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V_V
Physical phenomena surround us all the time. In a sense, all we see are physical phenomena. But, strictly speaking, they are divided into several types:
· mechanical
· sound
· thermal
· optical
· electric
magnetic
An example of mechanical phenomena is the interaction of some bodies, for example, a ball and the floor, when the ball bounces when hit. The rotation of the Earth is also a mechanical phenomenon.
Sound phenomena are the propagation of sound in a medium, such as air or water. For example, an echo, the sound of a flying plane.
Optical phenomena are everything related to light. Refraction of light in a prism, reflection of light in water or a mirror.
Thermal phenomena are associated with the fact that various bodies change their temperature and physical/aggregate state: ice melts and turns into water, water evaporates and turns into steam.
Electrical phenomena are associated with the appearance of electrical charges. For example, when clothing or other fabrics are electrified. Or lightning appears during a thunderstorm.
Magnetic phenomena are related to electrical ones, but concern the interaction of magnetic fields. For example, the operation of a compass, the northern lights, the attraction of two magnets to each other.
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buzz
Left a comment on June 25, 2018:
Phenomena in which there is no transformation of one substance into another are classified as physical phenomena. Physical phenomena can lead to a change, for example, in the state of aggregation or temperature, but the composition of the substances will remain the same.
All physical phenomena can be divided into several groups.
Mechanical phenomena are phenomena that occur with physical bodies when they move relative to each other (the revolution of the Earth around the Sun, the movement of cars, the flight of a parachutist).
Electrical phenomena are phenomena that occur with the appearance, existence, movement and interaction of electrical charges (electric current, telegraphy, lightning during a thunderstorm).
Magnetic phenomena are phenomena associated with the appearance of magnetic properties in physical bodies (the attraction of iron objects by a magnet, turning the compass needle to the north).
Optical phenomena are phenomena that occur during the propagation, refraction and reflection of light (rainbows, mirages, reflection of light from a mirror, the appearance of shadows).
Thermal phenomena are phenomena that occur during heating and cooling of physical bodies (melting snow, boiling water, fog, freezing of water).
Atomic phenomena are phenomena that arise when the internal structure of the substance of physical bodies changes (the glow of the Sun and stars, an atomic explosion).
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Oleg74
Left a comment on June 25, 2018:
Natural phenomena are changes in nature. Complex natural phenomena are considered as a set of physical phenomena - those that can be described using the corresponding physical laws. Physical phenomena can be thermal, light, mechanical, sound, electromagnetic, etc.
Mechanical physical phenomena
The flight of a rocket, the fall of a stone, the rotation of the Earth around the Sun.
Light physical phenomena
A flash of lightning, the glow of a light bulb, light from a fire, solar and lunar eclipses, a rainbow.
Thermal physical phenomena
Freezing of water, melting of snow, heating of food, combustion of fuel in an engine cylinder, forest fire.
Sound physical phenomena
Bell, singing, thunder.
Electromagnetic physical phenomena
Lightning discharge, electrification of hair, attraction of magnets.
For example, thunderstorms can be considered as a combination of lightning (electromagnetic phenomenon), thunderclaps (sound phenomenon), the movement of clouds and falling raindrops (mechanical phenomena), and a fire that can occur as a result of lightning striking a tree (thermal phenomenon).
By studying physical phenomena, scientists, in particular, establish their relationship (a lightning discharge is an electromagnetic phenomenon, which is necessarily accompanied by a significant increase in temperature in the lightning channel - a thermal phenomenon). The study of these phenomena in their interrelation made it possible not only to better understand the natural phenomenon - a thunderstorm, but also to find a way for the practical application of an electric discharge - electric welding of metal parts.
Lesson objectives.
Educational: based on students’ knowledge from the natural history course and a computer presentation, concretize students’ knowledge about physical and chemical phenomena, using examples to identify their differences; Based on the life experience of students, introduce them to the signs of chemical reactions and the conditions for their occurrence and course.
Developmental: to promote the development of students’ creative thinking, the ability to establish cause-and-effect relationships, the dependence of the flow of chemical reactions on external conditions, to develop general educational and practical skills when observing and performing a chemical experiment.
Educational: to form students’ scientific worldview and interest in the subject.
Lesson type: learning a new topic.
Methods: verbal-visual, practical, partially search, working with a textbook.
Forms of organization of cognitive activity: frontal, group, individual.
Students must:
know: definition of physical and chemical phenomena, signs and conditions for the flow of chemical reactions, the significance of physical and chemical phenomena in human life.
be able to: distinguish between physical and chemical phenomena, apply knowledge about physical and chemical phenomena in practice.
