Speech therapy portal / Experience exchange / Definition of the word diffusion in biology. Abstract: Topic: “Diffusion in living and inanimate nature. Zharalardy emdeu biology syndagy diffusion

Definition of the word diffusion in biology. Abstract: Topic: “Diffusion in living and inanimate nature. Zharalardy emdeu biology syndagy diffusion

08.02.2024

Diffusion

An example of diffusion is the mixing of gases (for example, the spread of odors) or liquids (if ink is dropped into water, the liquid will become uniformly colored after some time). Another example is associated with a solid: atoms of contacting metals mix at the contact boundary. Particle diffusion plays an important role in plasma physics.

Usually, diffusion is understood as processes accompanied by the transfer of matter, but sometimes other transfer processes are also called diffusion: thermal conductivity, viscous friction, etc.

The rate of diffusion depends on many factors. Thus, in the case of a metal rod, thermal diffusion occurs very quickly. If the rod is made of a synthetic material, thermal diffusion occurs slowly. Diffusion of molecules in the general case proceeds even more slowly. For example, if a piece of sugar is placed at the bottom of a glass of water and the water is not stirred, it will take several weeks before the solution becomes homogeneous. Diffusion of one solid substance into another occurs even more slowly. For example, if copper is coated with gold, then diffusion of gold into the copper will occur, but under normal conditions (room temperature and atmospheric pressure) the gold-bearing layer will reach a thickness of several microns only after several thousand years.

A quantitative description of diffusion processes was given by the German physiologist A. Fick ( English) in 1855

general description

All types of diffusion obey the same laws. The rate of diffusion is proportional to the cross-sectional area of the sample, as well as the difference in concentrations, temperatures or charges (in the case of relatively small values of these parameters). Thus, heat will spread four times faster through a rod with a diameter of two centimeters than through a rod with a diameter of one centimeter. This heat will spread faster if the temperature difference across one centimeter is 10°C instead of 5°C. The rate of diffusion is also proportional to the parameter characterizing a particular material. In the case of thermal diffusion, this parameter is called thermal conductivity, in the case of the flow of electric charges - electrical conductivity. The amount of substance that diffuses over a given time and the distance traveled by the diffusing substance are proportional to the square root of the diffusion time.

Diffusion is a process at the molecular level and is determined by the random nature of the movement of individual molecules. The rate of diffusion is therefore proportional to the average speed of the molecules. In the case of gases, the average speed of small molecules is greater, namely, it is inversely proportional to the square root of the mass of the molecule and increases with increasing temperature. Diffusion processes in solids at high temperatures often find practical application. For example, certain types of cathode ray tubes (CRTs) use thorium metal diffused through tungsten metal at 2000 °C.

If in a mixture of gases the mass of one molecule is four times greater than another, then such a molecule moves twice as slow as its movement in a pure gas. Accordingly, its diffusion rate is also lower. This difference in the rate of diffusion of light and heavy molecules is used to separate substances with different molecular weights. An example is isotope separation. If a gas containing two isotopes is passed through a porous membrane, the lighter isotopes pass through the membrane faster than the heavier ones. For better separation, the process is carried out in several stages. This process was widely used to separate uranium isotopes (separation of 235 U from the bulk 238 U). Since this separation method requires a lot of energy, other, more economical separation methods have been developed. For example, the use of thermal diffusion in a gas environment is widely developed. A gas containing a mixture of isotopes is placed in a chamber in which a spatial temperature difference (gradient) is maintained. In this case, heavy isotopes are concentrated in the cold region over time.

Fick's equations

From the point of view of thermodynamics, the driving potential of any leveling process is an increase in entropy. At constant pressure and temperature, the role of such potential is the chemical potential µ , which determines the maintenance of matter flows. The flow of particles of matter is proportional to the potential gradient

In most practical cases, concentration is used instead of chemical potential C. Direct replacement µ on C becomes incorrect in the case of high concentrations, since the chemical potential is no longer related to the concentration according to the logarithmic law. If we do not consider such cases, then the above formula can be replaced with the following:

which shows that the flux density of the substance J proportional to the diffusion coefficient D[()] and concentration gradient. This equation expresses Fick's first law. Fick's second law relates spatial and temporal changes in concentration (diffusion equation):

Diffusion coefficient D depends on temperature. In a number of cases, over a wide temperature range, this dependence is the Arrhenius equation.

An additional field applied parallel to the chemical potential gradient disrupts the steady state. In this case, diffusion processes are described by the nonlinear Fokker-Planck equation. Diffusion processes are of great importance in nature:

Nutrition, respiration of animals and plants;
Penetration of oxygen from blood into human tissues.

