home Fairy tales What is the importance of diffusion for processes. Abstract: Topic: "Diffusion in animate and inanimate nature

What is the importance of diffusion for processes. Abstract: Topic: "Diffusion in animate and inanimate nature

A few words about human digestion The greatest absorption of nutrients occurs in the small intestines, the walls of which are specially adapted for this. The area of the inner surface of the human intestine is 0.65 square meters. It is covered with villi - microscopic formations of the mucous membrane with a height of 0.2-1 mm, due to which the area of the real surface of the intestine reaches 4-5 square meters, i.e. reaches 2-3 times the surface area of the whole body. The absorption of nutrients in the intestine is made possible by diffusion.

Breathing - the transfer of oxygen from the environment into the body through its integuments - occurs the faster, the larger the surface area of the body and the environment, and the slower, the thicker and denser the integuments of the body. Hence, it is clear that small organisms, whose surface areas are large in comparison with the volume of the body, can do without special respiratory organs at all, being satisfied with the flow of oxygen exclusively through the outer shell (if it is sufficiently thin and moist). In larger organisms, respiration through the skin may be more or less sufficient only if the integument is extremely thin (amphibians); with coarse integuments, special respiratory organs are needed. The main physical requirements for these organs are maximum surface and minimum thickness, high moisture content of the integument. The first is achieved by numerous ramifications or folds (pulmonary alveoli, fringed gills).

But how does a person breathe? In humans, the entire surface of the body takes part in breathing - from the thickest epidermis of the heels to the scalp covered with hair. The skin on the chest, back and abdomen breathes especially intensively. It is interesting that in terms of respiration intensity these areas of the skin are significantly superior to the lungs. With a respiratory surface of the same size, oxygen can be absorbed by 28% and released carbon dioxide even 54% more than in the lungs. However, in the entire respiratory process, the participation of the skin is negligible in comparison with the lungs, since the total surface area of the lungs, if you expand all 700 million alveoli, microscopic bubbles, through the walls of which gas exchange between air and blood occurs, is about 90-100 square meters and the total surface area of human skin is about 2 square meters, that is, 45-50 times less.

The role of diffusion in plant nutrition.

The main role in diffusion processes in living organisms is played by cell membranes, which have selective permeability. The passage of substances through the membrane depends on:

* molecular size;
* electric charge;
* on the presence and number of water molecules;
* on the solubility of these particles in fats;
* from the structure of the membrane.

There are two forms of diffusion: a) dialysis is the diffusion of solute molecules; b) osmosis is the diffusion of a solvent through a semipermeable membrane. Soil solutions contain mineral salts and organic compounds... Water from the soil enters the plant by osmosis through the semipermeable membranes of root hairs. The concentration of water in the soil turns out to be higher than inside the root hairs; therefore, diffusion occurs from the zone with a higher concentration to the zone with a lower concentration. Then the concentration of water in these cells becomes higher than in the overlying ones - a root pressure arises, causing an upward flow of juice along the roots and stem, and the loss of water by the leaves ensures further absorption of water.

Mineral substances enter the plant: a) by diffusion; b) sometimes by active transfer against the concentration gradient, accompanied by energy expenditure. There is also turgor pressure - this is the pressure exerted by the contents of the cell on the cell wall. It is almost always below the osmotic pressure of the sap cell, because the outside is not pure water, but a saline solution. Turgor pressure value:

- preservation of the form of the plant organism;
- ensuring growth in young plant cells;
- maintaining the elasticity of plants (demonstration of cactus and aloe plants);
- shaping in the absence of reinforcing fabric (demonstration of a tomato);

Speaking about the importance of osmosis for living organisms, we cannot but dwell on plasmolysis.

Plasmolysis.

If the concentration of salts in the liquid bathing the cell is higher than in the cell sap, as, for example, when a lettuce leaf is immersed in a concentrated saline solution, then the water of the cell sap diffuses from the cell, moving from the zone with a higher concentration of water to the zone with a lower concentration. Finally, the cell content loses its ability to exert pressure on the cell wall, in other words, the turgor pressure drops to zero and the lettuce withers (demonstration). When the volume of cell sap decreases as a result of water loss, the cytoplasm of the cell is no longer pressed against the cellulose cell wall. Instead, the cytoplasm lags behind the cell wall undergoing plasmolysis. Plant cells that are too long in a high concentration of saline will die. If, after a short-term maintenance in such a solution, the cells are transferred to clean water, then they can restore their turgency.

Turgor pressure makes the plant cell hard, capable of recovering from deformation under the influence of some external force.

Plasmolysis is a reversible process. The reverse process is called deplasmolysis, this is a property of the plasma membrane.

Thus, diffusion is of great importance in the life processes of humans, animals and plants. Due to diffusion, oxygen from the lungs penetrates into the human blood, and from the blood - into the tissues.

In addition to the wide manifestation of diffusion in the life of living organisms, it is used in Everyday life and industry.

If two substances are separated by a semi-permeable septum (membrane), diffusion proceeds in one direction. This phenomenon is called osmosis.

Osmosis from the Greek - push, pressure. During osmosis, the concentration of the solution is equalized on both sides of the membrane, which allows small molecules of a solvent to pass through, but does not allow larger molecules of a solute to pass through. Osmosis flows from a pure solvent to a solution or from a dilute solution to a concentrated one. Osmosis was first observed by the French chemist Nolle in 1748.

The transfer of solvent molecules is due to osmotic pressure or diffusion pressure. This is a thermodynamic parameter that characterizes the tendency of a solution to decrease in concentration when in contact with a pure solvent.

Osmotic pressure is due to a decrease in the chemical potential of a solvent in the presence of a solute. Osmotic pressure in extremely dilute solutions does not depend on the nature of the solvent and solutes; at constant temperature, it is determined only by the number of particles. The first measurements of osmotic pressure were made by the German botanist Pfeffer in 1877, investigating aqueous solutions of sugar.

Solutions with the same osmotic pressure are called isoosmotic. Thus, various blood substitutes and saline solutions are isoosmotic relative to the internal fluids of the body. If one solution has a higher osmotic pressure in comparison with another, it is called hypertonic, and one that has a lower osmotic pressure is called hypotonic.

Research

Performed: Ryakhovskaya Oksana
student of grade 7 "D"
MBOU them. Leo Tolstoy

Supervisor: Physics teacher
MBOU them. Leo Tolstoy

T.V. Shlyapina

Introduction.
I. Definition of the concept of "diffusion".
1.1. Definition of the concept of "diffusion".
1.2. Osmosis.

II. Diffusion around us.
2.1. The role of diffusion in everyday life and technology.
2.2. Diffusion in human life
2.3. Diffusion in wildlife.

III. The influence of human activity on the course of diffusion processes in nature.

IV. Practical experiments to support the theory.

4.1.Experiment No. 1. Observation of diffusion when mixing two liquids.