Equipment: computer, multimedia projector, presentation.
On the teacher's desk.
- A mixture of iron and sulfur powders, test tube, alcohol lamp, tripod.
On the students' desks.
- A tripod, a flask of water closed with a stopper with a gas outlet tube, a beaker, a glass plate, an alcohol lamp.
- Iron filings, sulfur powder, filter paper, magnet, cylinder of water.
During the classes
I. Organizational stage
Teacher greeting students.
Checking the readiness of students and their workplaces for the lesson.
II. Communicating the topic and objectives of the lesson
In natural history lessons, you gained initial knowledge about phenomena occurring in nature. Today in the lesson you will expand your knowledge about physical and chemical phenomena, learn to distinguish them from each other, get acquainted with the signs and conditions of chemical reactions and their significance in human life (slide No. 1) .
III. Learning a new topic
Plan for studying a new topic:
1. Phenomena occurring in nature. Classification of phenomena.
2. Physical phenomena.
- Laboratory experiment “Water evaporation and steam condensation”.
3. Chemical phenomena.
- Laboratory experiment “Studying the properties of iron and sulfur.”
- Demonstration experiment “Heating a mixture of iron and sulfur. Study of the properties of the resulting substance.”
4. Signs of chemical reactions. Demonstration of a video clip.
5. Conditions for the occurrence and course of chemical reactions (student message).
6. The meaning of physical phenomena and chemical reactions.
1. Phenomena occurring in nature. Classification of phenomena
Teacher: Guys, what surrounds us? (slide number 2)
Student: Nature. Inanimate and alive.
Teacher: Changes constantly occur in nature. Give examples.
Day turns to night (slide number 3)
It rains or snows, water evaporates (slide number 4)
The grass is green, the stream is flowing (slide number 5)
The wind is blowing, the fire is burning (slide number 6)
A man prepares food. (slide number 7)
Teacher: What can you call these changes?
Student: All changes occurring in nature are called natural phenomena.
Teacher: How are all natural phenomena classified?
Student: Natural phenomena can be biological, physical and chemical (slide number 8). Let's get acquainted with physical and chemical phenomena.
2. Physical phenomena
Teacher: What phenomena are called physical?
Student: Phenomena in which there is no transformation of one substance into another are called physical. For example: wax melting, water evaporating, ice melting (slide number 9).
Laboratory experience
“Evaporation of water and condensation of steam”
Teacher: Let’s conduct the experiment “Evaporation of water and condensation of steam.” Assemble the device as shown on the slide (slide number 10) , check its tightness. Observing safety precautions when working with an alcohol lamp and glassware, light the alcohol lamp and heat the flask with water.
What are you observing?
Student: When liquid water boils, it turns into a gaseous state (water vapor). When water vapor hits a glass plate, it condenses into water droplets.
Teacher: What is the essence of physical phenomena?
Student: During physical phenomena, the state of aggregation and form of matter changes (slide number 11).
3. Chemical phenomena
Teacher: Chemical phenomena are a completely different matter. Burning fire, souring milk, rusting iron and steel products (slide number 12).
What happens during chemical events?
Student: During chemical phenomena, some substances are transformed into others.
Laboratory experience
“Study of the properties of sulfur and iron”
Teacher: Let's do it experiment “Studying the properties of sulfur and iron” according to plan (slide number 13). Determine the color of the substances.
Teacher: Do the properties of substances in a mixture change?
Student: No. The substances included in the mixture retain their individual properties.
Demonstration experiment “Heating a mixture of iron and sulfur.
Study of the properties of the resulting substance”
Teacher: Let's heat the resulting mixture of sulfur and iron (slide number 15). Let's take a mixture of sulfur and iron and heat it in a test tube.
What are you observing?
Student: The mixture began to darken, then became red hot.
Teacher: Let’s extract from the test tube what is formed after the reaction and study its properties (color, relationship to water and magnet). To do this, grind the resulting substance and apply a magnet to it.
What are you observing?
Student: Powder is not attracted by a magnet.
Teacher: Let’s put the resulting substance in water.
What are you observing?
Student: The substance sinks and is not separated into sulfur and iron.
Teacher: What happened when the mixture of sulfur and iron was heated?
Student: When a mixture of sulfur and iron was heated, a new substance was formed, which in its properties differs from the properties of the original substances (slide number 16).
Teacher: Chemical phenomena are called chemical reactions.
