Everyone knows that wet clothes are colder than dry clothes, especially when there is wind. It is also known that by wrapping a vessel with water in a wet rag and exposing it to the wind on a hot day, we noticeably cool the water in the vessel. Sometimes, for the same purpose, in hot countries they use special vessels with porous walls, through which water slowly seeps, keeping them wet all the time. These observations show that evaporation causes cooling of the liquid, and at the same time the surrounding bodies. In this case, the heat of vaporization is borrowed from the liquid itself.
Particularly strong cooling occurs if evaporation occurs very quickly, so that the evaporating liquid does not have time to receive heat from the surrounding bodies. Rapid evaporation is easy to achieve with volatile liquids. For example, when ether or ethyl chloride evaporates, lower cooling is easily obtained (Fig. 490). Doctors use this when they need to freeze a patient's skin to make it insensitive to pain. Evaporative cooling can also be observed in the following experiment. Two glass balls are connected by a curved glass tube (cryophore, Fig. 491). The balls contain water and its vapor, the air has been removed. Ball C is placed in a cooling mixture (a mixture of snow and salt). Then the water in the ball freezes. The reason for this is this. Cooling the ball causes increased condensation of vapors in it. As a result, the water in the ball evaporates and therefore cools. The temperature drops so much that the water in the ball freezes.
Rice. 490. By blowing air through the tube, i.e., accelerating the evaporation of ether, you can make the water at the bottom of the test tube freeze
Rice. 491. When the ball cools, the water in the ball freezes
Cooling during evaporation and the release of heat during condensation of vapors play an extremely important role in nature, determining the moderation of the climate of coastal countries. Note that the evaporation of sweat from the skin of humans and animals is the way the body regulates body temperature. During hot weather, the skin sweats and the evaporation of sweat cools it.
296.1. Why is it difficult to withstand the heat in rubber clothing?
296.2. Why does fanning make it easier to cope with the heat?
296.3. There are two glasses of the same shape and size, one metal and the other porcelain. The same amount of water is poured into glasses and left in the room for a long time. Is the temperature of the water the same in the glasses?
During evaporation, the liquid leaves molecules whose kinetic energy is greater than their average kinetic energy. Therefore, the average kinetic energy of the remaining liquid molecules decreases. And this means a decrease in the temperature of the evaporating liquid. This is why you feel cool on a hot summer day immediately after swimming. The evaporation of water from the surface of the body leads to its cooling. It is also known that wet clothes are colder than dry ones, especially when there is wind. Very strong cooling occurs if evaporation occurs quickly. With the rapid evaporation of ether at atmospheric pressure, cooling below 0 °C can occur. It can be detected like this. Pour a little ether into a concave spectacle glass and place it on a table moistened with water. When the ether evaporates quickly (evaporation is accelerated by blowing air over the ether), the glass freezes to the table surface. Doctors use cooling during the evaporation of volatile liquids when they need to freeze the patient’s skin to make it insensitive to pain.
In hot countries, water is usually kept in porous clay vessels to cool water. Water seeping through the pores of the vessel evaporates, cooling the water in the vessel.
If you deprive a liquid of the opportunity to evaporate, its cooling will occur much more slowly. Remember how long it takes for fatty soup to cool. A layer of fat on its surface prevents the release of fast water molecules. The liquid hardly evaporates, and its temperature drops slowly (fat itself evaporates extremely slowly, since its large molecules are more tightly coupled to each other than water molecules).
Evaporation of solids
Not only liquids evaporate, but also solids. Molecules that are located near the surface of a solid and have sufficient kinetic energy are able to leave the body. The process of transition of a substance from a solid state directly to a gaseous state is called sublimation or sublimation.
For example, naphthalene or camphor evaporate at room temperature and normal pressure, bypassing the liquid state. Bromine or iodine crystals evaporate in the same way, especially if they are heated. Ice also evaporates. If you hang wet laundry in the cold, the water freezes, and then the ice evaporates and the laundry dries.
When liquids evaporate, they cool down as the fastest molecules leave the liquid.
§ 6.2. Equilibrium between liquid and vapor
The most interesting state of gas is saturated vapor. It is in equilibrium with the liquid.