4.2. Experience number 2. Observation of diffusion when mixing a granular body with a liquid.
4.3. Experience No. 3 Observation of the phenomenon of diffusion in liquids.
4.4. Experience No. 4 Study of the dependence of the rate of diffusion on the temperature.
4.5. Experience No. 5 Observation of the phenomenon of diffusion in gases.
4.6. Experience No. 6 Influence of various substances on the water surface on the diffusion process.

V. Sociological survey.
5.1. Methodology for conducting a sociological survey on the problem of ecology.
5.2. Analysis of the results.

Vi. Conclusion.
Vii. List of used literature and Internet resources

Introduction

The structure of matter is one of the main problems of science, and the basis modern physics is atomic-molecular teaching.
At present, the evidence for the provisions of the molecular kinetic theory is so numerous and convincing that the existence of molecules is recognized as an established fact. Of the large number of scientific theses and experimental facts related to molecular kinetic theory, the diffusion phenomenon, which I met in the 7th grade in physics lessons, aroused the greatest interest in me.
Every morning, drinking a mug of tea, we do not realize that we are observing the phenomenon of diffusion. I became interested in this phenomenon because it is one of the important processes in the life support of people and the living nature of the Earth.
The role played by diffusion in the world around us can hardly be overestimated. It is found everywhere, its manifestations are in nature, and in technology, and in everyday life. Unfortunately, diffusion processes can have not only a positive, but also a negative effect on the vital activity of plants, animals and humans.

In the course of work, I set myself the following goals:

deepen your knowledge on this topic;

investigate the features of diffusion in various media and consider its application;

show the role of diffusion processes in ecological balance.

Tasks:

1. Find the necessary material in the literature, the Internet, study and analyze it.

2. Find out where in living and inanimate nature (physics and biology) there are diffusion phenomena, what value they have, where they are applied by humans.

3. Describe and design the most interesting experiences on this phenomenon.

In my work, I used the following research methods:

observation

experiment,

sociological survey.

I. Definition of the concept of "diffusion".

1.1. Definition of the concept of "diffusion".

Diffusion ( lat. diffusio- spreading, spreading, dispersing) - the process of transfer of matter or energy from an area of high concentration to an area of low concentration. This process is due to the chaotic thermal movement of molecules and consists in the transfer of particles and the mutual penetration of substances. Diffusion occurs in the direction of a decrease in the concentration of a substance and leads to a uniform distribution of the substance over the entire volume it occupies. This phenomenon takes place in gases, liquids and solids, and both the particles of foreign substances in them and their own particles (self-diffusion) can diffuse. Diffusion of large particles suspended in a gas or liquid is carried out due to their Brownian motion.
The fastest diffusion processes occur in gases, slower in liquids, and even slower in solids, which is due to the nature of the thermal motion of particles in these media.
The most famous example of diffusion is the mixing of gases or liquids (if ink is dropped into water, then the liquid will become uniformly colored after a while). Another example is related to a solid body: if one end of the rod is heated or electrically charged, heat (or, accordingly, electric current) spreads from the hot (charged) part to the cold (uncharged) part. In the case of a metal rod, thermal diffusion develops rapidly and the current flows almost instantaneously. If the rod is made of synthetic material, thermal diffusion is slow and diffusion of electrically charged particles is very slow. The diffusion of molecules is generally even slower. For example, if a sugar cube is lowered to the bottom of a glass of water and the water is not stirred, then several weeks will pass before the solution becomes homogeneous.
The diffusion of one solid into another occurs even more slowly. For example, if copper is covered with gold, then diffusion of gold into copper will occur, but under normal conditions the gold-bearing layer will reach a thickness of several micrometers only after a few thousand years.

When a particle moves in a substance, it constantly collides with its molecules. This is one of the reasons why diffusion under normal conditions is slower than normal motion. What determines the diffusion rate?

First, from the average distance between particle collisions, i.e. free path length. The greater this length, the faster the particle penetrates into the substance.

Secondly, the pressure affects the speed. The denser the packing of particles in a substance, the more difficult it is for an alien particle to penetrate into such a packing.

Thirdly, the molecular weight of a substance plays an important role on the rate of diffusion. The larger the target, the more likely it is to hit, and after a collision, the speed always slows down.

And fourthly, the temperature. As the temperature rises, the vibrations of the particles increase, and the speed of the molecules increases. However, the speed of diffusion is a thousand times slower than the speed of free movement.

1.2. Osmosis.

When we want to quench our thirst, we drink water. But how does the drunk water get into the cells of our body? And this happens thanks to osmosis. If two solutions with different concentrations are brought into contact, then these solutions will mix as a result of diffusion. And if two such solutions are separated by an impermeable partition, then nothing will work at all.
But if two such solutions are separated by a partition that allows the solvent molecules to pass through, but traps the solute molecules, then the solvent molecules will pass into a more concentrated solution, diluting it more and more. Arises osmosis- directional movement of solvent molecules through a semi-permeable partition separating two solutions of different concentrations. Diffusion of the solvent continues until equilibrium is established in the system as a result of equalization of concentrations on both sides of the baffle or as a result of osmotic pressure.

The shells of all living cells, without exception, have a remarkable ability to pass water molecules and retain molecules of substances dissolved in it - it is thanks to this that the cell can quench its thirst

The diffusion of ions in aqueous solutions is especially important for living organisms. No less important is the role of diffusion in respiration, photosynthesis, and transpiration of plants; in the transfer of air oxygen through the walls of the alveoli of the lungs and its entry into the blood of humans and animals. Diffusion of molecular ions across membranes is carried out using an electric potential inside the cell. Possessing selective permeability, membranes play the role of customs in the movement of goods across the border: some substances are allowed through, others are detained, and others are generally “expelled” from the cage. The role of membranes in the life of cells is very important. A dying cell loses control over the ability to regulate the concentration of substances across the membrane. The first sign of cell dying is the beginning changes in permeability and a malfunction of its outer membrane.

I tried to make a curious experience. I took a lemon and cut off a few thin slices. At the same time, there was practically no juice. I sprinkled the lemon slices with sugar - and after a while the juice flowed out of them. Then osmosis began to act: juice flowed out of the lemon, as if trying to dilute the concentrated sugar solution formed on its surface as much as possible.
And if you grind the chopped cabbage with salt, then its volume will sharply decrease, and the cabbage itself will become wet. This is also osmosis, only in this case, there is salt outside the cell.

Osmosis finds practical application in the process of water purification.