Geometric description of the Fick equation

In the second Fick equation, on the left side is the rate of change of concentration over time, and on the right side of the equation is the second partial derivative, which expresses the spatial distribution of concentration, in particular, the convexity of the temperature distribution function projected onto the x-axis.

Notes

Literature

Bokshtein B. S. Atoms wander around the crystal. - M.: Nauka, 1984. - 208 p. - (Library "Quantum". Issue 28). - 150,000 copies.

Links

Diffusion (video lesson, 7th grade program)
Diffusion of impurity atoms on the surface of a single crystal

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Synonyms:

See what “Diffusion” is in other dictionaries:

- [lat. diffusio spread, spreading] physical, chemical. penetration of molecules of one substance (gas, liquid, solid) into another by direct contact or through a porous partition. Dictionary of foreign words. Komlev N.G.,... ... Dictionary of foreign words of the Russian language

Diffusion- – penetration into the environment of particles of one substance by particles of another substance, occurring as a result of thermal movement in the direction of decreasing the concentration of another substance. [Blum E.E. Dictionary of basic metallurgical terms. Ekaterinburg … Encyclopedia of terms, definitions and explanations of building materials

Modern encyclopedia

- (from Latin diffusio, spreading, dispersion), movement of particles of a medium, leading to the transfer of a substance and equalization of concentrations or the establishment of an equilibrium distribution of concentrations of particles of a given type in the medium. In the absence of… … Big Encyclopedic Dictionary

DIFFUSION, the movement of a substance in a mixture from an area of high concentration to an area of low concentration, caused by the random movement of individual atoms or molecules. Diffusion stops when the concentration gradient disappears. Speed… … Scientific and technical encyclopedic dictionary

diffusion- and, f. diffusion f., German Diffusion lat. diffusio spreading, spreading. Mutual penetration of contacting substances into each other due to the thermal movement of molecules and atoms. Diffusion of gases and liquids. BAS 2. || trans. They… … Historical Dictionary of Gallicisms of the Russian Language

Diffusion- (from the Latin diffusio distribution, spreading, dispersion), the movement of particles of the medium, leading to the transfer of matter and the equalization of concentrations or the establishment of their equilibrium distribution. Typically, diffusion is determined by thermal motion... ... Illustrated Encyclopedic Dictionary

The movement of particles in the direction of decreasing their concentration, caused by thermal movement. D. leads to equalization of the concentrations of the diffusing substance and uniform filling of the volume with particles.... ... Geological encyclopedia

The article shows the role of diffuse processes in wounds sutured in the traditional way and the method proposed by the authors. The improvement of diffuse processes in wounds during treatment with the hardware method is theoretically justified.

The problem of healing wounds of various etiologies is one of the main areas of medicine that has not lost its importance to this day. Treatment of this pathology in the shortest possible time without purulent complications is possible only if medical institutions are sufficiently supplied with modern effective wound-healing drugs.

During the wound process, the local and general reaction of the body is directly dependent on the severity and characteristics of damage to tissues and organs. Local and general reactive processes during regeneration processes are in a direct and inverse relationship, being interdependent and mutually influencing. The basis of wound treatment is the ability to control the course of the wound process. This problem is invariably in the field of view of scientists and practicing surgeons.

A large number of wound treatment methods used belong to the pharmacological group. At the same time, a large number of technical devices for the treatment of wounds were proposed. However, the most common method of suturing wounds is a circular vertical suture.

The human skin, consisting of collagen proteins, is an ideal natural membrane that performs numerous metabolic and protective functions. These processes are mainly due to diffusion. Diffusion (from Latin diffusio - spreading, spreading), mutual penetration of contacting substances into each other due to the movement of particles of the substance.

Diffusion is a process at the molecular level and is determined by the random nature of the movement of individual molecules. The rate of diffusion is therefore proportional to the average speed of the molecules. Diffusion occurs in the direction of a decrease in the concentration of a substance and leads to a uniform distribution of the substance throughout the entire volume it occupies (to equalize the chemical potential of the substance).

The role of diffuse processes in the pathogenesis and treatment of wound healing is very great. For example, in skin transplantology, the thickness of the flaps plays a huge role in the healing of burn wounds, as it has a positive effect on the diffusion processes between the graft and the wound surface.

However, the significance of diffuse processes in a wound has practically not been studied. The edges of the wound are conductive systems in which diffuse processes should take place under normal conditions. This process is shown schematically in Figure 1.