Saturated steam
The amount of liquid in an open container continuously decreases due to evaporation. But if the vessel is tightly closed, then this does not happen, which can be explained as follows.
At the first moment, after we pour the liquid into the vessel and close it, the liquid will evaporate and the vapor density above the liquid will increase. However, at the same time, the number of molecules returning to the liquid as a result of chaotic thermal motion will also increase. The greater the density of the vapor, the greater the number of its molecules returning to the liquid. In an open vessel, the picture is different: the molecules that have left the liquid may not return to the liquid.
In a closed vessel, an equilibrium state is eventually established: the number of molecules leaving the surface of the liquid becomes equal to the number of vapor molecules returning to the liquid at the same time. This equilibrium is called dynamic or mobile. In dynamic equilibrium between a liquid and its vapor, both evaporation of the liquid and condensation of the vapor occur simultaneously, and both processes, on average, compensate each other (Fig. 6.2).
Steam located V dynamic equilibrium with its liquid is called saturated vapor. This name emphasizes that a larger amount of steam cannot be present in a given volume at a given temperature. If the air is pumped out from a container with a liquid, then only its saturated vapor will be above the surface of the liquid.
At a given temperature, saturated steam has the greatest number of molecules per unit volume (and therefore the greatest density) and exerts the greatest pressure.
In nature, technology and everyday life, we often observe the transformation of liquid and solid bodies into a gaseous state. On a clear summer day, puddles left after rain and wet laundry dry quickly. Decreasing over time, pieces of dry ice disappear, pieces of naphthalene “melt”, which we sprinkle on woolen items, etc. In all these cases, vaporization is observed - the transition of substances into a gaseous state - steam.
There are two ways for a liquid to change into a gaseous state: evaporation and boiling. Evaporation occurs from an open free surface separating liquid from gas, for example from the surface of an open vessel, from the surface of a reservoir, etc. Evaporation occurs at any temperature, but for any liquid its rate increases with increasing temperature. The volume occupied by a given mass of substance increases abruptly during evaporation.
Two main cases must be distinguished. The first is when evaporation occurs in a closed vessel and the temperature at all points of the vessel is the same. For example, water evaporates inside a steam boiler or in a kettle closed with a lid if the temperature of the water and steam is below the boiling point. In this case, the volume of steam generated is limited by the space of the vessel. The vapor pressure reaches a certain limiting value at which it is in thermal equilibrium with the liquid; such steam is called saturated, and its pressure is called vapor pressure.
The second case is when the space above the liquid is not closed; This is how water evaporates from the surface of the pond. Here, equilibrium is almost never achieved and the steam is unsaturated, and the rate of evaporation depends on many factors.
A measure of the rate of evaporation is the amount of substance escaping per unit time from a unit of free surface of the liquid. John Dalton, an English physicist and chemist, at the beginning of the 19th century found that the rate of evaporation is proportional to the difference between the pressure of saturated vapor at the temperature of the evaporating liquid and the actual pressure of the real vapor that exists above the liquid. If both liquid and vapor are in equilibrium, then the evaporation rate is zero. Exactly, it happens, but the reverse process - condensation - also occurs at the same speed. The rate of evaporation also depends on whether it occurs in a calm or moving atmosphere; its speed increases if the resulting vapor is blown away by an air stream or pumped out by a pump.
If evaporation occurs from a liquid solution, then different substances evaporate at different rates. The rate of evaporation of a given substance decreases with increasing pressure of spatial gases, such as air. Therefore, evaporation into emptiness occurs at the highest speed. On the contrary, by adding an extraneous inert gas to the vessel, evaporation can be greatly slowed down. .
During evaporation, molecules escaping from a liquid must overcome the attraction of neighboring molecules and do work against the surface tension forces holding them in the surface layer. Therefore, for evaporation to occur, heat must be imparted to the evaporating substance, drawing it from the internal energy reserve of the liquid itself, or by taking it away from surrounding bodies. The amount of heat that must be imparted to a liquid at a given temperature and pressure in order to convert it into vapor at this temperature and pressure is called the heat of vaporization. The vapor pressure increases with increasing temperature, the stronger the higher the heat of evaporation.
