Presentation for the lesson Pure substances and mixtures presentation for a chemistry lesson (8th grade) on the topic. Presentation for the lesson Pure substances and mixtures presentation for a chemistry lesson (8th grade) on the topic Presentation on the topic composition of the substance of a mixture

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PURE SUBSTANCES MIXTURES

WORK PLAN Characteristics of the substance: according to different types of classification; 2. The concept of “pure substance” and “mixture”: characteristics of the concepts; qualification of pure substances; classification of mixtures; 3. Experimental work. Conclusions.

Characteristics of a substance BY COMPOSITION BY AGREGATE STATE BY PHYSICAL PROPERTIES

Differences in the properties of substances Internet resource http://www.alhimik.ru / teleclass / tests /test003.htm

PURE SUBSTANCES MIXTURES

PURE SUBSTANCE MIXTURE

A PURE SUBSTANCE A MIXTURE CONSISTS OF IDENTICAL PARTICLES (ATOMS, MOLECULES, IONS)

A PURE SUBSTANCE A MIXTURE CONSISTS OF IDENTICAL PARTICLES (ATOMS, MOLECULES, IONS) CONSISTS OF SEVERAL DIFFERENT SUBSTANCES

According to the current regulations in Russia, the following qualifications have been established for reagents: pure (pure grade), pure for analysis (analytical grade), chemically pure (reagent grade), extra pure (extra pure grade)

EXPERIMENT Safe work rules! TASK: 1) PREPARATION OF THE MIXTURE; 2) STUDY OF THE PROPERTIES OF THE MIXTURE.

MIXTURES OF HOMOS - GENE (similar) HETEROGENEOUS (heterogeneous)

oxygen O 2 hydrogen H 2 water H 2 O pure, simple substances complex substance mixture: homogeneous; heterogeneous

WHAT SUBSTANCE ARE WE TALKING ABOUT? In living cells and depths Life gives to hemoglobin. He is a courageous metal, but he is in a side group. And especially personal pride - It’s made of excellent steel! Fe

WHAT SUBSTANCE ARE WE TALKING ABOUT? Yellow, sunny, beautiful Non-metal. How famous! It has lived in the world for hundreds of years and is used in medicine. With hydrogen it is terrible, poisonous and... oh, dangerous! All living beings die twice or twice. S

EXPERIMENT Substances: IRON - Fe SULFUR - S TASK: CHARACTERISTICS OF THE PHYSICAL PROPERTIES OF SUBSTANCES; 2) PREPARATION OF THE MIXTURE; 3) STUDY OF THE PROPERTIES OF THE MIXTURE.

Comparative characteristics of a mixture and a pure substance Signs of comparison Pure substance Mixture Composition of a substance Physical properties Separation

Comparative characteristics of a mixture and a pure substance Signs of comparison Pure substance Mixture Composition Constant Variable (variable) Substances Physical properties Separation

Comparative characteristics of a mixture and a pure substance Signs of comparison Pure substance Mixture Composition Constant Variable (variable) Substances One and the same Different Physical properties Separation

Lesson summary 1. Concepts: “pure substance” qualification of pure substances; “mixture” classification of mixtures; 2. Studied the properties of substances in the mixture

Please tidy up your workspace! Thank you for your work!

Lesson objectives:

To figure out:

Which substance is considered pure?
What is a mixture?
What types of mixtures are there?
In what ways can a mixture be separated?

Definition of “mixture”

was given in the 17th century. English scientist Robert Boyle:

“A mixture is an integral system consisting of heterogeneous components.”

Comparative characteristics pure substance and mixture

Signs of comparison

Pure substance

Compound

Mixture

Constant

Substances

Same

Fickle

Physical properties

Energy change during formation

Various

Permanent

Happening

Fickle

Separation

Not happening

Through chemical reactions

By physical methods

They call them clean substances that have a constant composition and constant physical properties.

Mixture is a combination of different substances.

Milk
Metal alloys
Solutions
Fog
Concrete
and others

distinctive feature of mixtures

In mixtures, each of the constituent substances retains its individual properties.

These are mixtures in which particles of substances are visible to the naked eye.

These are mixtures in which particles of substances cannot be seen.

Homogeneous

Heterogeneous

suspensions

liquid

emulsions

Gaseous

hard

Test your knowledge Name the pure ones from the proposed substances:

Water in the river
Water in the cloud
Sugar
Petrol
Salt

Test your knowledge

1. The mixture is:

A. Distilled water

C. Aluminum

2. The following is not a mixture:

Distilled water
The soil

Test your knowledge

3.Indicate heterogeneous mixtures

A) granulated sugar + water

B) sulfur + iron filings

C) table salt + water

Test your knowledge

4. Specify homogeneous mixtures

B) river sand + water

C) oil + water

Test your knowledge

5. In what case are we talking about water as a pure substance?

A) sea water tastes salty

B) distilled water is obtained by cooling water vapor

C) mineral water is used to treat certain diseases

Test your knowledge

6. Label the mixture whose main component is gas

A) oxygen

B) carbon dioxide

Explain from a chemical point of view:

“Meanwhile, the Needlewoman returns, strains the water, pours it into jugs; and what a trick: if the water is unclean, he will roll up a sheet of paper, put coals and coarse sand in it, insert that paper into a jug and pour water into it, and the water, you know, passes through the sand and through the coals and drips into the jug clean like crystal..."