The schematic diagram shows that the surgical wound (1), sutured with traditional circular vertical sutures according to the classification of A.N. Golikov, has certain disadvantages. The surgical suture (2), which is a means of bringing the edges of the wound closer together, carries out complete ischemia (5) of the tissue, which leads to the formation of “silent areas” for the passage of diffusion processes, which leads to deformation (4) of the diffusion vector (3). As a result, the traditionally used surgical suture leads to the artificial formation of tissue areas that are not involved in regeneration processes. Moreover, in unfavorable cases, these “tissue defects” are sources of formation of foci of the infectious process. Because, as a result, the tissue, deprived of access to nutrients, oxygen, etc., becomes necrotic, which ends in the formation of a scar. Otherwise, necrotic masses of tissue are a favorable breeding ground for pathogens.

The hardware method received a security document from the National Institute of Intellectual Property of the Republic of Kazakhstan No. 13864 dated August 15, 2007. The main principle of the proposed method is the tight closure of the edges of the wounds to each other using physical and mechanical techniques. A nylon line of sufficient length is applied along the edge of the wound, creating a “ligature arc”, which is fixed at the ends to the ends of the apparatus of the author’s design.

The author's apparatus, when assembled, has the shape of a frame, in the form of a quadrangular parallelogram, the sides of which are made up of rods, and the ends are movable bars located and fixed to the rods with two nuts at both ends of the pins; holes of the same diameter are drilled on the movable bars for the rods and fixation of the threads ligatures (Fig. 2).

regeneration processes. The effectiveness of the hardware method has been proven experimentally and clinically.

Thus, a theoretical justification for the effectiveness of the proposed hardware method in comparison with traditional methods of wound suturing has been proposed. This is due to an increase in pressure on the wound area, (due to the design features of the device) leading to a local increase in the diffusion rate.

Literature

Golikov A.N. Healing of a granulating wound closed with sutures. – Moscow: 1951. – 160 p.
Waldorf H., Fewres J. Wound healing // Adv. Derm. – 1995. No. 10. – P. 77–96.
Abaturova E.K., Baimatov V.N., Batyrshina G.I. The influence of biostimulants on the wound process // Morphology. – 2002. – T. 121, No. 2–3. – P.6.
Kochnev O.S., Izmailov G.S. Methods of suturing wounds. – Kazan: 1992. – 160 p.
Kiselev S.I. The importance of donor skin resources in the choice of rational surgical tactics in patients with deep burns: Abstract of thesis. ...candidate of medical sciences. Ryazan, 1971. 17 p.

Zharalardy emdeu biology syndagy diffusion

Tuyin Makalada adettegi addispen zhane makala avtorlarymen usynylyp otyrgan apparatus adistin zharalard emdeudeg diffusion processor turaly itylgyn. Zharalard diffusion protsessterdin apparatusa adistin zhaksargany theory zhuzinde daleldip korsetildi.

DIFFUSION INBIOLOGYHealing

Abstract The article shows the role of diffuse processes in wounds sutured in the traditional way and the method proposed by the authors. The diffuse processes in wounds have been justified theoretically.

Esirkepov M.M., Nurmashev B.K., Mukanova U.A.

South Kazakhstan State Medical Academy, Shymkent

The text of the work is posted without images and formulas.
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Introduction

Relevance of the work. Diffusion is a fundamental phenomenon of nature. It underlies the transformations of matter and energy. Its manifestations take place at all levels of organization of natural systems on our planet, starting from the level of elementary particles, atoms and molecules, and ending with the geosphere. It is widely used in technology and in everyday life.

The essence of diffusion is the movement of particles of a medium, leading to the transfer of substances and equalization of concentrations or the establishment of an equilibrium distribution of particles of a given type in the medium. The diffusion of molecules and atoms is due to their thermal motion.

Diffusion is also a fundamental process that underlies the functioning of living systems at any level of organization, from the level of elementary particles (electron diffusion) to the biosphere level (the circulation of substances in the biosphere).

It plays a huge role in nature, in human life and in technology. Diffusion processes can have both positive and negative effects on the life of humans and animals. An example of a positive impact is maintaining a uniform composition of atmospheric air near the Earth's surface. Diffusion plays an important role in various fields of science and technology, in processes occurring in living and inanimate nature. It influences the course of chemical reactions.

With the participation of diffusion or when this process is disrupted and changed, negative phenomena in nature and human life can occur, such as extensive pollution of the environment with the products of human technical progress.

Goal of the work: Investigate the features of diffusion in gases, liquids and solids and find out the use of diffusion by humans and the manifestation of diffusion in nature, consider the influence of diffusion processes on the ecological balance in nature and the influence of humans on diffusion processes.