If the evaporating liquid is not supplied with heat from the outside or is supplied insufficiently, then the liquid cools. By forcing a liquid placed in a vessel with non-heat-conducting walls to evaporate intensively, it is possible to achieve significant cooling. According to the kinetic theory, during evaporation, faster molecules escape from the surface of the liquid; the average energy of the molecules remaining in the liquid decreases.
Evaporation is accompanied by a decrease in the amount of substance and a decrease in its temperature. When a liquid evaporates, some of the fastest moving molecules can fly out from the surface layer. These molecules have kinetic energy greater than or equal to the work that must be done against the cohesive forces holding them inside the liquid. In this case, the temperature of the liquid, determined by the average speed of the random movement of molecules, decreases. A decrease in liquid temperature indicates that the internal energy of the evaporating liquid decreases. Part of this energy is spent on overcoming adhesion forces and on performing work by the expanding steam against external pressure. On the other hand, there is an increase in the internal energy of that part of the substance that has turned into vapor due to an increase in the distance between the vapor molecules compared to the distance between the liquid molecules. Therefore, the internal energy of a unit mass of steam is greater than the internal energy of a unit mass of liquid at the same temperature.
Sometimes evaporation is also called sublimation, or sublimation, that is, the transition of a solid into a gaseous state, bypassing the liquid stage. Almost all of their patterns are really similar. The heat of sublimation is greater than the heat of evaporation by approximately the heat of fusion.
At temperatures below the melting point, the saturated vapor pressure of most solids is very low and there is practically no evaporation. There are, however, exceptions. Thus, water at 0 ° C has a saturated vapor pressure of 4.58 mm Hg, and ice at - 1 ° C - 4.22 mm Hg. and even at - 10°C - 1.98 mm Hg.
These relatively large water vapor pressures explain the easily observed evaporation of solid ice, in particular, the well-known fact of wet laundry drying in the cold. The evaporation of a solid can also be observed in the evaporation of artificial ice, naphthalene, and snow.
The phenomenon of evaporation underlies distillation, one of the common methods of chemical technology. Distillation is the process of separating multicomponent liquid mixtures by partial evaporation and subsequent condensation of the vapors. As a result of this process, liquid mixtures are separated into separate fractions that differ in composition and boiling points.
Physical phenomenon - boiling
The second method of vaporization is boiling, which is characterized, in contrast to evaporation, by the fact that the formation of vapor occurs not only on the surface, but throughout the entire mass of the liquid. Boiling becomes possible if the saturated vapor pressure of the liquid becomes equal to the external pressure. Therefore, this liquid, being under a given external pressure, boils at a very specific temperature. Usually the boiling point is given for atmospheric pressure. For example, water at atmospheric pressure boils at 373 K or 100°C.
The difference in boiling points of various substances is used in technology for the so-called distillation of mixtures, components of which differ greatly in boiling point, for example, for the distillation of petroleum products.
The dependence of the boiling point on pressure is explained by the fact that external pressure prevents the growth of vapor bubbles inside the liquid. Therefore, at increased pressure, the liquid boils at a higher temperature. When pressure changes, the boiling point changes over a wider range than the melting point.
Boiling is a special type of vaporization, different from evaporation. External signs of boiling: a large number of small bubbles appear on the walls of the vessel; the volume of bubbles increases and the lifting force begins to affect; More or less violent and irregular movements of bubbles occur within the liquid. Bubbles burst on the surface The process of floating and destruction of bubbles filled with air and steam on the surface of a liquid is characterized by boiling. Liquids have their own boiling points.
Bubbles that form when a liquid boils most easily arise from bubbles of air or other gases normally present in the liquid. Such bubbles - boiling centers - often stick to the walls of the vessel, so boiling begins earlier at the walls.
Air bubbles contain water vapor. Thanks to the numerous bubbles, the evaporation surface of the liquid increases sharply. Steam formation occurs throughout the entire volume of the vessel. Hence the characteristic signs of boiling: bubbling, a sharp increase in the amount of steam, a cessation of temperature rise until complete boiling.