4. Signs of chemical reactions
Teacher: The fact that a chemical reaction has occurred can be judged by its signs. Watch a video demonstrating the experience (slide number 17).
What signs of chemical reactions did you observe during the demonstration experiments?
Student: We observed such signs of chemical reactions as changes in color, precipitation, release of gas, release of energy.
Teacher: On the next slide (slide number 18) shows all the signs that can be observed during chemical reactions.
Teacher: For a chemical reaction to begin, certain conditions are necessary.
Conditions for the occurrence and course of chemical reactionsStudent message (slide number 19)
| The most important condition for the occurrence of chemical reactions
- contact of substances. For example, rust forms on the surface of an iron product if it comes into contact with moist air. Another condition is the grinding of substances. What will flare up better - a log or thin splinters? Many reactions occur in solution, so the starting materials must be dissolved. The third condition is heating the substance to a certain temperature. For example, copper does not react with oxygen under normal conditions. For the reaction to occur, the copper must be heated. Coal and wood are also heated to a certain temperature so that they begin to burn. Sometimes high temperature is needed throughout the entire reaction - otherwise the reaction will stop. For example, oxygen in the laboratory is obtained from the decomposition of potassium permanganate with constant heating of the latter (slide number 20) . In this case, the temperature is condition for a chemical reaction to occur. – Other conditions for chemical reactions |
6. the action of pressure, the presence of catalysts - substances that accelerate a chemical reaction. By changing flow conditions, you can speed up or stop a chemical reaction.
The meaning of physical phenomena and chemical reactions Teacher: Study the text of paragraph §3 “The significance of physical phenomena and chemical reactions”, fill in
table:
The meaning of physical phenomena and chemical reactions
IV. Consolidation Frontal survey
What conditions are necessary for chemical reactions to occur?
Test “Physical and chemical phenomena.
1, 2. Identify physical and chemical phenomena (slides No. 22, 23)
3. Phenomena in which the shape and state of aggregation of a substance changes are called... (slide number 24)
A – chemical
B – physical
B – biological
4. Phenomena in which the transformation of one substance into another occurs is called ... (slide number 25)
A – physical
B – chemical
B – biological
5. Physical phenomena include: (slide number 26)
A – glass melting
B – wood burning
B – evaporation of water
G – sour milk
D – dissolution of salt in water
E – rotten eggs
6. Chemical phenomena include: (slide number 27)
A – rusting of iron
B – fog formation
B – fruit rotting
G – wax melting
D – burning of kerosene
E – water evaporation
7. Indicate a sign of a chemical reaction when an acid acts on soda: (slide number 28)
A – formation of sediment
B – color change
B – gas evolution
8. Indicate a sign of a chemical reaction when iron rusts: (slide number 29)
A – gas evolution
B – formation of sediment
B – color change
9. Indicate a sign of a chemical reaction when wood burns: (slide number 30)
A – color change
B – precipitation
B – heat release
V. Summing up the lesson, grading
VI. Homework
Literature
- Alikberova L.Yu. Entertaining chemistry: A book for students, teachers, parents. – M.: Ast-Press, 1999.
- Rudzites G.E., Feldman F.G. Chemistry. 8th grade: Textbook for general education - M.: Enlightenment, 2007.
- Khripkova A.G. and others. Natural science: textbook for 7th grade of general education institutions. – M.: Education, 2005.
- http://chemistry.r2.ru/
- http://www.chem.msu.su/rus/elibrary/
- CD “Big Encyclopedia of Cyril and Methodius 2009”. – Cyril and Methodius LLC, 2009.
- CD “General and Inorganic Chemistry”: In-depth course on general and inorganic chemistry. – Laboratory of Multimedia Systems, MarSTU, 2001.
We are surrounded by an infinitely diverse world of substances and phenomena.
Changes are constantly taking place in it.
Any changes that occur to bodies are called phenomena. The birth of stars, the change of day and night, the melting of ice, the swelling of buds on trees, the flashing of lightning during a thunderstorm, and so on - all these are natural phenomena.
Physical phenomena
Let us remember that bodies are made of substances. Let us note that during some phenomena the substances of bodies do not change, but during others they do. For example, if you tear a piece of paper in half, then, despite the changes that have occurred, the paper will remain paper. If you burn the paper, it will turn into ash and smoke.
Phenomena in which the size, shape of bodies, the state of substances may change, but substances remain the same, do not transform into others, are called physical phenomena(evaporation of water, glow of a light bulb, sound of the strings of a musical instrument, etc.).
