Solar energy powers an incredibly powerful heat engine, which, overcoming gravity, easily lifts a huge cube into the air (each side is about eighty kilometers). Thus, a meter thick water layer evaporates from the surface of our planet in a year.

During evaporation, a liquid substance gradually turns into a vapor or gaseous state after the smallest particles (molecules or atoms), moving at a speed sufficient to overcome the cohesive forces between particles, break away from the surface.

Although the evaporation process is better known as the transition liquid substance into steam, there is dry evaporation, when at sub-zero temperatures ice passes from solid state into vapor without passing through the liquid phase. For example, if washed damp linen is hung out to dry in the cold, it becomes very hard when frozen, but after a while, softening, it becomes dry.

How liquid escapes

The molecules of a liquid are located close to each other, and, despite the fact that they are interconnected by forces of attraction, they are not attached to certain points, and therefore move freely over the entire area of ​​\u200b\u200bthe substance (they constantly collide with each other and change their speed).

Particles that go to the surface pick up a pace during their movement, sufficient to leave the substance. Once at the top, they do not stop their movement and, having overcome the attraction of the lower particles, fly out of the water, transforming into steam. In this case, part of the molecules due to chaotic motion returns to the liquid, the rest go further into the atmosphere. Evaporation does not end there, and the following molecules break out to the surface (this happens until the liquid completely evaporates).

If we are talking, for example, about the water cycle in nature, one can observe the process of condensation, when the steam, having concentrated, returns back under certain conditions. Thus, evaporation and condensation in nature are closely interconnected, since thanks to them, a constant exchange of water between the earth, land and atmosphere is carried out, due to which the environment is supplied with a huge amount of useful substances.

1. Density. The denser the substance, the closer the molecules are in relation to each other, the more difficult it is for the upper particles to overcome the force of attraction of other atoms, therefore, the evaporation of the liquid is slower. For example, methyl alcohol volatilizes much faster than water (methyl alcohol - 0.79 g / cm3, water - 0.99 g / cm3).
2. Temperature. The rate of evaporation is also affected by the heat of evaporation. Despite the fact that the evaporation process occurs even at sub-zero temperatures, than more temperature substances, the higher the heat of evaporation, which means that the faster the particles move, which, increasing the intensity of evaporation, massively leave the liquid (therefore, boiling water evaporates faster than cold water). Due to the loss of fast molecules, the internal energy of the liquid decreases, and therefore the temperature of the substance during evaporation goes down. If the liquid at this time is near a heat source or directly heated, its temperature will not decrease, just as the evaporation rate will not decrease.
3. surface area. The more surface area a liquid occupies, the more molecules escape from it, the higher the rate of evaporation. For example, if you pour water into a pitcher with a narrow neck, the liquid will disappear very slowly, as the evaporated particles will begin to settle on the tapering walls and descend. At the same time, if you pour water into a bowl, the molecules will freely leave the surface of the liquid, since they will have nothing to condense on in order to return to the water.
4. Wind. The evaporation process will be much faster if air moves over the container in which the water is located. The faster he does this, the faster the evaporation rate. It is impossible not to take into account the interaction of wind with evaporation and condensation. Water molecules, rising from the ocean surface, partially return back, but most of them condense high in the sky and form clouds, which the wind distills onto land, where drops fall in the form of rain and, penetrating into the ground , after some time they return to the ocean, supplying vegetation growing in the soil with moisture and dissolved minerals.

Role in plant life

The importance of evaporation in the life of vegetation cannot be overestimated, especially considering that a living plant is eighty percent water. Therefore, if the plant lacks moisture, it may die, since along with water it will not receive the nutrients and microelements necessary for life.

Water, moving through the plant body, carries and forms organic substances inside it, for the formation of which the plant needs sunlight. And here an important role is played by evaporation, since the sun's rays have the ability to heat objects extremely strongly, and therefore can cause the plant to die from overheating (especially on hot summer days). To avoid this, water is evaporated by the leaves, through which a lot of liquid is released at this time (for example, from one to four glasses of water evaporates from corn per day).

This means that the more water enters the plant's body, the more intense the evaporation of water from the leaves, the plant will cool more and grow normally. Evaporation of water by plants can be felt if you touch the green leaves while walking on a hot day: they will definitely turn out to be cool.