But if the liquid is free of gases, then the formation of vapor bubbles in it is difficult. Such a liquid can be overheated, that is, heated above the boiling point without it boiling. If an insignificant amount of gas or solid particles, to the surface of which air has adhered, is introduced into such a superheated liquid, it will instantly boil explosively. The temperature of the liquid drops to the boiling point. Such phenomena can cause explosions in steam boilers, so they need to be prevented. Back in 1924, F. Kendrick and his colleagues managed to heat liquid water to 270ºC at normal atmospheric pressure. At this temperature, the equilibrium pressure of water vapor is 54 atm. From the above it follows that boiling processes can be controlled by increasing or decreasing pressure, as well as reducing the number of “seeds”. Modern research has shown that, ideally, water is heated to approximately 300ºC, after which it instantly becomes cloudy and explodes to form a rapidly expanding steam-water mixture.
Thus, boiling, like evaporation, is vaporization. Evaporation occurs from the surface of a liquid at any temperature and any external pressure, and boiling is vaporization in the entire volume of the liquid at a temperature specific for each substance, depending on the external pressure.
To ensure that the temperature of the evaporating liquid does not change, certain amounts of heat must be supplied to the liquid. A physical quantity showing the amount of heat required to convert a liquid with a mass of 1 kg into vapor without changing temperature is called the specific heat of vaporization. This value is denoted by the letter L and measured in J/kg. = J/kg
Steam condensation is the opposite process of vaporization. The phenomenon of vaporization and condensation explains the water cycle in nature, the formation of fog, and dew.
The amount of heat that steam releases when condensing is determined by the same formula. = J
It has been experimentally established that, for example, the specific heat of vaporization of water at 100°C is equal to 2.3 106 J/kg, that is, to convert water with a mass of 1 kg into steam at a boiling point of 100°C, 2.3 106 J of energy is required.
Air humidity
Due to all kinds of evaporation, the atmosphere of our planet contains a huge amount of water vapor, especially in the layers closest to the earth. The presence of water vapor in the air is a necessary condition for the existence of life on the globe. However, both dry air and too humid air are unfavorable for the animal and plant world. Moderate air humidity creates a necessary condition for normal human life and activity. Excess humidity is harmful for a number of production processes, during storage of products and materials. How to estimate the degree of air humidity, i.e. the amount of water vapor it contains? This assessment is especially important for weather forecasting, since the content of water vapor in the atmosphere is one of the most important factors determining weather. Without knowledge of air humidity, it is impossible to make a forecast of weather conditions, which is so necessary for agriculture, transport, and a number of other sectors of the national economy. To find out how much steam is contained in the air, in principle, pass a certain volume of air through a substance that absorbs water vapor, and so find the mass of steam contained in 1 m3 of air.
The value measured by the amount of water vapor contained in 1 cm3 of air is called absolute air humidity. In other words, absolute air humidity is measured by the density of water vapor in the air.
In practice, it is very difficult to measure the amount of steam contained in 1 m3 of air. But it turned out that the numerical value of absolute humidity differs little from the partial pressure of water vapor under the same conditions, measured in millimeters of mercury. The partial pressure of a gas is measured much more simply, therefore in meteorology, absolute air humidity is usually called the partial pressure of water vapor contained in it at a given temperature, measured in millimeters of mercury.
But, knowing the absolute humidity of the air, it is still impossible to determine how dry or humid it is, since the latter also depends on temperature. If the temperature is low, then a given amount of water vapor in the air may be very close to saturation, i.e. the air will be damp. At higher temperatures, the same amount of water vapor is far from saturated and the air is dry.
To judge the degree of air humidity, it is important to know whether the water vapor in it is close or far from the saturation state. For this purpose, the concept of relative humidity is introduced.
Relative air humidity is a value measured by the ratio of absolute humidity to the amount of steam required to saturate 1 m 3 of air at that temperature. It is usually expressed as a percentage. In other words, relative air humidity shows what percentage absolute humidity is of the density of water vapor saturating the air at a given temperature:
In meteorology, relative humidity is a quantity measured by the ratio of the partial pressure of water vapor. Contained in the air, the pressure of water vapor saturating the air at the same temperature.
Relative air humidity depends not only on absolute humidity, but also on temperature. If the amount of water vapor in the air does not change, then with decreasing temperature the relative humidity increases, since the lower the temperature, the closer the water vapor is to saturation. To calculate relative humidity, use the values given in the corresponding tables
Water is a solvent
Water is a good solvent. Solutions are homogeneous systems consisting of solvent molecules and solute particles, between which physical and chemical interactions occur. For example: mechanical stirring is a physical phenomenon, heating when dissolving sulfuric acid in water is a chemical phenomenon.