II. Diffusion around us.

2.1. The role of diffusion in everyday life and technology.

Diffusion is used in many technological processes: salting, sugar production (sugar beet chips are washed with water, sugar molecules diffuse from the chips into the solution), jam cooking, fabric dyeing, laundry, carburizing, welding and soldering of metals, including diffusion welding in vacuum (metals are welded that cannot be joined by other methods - steel with cast iron, silver with stainless steel, etc.) and diffusion metallization of products (surface saturation of steel products with aluminum, chromium, silicon), nitriding - saturation of the steel surface with nitrogen (steel becomes hard, wear-resistant), carburizing - saturation of steel products with carbon, cyanidation - saturation of the steel surface with carbon and nitrogen.
The diffusion of odors in the air is the most common example of diffusion in gases. Why does the smell spread not instantly, but after a while? The fact is that during movement in a certain direction of the molecule odorous substance collide with air molecules. The trajectory of movement of each gas particle is a broken line, since during collisions, particles change direction and speed of their movement.
By means of diffusion, various gaseous substances spread in the air: for example, a person smells perfume, smoke, which spreads over long distances. The natural combustible gas we use at home is colorless and odorless. When a leak occurs, it is impossible to notice it, therefore, at distribution stations, the gas is mixed with a special substance that has a pungent, unpleasant odor that is easily felt by humans.
In liquids, diffusion proceeds more slowly than in gases, but this process can be accelerated by heating. For example, to make it faster
pickle cucumbers, pour them with hot brine. We know that sugar will dissolve more slowly in cold tea than in hot tea.
Another common example of the manifestation of diffusion in everyday life is the washing of colored items. It is not recommended to leave a wet, dark-colored cloth in contact with a white cloth for a long time. Diffusion begins, the dye molecules penetrate into the white fabric.

It should be noted that diffusion has found wide application in the electronics industry; many semiconductor devices are made with it. It is also used in the smelting of many metals such as steel. To give the steel parts significant strength, they are placed in special furnaces, where, being in a heated state, they are saturated with carbon. Carbon atoms penetrate surface layer metal and increase its strength.
Diffusion is widely used in metallization.
Metallization is a method of increasing mechanical properties and increasing corrosion resistance by saturating the near-surface layers with metal alloying elements. It is carried out due to the activation of diffusion processes at elevated temperatures and some additional types of exposure. Therefore, the search for ways to increase the efficiency of metallization is directly related to the study of diffusion processes.

As you can see from the above examples, diffusion plays a very important role in everyday life and technology.

2.2. Diffusion in human life

Studying the phenomenon of diffusion, I came to the conclusion that it is thanks to this phenomenon that a person lives. After all, as you know, the air we breathe consists of a mixture of gases: nitrogen, oxygen, carbon dioxide and water vapor. It is located in the troposphere - in the lower atmosphere. If there were no diffusion processes, then our atmosphere would simply stratify under the action of gravity, which acts on all bodies on the surface of the Earth or near it, including air molecules. Below there would be a heavier layer of carbon dioxide, above it - oxygen, above - nitrogen and inert gases. But for normal life, we need oxygen, not carbon dioxide.

Diffusion also occurs in the human body itself. Human breathing and digestion is based on diffusion. If we talk about breathing, then at each moment of time in the blood vessels that encircle the alveoli there is about 70 ml of blood, from which carbon dioxide diffuses into the alveoli, and oxygen in the opposite direction. The huge surface of the alveoli makes it possible to reduce the thickness of the layer of blood exchanging gases with intraalveolar air to 1 micron, which makes it possible to saturate this amount of blood with oxygen in less than 1 s and free it from excess carbon dioxide.

As can be seen from the above examples, diffusion processes play a very important role in people's lives.

2.3. Diffusion in nature.

Over the past decades, people have radically changed their view of the forests of the Earth. And they realized that the forest is not just future firewood, boards, logs, but one of the main links in a huge natural chain. Forests are the lungs of the planet that help all living things breathe. One hectare of forest per year cleans 18 million cubic meters of air from carbon dioxide, absorbs 64 tons of other gases and dust, supplying millions of cubic meters of oxygen in return. The air purification process takes place through diffusion.

Observing ants, I always wondered how they, in a huge world for them, would recognize their way home. It turns out that the phenomenon of diffusion opens this riddle. Ants mark their path with droplets of odorous liquid.

Can living organisms use scent in a duel? Having lifted up a long bushy tail in black and white stripes, a ring-tailed lemur sends messages to congeners, emitting a strong smell. Diffusion in action! If two competing clans collide, the males, stretching out their tails between their legs, rub it with their wrists, the glands of which secrete a caustic secret. Then, getting on all fours, they fold the "charged" tail over their heads and approach the enemy, blowing at him the smell of threat. He who was not afraid won!

The most common way insects communicate is through olfactory chemicals. There are attractive aromas (attractants), and there are repulsive (repellents), perceived by the olfactory holes (pores) on the antennae. Attractants include pheromones and hormones. "The queen is here," says one of the pheromones in the bee's nest. “From this spare male to grow a producer, and from this - a soldier,” - the order sounds through the pheromone in the nest of termites. And what about repellents? “There are many of us, there is not enough food for everyone, wait to grow,” a smelly signal follows from the first mosquito hatch. And the mosquito larvae of the next hatch humbly await the order to turn into mosquitoes.

Through diffusion, insects find food for themselves. Butterflies, fluttering between plants, always find their way to a beautiful flower. The bees, having discovered a sweet object, storm it with their swarm.

And the plant grows, blooms for them, too, thanks to diffusion. After all, we say that the plant breathes and exhales air, drinks water, receives various micro-additives from the soil.

Carnivores also find their prey through diffusion. Sharks and piranha fish smell blood at a distance of several kilometers. The principle of diffusion is based on the mixing of fresh water with salty water when rivers flow into the sea.

In all the above examples, we observe the mutual penetration of molecules of substances, i.e. diffusion, which, as we see, is of great importance in nature, but this phenomenon is also harmful in relation to environmental pollution.

III. The influence of human activity on the course of diffusion processes in nature.

Humanity certainly influences various ecological systems... Examples of such, most often hazardous, impacts are drainage of bogs, deforestation, destruction of the ozone layer, river currents, and waste disposal into the environment.

In air pollution with harmful products industrial production and vehicle exhaust, diffusion plays a huge role. It also makes a huge contribution to the pollution of rivers, seas, oceans with human waste products. The annual discharge of industrial and domestic wastewater in the world amounts to tens of trillions of tons.
One of the examples of the negative human influence on diffusion processes in nature are large-scale accidents occurring in the basins of different water bodies. Thus, according to experts, about 10 million tons of oil gets into the ocean annually. Oil on water forms a thin film that prevents gas exchange between water and air. While settling to the bottom, oil gets into bottom sediments, where it disrupts the natural processes of life of bottom animals and microorganisms. In addition to oil, the release into the ocean of household and industrial Wastewater containing, in particular, such dangerous pollutants as lead, mercury, arsenic, which have a strong toxic effect... The background concentrations of such substances in many places have already been exceeded tenfold.

Due to the phenomenon of diffusion, the air is polluted with wastes from different factories, because of it, harmful human waste penetrates into the soil, water, and then has a harmful effect on the life and functioning of animals and plants. The area of land polluted by industrial emissions, etc. is increasing. More than 2 thousand hectares of land are occupied by dumps of industrial and domestic waste. One of the issues that are difficult to solve at the present time is the issue of disposal of industrial waste, including toxic.