Communication with a person

No less important is the role of evaporation in the life of the human body: it fights heat through sweating. Evaporation occurs usually through the skin and also through the respiratory tract. This can be easily seen during illness, when the body temperature rises, or during sports, when the intensity of evaporation increases.

Through the skin and respiratory tract, water not only leaves the body, but also enters it along with fumes. environment(it is not for nothing that doctors often prescribe seaside vacations for their patients). Unfortunately, along with useful elements, harmful particles often get into it, among them - chemical substances, harmful fumes that cause irreparable damage to health.

Some of them are toxic, others cause allergies, others are carcinogenic, others cause cancer and other equally dangerous diseases, while many have several harmful properties at once. Harmful fumes enter the body mainly through the respiratory organs and skin, after which, once inside, they are instantly absorbed into the bloodstream and spread throughout the body, causing toxic effects and causing serious diseases.

In this case, much depends on the area where a person lives (near a factory or plant), the premises in which he lives or works, and also the time spent in conditions hazardous to health.

Harmful fumes can enter the body from household items, such as linoleum, furniture, windows, etc. In order to save life and health, it is advisable to avoid such situations and the best way out would be to leave the dangerous territory, up to the exchange of an apartment or work, and when arranging a home, pay attention to the quality certificates of the purchased materials.

student of grade 9 B Chernyshova Christina MBOU secondary school No. 27 of Stavropol.

The subject of this research work- study of the dependence of the evaporation rate on various external conditions. This problem remains relevant in various technological fields and in the nature around us. Suffice it to say that the water cycle in nature occurs through the phases of evaporation and bulk condensation. From the water cycle, in turn, depend on such important phenomena as the solar impact on the planet or simply the normal existence of living beings in general.

Hypothesis: the evaporation rate depends on the type of substance, the surface area of ​​the liquid and air temperature, the presence of moving air currents above its surface.

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MUNICIPAL BUDGET GENERAL EDUCATIONAL INSTITUTION

SECONDARY EDUCATIONAL SCHOOL № 27

Research work:

"Evaporation and factors influencing this process"

Completed by: student of grade 9 B

Chernyshova Christina.

Teacher: Vetrova L.I.

Stavropol

2013

I.Introduction…………………………………………………………………....…….3

II Theoretical part………………………………...…………………………….4

1.Basic provisions of the molecular kinetic theory…………………4

2. Temperature…………………………………………………………..………...6

3. Feature liquid state substances……………………………..... 7

4. Internal energy …………………………………………………….……..8

5. Evaporation……………………………………………………………………..10

III.Research part………………………………..…………………..14

IV.Conclusion……………………………………………………………….…..21

V. Literature……………………………………………………………………….22

Introduction

The topic of this research work is the study of the dependence of the evaporation rate on various external conditions. This problem remains relevant in various technological fields and in the nature around us. Suffice it to say that the water cycle in nature occurs through the phases of evaporation and bulk condensation. From the water cycle, in turn, depend on such important phenomena as the solar impact on the planet or simply the normal existence of living beings in general.

Evaporation is widely used in industrial practice for cleaning substances, drying materials, separating liquid mixtures, and air conditioning. Evaporative cooling of water is used in circulating water supply systems of enterprises.

In carburetor and diesel engines, the size distribution of fuel particles determines the rate of their combustion, and hence the process of engine operation. Condensation mists are not only water vapor formed during the combustion of various fuels, but many condensation nuclei are formed, which can serve as condensation centers for other vapors. These complex processes determine the coefficient useful action engines and fuel loss. The achievement of the best results in the study of these phenomena could serve as information for the movement of technical progress in our country.

So , the purpose of this work- investigate the dependence of the evaporation rate on various environmental factors and, using graphs and careful observations, notice patterns.

Hypothesis : the evaporation rate depends on the type of substance, the surface area of ​​the liquid and air temperature, the presence of moving air currents above its surface.

During the study, we used various simple instruments, such as a thermometer, as well as Internet resources and other literature.

II Theoretical part.

1. Main provisions of the molecular-kinetic theory

The properties of substances found in nature and technology are diverse and varied: glass is transparent and brittle, while steel is elastic and opaque, copper and silver are good conductors of heat and electricity, while porcelain and silk are bad, etc.

What is internal structure any substance? Is it solid (continuous) or has a granular (discrete) structure similar to that of a sand pile?

