaCl– table salt – is a constant companion of a person throughout his life, as eloquently evidenced by the history of mankind.

What is the meaning of the famous proverb “Having eaten unsalted”?

What, in your opinion, are the prerequisites for the emergence of the ancient cities of Russia - Solikamsk, Soligorsk, Solvychegorsk, etc.?

Posing a problematic question: “What explains this attitude of people towards an ordinary substance known to all of us? Why is table salt always and everywhere considered an essential product?” (Table salt as a food additive is the most important source of the formation of hydrochloric acid in the body, which is a necessary component of gastric juice. The intake of sodium chloride into the body maintains the constancy of the chemical composition of the blood).

Consolidation of the studied material.

Doing independent work.

Write down equations for feasible reactions:

1 option

NaOH + HCl →

NaCl + AgNO 3 →

NaCl + KNO 3 →

Na 2 CO 3 + HCl →

Option 2

Ca( OH) 2 + HCl →

KCl + AgNO 3 →

HCl + AgNO 3 →

K 2 CO 3 + HCl →

Option 3

Ba( OH) 2 + HCl →

BaCl 2 + AgNO 3 →

KCl + AgNO 3 →

BaCO 3 + HCl →

Homework . Learn the material § 15, complete No. 3, 5 p. 58. Individual task * No. 4 p. 58.

1 option

NaOH + HCl →

NaCl + AgNO 3 →

NaCl + KNO 3 →

Na 2 CO 3 + HCl →

Option 2

Ca( OH) 2 + HCl →

KCl + AgNO 3 →

HCl + AgNO 3 →

K 2 CO 3 + HCl →

3 option

Ba(OH) 2 + HCl →

BaCl 2 + AgNO 3 →

KCl + AgNO 3 →

BaCO 3 + HCl →

Hydrogen chloride... Spelling dictionary-reference book

HYDROGEN CHLORIDE- (HCl) is a colorless gas that fumes in air with a pungent odor, toxic; density 1.64 kg/m3, tmelt = 84.8 °C. It dissolves very well in water to form hydrochloric (hydrochloric) acid. In industry it is obtained by direct synthesis from (see) and... ... Big Polytechnic Encyclopedia

hydrogen chloride- chem. connection for chlorot with hydrogen, bezboen gas, se dissolved in water like solna kiselina hydrochloric kiselina chem. compound on chlorot and hydrogen, on, hydrogen chloride and is widely used in the chemical industry ... Macedonian dictionary

hydrogen chloride- vandenilio chloridas statusas T sritis chemija formulė HCl atitikmenys: engl. hydrochloric acid; hydrogen chloride rus. hydrogen chloride; hydrogen chloride... Chemijos terminų aiškinamasis žodynas

Hydrogen chloride (see Chlorine) ... Encyclopedic Dictionary F.A. Brockhaus and I.A. Efron

- (hydrogen chloride), HCl, a colorless gas that fumes in air; melting point 114.2°C, boiling point 85.1°C. It dissolves well in water to form hydrochloric acid. In industry it is obtained as a by-product during the chlorination of organic compounds, synthesis... encyclopedic Dictionary

- (hydrogen chloride), HC1, colorless, gas fuming in air; tnl 114.2 °C, boiling point 85.1 °C. It dissolves well in water to form hydrochloric acid. In industry it is obtained as a by-product during the chlorination of organic matter. compound, synthesis from elements... ... Natural science. encyclopedic Dictionary

Hydrogen chloride is a colorless gas heavier than air with a pungent odor, which consists of equal volumes of chlorine and hydrogen, formula: HCl

A mixture of chlorine and hydrogen reacts violently and explodes even in sunlight, forming hydrogen chloride.

Hydrogen chloride itself is not a flammable gas.

In the laboratory, you can obtain hydrogen chloride using concentrated sulfuric acid + table salt and heating this mixture.

Hydrogen chloride gas dissolves well in water, the solution itself is called.