(Odoevsky V.F. “Moroz Ivanovich”)

Homework:

§ 24, ex. 4,5,6,7

Creative task.

1. Create tasks for separating a mixture.

2. You were given a mixture consisting of salt and chalk. Suggest ways to separate this mixture.

Presentation in MS Power Point (application)
Computer, projector

Reagents

A mixture of iron and sulfur powders, a solution of table salt, a mixture of sand and water, a solution of methyl orange; filters, evaporation dish, laboratory stand with ring, alcohol lamp, funnel, glass rod, beakers, flasks, magnet, pipette.

Demonstration experiment:

Separation of the mixture by filtration;
Separation of the mixture by magnet;
Separation of a mixture of substances by evaporation.

Task cards for group work.

Separation of a mixture (solution) of a soluble substance and a solvent:

Table salt solution, laboratory stand with ring, porcelain dish (evaporation), alcohol lamp, crucible tongs, glass rod.

Separating a mixture of a water-insoluble substance and a solvent (soluble substance):

Laboratory stand with a ring, funnel, filter paper, glass rod, flask or beaker.

Separation of a mixture of iron and sulfur:

Iron filings, sulfur powder, magnet, 2 filters.

Filter, methyl orange solution, pipette.

During the classes

I.Organizing time. Checking homework.

What compounds are called oxides? (Oxides are complex compounds consisting of two elements, one of which is oxygen with an oxidation state of (-2))
What compounds are called acids? (Acids are complex substances consisting of hydrogen atoms and an acid residue)
What compounds are called bases? (A base is a complex substance consisting of metal atoms and one or more hydroxyl groups OH-)
What compounds are called salts? (Salts are complex substances consisting of metal atoms and acid residues)

2. Test work (5-7 minutes) on sheets of paper. On slides 1-2- test questions.

3. The test work is submitted to the teacher (results are announced at the next lesson).

II.Preparation for the perception of new material. Announcement of the topic.

1. Conversation

1. We are well aware of what cleanliness is. A clean notebook, clean hands, a clean sheet... And what substance is considered clean? Are there pure substances in nature? How does a pure substance differ from a mixture of substances?

2. What do you think will be the topic of our lesson today? (slide 3)

2. Students write down the date and topic of the lesson in their notebooks.

What do you think we should find out in class today?

Goals lesson are discussed with students.

Students are asked to: find out which substance is considered pure and what a mixture is; find out where pure substances and mixtures are used; learn how to separate substances.

As a result of the discussion - slide 4.

3. Explanation of new material.

At this stage of the lesson, the teacher forms the concept of pure substances and mixtures. Students are familiar with the concept of “matter” (this is what physical bodies are made of). Therefore, first we give a definition "mixtures of substances"

The teacher invites students to look at the mixtures on the demonstration table and examples of mixtures presented on slide 5.

Next, the guys give a definition mixtures, How systems from their several substances in direct contact with each other. This wording appears on the slide after a mouse click.

The teacher adds that there are no absolutely pure substances in nature. Substances are found mainly in the form of mixtures. The teacher gives examples of mixtures, the children write them down in their notebooks: air, sea water, milk, metal alloys, solutions, fog, etc. He talks about air as a mixture that consists of gases - nitrogen, oxygen, argon, etc. ( slide 6).

Look carefully at the mixtures on the table. What is the difference between them?

Homogeneous

Heterogeneous

Sugar solution in water, salt solutions, air

Fe + S mixture, sand and sugar, clay with water, sand with water

Heterogeneous are called mixtures in which the particles of the substances making up the mixture are visible to the naked eye or with the help of a microscope.

Homogeneous are called mixtures in which particles of substances included in the mixture cannot be seen (even with a microscope).

For scientific research and industry, pure substances are mainly required. Some impurities, even in small quantities, can greatly change the properties of substances. For example, in semiconductor technology, ultrapure substances are used, where impurities amount to only 1 atom per million atoms of the main element (Si, Ge). Exceeding the norm leads to a sharp deterioration in the semiconductor properties of these substances. At the same time, it is necessary to emphasize that it is impossible to obtain an absolutely pure substance, because any pure substance contains, albeit a negligible amount of impurities.

Do you think sea water and pure distilled water will have the same properties? (the guys assume not). Slide 8. The teacher explains the conditions of the experiment: distilled and sea water were heated to boiling in 2 vessels. After a certain time, the boiling temperatures in these vessels were measured using Archimedes sensors. Together we discuss the results of the experiment. The problem arises: “Why is t bp not constant for sea water at different time intervals compared to t bp of distilled water?”

Students suggest that the salinity of sea water affects the boiling point.

With the help of the teacher, the definition is formulated: “A pure substance is a substance that has constant physical properties (boiling points, melting points, density).

In their notebooks, the children write down the definition of “pure substance”

Clean is a substance that has permanent physical properties.