The question of the structure of matter was raised in Ancient Greece, however, the lack of experimental data made its solution impossible, and for a long time (over two millennia) it was not possible to verify the brilliant guesses about the structure of matter, expressed by the ancient Greek thinkers Leucippus and Democritus (460-370 BC), who taught that Everything in nature is made up of atoms in constant motion. Their teaching was subsequently forgotten, and in the Middle Ages, matter was already considered continuous, and the change, the state of bodies was explained with the help of weightless liquids, each of which personified a certain property of matter and could both enter the body and leave it. For example, it was believed that the addition of caloric to the body causes it to heat up, on the contrary, the cooling of the body occurs due to the outflow of caloric, etc.

AT mid-seventeenth in. the French scientist P. Gassendi (1592-1655) returned to the views of Democritus. He believed that in nature there are substances that cannot be decomposed into simpler components. Such substances are now called chemical elements, for example, hydrogen, oxygen, copper, etc. According to Gassendi, each element consists of atoms of a certain type.

There are relatively few different elements in nature, but their atoms, when combined into groups (there may be identical atoms among them), give the smallest particle of a new type of substance - a molecule. Depending on the number and type of atoms in a molecule, substances with various properties are obtained.

In the XVIII century. the works of M. V. Lomonosov appeared, which laid the foundations of the molecular-kinetic theory of the structure of matter. Lomonosov resolutely fought for the expulsion from physics of weightless liquids like caloric, as well as atoms of cold, smell, etc., which were widely used at that time to explain the corresponding phenomena. Lomonosov proved that all phenomena are naturally explained by the motion and interaction of the molecules of matter. - |In early XIX centuries, the English scientist D. Dalton (1766-1844) showed that, using only the concepts of atoms and molecules, it is possible to derive and explain chemical laws known from experiments. Thus, he scientifically substantiated the molecular structure of matter. After the work of Dalton, the existence of atoms and molecules was recognized by the vast majority of scientists.

By the beginning of the XX century. the dimensions, masses and speeds of movement of the molecules of matter were measured, the arrangement of individual atoms in molecules was clarified, in a word, the construction of the molecular-kinetic theory of the structure of matter was finally completed, the conclusions of which were confirmed by many experiments.

The main provisions of this theory are as follows:

1) any substance consists of molecules, between which there are intermolecular gaps;

2) molecules are always in continuous random (chaotic) motion;

3) both attractive and repulsive forces act between molecules. These forces depend on the distance between the molecules. They have a significant value only at very small distances and rapidly decrease as the molecules move away from each other. The nature of these forces is electrical.

2. Temperature.

If all bodies consist of continuously and randomly moving molecules, then what will be the change in the speed of movement of molecules, i.e., their kinetic energy, and what sensations will these changes cause in a person? It turns out that the change in the average kinetic energy forward movement molecules is associated with heating or cooling bodies.

Often a person determines the warmth of the body by touch, for example, touching a heating radiator with a hand, we say: the radiator is cold, warm or hot. However, the definition of body heat to the touch is often misleading. When in winter a person touches a wooden and metal body with his hand, it seems to him that the metal object is colder than the wooden one, although in reality their heating is the same. Therefore, it is necessary to establish a value that would objectively evaluate the body's heating, and create an instrument for measuring it.

The value characterizing the degree of heating of the body is called temperature. An instrument for measuring temperature is called a thermometer. The action of the most common thermometers is based on the expansion of bodies when heated and contraction when cooled. When two bodies come into contact with different temperatures energy is exchanged between bodies. In this case, a more heated body (with a high temperature) loses energy, and a less heated body (with a low temperature) gains it. Such an exchange of energy between bodies leads to the equalization of their temperatures and ends when the temperatures of the bodies become equal.

The feeling of heat in a person occurs when he receives energy from the surrounding bodies, that is, when their temperature is higher than the temperature of a person. The sensation of cold is associated with the release of energy by a person to surrounding bodies. In the above example, a metal body seems colder to a person than a wooden one, because the energy from the hand is transferred to the metal bodies faster than to the wooden ones, and in the first case the temperature of the hand drops faster.

3. Characteristics of the liquid state of matter.

Molecules of a liquid for some time t oscillate around a randomly arisen equilibrium position, and then jump to a new position. The time during which the molecule oscillates around the equilibrium position is called the "settled life" time of the molecule. It depends on the type of liquid and its temperature. When the liquid is heated, the time of "sedentary life" decreases.

