To use the preview of presentations, create a Google account (account) and sign in: https://accounts.google.com
Slides captions:
Pure substances and mixtures. Physical phenomena in chemistry.
Pure substances are substances that have constant physical properties.
A mixture is a combination of different substances that can be separated because they have different physical properties (eg different boiling points). Substances in a mixture are not bound 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 Mixture of table salt with sand, clay with water, iron filings with clay
Problem: How to get pure substances?
The basis for obtaining pure substances was physical processes that occur without changing the composition of the substance, but with a change in the aggregate states of substances.
Heterogeneous mixtures Settling Filtration Magnet action Settling 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 common salt from sea water Sugar production Distilled water production Separation and purification of medicinal substances
How to purify water while hiking?
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. To reveal the meaning of mixtures in nature and human life.2. Educational: F...
- 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, evaporating cup, laboratory stand with ring, spirit lamp, funnel, glass rod, chemical beakers, flasks, magnet, pipette.
Demo Experiment:
- Separation of the mixture by filtration;
- Separation of the mixture with a magnet;
- Separation of a mixture of substances by evaporation.
Cards with tasks for group work.
Separation of a mixture (solution) of a solute and a solvent:
Salt solution, laboratory stand with ring, porcelain cup (evaporator), spirit lamp, crucible tongs, glass rod.
Separation of a mixture of a water-insoluble substance and a solvent (solute):
Laboratory tripod with 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? (The base is a complex substance consisting of metal atoms and one or more hydroxo groups OH-)
- What compounds are called salts? (Salts are complex substances consisting of metal atoms and acidic residues)
2. Verification work (5-7 minutes) on sheets. On the slides 1-2- Verification questions.
3. The test work is handed over to the teacher (the results are announced at the next lesson).
II.Preparation for the perception of new material. Theme announcement.
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? What is the difference between a pure substance and a mixture of substances?
2. What do you think will be the topic of our lesson today? (slide 3)
2. Recording the date and topic of the lesson by students in a notebook.
What do you think we should learn in class today?
Goals lessons are discussed with students.
Students suggest: find out what 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.
On the this stage Lesson teacher forms the concept of a pure substance and mixture. Students know the concept of "substance" (this is what physical bodies are made of). Therefore, we first define "mixtures of substances".
The teacher invites the students to consider the mixtures on the demonstration table and the examples of mixtures presented on slide 5.
Next, the guys define mixtures, how systems from of 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 occur mainly in the form of mixtures. The teacher gives examples of mixtures, the guys write them in 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 closely at the mixtures on the table. What is the difference between them?
Homogeneous
Heterogeneous
A solution of sugar in water, salt solutions, air
Fe +S mixture, sand and sugar, clay with water, sand with water
Heterogeneous are called mixtures in which particles of the substances that make up the mixture are visible to the naked eye or using a microscope.
Homogeneous called mixtures in which particles of the substances included in the mixture cannot be seen (even with a microscope).
For scientific research and industry, mostly pure substances are required. Some impurities, even in small quantities, can greatly change the properties of substances. For example, ultrapure substances are used in semiconductor technology, where impurities are 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 must be emphasized that it is impossible to obtain an absolutely pure substance, because any pure substance contains, although a negligible small amount of impurities.
Do you think sea water and pure distilled water will have the same properties? (Guys assume not). Slide 8. The teacher explains the conditions of the experiment: distilled and sea water were heated to a boil 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 bale of sea water not constant at different intervals compared to t bale of distilled water?”
Students suggest that the salinity of sea water affects tboil.
With the help of a teacher, a definition is formulated “A pure substance is a substance that has constant physical properties (boiling points, melting points, density).
In notebooks, the guys write down the definition of "pure substance"
clean A substance is called a substance that has constant physical properties.
The teacher adds that impurities in a pure substance, although they are in small quantities, but they do not affect the physical and Chemical properties. An example of a pure substance is distilled water.
On display slide 9.
The children write their conclusions in their notebooks.
The teacher draws the attention of children 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 the separation of a mixture of iron and sulfur using a magnet (work out with the child in advance the methodology for performing the experiment and then the student conducts the demonstration)
Next step of the lesson- acquaintance with the main methods of separation of 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 method of separation is based. On the slides 11-13 the areas of application of different methods for cleaning inhomogeneous mixtures are shown.
Demonstration of the separation of a mixture of sand and water by filtration. Attention is drawn to the correctness of the experiment ( slide 11).
Familiarity 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 method of separation.