The teacher adds that in a pure substance there are impurities in small quantities, but they do not affect the physical and chemical properties. An example of a pure substance is distilled water.

Demonstrated slide 9.

The guys write down their conclusions in notebooks.

The teacher draws the children’s attention to the distinctive feature of mixtures: “In mixtures, each of their constituent substances retains its individual properties. To confirm this, the teacher conducts experiments:

Demonstration of separating a mixture of iron and sulfur using a magnet (work out the method of performing the experiment with the child in advance and then the demonstration is carried out by the student)

Next stage of the lesson- familiarization with the main methods of separating mixtures, which are presented in the form of a diagram: Slide 10.

At the same time, it is clarified on what physical properties of substances each separation method is based. On slides 11-13 The areas of application of different methods for purifying heterogeneous mixtures are shown.

Demonstration of separation of a mixture of sand and water by filtration. Attention is drawn to the correctness of the experiment ( Slide 11).

Acquaintance with methods for separating homogeneous mixtures continues with the help of slide 14, students' attention is focused on the physical properties of the substances used in this separation method.

On slides 14-18 areas of application of different methods for purifying homogeneous mixtures are shown.

4. Consolidation

1. Group work.

Each group received the task “How to separate the mixture?”

I had to describe my actions. After 1 minute, each group voiced their answer. The tasks involved real-life situations where it was necessary to purify water in field conditions, etc.

2. Answer the questions presented on slides 19 - 21

5. Reflection.

What new did you learn in class today?

What do you remember?

What did you like and what didn’t work, in your opinion?

6. Summarizing

7. Homework:§ 23 ex. 1,2,4

Creative task.

1. Create tasks for separating a mixture.

2. You were given a mixture consisting of salt and chalk.

Suggest ways to separate this mixture.

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"presentation for the lesson "Pure substances and mixtures""

WRITE SEPARATELY THE FORMULAS OF OXIDES, ACIDS, BASES AND SALTS:

KCl, MnO 2, H 2 SO 4, KOH,

KCl, MnO 2, H 2 SO 4, KOH,

CO 2, NaNO 3, H 2 CO 3, Al(OH) 3.

Name the connections

Make up formulas for chemical compounds:

Sodium oxide

Hydrochloric acid

Sodium oxide Hydrochloric acid

Calcium phosphate

Barium hydroxide

Pure substances and mixtures. Methods for separating mixtures

Lesson topic: Pure substances and mixtures

Lesson objectives:

Find out which substance is considered pure.
What is a mixture? What types of mixtures are there?
Find out the differences between a mixture and a chemical compound.
In what ways can mixtures be separated?
Where are pure substances and mixtures used?

A mixture is a system of several substances.

Air
Milk
Metal alloys
Solutions
Fog
Concrete

Homogeneous

Heterogeneous

suspensions

liquid

emulsions

Gaseous

hard

A pure substance has a constant composition.
A pure substance has constant physical properties (density, hardness, electrical conductivity, t boil, t melt)

Methods for separating mixtures

Heterogeneous mixtures

Advocacy

Methods for separating mixtures

Homogeneous mixtures

Evaporation

Distillation (or distillation)

Tap water
Carbon dioxide
Sea water
Milk
Oxygen

2. The mixture is:

A. Distilled water

D. Aluminum

Air
Water in the river
Water in the cloud
Sugar
Petrol
Salt

Homework:

§ 23, ex. 1,2,4

Creative task.

1. Create problems for separating a mixture of different substances.

2. You were given a mixture consisting of iron filings, salt and chalk. Make a plan for separating this mixture.

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Pure substances and mixtures. Physical phenomena in chemistry.

Substances that have constant physical properties are called pure.

A mixture is a combination of different substances that can be separated because they have different physical properties (for example, different boiling points). The substances in the mixture are not linked by chemical bonds, so they can be separated from each other.

Mixtures Homogeneous (homogeneous) Heterogeneous (heterogeneous) Solutions of table salt (sodium chloride) and sugar in water, air A mixture of table salt with sand, clay with water, iron filings with clay

Problem: How to obtain pure substances?

The production of pure substances was based on physical processes that occur without changing the composition of the substance, but with a change in the aggregate states of the substances.

Heterogeneous mixtures Sedimentation Filtration Magnetic action Sedimentation of clay particles in water. Used for drinking water purification Used for drinking water purification Separation of iron from other substances

Homogeneous mixtures Evaporation Crystallization Distillation (distillation) Chromatography Isolation of table salt from sea water Sugar production Obtaining distilled water Separation and purification of medicinal substances

How to purify water while camping?

The following mixtures are given: - iron and copper filings; - sawdust and clay; - river sand and sugar. Suggest ways to separate them.

On the topic: methodological developments, presentations and notes

Lesson summary "Pure substances and mixtures. Methods for separating mixtures"

Lesson objectives:1. Educational: Give the concept of a pure substance and a mixture of substances, the similarities and differences between them. Reveal the meaning of mixtures in nature and human life.2. Educational: F...

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On the topic: methodological developments, presentations and notes

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"presentation for the lesson "Pure substances and mixtures""