The essence of diffusion

Demonstrates diffusion in gases by spraying deodorant in the corner of the classroom. The spread of odor is explained by the movement of molecules. This movement is continuous and disorderly. Colliding with the molecules of gases that make up the air, the deodorant molecules change the direction of their movement many times and, moving randomly, scatter throughout the room.

The process of penetration of particles (molecules, atoms, ions) of one substance between particles of another substance due to chaotic movement is called diffusion(from Latin diffusio - distribution, spreading, dispersion). Thus, diffusion is the result of the chaotic movement of all particles of a substance, of any mechanical action.

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 is the transfer of a substance caused by the spontaneous equalization of a non-uniform concentration of atoms or molecules of different types. If portions of different gases are introduced into a vessel, then after some time all the gases are evenly mixed: the number of molecules of each type per unit volume of the vessel will become constant, the concentration will level out. Diffusion is explained as follows. First, the interface between the two media is clearly visible between the two bodies (Fig. 1a). Then, due to their movement, individual particles of substances located near the boundary exchange places.

The boundary between substances blurs (Fig. 1b). Having penetrated between the particles of another substance, the particles of the first begin to exchange places with the particles of the second, located in ever deeper layers. The interface between substances becomes even more blurred. Due to the continuous and random movement of particles, this process ultimately leads to the solution in the vessel becoming homogeneous (Fig. 1c).

Fig.1. Explanation of the phenomenon of diffusion.

Diffusion in nature

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 may be equalization of the temperature in the room during ventilation. In the same way, air pollution occurs with harmful industrial products and vehicle exhaust gases. The natural flammable gas we use at home is colorless and odorless. If there is a leak, it is impossible to notice it, so at distribution stations the gas is mixed with a special substance that has a sharp, unpleasant odor that is easily perceived by humans.

Thanks 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 influence of gravity: below there would be a layer of heavy carbon dioxide, above it - oxygen, above - nitrogen and inert gases.

We also observe this phenomenon in the sky. Dispersing clouds are also an example of diffusion, and as F. Tyutchev accurately said about this: “Clouds are melting in the sky...”

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

In the summer, watching the ants, I always wondered how they, in this huge world for them, would find out the way home. It turns out that this mystery is also revealed by the phenomenon of diffusion. Ants mark their path with droplets of odorous liquid

Thanks to diffusion, insects find their food. Butterflies, fluttering between plants, always find their way to a beautiful flower. Bees, having discovered a sweet object, storm it with their swarm.

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

Carnivores also find their victims through diffusion. Sharks can smell blood from several kilometers away, just like piranha fish.

The ecology of the environment is deteriorating due to the release of chemicals and other harmful substances into the atmosphere, water, and all this spreads and pollutes vast areas. But trees release oxygen and absorb carbon dioxide through diffusion.

The principle of diffusion is based on the mixing of fresh water with salt water when rivers flow into the seas. Diffusion of solutions of various salts in the soil contributes to normal plant nutrition.

In all the examples given, we observe the mutual penetration of molecules of substances, i.e. diffusion. Many physiological processes in the human and animal body 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.

2.1 Diffusion in the plant kingdom

K.A. Timiryazev said: “Whether we talk about the nutrition of the root due to the substances found in the soil, whether we talk about the aerial nutrition of the leaves due to the atmosphere or the nutrition of one organ at the expense of another, neighboring one - everywhere we will resort to the same reasons for explanation : diffusion".

Indeed, in the plant world the role of diffusion is very important. For example, the great development of the leaf crown of trees is explained by the fact that diffusion exchange through the surface of the leaves performs not only the function of respiration, but partially also nutrition. Currently, foliar feeding of fruit trees by spraying their crowns is widely practiced.

Diffuse processes play a major role in supplying natural reservoirs and aquariums with oxygen. Oxygen reaches deeper layers of water in stagnant waters due to diffusion through their free surface. Therefore, any restrictions on the free surface of the water are undesirable. For example, leaves or duckweed covering the surface of the water can completely stop the access of oxygen to the water and lead to the death of its inhabitants. For the same reason, vessels with a narrow neck are unsuitable for use as an aquarium.

In the process of metabolism, when complex nutrients or their elements are broken down into simpler ones, the energy necessary for the life of the body is released.