At high concentrations, hydrochloric acid seems to smoke in the air, as hydrogen chloride is gradually released from the solution into the external moisture of the air. When heated, the release of hydrogen chloride becomes more intense.

Hydrochloric acid is widely used to remove rust from surfaces. However, this can only be done with the use of inhibitors (additives that slow down the reaction of the metal with the acid) so that the acid does not spoil the metal itself. Salts are also obtained from acid, used in medicine, etc. This acid is even secreted by our stomach to digest food, but the concentration there is very low (0.2-0.5%).

Salts of this acid are called chlorides. Chlorides are also generally soluble in water.

If you add silver nitrate (AgNO 3) to hydrochloric acid or its salt, a white cheesy precipitate forms. This precipitate is insoluble in acids, which always makes it possible to establish the presence of chloride ions.

DEFINITION

Hydrogen chloride(hydrochloric acid, hydrochloric acid) is a complex substance of inorganic nature that can exist in both liquid and gaseous states.

In the second case, it is a colorless gas, highly soluble in water, and in the first, it is a solution of a strong acid (35-36%). The structure of the hydrogen chloride molecule, as well as its structural formula, is shown in Fig. 1. Density - 1.6391 g/l (n.s.). The melting point is - (-114.0 o C), boiling point - (-85.05 o C).

Rice. 1. Structural formula and spatial structure of the hydrogen chloride molecule.

The gross formula of hydrogen chloride is HCl. As is known, the molecular mass of a molecule is equal to the sum of the relative atomic masses of the atoms that make up the molecule (we round off the values ​​of the relative atomic masses taken from D.I. Mendeleev’s Periodic Table to whole numbers).

Mr(HCl) = Ar(H) + Ar(Cl);

Mr(HCl) = 1 + 35.5 = 36.5.

Molar mass (M) is the mass of 1 mole of a substance. It is easy to show that the numerical values ​​of the molar mass M and the relative molecular mass M r are equal, however, the first quantity has the dimension [M] = g/mol, and the second is dimensionless:

M = N A × m (1 molecule) = N A × M r × 1 amu = (N A ×1 amu) × M r = × M r .

It means that the molar mass of hydrogen chloride is 36.5 g/mol.

The molar mass of a substance in the gaseous state can be determined using the concept of its molar volume. To do this, find the volume occupied under normal conditions by a certain mass of a given substance, and then calculate the mass of 22.4 liters of this substance under the same conditions.

To achieve this goal (calculation of molar mass), it is possible to use the equation of state of an ideal gas (Mendeleev-Clapeyron equation):

where p is the gas pressure (Pa), V is the gas volume (m 3), m is the mass of the substance (g), M is the molar mass of the substance (g/mol), T is the absolute temperature (K), R is the universal gas constant equal to 8.314 J/(mol×K).

Examples of problem solving

EXAMPLE 1

Exercise	In which of the following substances the mass fraction of the oxygen element is greater: a) in zinc oxide (ZnO); b) in magnesium oxide (MgO)?
Solution	Let's find the molecular weight of zinc oxide: Mr (ZnO) = Ar(Zn) + Ar(O); Mr (ZnO) = 65+ 16 = 81. It is known that M = Mr, which means M(ZnO) = 81 g/mol. Then the mass fraction of oxygen in zinc oxide will be equal to: ω (O) = Ar (O) / M (ZnO) × 100%; ω(O) = 16 / 81 × 100% = 19.75%. Let's find the molecular weight of magnesium oxide: Mr (MgO) = Ar(Mg) + Ar(O); Mr (MgO) = 24+ 16 = 40. It is known that M = Mr, which means M(MgO) = 60 g/mol. Then the mass fraction of oxygen in magnesium oxide will be equal to: ω (O) = Ar (O) / M (MgO) × 100%; ω(O) = 16 / 40 × 100% = 40%. Thus, the mass fraction of oxygen is greater in magnesium oxide, since 40>19.75.
Answer	The mass fraction of oxygen is greater in magnesium oxide