Physical phenomena are extremely diverse. Among them there are mechanical, thermal, electrical, light and etc.
Let's remember how clouds float across the sky, an airplane flies, a car drives, an apple falls, a cart rolls, etc. In all of the above phenomena, objects (bodies) move. Phenomena associated with a change in the position of a body in relation to other bodies are called mechanical(translated from Greek “mechane” means machine, weapon).
Many phenomena are caused by alternating heat and cold. In this case, changes occur in the properties of the bodies themselves. They change shape, size, the state of these bodies changes. For example, when heated, ice turns into water, water into steam; When the temperature drops, steam turns into water, and water into ice. Phenomena associated with heating and cooling of bodies are called thermal(Fig. 35).
Rice. 35. Physical phenomenon: transition of a substance from one state to another. If you freeze drops of water, ice will form again
Let's consider electric phenomena. The word "electricity" comes from the Greek word "electron" - amber. Remember that when you quickly take off your wool sweater, you hear a slight cracking sound. If you do the same in complete darkness, you will also see sparks. This is the simplest electrical phenomenon.
To get acquainted with another electrical phenomenon, do the following experiment.
Tear small pieces of paper and place them on the table surface. Comb clean and dry hair with a plastic comb and hold it to the pieces of paper. What happened?
Rice. 36. Small pieces of paper are attracted to the comb
Bodies that are capable of attracting light objects after rubbing are called electrified(Fig. 36). Lightning during a thunderstorm, auroras, electrification of paper and synthetic fabrics are all electrical phenomena. The operation of the telephone, radio, television, and various household appliances are examples of human use of electrical phenomena.
Phenomena that are associated with light are called light phenomena. Light is emitted by the Sun, stars, lamps and some living creatures, such as fireflies. Such bodies are called glowing.
We see under the condition of exposure to light on the retina of the eye. In absolute darkness we cannot see. Objects that do not themselves emit light (for example, trees, grass, the pages of this book, etc.) are visible only when they receive light from some luminous body and reflect it from their surface.
The moon, which we often talk about as a night luminary, is in fact only a kind of reflector of sunlight.
By studying the physical phenomena of nature, man learned to use them in everyday life.
1. What are called natural phenomena?
2. Read the text. List what natural phenomena are named in it: “Spring has come. The sun is getting hotter and hotter. The snow is melting, streams are flowing. The buds on the trees have swelled and the rooks have arrived.”
3. What phenomena are called physical?
4. From the physical phenomena listed below, write down the mechanical phenomena in the first column; in the second - thermal; in the third - electric; in the fourth – light phenomena.
Physical phenomena: flash of lightning; snow melting; coast; melting metals; operation of an electric bell; rainbow in the sky; sunny bunny; moving stones, sand with water; boiling water.
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>> Physical and chemical phenomena (chemical reactions). Let's experiment at home. External effects in chemical reactions
Physical and chemical phenomena (chemical reactions)
The material in this paragraph will help you figure out:
>what is the difference between physical and chemical phenomena.(chemical reactions);
> what external effects accompany chemical reactions.
In natural history lessons, you learned that various physical and chemical phenomena occur in nature.
Physical phenomena.
Each of you has repeatedly observed how ice melts, water boils or freezes. Ice, water and water vapor consist of the same molecules, so they are one substance (in different states of aggregation).
Phenomena in which a substance does not transform into another are called physical.
Physical phenomena include not only changes in substances, but also the glow of hot bodies, the passage of electric current in metals, the spread of the smell of substances in the air, the dissolution of fat in gasoline, and the attraction of iron to a magnet. Such phenomena are studied by the science of physics.
Chemical phenomena (chemical reactions).
One of the chemical phenomena is combustion. Let's consider the process of burning alcohol (Fig. 46). It occurs with the participation of oxygen contained in the air. When burned, alcohol seemingly turns into a gaseous state, just as water turns into steam when heated. But that's not true. If the gas obtained as a result of the combustion of alcohol is cooled, then part of it will condense into liquid, but not into alcohol, but into water. The rest of the gas will remain. With the help of additional experiment it can be proven that this residue is carbon dioxide.
Rice. 46. Burning alcohol
So the alcohol that burns and oxygen, which participates in the combustion process, are converted into water and carbon dioxide.
Phenomena in which some substances are transformed into others are called chemical phenomena or chemical reactions.
Substances that enter into a chemical reaction are called starting substances, or reagents, and those that are formed are called final substances, or reaction products.