2.2 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 sizes;

Electric charge;

On the presence and number of water molecules;

From 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 molecules of a dissolved substance; b) osmosis is the diffusion of solvent through a semi-permeable membrane. Soil solutions contain mineral salts and organic compounds. Water from the soil enters the plant by osmosis through the semi-permeable membranes of the root hairs. The concentration of water in the soil is higher than inside the root hairs, so diffusion occurs from an area of higher concentration to an area of lower concentration. Then the water concentration in these cells becomes higher than in the overlying ones - root pressure arises, causing an upward flow of sap through the roots and stem, and the loss of water by the leaves ensures further water absorption.

Minerals enter the plant: a) by diffusion; b) sometimes by active transport against a concentration gradient, accompanied by energy consumption. There are also turgor pressure is the pressure exerted by the contents of the cell on the cell wall. It is almost always lower than the osmotic pressure of the sap cell, because outside there is not pure water, but a saline solution. Turgor pressure value:

Preservation of the shape of the plant organism;

Ensuring growth in young plant cells;

Preserving the elasticity of plants (demonstration of cactus and aloe plants);

Shape formation in the absence of reinforcing fabric (demonstration of a tomato);

Application of diffusion in medicine.

More than 30 years ago, the German doctor William Kolf used an “artificial kidney” device. Since then it has been used: for emergency chronic care for acute intoxication; to prepare patients with chronic renal failure for kidney transplantation; for long-term (10-15 years) life support for patients with chronic kidney disease.

The use of an artificial kidney device is becoming more of a therapeutic procedure; the device is used both in the clinic and at home. With the help of the device, the recipient was prepared for the world's first successful kidney transplantation, performed in 1965 by academician B.V. Petrovsky.

The device is a hemodialyzer in which the blood comes into contact with a saline solution through a semi-permeable membrane. Due to the difference in osmotic pressure, ions and molecules of metabolic products (urea, uric acid), as well as various toxic substances that must be removed from the body, pass through the membrane from the blood into the saline solution. The device is a system of flat channels separated by thin cellophane membranes, through which blood and dialysate - a saline solution enriched with a gas mixture of CO 2 + O 2 - slowly move in counter flows. The device is connected to the patient’s circulatory system using catheters inserted into the hollow (blood inlet) into the dialysate) and ulnar (outlet) vein. Dialysis lasts 4-6 hours. This achieves blood purification from nitrogenous wastes in case of insufficient kidney function, i.e. the chemical composition of the blood is regulated.

Biology teacher: The following message will help you understand and understand the forms of diffusion, osmosis and dialysis.

Application of diffusion in technology and in everyday life

Diffusion has wide applications in industry and everyday life. Diffusion welding of metals is based on the phenomenon of diffusion. The diffusion welding method, without the use of solders, electrodes and fluxes, connects metals, non-metals, metals and non-metals, and plastics. The parts are placed in a closed welding chamber with strong vacuum, compressed and heated to 800 degrees. In this case, intense mutual diffusion of atoms occurs in the surface layers of contacting materials. Diffusion welding is used mainly in the electronics and semiconductor industries, and precision engineering.

A diffusion apparatus is used to extract soluble substances from crushed solid material. Such devices are widespread mainly in beet sugar production, where they are used to obtain sugar juice from beet chips heated together with water.

Neutron diffusion plays a significant role in the operation of nuclear reactors, that is, the propagation of neutrons in matter, accompanied by multiple changes in the direction and speed of their movement as a result of collisions with atomic nuclei. The diffusion of neutrons in a medium is similar to the diffusion of atoms and molecules in gases and obeys the same laws.

As a result of the diffusion of carriers in semiconductors, an electric current arises. The movement of charge carriers in semiconductors is due to the heterogeneity of their concentration. To create, for example, a semiconductor diode, indium is fused into one of the surfaces of germanium. Due to the diffusion of indium atoms deep into the germanium single crystal, a p-n junction is formed in it, through which a significant current can flow with minimal resistance.

The process of metallization is based on the phenomenon of diffusion - covering the surface of a product with a layer of metal or alloy to impart to it physical, chemical and mechanical properties that differ from the properties of the metallized material. It is used to protect products from corrosion, wear, increase contact electrical conductivity, and for decorative purposes; thus, carburization is used to increase the hardness and heat resistance of steel parts. It consists in placing steel parts in a box with graphite powder, which is installed in a thermal furnace. Due to diffusion, carbon atoms penetrate into the surface layer of parts. The penetration depth depends on the temperature and holding time of the parts in the thermal oven.

Human influence on the course of diffusion in nature.