An urgent problem is air pollution from exhaust gases, products of processing harmful substances emitted into the atmosphere by various factories. Several medical studies have shown a relationship between the incidence of respiratory and upper respiratory tract diseases and the state of the air. There is a direct relationship between the rate of respiratory diseases and the volume of emissions of harmful substances into the atmosphere. The listed examples of diffusion have a harmful effect on various processes occurring in nature.

Warning about the possible consequences of the expanding human invasion of nature, half a century ago Academician V. I. Vernadsky wrote: "Man becomes a geological force capable of changing the face of the Earth." This warning was prophetically justified. Consequences human activity are manifested in the depletion of natural resources, pollution of the biosphere with industrial waste, destruction of natural ecosystems, changes in the structure of the Earth's surface, climate change.

I would like to hope that people will nevertheless pay attention to this and do everything possible to save our planet, and not destroy it ...

IV. Practical experiments to support the theory.

How many amazing and interesting things are happening around us! I want to learn a lot, try to explain it myself. That is why I decided to conduct a series of experiments, during which I tried to find out whether the theory of diffusion is really fair, whether it finds its confirmation in practice. Any theory can be considered reliable only if it is repeatedly confirmed experimentally.

4.1. Experience number 1. Take two test tubes: one half filled with water, the other half filled with sand. Pour water into a test tube with sand. The volume of a mixture of water and sand in a test tube is less than the sum of the volumes of water and sand.

4.2. Experience number 2. Half fill a long glass tube with water, and then pour tinted alcohol on top. Mark the total liquid level in the tube with a rubber ring. After mixing water and alcohol, the volume of the mixture decreases.

(Experiments 1 and 2. prove that there are gaps between the particles of a substance; during diffusion, they are filled with particles of a substance - an alien.)

4.3. Experience No. 3 Observation of the phenomenon of diffusion in liquids.

Target : study diffusion in a liquid. Observe the dissolution of pieces of potassium permanganate in water, at a constant temperature (at t = 20 ° C)

Devices and materials : flask with water, thermometer, potassium permanganate.

I took a piece of potassium permanganate and a vessel with clean water at a temperature of 22 ° C. I put a piece of potassium permanganate in a vessel and began to watch what was happening. After 1 minute, the water in the vessel begins to color. Water is a good solvent. Under the action of water molecules, the bonds between the molecules of the solids of potassium permanganate are destroyed.
Eighteen minutes have elapsed since the start of the experiment. The color of the water becomes more intense. Water molecules penetrate between the molecules of potassium permanganate, breaking the forces of attraction. Simultaneously with the forces of attraction between the molecules, repulsive forces begin to act and, as a result, destruction occurs crystal lattice solid matter... The process of dissolving potassium permanganate is over. The experiment took 1 hour 27 minutes. The water is completely crimson.

Can be done conclusion that the phenomenon of diffusion in a liquid is a long-term process, as a result of which the dissolution of solids occurs.
Having carried out the same experiment, but stirring the water (shaking), I was convinced that the diffusion process occurs much faster (2 minutes).

4.4. Experience No. 4 Study of the dependence of the rate of diffusion on the temperature.

Target : study how water temperature affects the rate of diffusion.

Devices and materials : thermometers - 2 pcs, stopwatch - 1 pc, cones - 4 pcs, tea, potassium permanganate.

: (experience of making tea at an initial temperature of 20 ° C and at a temperature of 91 ° C in two glasses
We took two vessels with water at t = 20 ° C and t = 91 ° C. From this experience, it can be concluded that the rate of diffusion is influenced by temperature: the higher the temperature, the higher the rate of diffusion.

I got the same results when I took 2 glasses of water instead of tea. In one of them there was water at room temperature, in the second boiling water.

I dipped the same amount of potassium permanganate into each glass. In the glass where the water temperature was higher, the diffusion process proceeded much faster.

Therefore, the diffusion rate depends on the temperature - the higher the temperature, the more intense the diffusion occurs.

4.5. Experience No. 5 Observation of the phenomenon of diffusion in gases.

Target: study of changes in gas diffusion in air depending on changes in room temperature.

Devices and materials : stopwatch, perfume, thermometer.

Description of the experience and the results obtained : I investigated the time of the spread of the smell of perfume in the room V = 60m 3 at a temperature of t = +15 0 (the room was brought to the required temperature by ventilation). The time from the beginning of the spread of the smell in the room, to the receipt of obvious sensitivity in people standing at a distance of 5 m from the object under study (perfume) was recorded. Then the room was thoroughly ventilated and, 3 hours after this experiment, the temperature was increased to 20 ° C. Then the experiment was repeated bringing the temperature to 25 ° C. For all the data obtained, the arithmetic mean value was determined. I gave the experimental data in the table.

t 0 premises	+15 0	+20 0	+25 0
Perfume smell spreading time, s
Number of experiments

If we assume that the diffusion processes are directly proportional to the time the perfume smell spreads in the room, then as a result this study it is possible to reveal the dependence of the time of the spread of the smell of perfume in the room, and hence the rate of diffusion on the change in air temperature.

The data obtained indicate that the rate of spread of the smell of perfume depends on the increase in the temperature of the room as follows: with an increase in temperature from +15 0 to 5 0, this parameter decreased by 8.9 sec. This indicates that the smell has spread faster. With a further increase in the room temperature by 5 0 (up to 25 0), it decreased by 15.3 seconds, which indicates an acceleration in the spread of odor. Thus, the analysis of the indicators of the time of the spread of the smell of perfume in the room showed that diffusion accelerates with increasing temperature.

Conclusion : the higher the temperature of the gases, the faster the diffusion processes occur. For example, when hot gases are released from the pipes of various enterprises (or from the exhaust pipes of cars), these substances harmful to the health of people and animals spread very quickly. This happens even faster in the summer.

^ 4.6. Experience No. 6 Influence of various substances on the water surface on the diffusion process

Target : study how different substances on the water surface affect the rate of evaporation of water and draw a conclusion about the rate of diffusion.

Devices and materials : thermometers - 3 pieces, stopwatch - 1 piece, saucers of water - 3 pieces, kerosene, vegetable oil.

Description of the experience and the results obtained : I poured water of the same mass and the same temperature (36 degrees) into the saucers, then I left water in the first saucer (5 ml), in the second I poured kerosene (5 ml), in the third - vegetable oil (5 ml). The vegetable oil in our experiment mimicked oil. Time was recorded, every 10 minutes readings of thermometers placed in all liquids were taken. The measurement results are recorded in the table.

Time, s	Temperature pure water	Kerosene water temperature	Water temperature with vegetable oil

When evaporated, individual molecules fly out of the water. Since water, covered with a film of gasoline, kerosene and vegetable oil, cools more slowly, we can say that it is more difficult for oxygen molecules to leave the water.

Conclusion : in the presence of various substances on the surface of the water, the diffusion process is slower. So in the surrounding nature spilled oil disrupts diffusion processes and can lead to undesirable environmental impact.

