Anomalies in the properties of water. Open Library - open library of educational information
Water is the most amazing and most mysterious substance on Earth. It plays a crucial role in all life processes and phenomena occurring on our planet and beyond. That is why ancient philosophers considered water (hydor) as the most important component of matter.
Modern science has approved the role of water as a universal, planetary component that determines the structure and properties of countless objects of animate and inanimate nature.
The development of molecular and structural-chemical concepts made it possible to explain the exceptional ability of water molecules to form bonds with the molecules of almost all substances.
The role of bound water in the formation of the most important physical properties of hydrated organic and inorganic substances. Great and growing scientific interest is attracted by the problem biological role water.
The outer shell of our planet inhabited by living organisms - the biosphere is the receptacle of life on Earth. Its fundamental principle, its indispensable component is water. Water is both a building material that is used to create all living things, and the environment in which all life processes take place, and a solvent that removes harmful substances from the body, and a unique transport that supplies biological structures with everything necessary for the normal flow of the most complex processes in them. physical and chemical processes. And this comprehensive influence of water on any living structure can be not only positive, but also negative. Depending on its state, water can be both a creator of blooming life and its destroyer, a gravedigger - everything depends on its chemical and isotopic composition, structural, bioenergetic properties. It is no coincidence that Academician I. V. Petryanov said: "Water is a true miracle of nature!"
The anomalous properties of water were discovered by scientists as a result of long and laborious research. These properties are so familiar and natural in our everyday life that the average person is not even aware of their existence. At the same time, water, the eternal companion of life on Earth, is truly original and unique.
The anomalous properties of water indicate that the H 2 O molecules in water are quite strongly interconnected and form a characteristic molecular structure that resists any destructive influences, for example, thermal, mechanical, electrical. For this reason, for example, it takes a lot of heat to turn water into steam. This feature explains the relatively high specific heat of evaporation of water. It becomes clear that the structure of water, the characteristic bonds between water molecules, underlie the special properties of water. American scientists W. Latimer and W. Rodebush proposed in 1920 to call these special bonds hydrogen bonds, and since that time the idea of this type of bond between molecules has forever entered the theory chemical bond. Without going into details, we only note that the origin of the hydrogen bond is due to the quantum mechanical features of the interaction of the proton with atoms.
However, the presence of a hydrogen bond in water is only a necessary, but not a sufficient condition for explaining the unusual properties of water. The most important circumstance explaining the basic properties of water is the structure of liquid water as an integral system.
Rice. Hydrogen bond formation
As early as 1916, fundamentally new ideas about the structure of a liquid were developed. For the first time, using X-ray diffraction analysis, it was shown that a certain regularity of the arrangement of molecules is observed in liquids, or otherwise, a short-range order of the arrangement of molecules is observed. The first X-ray diffraction studies of water were carried out by Dutch scientists in 1922 by V. Keez and J. de Smedt. They showed that liquid water is characterized by an ordered arrangement of water molecules, i.e. water has a certain regular structure.
Indeed, the structure of water in a living organism in many respects resembles the structure of the crystal lattice of ice. And this is what explains now the unique properties of melt water, which retains the structure of ice for a long time. Melted water is much easier than usual to react with various substances, and the body does not need to spend additional energy on restructuring its structure.
Each water molecule in the crystal structure of ice participates in 4 hydrogen bonds directed to the vertices of the tetrahedron. In the center of this tetrahedron there is an oxygen atom, in two vertices there is a hydrogen atom, the electrons of which are involved in the formation of a covalent bond with oxygen. The two remaining vertices are occupied by pairs of valence electrons of oxygen, which do not participate in the formation of intramolecular bonds. When a proton of one molecule interacts with a pair of unshared oxygen electrons of another molecule, a hydrogen bond arises, which is less strong than an intramolecular bond, but powerful enough to hold adjacent water molecules nearby. Each molecule can simultaneously form four hydrogen bonds with other molecules at strictly defined angles equal to 109 ° 28 "directed to the vertices of the tetrahedron, which do not allow the formation of a dense structure during freezing (at the same time, in ice structures I, Ic, VII and VIII this tetrahedron is correct).
Rice. Crystal structure of ice
It is known that biological tissues are 70-90% water. This suggests that many physiological phenomena can reflect the molecular features not only of the solute, but equally of the solvent - water. Considerations of this kind, expressed by such prominent modern scientists as Szent-Györgyi, Polling, Klotz and others, have caused a new wave of heightened interest in questions of the structure and state of water in various systems.
The first theory about the structure of water was put forward by the English researchers J. Bernal and Fowler. They created the concept of the tetrahedral structure of water.
In the August 1933 issue of the newly created international journal of chemical physics "Journal of Chemical Physics" their classic work on the structure of the water molecule and its interaction with its own molecules and ions of various kinds was published.