Unfortunately, as a result of the development of human civilization, there is a negative impact on nature and the processes occurring in it. The diffusion process plays a big role in the pollution of rivers, seas, and oceans. For example, you can be sure that detergents poured into the sewer, for example, in Odessa, will end up off the coast of Turkey due to diffusion and existing currents. The annual discharge of industrial and domestic wastewater in the world amounts to tens of trillions of tons. An example of the negative impact of humans on diffusion processes in nature are large-scale accidents that occurred in the basins of various reservoirs. As a result of this phenomenon, oil and its products spread over the surface of the water and, as a result, diffusion processes are disrupted, for example: oxygen does not enter the water column, and fish die without oxygen.

Due to the phenomenon of diffusion, the air is polluted with waste from various factories, because of which 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 contaminated by emissions from industrial enterprises, etc., is increasing. Over 2 thousand hectares of land are occupied by industrial and household waste dumps. One of the currently difficult issues to resolve is the issue of recycling industrial waste, including toxic waste.

An urgent problem is air pollution from exhaust gases and products of the processing of harmful substances emitted into the atmosphere by various factories. Chimneys of enterprises emit carbon dioxide, nitrogen oxides and sulfur into the atmosphere. Currently, the total amount of gas emissions into the atmosphere exceeds 40 billion tons per year. Excess 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 process of diffusion 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.

Some medical studies have shown a connection between respiratory and upper respiratory tract morbidity and air quality. There is a direct relationship between the indicator of the level 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.

Pollution of water bodies leads to the disappearance of life in them, and water used for drinking has to be purified, which is very expensive. In addition, chemical reactions occur in contaminated water, releasing heat. The water temperature rises, and the oxygen content in the water decreases, which is bad for aquatic organisms. Due to rising water temperatures, many rivers no longer freeze in winter. To reduce the emission of harmful gases from industrial pipes and pipes of thermal power plants, special filters are installed. Such filters are installed, for example, at a thermal power plant in the Leninsky district of Chelyabinsk, but their installation is very expensive. To prevent pollution of water bodies, it is necessary to ensure that garbage, food waste, manure, and various types of chemicals are not thrown near the shores.

Considering global warming, it is important to study the change in diffusion rate as a function of increasing ambient temperature.

Experimental part.

I experience. Observation of the penetration of particles of one substance between the molecules of another substance .

Target : study the diffusion of solids and draw a conclusion about the rate of diffusion.

Devices and materials : gelatin, potassium permanganate, copper sulfate, Petria dish, tweezers, heating device.

The solid solution is gelatin. In order to prepare the solution, you need to immerse 1 spoon of gelatin in cold water for 2 hours so that the powder swells, then heat the mixture and dissolve the gelatin without bringing it to a boil, then pour it into a Petria dish (Fig. 3). When the gelatin had cooled, a crystal of potassium permanganate was introduced into the middle with a quick movement using tweezers into one glass, and copper sulfate into the other. And now we can observe the result of diffusion.

Here we observed the penetration of particles of potassium permanganate and copper sulfate between gelatin molecules. After 24 hours, it was observed that diffusion of potassium permanganate does not occur (Fig. 4), since potassium permanganate is a strong oxidizing agent.

Thus, diffusion in solids occurs more slowly. If strong oxidizing agents enter the environment, they lead to its destruction.

II experiment. Observation of the dissolution of gouache pieces in water at a constant temperature (at t = 22°C)

We took a piece of orange gouache and a vessel with clean water at a temperature of 22 °C. They put a piece of gouache in the vessel (Fig. 1) and began to observe what was happening. After 10 minutes, the water in the vessel begins to turn the color of gouache (solid) (Fig. 2). Water is a good solvent. Under the influence of water molecules, the bonds between the molecules of the gouache solids are destroyed. 25 minutes have passed since the start of the experiment. The color of the water becomes more intense (Fig. 3). Water molecules penetrate between the gouache molecules, breaking the forces of attraction. 45 minutes have passed since the beginning of the experiment (Fig. 4). Simultaneously with the attractive forces between the molecules, repulsive forces begin to act and, as a result, the crystal lattice of the solid substance (gouache) is destroyed. The process of dissolving the gouache is over. The experiment took 2 hours 50 minutes. The water was completely painted the color of gouache.

Thus, the phenomenon of diffusion is a long process, as a result of which solids dissolve.

Sh experience.Study of the dependence of the rate of diffusion on temperature and penetration into food products.

Target : study how temperature affects the rate of diffusion.

Devices and materials : thermometers - 2 pcs., watches - 1 pc., glass - 1 pc., iodine, potatoes, magnetic stirrer.

Description of the experience and results obtained : They took a glass, placed iodine in it and closed the glass with potatoes cut in half at t = 22 °C. After 15 minutes from the start of the experiment, the diffusion process is inactive. The heating process began after 4 minutes. The diffusion process began, after 1 minute, we see the penetration of iodine into the potatoes, after 2 minutes.