V. Sociological survey.

Purpose of the survey : draw people's attention to an environmental problem, as well as find out how they are informed about this problem and what they are doing at the household level to solve it.

Yes. No. I am at a loss to answer

5.1. Methodology for conducting a sociological survey on the problem of ecology

I interviewed people using a pre-developed questionnaire, ready-made expected answers were given to positions.

The survey was conducted anonymously. The survey involved 20 adults and 20 schoolchildren from grades 7 to 10. Both acquaintances (the majority) and bystanders on the street were interviewed.

5.2. Analysis of the results

The results of a sociological survey have shown that adults are much more concerned about environmental problems. So, from the adults we have simplified to the question: "Does diffusion affect the ecology?" 45% of adults answered affirmatively and 15% of schoolchildren three times less, and 35% of adults and 70% of schoolchildren answered negatively. Therefore, in school curriculum not enough attention is paid to this problem. On the whole, 30% of the surveyed population think about this issue and 45% do not.

It is possible that the adults, despite the anonymity of the survey, wanted to appear to us more “correct”, but perhaps they often have to deal with environmental problems in their daily life.

Based on the survey, the following can be done conclusions:

1. The inhabitants of our village do not pay enough attention to the problem of ecology.

2. Adults think about this problem more often.

3. When questioning, many people first thought about the problem of diffusion processes and their role in ecology.

Vi. Conclusion

Due to the increase in the scale of anthropogenic impact ( economic activity man), the balance in the biosphere is disturbed, which can lead to irreversible processes and raise the question of the possibility of life on the planet. This is due to the development of industry, energy, transport, Agriculture and other human activities. Already now, humanity is faced with serious environmental problems that require immediate solutions.

As shown in the work, diffusion processes play a key role in maintaining the balance of ecosystems. The manifestation of diffusion was shown in different areas science and technology, in the processes occurring in animate and inanimate nature. Diffusion is of paramount importance in the life of humans and animals; without this phenomenon, life on Earth would be impossible. But, unfortunately, as a result of their activities, people often have a negative impact on natural processes in nature.

The goals and tasks set in the work were fulfilled by me. I was able to conduct a study of diffusion processes, the experiment showed a good agreement between theory and practice. It was also possible to show how widely diffusion is used in the surrounding world.

Finally, I would like to note that in our country, nevertheless, insufficient attention is paid to the problem of environmental safety, which was shown by the survey.

I hope my work will help other students to better understand such an interesting and important phenomenon as diffusion, will contribute to the development of interest in physics.

Vii. List of used literature

Astafurov V.I., Busev A.I. The structure of matter: Book. For students. M .: Education, 1983
Alekseev S.V., Gruzdeva M.V., Muravyov A.G., Gushchina E.V. Workshop on ecology. M. JSC MDS, 1996
Biophysics in physics lessons. From work experience. M., "Education", 1984
A.I. Kitaygorodsky. Introduction to Physics. Publishing house "Science", 1979
Ryzhenkov A.P. Physics. Person. Environment. M. Enlightenment, 1996
https://ru.wikipedia.org/wiki/
https://globallab.org/de/project/cover/diffuzija_vokrug_nas.de.html#
http://wiki.iteach.ru/index.php

Sociological survey.

1. Does diffusion affect the environment?
2. Is environmental information important to you personally?
3. Do you think it is possible to protect nature?
4. Are you thinking about our problem?
5. Are you ready to participate in environmental improvement for a prepayment?
6. Do you want to change the environment for the better?
7. Do you want to get additional knowledge about ecology?

REVIEW

The presented work is devoted to the topic "Environmental aspects of diffusion".
The problem of this study has relevance in the modern world.
It should be noted the high importance and insufficient practical development of the problem in the course of physics high school, which determines the undoubted novelty of this study.
As part of achieving this goal, the author set and solved the following tasks:
1. Justify theoretical aspects and to reveal the nature of "diffusion";
2. Show the urgency of the problem in modern conditions;

3. Test the theory in practice by conducting a series of experiments;
4. Outline the development trends of this topic.

The work has a traditional structure and includes an introduction, body, conclusion and bibliography.
The introduction substantiates the relevance of the topic choice, sets the goal and objectives of the research, describes the research methods. Chapter one reveals the general issues of the topic, defines the basic concepts. Chapter Two discusses in more detail the question of where exactly we can observe the phenomenon of diffusion, and what application it finds. The third chapter is devoted to the influence of human activity on the course of diffusion processes in nature. Chapter four is of a practical nature and, on the basis of individual experiments, an analysis of theoretical conclusions, as well as prospects and development trends is made. The fifth chapter provides a sociological study, on the basis of which the author draws conclusions about the urgency of the problem.
According to the results of the study, a number of problems related to the topic under consideration were revealed, and conclusions were drawn about the need for further study of this issue. The topic is fully disclosed in accordance with the plan.

The sources of information for writing a work on the topic "Environmental aspects of diffusion" were the basic educational literature, fundamental theoretical works the largest thinkers in the area under consideration, the results of practical research by prominent domestic and foreign authors, articles and reviews in specialized and periodicals, reference books, and other relevant sources of information.

The word "diffusion" itself is of Latin origin - "diffusio" translated from Latin means "spreading, dispersing". In physics, diffusion means the process of interpenetration of microparticles when different materials come into contact. The academic definition of what diffusion is, sounds like this: "Diffusion is the mutual penetration of molecules of one substance into the intermolecular gaps of another substance due to their chaotic movement and collision with each other." What are the properties of diffusion, the reasons for its occurrence, how does this process manifest itself in different substances, read about it below.

Diffusion reasons

The cause of diffusion is the thermal motion of particles (atoms, molecules, ions, etc.).

To understand in more detail how diffusion mechanisms work, we will consider this phenomenon at specific example... If you take potassium permanganate (popularly known as potassium permanganate) (KMnO 4) and dissolve in water (H 2 O), then potassium permanganate will decompose into K + and MnO 4 - as a result of dissociation. It is also important to note that the water molecule is polarized and exists in the form of linked H + - OH- ions.

Due to the dissolution of potassium permanganate in water, a chaotic movement of ions of both substances will occur, as a result of which the adhered water ions will change their color and make room for other ions that have not yet reacted. The water will change color and acquire specific properties. Diffusion will take place between water and potassium permanganate.

This is how this process looks schematically.

Moreover, the movable particles during diffusion always spread evenly over the entire provided volume. The diffusion process itself takes a certain amount of time.

It is also important to know that the phenomenon of diffusion does not occur with all substances. For example, if water is mixed not with potassium permanganate, but with oil, then there will be no diffusion between them, since oil molecules are electrically neutral. The formation of some kind of connection with water molecules will be prevented by strong bonds within the oil molecule.

It is also worth noting that the diffusion rate will increase significantly with increasing temperature, which is quite logical, because with an increase in temperature, the speed of movement of particles inside a substance will increase and, as a result, the chance of their penetration into the molecules of another substance increases.