If a sufficiently small volume is isolated in a liquid, then during the time of "settled life" it retains an ordered arrangement of liquid molecules, i.e., there is a semblance of a crystal lattice solids. However, if we consider the arrangement of liquid molecules relative to each other in a large volume of liquid, then it turns out to be chaotic.

Therefore, we can say that in a liquid there is a "short range order" in the arrangement of molecules. The ordered arrangement of liquid molecules in small volumes is called quasi-crystalline (crystal-like). With short-term effects on the liquid, less than the time of "sedentary life", a great similarity of the properties of the liquid with the properties of the solid is found. For example, with a sharp impact of a small stone with a flat surface on water, the stone bounces off it, i.e., the liquid exhibits elastic properties. If a swimmer jumping from a tower hits the surface of the water with his whole body, he will be badly hurt, since under these conditions the liquid behaves like a solid body.

If the time of exposure to the liquid is longer than the time of the "sedentary life" of the molecules, then the fluidity of the liquid is detected. For example, a person freely enters the water from the river bank, etc. The main features of the liquid state are the fluidity of the liquid and the preservation of volume. The fluidity of a liquid is closely related to the time of "sedentary life" of its molecules. The shorter this time, the greater the mobility of the liquid molecules, i.e., the greater the fluidity of the liquid, and its properties are closer to those of a gas.

The higher the temperature of a liquid, the more its properties differ from the properties of a solid and become closer to the properties of dense gases. Thus, the liquid state of a substance is intermediate between the solid and gaseous state of the same substance.

4. Internal energy

Every body is a collection of a huge number of particles. Depending on the structure of the substance, these particles are molecules, atoms or ions. Each of these particles, in turn, has a rather complex structure. So, a molecule consists of two or more atoms, atoms consist of a nucleus and electron shell; the nucleus consists of protons and neutrons, etc.

The particles that make up a body are in constant motion; moreover, they interact in a certain way with each other.

The internal energy of a body is the sum of the kinetic energies of the particles of which it consists, and the energies of their interaction with each other (potential energies).

Let us find out under what processes the internal energy of the body can change.

1. First of all, it is obvious that the internal energy of a body changes when it is deformed. Indeed, the distance between particles changes during deformation; consequently, the energy of interaction between them also changes. Only in ideal gas, where the forces of interaction between particles are neglected, the internal energy does not depend on pressure.

2. Internal energy changes during thermal processes. Thermal processes are called processes associated with a change in both the temperature of the body and its state of aggregation - melting or solidification, evaporation or condensation. As the temperature changes, the kinetic energy movement of its particles. However, it should be emphasized that at the same time

and potential energy their interactions (with the exception of the rarefied gas case). Indeed, an increase or decrease in temperature is accompanied by a change in the distance between equilibrium positions at the nodes of the body's crystal lattice, which we register as thermal expansion of bodies. Naturally, the interaction energy of particles changes in this case. The transition from one state of aggregation to another is the result of a change in the molecular structure of the body, which causes a change in both the interaction energy of particles and the nature of their movement.

3. The internal energy of the body changes during chemical reactions. Indeed, chemical reactions are the processes of rearrangement of molecules, their disintegration into simpler parts or, conversely, the emergence of more complex molecules from simpler or from individual atoms (reactions of analysis and synthesis). In this case, the forces of interaction between atoms and, accordingly, the energies of their interaction change significantly. In addition, the nature of both the movement of molecules and the interaction between them changes, because the molecules of the newly arisen substance interact with each other differently than the molecules of the original substances.

4. Under certain conditions, the nuclei of atoms undergo transformations, which are called nuclear reactions. Regardless of the mechanism of the processes occurring in this case (and they can be very different), they are all associated with a significant change in the energy of the interacting particles. Consequently, nuclear reactions accompanied by a change internal energy body that contains these nuclei

5. Evaporation

The transition of a substance from a liquid to a gaseous state is called vaporization, and the transition of a substance from gaseous state to liquid by condensation.

One type of vaporization is evaporation. Evaporation is called vaporization, which occurs only from the free surface of a liquid adjacent to a gaseous medium. Let us find out how evaporation is explained on the basis of molecular-kinetic theory.

Since the molecules of a liquid perform chaotic motion, among the molecules of its surface layer there will always be molecules that move in the direction from the liquid to the gaseous medium. However, not all such molecules will be able to fly out of the liquid, since molecular forces act on them, drawing them back into the liquid. Therefore, only those of its molecules that have a sufficiently large kinetic energy can escape from the surface layer of a liquid.