The essence of the chemical reaction considered is conveyed by the following entry:
alcohol + oxygen -> water + carbon dioxide
starting materials final substances
(reagents) (reaction products)
The reactants and products of this reaction are made up of molecules. During combustion, a high temperature is created. Under these conditions, the molecules of the reagents disintegrate into atoms, which, when combined, form molecules of new substances - products. Therefore, all atoms are conserved during the reaction.
If the reactants are two ionic substances, then they exchange their ions. Other variants of interaction of substances are also known.
External effects accompanying chemical reactions.
By observing chemical reactions, you can record the following effects:
Change in color (Fig. 47, a);
gas release (Fig. 47, b);
formation or disappearance of sediment (Fig. 47, c);
appearance, disappearance or change in odor;
release or absorption of heat;
the appearance of a flame (Fig. 46), sometimes a glow.
Rice. 47. Some external effects during chemical reactions: a - appearance
coloring; b - gas release; c - appearance of sediment
Laboratory experiment No. 3
The appearance of color as a result of the reaction
Are solutions of soda ash and phenolphthalein colored?
Add 2 drops of phenolphthalein solution to a portion of soda solution I-2. What color appeared?
Laboratory experiment No. 4
Release of gas as a result of the reaction
Add a little chloride acid to the soda ash solution. What are you observing?
Laboratory experiment No. 5
The appearance of a precipitate as a result of the reaction
Add 1 ml of copper sulfate solution to the soda ash solution. What's happening?
The appearance of a flame is a sign of a chemical reaction, i.e. it indicates a chemical phenomenon. Other external effects can also be observed during physical phenomena. Let's give a few examples.
Example 1. Silver powder obtained in a test tube as a result of a chemical reaction is gray in color. If you melt it and then cool the melt, you will get a piece of metal, but not gray, but white, with a characteristic shine.
Example 2. If you heat natural water, gas bubbles will begin to emerge from it long before boiling. This is dissolved air; its solubility in water decreases when heated.
Example 3. An unpleasant odor in the refrigerator disappears if granules of silica gel, one of the silicon compounds, are placed in it. Silica gel absorbs molecules of various substances without destroying them. Activated carbon works in a similar way in a gas mask.
Example 4 . When water turns into steam, heat is absorbed, and when water freezes, heat is released.
To determine what kind of transformation has occurred - physical or chemical, you should carefully observe it, as well as comprehensively examine the substances before and after the experiment.
Chemical reactions in nature, everyday life and their significance.
Chemical reactions occur constantly in nature. Substances dissolved in rivers, seas, and oceans interact with each other, some react with oxygen. Plants absorb carbon dioxide from the atmosphere, water and dissolved substances from the soil and process them into proteins, fats, glucose, starch, vitamins, other compounds, as well as oxygen.
This is interesting
As a result of photosynthesis, about 300 billion tons of carbon dioxide are absorbed from the atmosphere each year, 200 billion tons of oxygen are released, and 150 billion tons of organic substances are formed.
Reactions involving oxygen, which enters living organisms during respiration, are very important.
Many chemical reactions accompany us in everyday life. They occur during frying meat, vegetables, baking bread, souring milk, fermenting grape juice, bleaching fabrics, burning various types of fuel, hardening cement and alabaster, blackening silver jewelry over time, etc.
Chemical reactions form the basis of such technological processes as the extraction of metals from ores, the production of fertilizers, plastics, synthetic fibers, medicines, and other important substances. By burning fuel, people provide themselves with heat and electricity. Using chemical reactions, they neutralize toxic substances and process industrial and household waste.
The occurrence of some reactions leads to negative consequences. Rusting of iron shortens the life of various mechanisms, equipment, vehicles, and leads to large losses of this metal. Fires destroy housing, industrial and cultural facilities, and historical values. Most foods spoil due to their interaction with oxygen in the air; in this case, substances are formed that have an unpleasant odor, taste and are harmful to humans.
conclusions
Physical phenomena are the phenomena in which each substance is conserved.
Chemical phenomena, or chemical reactions, are the transformation of one substance into another. They can be accompanied by various external effects.
Many chemical reactions occur in the environment, in plants, animals and humans, and accompany us in everyday life.
?
100. Match:
1) dynamite explosion; a) physical phenomenon;
2) solidification of molten paraffin; b) chemical phenomenon.
3) food burning in a frying pan;
4) the formation of salt during the evaporation of sea water;
5) separation of a strongly shaken mixture of water and vegetable oil;
6) fading of dyed fabric in the sun;
7) passage of electric current in the metal;
101. What external effects are accompanied by such chemical transformations: a) burning of a match; b) rust formation; c) fermentation of grape juice.