Diffusion formula

The diffusion process in a two-component system is written using Fick's law, and the corresponding equation:

In this equation, J is the density of the material, D is the diffusion coefficient, and ac / dx is the concentration gradient of the two substances.

The diffusion coefficient is called physical quantity, which is numerically equal to the amount of diffusing substance that penetrates per unit of time through a unit of surface, if the difference in density on two surfaces at a distance equal to a unit of length is equal to unity. It is important to note that the diffusion coefficient is temperature dependent.

Diffusion in solids

In solids, diffusion occurs very slowly, if at all. Indeed, solid bodies are characterized by the presence, and all particles are arranged in an orderly manner.

An example of the diffusion of solids is gold and lead. Located at a distance of 1 meter from each other, at room temperature of 20 C, these substances will gradually penetrate into each other, but this will all go very slowly, such diffusion will become noticeable no earlier than in 4-5 years.

Diffusion in liquids

The rate of diffusion in liquids is several times higher than in solids. The bonds between particles in a liquid are much weaker (usually their energy is enough for the formation of drops), and nothing interferes with the mutual penetration of particles into the molecules of two substances.

True, how quickly diffusion will take place depends on the nature and consistency of liquids, in thicker solutions it occurs more slowly, because the thicker the liquid, the stronger the bonds between molecules in it and the more difficult it is for molecules and particles to penetrate each other. For example, mixing two liquid metals can take several hours, while mixing water and potassium permanganate (from the example above) is done in a minute.

Diffusion in gases

In gases, diffusion occurs even faster than in liquids, there are practically no bonds between the particles of gaseous substances, and particles that are not adhered to each other easily mix with each other, penetrating into the molecules of other gases. Small adjustments in the diffusion of gases can only be made.

Examples of diffusion in the outside world

Due to diffusion:

a homogeneous composition of atmospheric air is maintained near the surface of our planet,
plants are nourished,
breathing of humans and animals is carried out.

Significant biological process- carried out, including by means of diffusion: as we know, thanks to energy sunlight water is decomposed by chlorophyll into components, which is released during this process, enters the atmosphere and is absorbed by all living organisms. So, the very process of oxygen absorption by humans and animals, and the metabolism of plants, all this is supported by diffusion, without which Life itself could not exist.

But this is globally, in simpler things, we can observe diffusion:

In a garden where flowers exude their scent through diffusion (particles of the flowers are mixed with particles of the surrounding air).
By dissolving sugar in tea or coffee, tea or coffee becomes sweet due to diffusion.
When cutting an onion, your eyes will begin to water, this also happens due to diffusion, onion molecules mix with air molecules and your eyes react to this.

There are many more such examples.

Diffusion, video

And in conclusion, an educational video on the topic of our article.

This article is available in English -.

Diffusion is a phenomenon in which there is a mutual penetration of molecules of one substance between the molecules of another. An example of diffusion in gases is the spread of odors in the air, but the smell does not spread instantly, but after a while. Why is this happening? It's just that the movement of the molecules of the odorous substance in a certain direction is hampered by the movement of air molecules. The trajectory of movement of each gas particle is a broken line, since in collisions, it changes direction and speed. Therefore, the diffusion penetration of molecules is much slower than their free movement. The phenomenon of diffusion shows that molecules are constantly moving chaotically and, moreover, in different directions. This movement is called molecular heat movement. Diffusion also proves that there are gaps between molecules. It is known that particles move in gases, liquids and solids, then diffusion is possible in these substances. Diffusion occurs most rapidly in gases, slower in liquids and slowest in solids. The fact is that in gases and liquids, the main type of thermal motion of particles leads to their mixing, but in solids, in crystals, where atoms perform small vibrations around the position of the lattice site, not. The diffusion rate depends on: aggregate state substances; molecular mass; temperature.

The phenomenon of diffusion plays an important role in nature. So, for example, due to diffusion, a homogeneous composition of atmospheric air near the Earth's surface is maintained. Trees release oxygen and absorb carbon dioxide through diffusion. The roots of plants capture the substances necessary for the plant from the soil water due to the diffusion flow into the roots. Many physiological processes occurring in the human body are based on the phenomenon of diffusion: such as respiration, absorption of nutrients in the intestines, etc. Diffusion is widely used in various fields of human activity ... This phenomenon is based, for example, diffusion welding of metals, nickel plating. The result of diffusion can be an equalization of the temperature in the room during ventilation. The phenomenon of diffusion is based on salting vegetables, cooking boiling, obtaining compotes and much more. In general, diffusion is of great importance in nature and human life, but this phenomenon is also harmful in relation to environmental pollution. The course of diffuse processes in nature is negatively influenced by human activity. Diffusion processes play an important role in the supply of oxygen to natural reservoirs. Oxygen enters the deeper layers of water in reservoirs due to diffusion through their free surface. Therefore, any pollution of the water surface is detrimental to all life in the reservoir. Pollutants emitted into the atmosphere from the chimneys of industrial and energy enterprises, exhaust gases of cars, due to diffusion, spread over long distances. The air and ground are still polluted with household waste. Pollutants enter food, air, water and cause great harm to human health. A striking manifestation of diffusion, directly related to environmental problems, is dirty, actually poisoned by the exhaust gases of cars, air within the boundaries of large cities, pollution of numerous reservoirs, soil, etc. with poisonous waste.

Let's conduct a study together and find out, using the example of the spread of an odorous substance in the air, how the phenomenon of diffusion contributes to air pollution (let's draw an analogy between the molecules of a pollutant and the molecules of an odorous substance). Here are examples of typical air pollutants, rivers and water bodies, fields and forests. We will find out what are the ways to protect the environment from pollution.

MUNICIPAL AUTONOMOUS EDUCATIONAL INSTITUTION OF THE BELOYARSK DISTRICT

"SECONDARY SCHOOL № 3, BELOYARSKY"

Research project
on the topic of
"The role of diffusion in our life"

Completed:

7c grade student

Nikolaev Oleg

Supervisor:

Tingaeva M.A.

Beloyarsky, 2015

I ... Introduction

1.1 Definition of diffusion

1.2 History of discovery
II. The phenomenon of diffusion, its essence

2.1 Description of the diffusion process

2.2 Explanation of the diffusion phenomenon

2.3 Regularities in the course of diffusion
III. Diffusion value

3.1 The role of diffusion in nature.

3.2 The role of diffusion in the preparation of solutions.

3.3 Diffusion and human safety.
3.4 Application of diffusion in medicine. Artificial kidney apparatus

3.5 Osmosis. Practical application of osmosis

3.6 Application of diffusion in technology and in everyday life

3.7 Harmful manifestation of diffusion IV. Practical part

V. Conclusion
VI. List of used literature

Introduction

In our daily life, we sometimes do not notice certain physical phenomena. For example, someone opened a bottle of perfume, and we, even from a great distance, will feel this smell. Climbing the stairs to our apartment, we can smell the food prepared at home. We put it in a glass with hot water tea bag, and we don't even notice how the tea leaves stains all the water in the cup.
So, the speech will goabout diffusion.