EXAMPLE 2

Exercise	In which of the following compounds is the mass fraction of metal greater: a) in aluminum oxide (Al 2 O 3); b) in iron oxide (Fe 2 O 3)?
Solution	The mass fraction of element X in a molecule of the composition NX is calculated using the following formula: ω (X) = n × Ar (X) / M (HX) × 100%. Let's calculate the mass fraction of each element of oxygen in each of the proposed compounds (we will round off the values ​​of relative atomic masses taken from D.I. Mendeleev's Periodic Table to whole numbers). Let's find the molecular weight of aluminum oxide: Mr (Al 2 O 3) = 2×Ar(Al) + 3×Ar(O); Mr (Al 2 O 3) = 2×27 + 3×16 = 54 + 48 = 102. It is known that M = Mr, which means M(Al 2 O 3) = 102 g/mol. Then the mass fraction of aluminum in the oxide will be equal to: ω (Al) = 2×Ar(Al) / M (Al 2 O 3) × 100%; ω(Al) = 2×27 / 102 × 100% = 54 / 102 × 100% = 52.94%. Let's find the molecular weight of iron (III) oxide: Mr (Fe 2 O 3) = 2×Ar(Fe) + 3×Ar(O); Mr (Fe 2 O 3) = 2×56+ 3×16 = 112 + 48 = 160. It is known that M = Mr, which means M(Fe 2 O 3) = 160 g/mol. Then the mass fraction of iron in the oxide will be equal to: ω (O) = 3×Ar (O) / M (Fe 2 O 3) × 100%; ω(O) = 3×16 / 160×100% = 48 / 160×100% = 30%. Thus, the mass fraction of the metal is greater in aluminum oxide, since 52.94 > 30.
Answer	The mass fraction of the metal is greater in aluminum oxide

20. Chlorine. Hydrogen chloride and hydrochloric acid

Chlorine (Cl) – stands in the 3rd period, in group VII of the main subgroup of the periodic system, serial number 17, atomic mass 35.453; refers to halogens.

Physical properties: yellow-green gas with a pungent odor. Density 3.214 g/l; melting point -101 °C; boiling point -33.97 °C, At ordinary temperature it easily liquefies under a pressure of 0.6 MPa. Dissolving in water, it forms yellowish chlorine water. It is highly soluble in organic solvents, especially hexane (C6H14), and carbon tetrachloride.

Chemical properties of chlorine: electronic configuration: 1s22s22p63s22p5. There are 7 electrons in the outer level. To complete the level, you need 1 electron, which chlorine accepts, exhibiting an oxidation state of -1. There are also positive oxidation states of chlorine up to + 7. The following chlorine oxides are known: Cl2O, ClO2, Cl2O6 and Cl2O7. They are all unstable. Chlorine is a strong oxidizing agent. It reacts directly with metals and non-metals:

Reacts with hydrogen. Under normal conditions, the reaction proceeds slowly, with strong heating or lighting - with an explosion, according to a chain mechanism:

Chlorine interacts with alkali solutions, forming salts - hypochlorites and chlorides:

When chlorine is passed into an alkali solution, a mixture of chloride and hypochlorite solutions is formed:

Chlorine is a reducing agent: Cl2 + 3F2 = 2ClF3.

Interaction with water:

Chlorine does not react directly with carbon, nitrogen and oxygen.

Receipt: 2NaCl + F2 = 2NaF + Cl2.

Electrolysis: 2NaCl + 2H2O = Cl2 + H2 + 2NaOH.

Finding in nature: contained in the following minerals: halite (rock salt), sylvite, bischofite; sea ​​water contains chlorides of sodium, potassium, magnesium and other elements.

Hydrogen chloride HCl. Physical properties: colorless gas, heavier than air, highly soluble in water to form hydrochloric acid.