102. Why do you think some food products (sugar, starch, vinegar, salt) can be stored indefinitely, while others (cheese, butter, milk) quickly spoil?
Experimenting at home
External effects in chemical reactions
1. Prepare small amounts of aqueous solutions of citric acid and baking soda. Pour portions of both solutions together into a separate glass. What's happening?
Add a few soda crystals to the remainder of the citric acid solution, and a few citric acid crystals to the remainder of the soda solution. What effects do you observe - the same or different?
2. Pour some water into three small glasses and add 1-2 drops of brilliant green alcohol solution, known as “zelenka,” to each. Add a few drops of ammonia to the first glass, and citric acid solution to the second. Has the color of the dye (green) in these glasses changed? If so, how exactly?
Write down the results of the experiments in a notebook and draw conclusions.
Popel P. P., Kryklya L. S., Chemistry: Pidruch. for 7th grade. zagalnosvit. navch. closing - K.: VC "Academy", 2008. - 136 p.: ill.
Lesson content lesson notes and supporting frame lesson presentation interactive technologies accelerator teaching methods Practice tests, testing online tasks and exercises homework workshops and trainings questions for class discussions Illustrations video and audio materials photographs, pictures, graphs, tables, diagrams, comics, parables, sayings, crosswords, anecdotes, jokes, quotes Add-ons abstracts cheat sheets tips for the curious articles (MAN) literature basic and additional dictionary of terms Improving textbooks and lessons correcting errors in the textbook, replacing outdated knowledge with new ones Only for teachers calendar plans training programs methodological recommendationsEverything that surrounds us: both living and inanimate nature, is in constant motion and is constantly changing: planets and stars move, it rains, trees grow. And a person, as is known from biology, constantly goes through some stages of development. Grinding grains into flour, falling a stone, boiling water, lightning, glowing a light bulb, dissolving sugar in tea, moving vehicles, lightning, rainbows are examples of physical phenomena.
And with substances (iron, water, air, salt, etc.) various changes or phenomena occur. The substance can be crystallized, melted, crushed, dissolved and again isolated from solution. However, its composition will remain the same.
Thus, granulated sugar can be crushed into a powder so fine that the slightest blow will cause it to rise into the air like dust. Sugar grains can only be seen under a microscope. Sugar can be divided into even smaller parts by dissolving it in water. If you evaporate water from a sugar solution, the sugar molecules again combine with each other to form crystals. But even when dissolved in water or when crushed, sugar remains sugar.
In nature, water forms rivers and seas, clouds and glaciers. When water evaporates, it turns into steam. Water vapor is water in a gaseous state. When exposed to low temperatures (below 0˚C), water turns into a solid state - turns into ice. The smallest particle of water is a water molecule. A water molecule is also the smallest particle of steam or ice. Water, ice and steam are not different substances, but the same substance (water) in different states of aggregation.
Like water, other substances can be transferred from one state of aggregation to another.
When characterizing a substance as a gas, liquid or solid, we mean the state of the substance under normal conditions. Any metal can not only be melted (transformed into a liquid state), but also turned into gas. But this requires very high temperatures. In the outer shell of the Sun, metals are in a gaseous state, because the temperature there is 6000˚C. And, for example, carbon dioxide can be converted into “dry ice” by cooling.
Phenomena in which there is no transformation of one substance into another are classified as physical phenomena. Physical phenomena can lead to a change, for example, in the state of aggregation or temperature, but the composition of the substances will remain the same.
All physical phenomena can be divided into several groups.
Mechanical phenomena are phenomena that occur with physical bodies when they move relative to each other (the revolution of the Earth around the Sun, the movement of cars, the flight of a parachutist).
Electrical phenomena are phenomena that occur with the appearance, existence, movement and interaction of electrical charges (electric current, telegraphy, lightning during a thunderstorm).
Magnetic phenomena are phenomena associated with the appearance of magnetic properties in physical bodies (the attraction of iron objects by a magnet, turning the compass needle to the north).
Optical phenomena are phenomena that occur during the propagation, refraction and reflection of light (rainbows, mirages, reflection of light from a mirror, the appearance of shadows).
Thermal phenomena are phenomena that occur during heating and cooling of physical bodies (melting snow, boiling water, fog, freezing of water).
Atomic phenomena are phenomena that arise when the internal structure of the substance of physical bodies changes (the glow of the Sun and stars, an atomic explosion).
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