Indeed, when a molecule passes through surface layer, it must do work against the molecular forces due to its kinetic energy. Those molecules whose kinetic energy is less than this work are drawn back into the liquid, and only those molecules escape from the liquid whose kinetic energy is greater than the specified work. Molecules escaping from the liquid form vapor above its surface. Since molecules escaping from a liquid acquire kinetic energy as a result of collisions with other molecules in the liquid, average speed random motion of molecules inside the liquid during its evaporation should decrease. Thus, a certain energy must be spent on the transformation of the liquid phase of a substance into a gaseous one. Vapor molecules located above the surface of the liquid, during their chaotic movement, can fly back into the liquid and return to it the energy that they carried away during evaporation. Consequently, during evaporation, vapor condensation always occurs simultaneously, accompanied by an increase in the internal energy of the liquid.

What factors affect the rate of evaporation of a liquid?

1. If you pour equal volumes of water, alcohol and ether into identical saucers and observe their evaporation, it turns out that the ether will evaporate first, then alcohol and the last to evaporate water. Therefore, the speed

Evaporation depends on the type of liquid.

2. The same liquid evaporates the faster, the larger its free surface. For example, if equal volumes of water are poured into a saucer and into a glass, then the water will evaporate from the saucer faster than from the glass.

3. It is easy to see that hot water evaporates faster than cold.

The reason for this is clear. The higher the temperature of the liquid, the greater the average kinetic energy of its molecules and, consequently, the more liquid leaves them in the same time.

4. In addition, the rate of evaporation of a liquid is the greater, the lower the external pressure on the liquid and the lower the vapor density of this liquid above its surface.

For example, when there is wind, the laundry dries faster than when it is not windy, because the wind carries away water vapor and thus helps to reduce the condensation of steam on the laundry.

Since energy is expended on the evaporation of a liquid due to the energy of its molecules, the temperature of the liquid decreases during the evaporation process. That is why the hand moistened with ether or alcohol is noticeably cooled. This also explains the feeling of cold in a person when he comes out of the water after bathing on a hot windy day.

If the liquid evaporates slowly, then due to heat exchange with the surrounding bodies, the loss of its energy is compensated by the influx of energy from the environment, and its temperature actually remains equal to the temperature environment. However, when high speed evaporation of a liquid, its temperature may be significantly lower than the ambient temperature. With the help of "volatile" liquids, such as ether, a significant decrease in temperature can be obtained.

We also note that many solids, bypassing the liquid phase, can directly pass into the gaseous phase. This phenomenon is called sublimation, or sublimation. The odor of solids (eg camphor, naphthalene) is explained by their sublimation (and diffusion). Sublimation is characteristic of ice, for example, laundry dries at temperatures below 0° G.

6. Hydrosphere and Earth's atmosphere

1. The processes of evaporation and condensation of water play a decisive role in the formation of weather and climate conditions on our planet. On a global scale, these processes are reduced to the interaction of the hydrosphere and the Earth's atmosphere.

The hydrosphere is made up of all the water available on our planet in all its states of aggregation; 94% of the hydrosphere falls on the World Ocean, the volume of which is estimated at 1.4 billion m3. It occupies 71% of the total area earth's surface, and if the solid surface of the Earth were a smooth sphere, then water would cover it with a continuous layer 2.4 km deep; 5.4% of the hydrosphere is occupied by groundwater, as well as glaciers, atmospheric and soil moisture. And only 0.6% falls on the fresh water of rivers, lakes and artificial reservoirs. This makes clear the importance of security. fresh water from pollution by industrial and transport waste.

2. The Earth's atmosphere is usually divided into several layers, each of which has its own characteristics. The lower surface layer of air is called the troposphere. Its upper boundary in the equatorial latitudes runs at an altitude of 16-18 km, and in the polar latitudes - at an altitude of 10 km. The troposphere contains 90% of the mass of the entire atmosphere, which is 4.8 1018 kg. The temperature in the troposphere decreases with height. First, by 1 °C for every 100 m, and then starting from a height of 5 km, the temperature drops to -70 °C.

Air pressure and density are constantly decreasing. The outermost layer of the atmosphere at an altitude of about 1000 km gradually passes into interplanetary space.

3. Studies have shown that every day about 7 10 3 km 3 water and about the same amount falls as precipitation.

Water vapor, carried away by ascending air currents, rises up, falling into the cold layers of the troposphere. As it rises, the vapor becomes saturated and then condenses to form raindrops and clouds.