From this experience we can conclude that the rate of diffusion is affected by temperature: the higher the temperature, the higher the rate of diffusion, which negatively affects food.

Thus, the air is polluted by waste from various factories, car exhaust gases penetrate food products, and then have a harmful effect on the life and functioning of humans, animals and plants.

IV experience.Study of the dependence of the rate of diffusion of gaseous substances into water at a constant temperature

Target : study the rate of diffusion of gaseous substances into water at a constant temperature and draw a conclusion about the rate of diffusion.

Devices and materials : thermometers - 1 piece, clock - 1 piece, flask - 1 piece, water, iodine.

Description of the experience and results obtained : Water of the same mass and the same temperature (22 °C) was poured into a flask, then vegetable oil (5 ml) was poured into another flask. Vegetable oil in our experiment imitated petroleum. The flasks were closed with tape with iodine glued to it. The observation was removed after 45 minutes.

The water, covered with a film of vegetable oil, is very faintly colored, which means that it is more difficult for oxygen molecules to penetrate into the water: fish and other aquatic inhabitants experience a lack of oxygen and may even die.

Conclusion : the presence of various substances on the surface of the water disrupts diffusion processes and can lead to undesirable environmental consequences.

Conclusion

We see how great the importance of diffusion is in inanimate nature, 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 many more positive factors and therefore we are talking about the enormous importance of diffusion in nature.

Nature makes extensive use of the capabilities inherent in the process of diffusion penetration and plays a vital role in the absorption of nutrition and oxygenation of the blood. In the flame of the Sun, in the life and death of distant stars, in the air we breathe, everywhere we see the manifestation of an almighty and universal diffusion.

Thus, diffusion is of great importance in the life processes of humans, animals and plants. Thanks to diffusion, oxygen from the lungs penetrates into the human blood, and from the blood into the tissues. But, unfortunately, people, as a result of their activities, often have a negative impact on natural processes in nature.

Studying diffusion, its role in the ecological balance of nature and the factors influencing its occurrence in nature, I came to the conclusion that it is necessary to attract public attention to environmental problems.

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Absolutely all people have heard about such a concept as diffusion. This was one of the topics in physics lessons in the 7th grade. Despite the fact that this phenomenon surrounds us absolutely everywhere, few people know about it. What does it mean anyway? What is it physical meaning, and how can you make life easier with its help? Today we will talk about this.

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Diffusion in Physics: Definition

This is the process of penetration of molecules of one substance between molecules of another substance. In simple terms, this process can be called mixing. During this mixing occurs the mutual penetration of molecules of a substance between each other. For example, when making coffee, instant coffee molecules penetrate water molecules and vice versa.

The speed of this physical process depends on the following factors:

Temperature.
Aggregate state of a substance.
External influence.

The higher the temperature of a substance, the faster the molecules move. Hence, mixing process occurs faster at high temperatures.

Aggregate state of matter - most important factor. In each state of aggregation, molecules move at a certain speed.

Diffusion can occur in the following states of aggregation:

Liquid.
Solid.

Most likely, the reader will now have the following questions:

What are the causes of diffusion?
Where does it happen faster?
How is it applied in real life?

The answers to them can be found below.

Causes

Absolutely everything in this world has its own reason. AND diffusion is no exception. Physicists understand perfectly well the reasons for its occurrence. How can we convey them to the average person?

Surely everyone has heard that molecules are in constant motion. Moreover, this movement is disordered and chaotic, and its speed is very high. Thanks to this movement and constant collision of molecules, their mutual penetration occurs.

Is there any evidence of this movement? Certainly! Remember how quickly you began to smell perfume or deodorant? And the smell of the food your mother is preparing in the kitchen? Remember how quickly preparing tea or coffee. All this could not have happened if not for the movement of molecules. We conclude that the main reason for diffusion is the constant movement of molecules.

Now only one question remains - what caused this movement? It is driven by the desire for balance. That is, in a substance there are areas with high and low concentrations of these particles. And thanks to this desire, they constantly move from an area of high concentration to a low concentration. They are constantly collide with each other, and mutual penetration occurs.

Diffusion in gases

The process of mixing particles in gases is the fastest. It can occur both between homogeneous gases and between gases with different concentrations.

Vivid examples from life:

You smell the air freshener through diffusion.
You smell the food being cooked. Note that you begin to feel it immediately, but the smell of the freshener after a few seconds. This is explained by the fact that at high temperatures the speed of movement of molecules is greater.
The tears you get when chopping onions. The onion molecules mix with air molecules, and your eyes react to this.