On the slides 14-18 the areas of application of different methods of purification of homogeneous mixtures are shown.
4. Fixing
1. Group work.
Each group was given the task "How to separate the mixture?"
I had to describe my actions. After 1 minute, each group voiced their answer. In the tasks, life situations were used, where it was required to purify water in field conditions, etc.
2. Answer the questions presented on slides 19 - 21
5. Reflection.
What new did you learn at the lesson 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. Make tasks for the separation of the mixture.
2. You were given a mixture of salt and chalk.
Suggest ways to separate this mixture.
View document content
«presentation for the lesson "Pure substances and mixtures"»
WRITE SEPARATELY THE FORMULA 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 compounds
Make formulas of 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 are the mixtures?
- Find out the difference between a mixture and a chemical compound.
- How 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
solid
- A pure substance has a constant composition.
- A pure substance has constant physical properties (density, hardness, electrical conductivity, t bale, t melt)
Methods for separating mixtures
Heterogeneous mixtures
settling
Methods for separating mixtures
Homogeneous mixtures
Evaporation
Distillation (or distillation)
- tap water
- Carbon dioxide
- Sea water
- Milk
- Oxygen
2. A 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. Make up tasks for separating a mixture of various substances.
2. You were given a mixture of iron filings, salt and chalk. Make a plan for separating this mixture.
To use the preview of presentations, create a Google account (account) and sign in: https://accounts.google.com
Slides captions:
PURE SUBSTANCES MIXTURES
WORK PLAN Characteristics of the substance: according to different types classification; 2. The concept of "pure substance" and "mixture": a description of the concepts; qualification of pure substances; classification of mixtures; 3. Experimental work. Conclusions.
Characteristics of the substance BY COMPOSITION BY AGGREGATE STATE BY PHYSICAL PROPERTIES
Differences in the properties of substances Resource on the Internet http://www.alhimik.ru/teleclass/tests/test003.htm
PURE SUBSTANCES MIXTURES
PURE SUBSTANCE MIXTURE
PURE SUBSTANCE A MIXTURE CONSISTS OF THE SAME PARTICLES (ATOMS, MOLECULES, IONS)
PURE SUBSTANCE A MIXTURE CONSISTS OF THE SAME PARTICLES (ATOMS, MOLECULES, IONS) CONSISTS OF SEVERAL DIFFERENT SUBSTANCES
According to the regulations existing in Russia, the following qualifications have been established for reagents: pure (pure) pure for analysis (analytically pure) chemically pure (chemically pure) extra pure (high purity)
EXPERIMENT Rules safe work! TASK: 1) MIXTURE PREPARATION; 2) INVESTIGATION OF MIXTURE PROPERTIES.
MIXTURES OF HOMO - GENE (uniformly related) HETEROGENEOUS (heterogeneous)
oxygen O 2 hydrogen H 2 water H 2 O pure, simple substances complex substance mixture: homogeneous; heterogeneous
WHAT SUBSTANCE IS WE TALKING ABOUT? In living cells and depths, Life provides hemoglobin. Courageous metal he is, But in the side group himself. And especially personal pride - Steel is excellent from it! Fe
WHAT SUBSTANCE IS WE TALKING ABOUT? Yellow, sunny, beautiful non-metal. How famous! Hundreds of years he lives in the world, In medicine applicable. With hydrogen, it's terrible, Poisonous and ... oh, dangerous! All living beings Die twice two. S
EXPERIMENT Substances: IRON - Fe SULFUR - S TASK: CHARACTERISTICS OF PHYSICAL PROPERTIES OF SUBSTANCES; 2) MIXTURE PREPARATION; 3) INVESTIGATION OF MIXTURE PROPERTIES.
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 Same Various Physical properties Separation
Comparative characteristics of a mixture and a pure substance Signs of comparison Pure substance Mixture Composition Constant Inconstant (variable) Substances The same Different Physical properties Constant Inconstant Separation
Comparative characteristics of a mixture and a pure substance Signs of comparison Pure substance Mixture Composition Constant Variable (variable) Substances The same Different Physical properties Constant Variable Separation Using chemical reactions Physical methods
Comparative characteristics of a mixture and a pure substance Signs of comparison Pure substance Mixture Composition Constant Variable (variable) Substances The same Different Physical properties Constant Variable Separation Using chemical reactions Physical methods
Lesson results 1. Concepts: "pure substance" qualification of pure substances; "mixture" classification of mixtures; 2. We studied the properties of substances in a mixture
please fix it workplace! Thank you for your work!