In the process of steam condensation in the atmosphere, on average, the amount of heat released per day is 1.6 10 22 J, which is tens of thousands of times greater than the energy generated on planet Earth during the same time. This energy is absorbed by the water as it evaporates. Thus, between the hydrosphere and the Earth's atmosphere there is a continuous exchange of not only matter (the water cycle), but also energy.

III. RESEARCH PART.

To study the evaporation processes and determine the dependence of the evaporation rate on various conditions, a number of experiments were carried out.

Experiment 1 Investigation of the dependence of evaporation rate on air temperature.

Materials: Glass plates, 3% hydrogen peroxide solution, vegetable oil, alcohol, water, stopwatch, thermometer, refrigerator.

Experiment progress:Using a syringe, we apply substances to glass plates and observe the evaporation of substances.

Alcohol Volume 0.5 10 -6 m 3

Air temperature: +24.

The result of the experiment: it took 3 hours for the complete evaporation of the liquid;

Water. Volume 0.5 10 -6 m 3

Air temperature: +24.

The result of the experiment: it took 5 hours to completely evaporate the liquid;

Hydrogen peroxide solution. Volume 0.5 10 -6 m 3

Air temperature: +24.

The result of the experiment: it took 8 hours for the complete evaporation of the liquid;

Vegetable oil. Volume 0.5 10 -6 m 3

Air temperature: +24.

The result of the experiment: it took 40 hours for the complete evaporation of the liquid;

We change the air temperature. We put the glasses in the refrigerator.

Alcohol. Volume 0.5 10 -6 m 3

Air temperature: +6.

The result of the experiment: it took 8 hours for the complete evaporation of the liquid;

Water. Volume 0.5 10 -6 m 3

Air temperature: +6.

The result of the experiment: it took 10 hours for the complete evaporation of the liquid;

Solution of hydrogen peroxide. Volume 0.5 10 -6 m 3

Air temperature: +6.

The result of the experiment: it took 15 hours to completely evaporate the liquid;

Vegetable oil. Volume 0.5 10 -6 m 3

Air temperature: +6

The result of the experiment: it took 72 hours for the complete evaporation of the liquid;

Conclusion: According to the results of the study, it is clear that different temperature the amount of time required for the evaporation of the same substances is different. For the same liquid, the evaporation process proceeds much faster at a higher temperature. This proves the dependence of the process under study on this physical parameter. As the temperature decreases, the duration of the evaporation process increases and vice versa.

Experiment 2 . Investigation of the dependence of the rate of the evaporation process on the surface area of ​​the liquid.

Target: Investigate the dependence of the evaporation process on the surface area of ​​the liquid.

Materials: Water, alcohol, watch, medical syringe, glass plates, ruler.

Experiment progress:We measure surface area using the formula: S=P·D 2 :4.

Using a syringe, we apply different liquids to the plate, give it the shape of a circle and observe the liquid until it completely evaporates. The air temperature in the room remains unchanged (+24)

Alcohol. Volume 0.5 10 -6 m 3

Surface area:0.00422m 2

The result of the experiment: it took 1 hour for the complete evaporation of the liquid;

Water. Volume 0.5 10 -6 m 3

2

The result of the experiment: it took 2 hours to completely evaporate the liquid;

Hydrogen peroxide solution. Volume 0.5 10 -6 m 3

Surface area: 0.00422 m 2

The result of the experiment: it took 4 hours for the complete evaporation of the liquid;

Vegetable oil. Volume 0.5 10 -6 m 3

Surface area: 0.00422 m 2

The result of the experiment: it took 30 hours for the complete evaporation of the liquid;

We change conditions. We observe the evaporation of the same liquids with a different surface area.

Alcohol. Volume 0.5 10 -6 m 3

2

The result of the experiment: it took 3 hours for the complete evaporation of the liquid;

Water. Volume 0.5 10 -6 m 3

Surface area: 0.00283 m 2

The result of the experiment: it took 4 hours for the complete evaporation of the liquid;

Hydrogen peroxide solution. Volume 0.5 10 -6 m 3

2

The result of the experiment: it took 6 hours for the complete evaporation of the liquid;

Vegetable oil. Volume 0.5 10 -6 m 3

Surface area 0.00283 m 2

The result of the experiment: it took 54 hours for the liquid to evaporate completely;

Conclusion: From the results of the study, it follows that from vessels with different surface areas, evaporation is carried out for different times. As can be seen from the measurements, this liquid evaporates faster from a vessel with a larger surface area, which proves the dependence of the process under study on this physical parameter. With a decrease in surface area, the duration of the evaporation process increases and vice versa.