Suspensions are suspensions in which small particles of solid matter are evenly distributed between water molecules. For example: a mixture of clay and water.
Emulsions are suspensions in which small droplets of a liquid are evenly distributed between the molecules of another liquid. For example: shaking kerosene, gasoline and vegetable oil with water.
A solution in which a given substance no longer dissolves at a given temperature is called saturated, and a solution in which the substance can still be dissolved is called unsaturated.
Solubility is determined by the mass of a substance, the mass of a substance capable of dissolving in 1000 ml of solvent at a given temperature.
The mass fraction of a solute is the ratio of the mass of the solute to the mass of the solution.
As in any other liquid, there are energy whose energy allows them to overcome intermolecular attraction. These molecules accelerate with force and fly to the surface. Therefore, if you cover a glass of water with a paper napkin, after a while it will become a little damp. But water evaporation occurs at different rates under different conditions. The key physical characteristics that influence the speed of this process and its duration are the density of the substance, temperature, surface area, presence. The greater the density of the substance, the closer the molecules are located to each other. This means that it is more difficult for them to overcome intermolecular attraction, and they fly to the surface in much smaller numbers. If you place two liquids with different densities (for example, water and methyl) under the same conditions, the one with a lower density will evaporate faster. The density of water is 0.99 g/cm3, and the density of methyl is 0.79 g/cm3. Therefore, the methanol will evaporate faster. An equally important factor influencing the rate of water evaporation is temperature. As already mentioned, evaporation occurs at any temperature, but as it increases, the speed of movement of the molecules increases, and they leave the liquid in greater numbers. Therefore the burning water evaporates faster than cold water. The intensity of water evaporation also depends on its surface area. Water poured into a bottle with a narrow neck will evaporate because... the ejected molecules will settle on the walls of the bottle tapering at the top and roll back. And the water molecules in the saucer will freely leave the liquid. The evaporation process will accelerate significantly if air currents move over the surface from which evaporation occurs. The fact is that in addition to the molecules leaving the liquid, they return back. And the stronger the air circulation, the fewer molecules that fall back into the water. This means that its volume will rapidly decrease.
Sources:
- evaporation of water
Scientists have been interested in the various properties of water for many years. Water can be in different states - solid, liquid and gaseous. At normal average temperature, water appears as a liquid. You can drink it and water plants with it. Water can spread and occupy certain surfaces and take the shape of the vessels in which it is located. So why is water liquid?
Water has a special structure due to which it takes the form of a liquid. It can pour, flow and drip. Crystals of solids have a strictly ordered structure. In gaseous substances, the structure is expressed as complete chaos. Water is an intermediate structure between a gaseous substance. The particles in the structure of water are located at short distances from each other and are relatively ordered. But as the particles move away from each other over time, the order of the structure quickly disappears.
The forces of interatomic and intermolecular influence determine the average distance between particles. Water molecules are made up of oxygen and hydrogen atoms, where the oxygen atoms of one molecule are attracted to the hydrogen atoms of another molecule. Hydrogen bonds are formed, which gives water certain fluidity properties, while the structure of the water itself is almost identical to the structure of the crystal. With the help of numerous experiments, water itself sets its own structure in a free volume.
When water combines with solid surfaces, the structure of the water begins to combine with the structure of the surface. Since the structure of the adjacent layer of water remains unchanged, its physical properties begin to change. The viscosity of water changes. It becomes possible to dissolve substances with a certain structure and properties. Water is initially a clear, colorless liquid. The physical properties of water can be called anomalous, since it has a fairly high boiling and freezing point.
Water has surface tension. For example, it has abnormally high freezing and boiling points, as well as surface tension. The specific evaporation and melting rates of water are significantly higher than those of any other substances. The amazing feature is that the density of water is higher than the density of ice, which allows ice to float on the surface of water. All these wonderful properties of water as a liquid are again explained by the existence in it of those hydrogen bonds by which molecules are connected.
The structure of a water molecule of three atoms in the geometric projection of a tetrahedron leads to the emergence of a very strong mutual attraction of water molecules to each other. It's all about the hydrogen bonds of molecules, because each molecule can form four absolutely identical hydrogen bonds with other water molecules. This fact explains that water is liquid.