Diffusion(Latin diffusio - spreading, spreading, dispersing, interaction) - a phenomenon in which there is a mutual penetration of molecules of one substance between the molecules of another.

Objective:
1.the study of the diffusion process

2.explanations of its importance in our life

3.Observation of its manifestations
4.description of useful and harmful properties
5. a description of the significance of this process in our life

Work tasks:
1.extend our knowledge
2.explain the diffusion process
3.prove the existence of this process
4. tell about where we can observe diffusion
5. to reveal the properties of diffusion.

Significance of work:
The practical significance of this research work lies in the fact that the results obtained will help in the study of this topic at school, will attract more attention of schoolchildren to this physical process.

Discovery of diffusion.

In 1827 Brown conducted research on plant pollen. He, in particular, was interested in how pollen participates in the fertilization process. Once he examined pollen of a North American plant isolated from the cells under a microscope. Clarkia pulchella(pretty clarke) elongated cytoplasmic grains suspended in water. Suddenly, Brown saw that the smallest solid grains, which could hardly be seen in a drop of water, were constantly trembling and moving from place to place. He found that these movements, in his words, "are not associated either with flows in the liquid, or with its gradual evaporation, but are inherent in the particles themselves."

Brown's observation was confirmed by other scientists. The smallest particles behaved as if they were alive, and the "dance" of particles accelerated with increasing temperature and decreasing particle size, and obviously slowed down when water was replaced by a more viscous medium. This amazing phenomenon never stopped: it could be observed for as long as desired. At first, Brown even thought that living things really got into the field of the microscope, especially since the pollen is the male reproductive cells of plants, but particles from dead plants, even from those dried up a hundred years earlier in herbariums, were also brought in. Then Brown wondered if these were the "elementary molecules of living things", about which the famous French naturalist Georges Buffon (1707-1788), the author of the 36-volume Natural history ... This assumption was dropped when Brown began to investigate apparently inanimate objects; at first it was very small particles of coal, as well as soot and dust London air, then finely ground inorganic substances: glass, many different minerals. “Active molecules” were everywhere: “In every mineral,” wrote Brown, “which I managed to grind into dust to such an extent that it could be suspended in water for some time, I found, in greater or lesser quantities, these molecules. "

I must say that Brown did not have any the latest microscopes... In his article, he specifically emphasizes that he had conventional biconvex lenses, which he had been using for several years. And then he writes: "Throughout the study, I continued to use the same lenses with which I began to work to give more credibility to my statements and to make them as accessible as possible for routine observation."

The phenomenon of diffusion, its essence

As we know, the molecules of any substance are at some distance from each other and constantly move chaotically. That is why individual molecules, for example ammonia, chaotically moving, penetrate into the gaps between air molecules, collide with them and, thus, move farther and farther from the source, i.e. from an open tube with ammonia. This movement is continuous and disorderly. Colliding with the molecules of gases that make up the air, ammonia molecules change their direction of movement many times and, randomly moving, scatter throughout the room. This is the phenomenon of diffusion.

Diffusion in gases and liquids is easier and faster than diffusion in solids, since molecules in gases and liquids, respectively, move more freely, and the distance between them is greater than in a solid.
The movements of particles during diffusion are completely random, all directions of displacement are equally probable.
Since particles move in gases, liquids, and solids, diffusion is possible in these substances. Diffusion - the transfer of matter caused by the spontaneous equalization of an inhomogeneous concentration of atoms or molecules different kind... If portions of various gases are admitted into the vessel, then after a while all gases are evenly mixed: the number of molecules of each type per unit volume of the vessel will become constant, the concentration will equalize.

Diffusion is explained as follows. First, the interface between the two media is clearly visible between the two bodies. Then, due to their movement, individual particles of substances located near the border exchange places.

The border between substances is blurring. Having penetrated between the particles of another substance, the particles of the first begin to exchange places with the particles of the second, which are in ever deeper layers. The interface between substances becomes even more vague. Due to the continuous and irregular movement of the particles, this process ultimately leads to the fact that the solution in the vessel becomes homogeneous.
Diffusion rateincreases with increasing temperature.
Let's turn to experience. Two glasses contain water, but one is cold and the other is hot. We put tea bags in glasses at the same time. It is easy to see that in hot water, tea colors the water faster, diffusion proceeds faster. The diffusion rate increases with increasing temperature, since the molecules of interacting bodies begin to move faster.

Diffusion occurs most rapidly in gases, slowest in liquids, and slowest in solids. The fact is that in gases and liquids, the main type of thermal motion of particles leads to their mixing, but in solids, in crystals, where atoms perform small vibrations around the position of the lattice site, not.

The role of diffusion in nature

The phenomenon of diffusion plays an important role in nature. So, for example, due to diffusion, a homogeneous composition of atmospheric air near the Earth's surface is maintained. Trees release oxygen and absorb carbon dioxide through diffusion. The roots of plants capture the substances necessary for the plant from the soil water due to the diffusion flow into the roots. Many physiological processes occurring in the human body are based on the phenomenon of diffusion: such as respiration, absorption of nutrients in the intestine, etc.
With the help of diffusion, various gaseous substances spread in the air: for example, the smoke of a fire spreads over long distances.
The result of this phenomenon can be an equalization of the temperature in the room during ventilation. In the same way, air pollution with harmful industrial products and exhaust gases from cars occurs. The natural combustible gas we use at home is colorless and odorless. When a leak occurs, it is impossible to notice it, therefore, at distribution stations, the gas is mixed with a special substance that has a pungent, unpleasant odor that is easily felt by humans.

Due to the phenomenon of diffusion, the lower layer of the atmosphere - the troposphere - consists of a mixture of gases: nitrogen, oxygen, carbon dioxide and water vapor. In the absence of diffusion, stratification would occur under the action of gravity: a layer of heavy carbon dioxide would appear below, oxygen would be above it, and inert gases would be nitrogen above it.

We also observe this phenomenon in the sky. Scattering clouds are also an example of diffusion, and as F. Tyutchev says exactly about this: "Clouds are melting in the sky ..."

In liquids, diffusion proceeds more slowly than in gases, but this process can be accelerated by heating. For example, in order to quickly pickle cucumbers, they are poured with hot brine. We know that sugar will dissolve more slowly in cold tea than in hot tea.

In the summer, watching ants, we always thought about how they, in a huge world for them, would recognize their way home. It turns out that the phenomenon of diffusion opens this riddle. Ants mark their path with droplets of odorous liquid.

And the plant grows, blooms for them, too, thanks to diffusion. After all, we say that the plant breathes and exhales air, drinks water, receives various micro-additives from the soil.

Carnivores also find their prey through diffusion. Sharks smell blood at a distance of several kilometers, just like piranha fish.