Experiment 3 Investigation of the dependence of the evaporation process on the type of substance.

Target: Investigate the dependence of the evaporation process on the type of liquid.

Devices and materials:Water, alcohol, vegetable oil, hydrogen peroxide solution, watch, medical syringe, glass plates.

The progress of the experiment.With a syringe we apply different kinds liquid on the plates and observe the process until complete evaporation. The air temperature remains unchanged. The temperatures of the liquids are the same.

The results of studies of the difference between the evaporation of alcohol, water, 3% hydrogen peroxide, vegetable oil, we get from the data of previous studies.

Conclusion: Different liquids require different amounts of time to completely evaporate. It can be seen from the results that the evaporation process proceeds faster for alcohol and water, and slower for vegetable oil, that is, it serves as evidence of the dependence of the evaporation process on the physical parameter - the type of substance.

Experiment 4 Investigation of the dependence of the rate of evaporation of a liquid on the velocity of air masses.

Target: to study the dependence of the rate of the evaporation process on the wind speed.

Devices and materials:Water, alcohol, vegetable oil, hydrogen peroxide solution, watch, medical syringe, glass plates, hair dryer.

Progress. We create an artificial movement of air masses with the help of a hair dryer, observe the process, wait until the liquid has completely evaporated. The hair dryer has two modes: simple mode, turbo mode.

In case of simple mode:

Alcohol. Volume: 0.5 10 -6 m 3

Surface area: 0.00283 m 2 The result of the experiment: it took about 2 minutes to completely evaporate the liquid;

Water. Volume 0.5 10 -6 m 3

Surface area: 0.00283 m 2

The result of the experiment: it took about 4 minutes to completely evaporate the liquid;

Solution of hydrogen peroxide. Volume: 0.5 10 -6 m 3

Surface area: 0.00283 m 2

The result of the experiment: it took about 7 minutes to completely evaporate the liquid;

Vegetable oil. Volume: 0.5 10 -6 m 3

Surface area: 0.00283 m 2 The result of the experiment: it took about 10 minutes to completely evaporate the liquid;

In case of turbo mode:

Alcohol. Volume: 0.5 10 -6 m 3

Surface area: 0.00283 m 2 The result of the experiment: it took about 1 minute to completely evaporate the liquid;

Water. Volume: 0.5 10 -6 m 3

Surface area: 0.00283 m 2

The result of the experiment: it took about 3 minutes to completely evaporate the liquid;

Solution of hydrogen peroxide. Volume: 0.5 10 -6 m 3

Surface area: 0.00283 m 2 The result of the experiment: it took about 5 minutes to completely evaporate the liquid;

Vegetable oil. Volume: 0.5 10 -6 m 3

Surface area: 0.00283 m 2

The result of the experiment: it took about 8 minutes to completely evaporate the liquid;

Conclusion: The evaporation process depends on the speed of movement of air masses over the surface of the liquid. The higher the speed, the faster the process and vice versa.

So, studies have shown that the intensity of evaporation of a liquid is different for different liquids and increases with an increase in the temperature of the liquid, an increase in its free surface area, and the presence of wind over its surface.

Conclusion.

As a result of the work, various sources of information on the evaporation process and the conditions for its occurrence were studied. The physical parameters that affect the rate of the evaporation process are determined. The dependence of the course of the evaporation process on physical parameters was investigated, and the analysis of the results obtained was carried out. The stated hypothesis turned out to be correct. Theoretical assumptions were confirmed in the course of research - the dependence of the rate of the evaporation process on physical parameters is as follows:

With an increase in the temperature of the liquid, the rate of the evaporation process increases and vice versa;

With a decrease in the area of ​​the free surface of the liquid, the rate of the evaporation process decreases and vice versa;

The rate of the evaporation process depends on the type of liquid.

Thus, the process of evaporation of liquids depends on such physical parameters as temperature, free surface area and type of substance.

This work is of practical importance, since it investigates the dependence of the intensity of evaporation - a phenomenon that we encounter in Everyday life, on physical parameters. Using this knowledge, you can control the course of the process.

Literature

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