It's no secret that fresh water
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 layer of water evaporates from the surface of our planet every 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 the particles, break away from the surface.
Despite the fact that the process of evaporation is better known as the transition of a liquid substance into vapor, there is dry evaporation, when at sub-zero temperatures ice passes from a solid state to a vapor state, bypassing the liquid phase.
For example, if you hang wet laundry to dry in the cold, it freezes and becomes very hard, but after some time it softens and becomes dry.
The molecules of the liquid are located almost right next to each other, and, despite the fact that they are connected by forces of attraction, they are not tied to certain points, and therefore move freely throughout the entire area of the substance (they constantly collide with each other and change their speed).
Particles that go to the surface gain momentum 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, some of the molecules return to the liquid due to chaotic movement, while the rest go further into the atmosphere.
Evaporation does not end there, and further 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, we can observe the process of condensation when steam, having concentrated, returns back under certain conditions. Thus, evaporation and condensation in nature are closely related to each other, since thanks to them there is a constant exchange of water between the earth, land and the atmosphere, due to which the environment is supplied with a huge amount of useful substances.
It is worth noting that the intensity of evaporation for each substance is different, and therefore the main physical characteristics that affect the rate of evaporation are:
- Density. The denser the substance, the closer the molecules are 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 occurs more slowly. For example, methyl alcohol evaporates much faster than water (methyl alcohol - 0.79 g/cm3, water - 0.99 g/cm3).
- 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, the higher the temperature of the substance, the higher the heat of evaporation, which means the faster the particles move, which, increasing the intensity of evaporation, leave the liquid en masse (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 decreases during evaporation. If at this time the liquid is near a heat source or directly heated, its temperature will not decrease, just as the intensity of evaporation will not decrease.
- Surface area. The larger the surface area a liquid occupies, the more molecules evaporate from it, the higher the evaporation rate. For example, if you pour water into a jug with a narrow neck, the liquid will disappear very slowly as the evaporated particles begin to settle on the narrowing 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 there will be nothing for them to condense on in order to return to the water.
- Wind. The evaporation process will be much faster if air moves above the container in which the water is located. The faster he does this, the greater 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 drives to land, where drops fall in the form of rain and penetrate 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 is difficult to overestimate, especially considering that a living plant consists of eighty percent water. Therefore, if a plant does not have enough moisture, it may die, since the nutrients and microelements necessary for life will not be supplied to it along with water.
Water, moving through the plant body, transports and forms organic substances inside it, for the formation of which the plant needs sunlight.
But here evaporation plays an important role, since the sun’s rays have the ability to heat objects extremely strongly, and therefore can cause the death of a plant from overheating (especially on hot summer days). To avoid this, water evaporates from the leaves, through which a lot of liquid is released at this time (for example, from one to four glasses of water evaporate from corn per day).
This means that the more water enters the plant’s body, the more intense the evaporation of water by the leaves will be, the plant will cool more and grow normally. You can feel the evaporation of water by plants if you touch the green leaves while walking on a hot day: they will definitely be cool.
Connection with a person
The role of evaporation in the life of the human body is no less important: it fights heat through sweating. Evaporation usually occurs through the skin, as well as through the respiratory tract. This can be easily noticed during illness, when the body temperature rises, or during sports, when the rate of evaporation increases.
If the load is small, the body leaves from one to two liters of fluid per hour, with more intense sports, especially when the external temperature exceeds 25 degrees, the intensity of evaporation increases and from three to six liters of fluid can come out with sweat.
Through the skin and respiratory tract, water not only leaves the body, but also enters it along with environmental evaporations (it’s not for nothing that doctors often prescribe seaside holidays to their patients). Unfortunately, along with useful elements, it often contains harmful particles, including chemicals and harmful fumes, which 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 system and skin, after which, once inside, they are instantly absorbed into the blood and spread throughout the body, causing toxic effects and causing serious illnesses.
In this case, a lot depends on the area where the person lives (near a factory or plant), the premises in which he lives or works, as well as the time spent in conditions hazardous to health. Harmful fumes can enter the body from household items, for example, linoleum, furniture, windows, etc.