The ecology of the environment is deteriorating due to emissions of chemical and other harmful substances into the atmosphere, into water, and all this spreads and pollutes vast territories. Trees, on the other hand, release oxygen and absorb carbon dioxide through diffusion.
The principle of diffusion is based on the mixing of fresh water with salty water when rivers flow into the sea. Diffusion of solutions of various salts in the soil contributes to the normal nutrition of plants.

In all the above examples, we observe the mutual penetration of molecules of substances, i.e. diffusion. Many physiological processes in humans and animals are based on this process: such as respiration, absorption, etc. In general, diffusion is of great importance in nature, but this phenomenon is also harmful in relation to environmental pollution.

The role of diffusion in the preparation of solutions.

Physical theory solutions was proposed by W. Ostwald (Germany) and S. Arrhenius (Sweden). According to this theory, the particles of the solvent and solute (molecules, ions) are evenly distributed throughout the volume of the solution due to diffusion processes. In this case, there is no chemical interaction between the solvent and the solute.
That is diffusion processes in gases, liquid gels are widely used in chemistry. For example, for the preparation of solutions, for the enrichment of air with oxygen in the metallurgical industry. Diffusion underlies many technological processes: adsorption, drying, extraction, membrane separation methods, etc.

Diffusion and human safety

Combustible natural gas used for cooking in the home is colorless and odorless. To make the flow of gas into the room noticeable, combustible gas is pre-mixed with pungent-smelling substances. This allows you to quickly notice the presence of a gas leak in the room.

The use of diffusion in medicine. Artificial kidney apparatus

More than 30 years ago, the German physician William Kolff used the "artificial kidney" apparatus. Since then, it has been used: for emergency chronic care in acute intoxication; to prepare patients with chronic renal failure for kidney transplantation; for long-term (10-15 years) life support of patients with chronic disease kidneys.
An artificial kidney is a device designed to remove toxins from the human blood that accumulate in the kidneys when they are severely damaged - usually it is chronic and acute forms kidney failure.

The operation of the device is based on the principles of dialysis - this is the removal of low molecular weight substances from colloidal solutions due to diffusion and the difference between the osmotic pressure on both sides of the semi-permeable cellophane membrane.

Hemodialysis is the most popular treatment for advanced kidney failure. This procedure allows a person to continue to lead an active lifestyle, despite the defective kidney function.

The use of diffusion in technology.

Diffusion phenomena widely used in engineering. For example, when extracting sugar from beets, the latter is finely chopped and placed in special metal vessels (diffusers) through which hot water flows. The sugar in the beets diffuses into the flowing water. Crystalline sugar is isolated from the resulting solution.

Application in everyday life.

The phenomenon of diffusion can be observed at home quite often: when we use an aroma lamp with essential oils or sprays for the body or feet, perfume, we spray means to destroy mosquitoes and flies indoors, when we glue something or when we drink tea or coffee. In a mug tea with sugar and a slice of lemon. We stir hot water with a spoon - this accelerates the process of penetration of sugar and lemon molecules between water molecules. Also, salting, pickling, compotes - all this, too, thanks to diffusion.

Harmful manifestation of diffusion.

Diffusion is not always a good thing for a person. Unfortunately, it is necessary to note the harmful manifestations of this phenomenon. Chimneys of enterprises emit carbon dioxide, nitrogen oxides and sulfur into the atmosphere. At present, the total amount of gas emissions into the atmosphere exceeds 40 billion tons per year. An excess of carbon dioxide in the atmosphere is dangerous for the living world of the Earth, disrupts the carbon cycle in nature, and leads to the formation of acid rain. The diffusion process plays a large role in the pollution of rivers, seas and oceans. The annual discharge of industrial and domestic wastewater in the world is approximately 10 trillion tons.
Pollution of water bodies leads to the disappearance of life in them, and the water used for drinking has to be purified, which is very expensive. In addition, contaminated water occurs chemical reactions with the release of heat. The water temperature rises, while the oxygen content in the water decreases, which is bad for aquatic organisms. Due to the rise in water temperature, many rivers now do not freeze in winter.
To reduce the emission of harmful gases from industrial pipes, pipes of thermal power plants, special filters are installed. To prevent pollution of water bodies, it is necessary to ensure that garbage, food waste, manure, and various kinds of chemicals are not thrown near the coast.
We see how great the significance of diffusion in inanimate nature is, and the existence of living organisms would be impossible if it were not for this phenomenon. Unfortunately, we have to deal with the negative manifestation of this phenomenon, but there are much more positive factors, and therefore we are talking about the enormous importance of diffusion in nature.

Practical part

Experience number 1 Observation of the phenomenon of diffusion in a liquid.

Target: observation of diffusion in a liquid, the effect of temperature on the course of diffusion.
Devices and materials: a glass of cold water, a solution of "brilliant green", a plate of hot water, a pipette.

a) "brilliant green" was dropped into a glass of water and observed how the diffusion process takes place;
b) carried out the same experiment by placing a glass of water in a plate of hot water, the process took place much faster than in the first case

Conclusion: after running the experiment, we found that diffusion is observed in liquids and with increasing temperature the rate of this process increases.

Experience number 2 Observation of the phenomenon of diffusion in gases.

Target: observation of diffusion in gases.
Devices and materials: perfume bottle with spray bottle, air.
Description of the experience and the results obtained:
a) spray perfume;
b) the spread of the smell throughout the room.
Conclusion: after conducting the experiment, we found that diffusion is observed in gases.

Experience number 3 Observation of the phenomenon of diffusion in solids.

Target: observation of diffusion in solids.
Devices and materials: apple, brilliant green solution, pipette.
Description of the experience and the results obtained:
a) cut the apple, "drip brilliant green" on one half of the apple
b) we observe how the spot spreads over the surface.
Conclusion: in the course of this experiment, we observed diffusion in solids, noticed that this process proceeds in solids much more slowly than in gases and liquids.

Conclusion

In the course of this research work, it can be concluded that diffusion plays a huge role in the life of humans and animals.

Nature makes extensive use of the possibilities inherent in the process of diffusion penetration. Diffusion plays an essential role in the absorption of nutrition and oxygenation of the blood in the air we breathe, everywhere we see the manifestation of an omnipotent and universal diffusion.

Studying diffusion, we came to the conclusion that it is present in all spheres of human life, without this phenomenon life on Earth would be impossible.

List of used literature
1. Peryshkin A.V. Physics. 7 cl. - 14th ed., Stereotype. - M .: Bustard, 2010.
2.Koshkin I.I., Shirkevich M.G. Reference for elementary physics... - M .: Nauka, 1980.
3. Trofimova TI Physics Course. - M .: Higher school, 1990.
4. Yavorskiy BM, Detlaf AA Handbook of physics. - M .: Nauka, 1985.
5. Shatalov V.F. Physics for life. M.-SPb, 2003.
6. O. F. Kabardin, S. I. Kabardina. Physics grade 7. M., 2011.
7. N.K. Martynova, Physics 7-9. M., 2011.