How does diffusion occur in liquids?

Diffusion in liquids is slower. It can last from a few minutes to several hours.

The most striking examples from life:

Making tea or coffee.
Mixing water and potassium permanganate.
Preparing a solution of salt or soda.

In these cases, diffusion occurs very quickly (up to 10 minutes). However, if an external influence is applied to the process, for example, stirring these solutions with a spoon, then the process will go much faster and will take no more than one minute.

Diffusion when mixing thicker liquids will take much longer. For example, mixing two liquid metals can take several hours. Of course, you can do this in a few minutes, but in this case it will work low quality alloy.

For example, diffusion when mixing mayonnaise and sour cream will take a very long time. However, if you resort to the help of external influence, then this process will not take even a minute.

Diffusion in solids: examples

In solids, the mutual penetration of particles occurs very slowly. This process may take several years. Its duration depends on the composition of the substance and the structure of its crystal lattice.

Experiments proving that diffusion in solids exists.

Adhesion of two plates of different metals. If you keep these two plates close to each other and under pressure, within five years there will be a layer between them 1 millimeter wide. This small layer will contain molecules of both metals. These two plates will be fused together.
A very thin layer of gold is applied to a thin lead cylinder. After which this structure is placed in an oven for 10 days. The air temperature in the oven is 200 degrees Celsius. After this cylinder was cut into thin discs, it was very clearly visible that the lead had penetrated into the gold and vice versa.

Examples of diffusion in the environment

As you already understood, the harder the medium, the lower the rate of mixing of molecules. Now let's talk about where in real life you can get practical benefits from this physical phenomenon.

The process of diffusion occurs in our lives constantly. Even when we lie on the bed, a very thin layer of our skin remains on the surface of the sheet. It also absorbs sweat. It is because of this that the bed becomes dirty and needs to be changed.

So, the manifestation of this process in everyday life can be as follows:

When you spread butter on bread, it gets absorbed into it.
When pickling cucumbers, the salt first diffuses with the water, after which the salt water begins to diffuse with the cucumbers. As a result, we get a delicious snack. Banks need to be rolled up. This is necessary to ensure that the water does not evaporate. More precisely, water molecules should not diffuse with air molecules.
When washing dishes, molecules of water and detergent penetrate into the molecules of the remaining pieces of food. This helps them come off the plate and make it cleaner.

Manifestation of diffusion in nature:

The process of fertilization occurs precisely due to this physical phenomenon. The molecules of the egg and sperm diffuse, after which the embryo appears.
Soil fertilization. By using certain chemicals or compost, the soil becomes more fertile. Why is this happening? The idea is that fertilizer molecules diffuse with soil molecules. After which the process of diffusion occurs between the molecules of the soil and the plant root. Thanks to this, the season will be more productive.
Mixing industrial waste with air greatly pollutes it. Because of this, the air within a kilometer radius becomes very dirty. Its molecules diffuse with molecules of clean air from neighboring areas. This is how the environmental situation in the city is deteriorating.

Manifestation of this process in industry:

Siliconization is the process of diffusion saturation with silicon. It is carried out in a gas atmosphere. The silicon-saturated layer of the part does not have very high hardness, but has high corrosion resistance and increased wear resistance in sea water, nitric, hydrochloric and sulfuric acids.
Diffusion in metals plays an important role in the manufacture of alloys. To obtain a high-quality alloy, it is necessary to produce alloys at high temperatures and with external influences. This will significantly speed up the diffusion process.

These processes occur in various industries:

Electronic.
Semiconductor.
Mechanical engineering.

As you understand, the process of diffusion can have both positive and negative effects on our lives. You need to be able to manage your life and maximize the benefits of this physical phenomenon, as well as minimize the harm.

Now you know the essence of such a physical phenomenon as diffusion. It consists in the mutual penetration of particles due to their movement. And in life absolutely everything moves. If you are a student, then after reading our article you will definitely receive a grade of 5. Good luck to you!

Diffusion is a process at the molecular level and is determined by the random nature of the movement of individual molecules. The rate of diffusion is therefore proportional to the average speed of the molecules. Diffusion occurs in the direction of a decrease in the concentration of a substance and leads to a uniform distribution of the substance throughout the entire volume it occupies (to equalize the chemical potential of the substance).

regeneration processes. The effectiveness of the hardware method has been proven experimentally and clinically.

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Kiselev S.I. The importance of donor skin resources in the choice of rational surgical tactics in patients with deep burns: Abstract of thesis. ...candidate of medical sciences. Ryazan, 1971. 17 p.

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