Rice. Tetrahedral structure of water
In their scientific intuition, J. Bernal and R. Fowler relied on the extensive material of accumulated experimental and theoretical data in the field of studying the structure of the water molecule, the structure of ice, the structure of simple liquids, and on the data of X-ray diffraction analysis of water and aqueous solutions. First of all, they defined the role hydrogen bonds in water. It was known that there are covalent and hydrogen bonds in water. Covalent bonds do not break during phase transitions of water: water-steam-ice. Only electrolysis, heating water on iron, etc. breaks the covalent bonds of water. Hydrogen bonds are 24 times weaker than covalent bonds. When ice and snow melt, hydrogen bonds in the resulting water are partially preserved, in water vapor they are all broken.
Rice
. When ice melts, hydrogen atoms are periodically destroyed and formed again. Jump time is 10 -12
seconds.
Attempts to present water as an associated liquid with dense packing of water molecules, like balls of some container, did not correspond to elementary factual data. In this case, the specific gravity of water would have to be not 1 g/cm 3 , but more than 1.8 g/cm 3 .
The second important evidence in favor of the special structure of the water molecule was that, unlike other liquids, water - this was already known - had a strong electric moment, which constituted its dipole structure. Therefore, it was impossible to imagine the presence of a very strong electric moment of the water molecule in the symmetrical structure of two hydrogen atoms relative to the oxygen atom, arranging all the atoms included in it in a straight line, i.e. N-O-N.
Experimental data, as well as mathematical calculations, finally convinced British scientists that the water molecule is "one-sided" and has an "angular" design, and both hydrogen atoms must be shifted in one direction relative to the oxygen atom by an angle of 104.5 0:
Rice. on the right - The structure of the water molecule
That is why the Bernal-Fowler water model is three-structured, with several separate types of structures. According to this model, the structure of water is determined by the structure of its individual molecules.
Later, the idea was developed to consider liquid water as a pseudocrystal, according to which water in the liquid state is like a mixture of three components with different structures (the structure of ice, crystalline quartz, and the densely packed structure of ordinary water).
Water is an openwork pseudo-crystal in which individual tetrahedral H 2 O molecules are linked to each other by directional hydrogen bonds, forming hexagonal structures as in the structure of ice.
Rice. Water as a pseudo-crystal
Subsequently, the Bernal-Fowler water model was refined and revised. On its basis, more than 20 models of the structure of water have arisen, which can be divided into 5 groups; 1) continuous, 2) mixed models of water structure (two-three-structure), 3) models with filling voids, 4) cluster and 5) models of associates.
Continuous models of the structure of water postulate that water is a single tetrahedral network of hydrogen bonds between individual water molecules that bend as ice melts.
Rice. Continuous water model
Mixed models: water is a mixture of two or three structures, for example, single molecules, their associates of varying complexity - clusters.
Further improvement of this model led to the creation of a model with filling voids (including clathrate models) and cluster models. Moreover, clusters can contain more than a few hundred H 2 O molecules and, like shimmering clusters, continuously arise and collapse due to local density fluctuations.
The cluster model of water structure by A. Frank and V. Ven, improved by G. Nemethy-G, is widely known. Sheragoy (1962). According to this model, in liquid water, along with monomeric molecules, there are clusters, swarms of H 2 O molecules, united by hydrogen bonds with a lifetime of 10 -10 - 10 -11 sec. They are destroyed and recreated.
Almost all water cluster hypotheses are based on the fact that liquid water consists of a network of 4-fold bound H 2 O molecules and monomers that fill the space between clusters. On the boundary surfaces of the clusters there are 1, 2, or 3-fold linked molecules. This model is also called the "scintillating clusters" model. According to S. Zenin, clusters and associates are the basis of the structural memory of water - long-term (stable) and short-term (labile, unstable associates).
At present, a large number of hypotheses and models of the structure of water are known. Some researchers talk about the presence in water of 10 different water structures with unequal crystal lattices, different densities and melting points.
Professor I.Z. Fisher in 1961 introduced the concept that the structure of water depends on the time interval during which it is determined. He distinguished three types of water structure.
1. Instantaneous structure (measurement time t 2. The structure of water in the middle periods of time when t d< t >to. Structures 1 and 2 are common with the structure of ice. This structure exists longer than the oscillation time, but less than the diffusion time t d. 3. Structure typical for longer periods of time (>t d), when the H 2 O molecule moves over long distances. D. Ezenberg and V. Koutsman associated the names of these three structures of water with the types of movement of its molecules, they called the 1st structure the I-structure (from the English instantenous - instant), the 2nd - the V-structure (from the English vibrational - vibrational) , 3rd - D-structure (from the English diffusion - diffusion). An X-ray diffraction study of water crystals by Morgan and Warren showed that water has a structure similar to that of ice. In water, as well as in ice, each oxygen atom is surrounded, as in a tetrahedron, by other oxygen atoms. The distance between neighboring molecules is not the same. At 25°C, each water molecule in the framework has one neighbor at a distance of 2.77 Å and three - at a distance of 2.94 Å, on average - 2.90 Å. The average between the nearest neighbors of a water molecule is approximately 5.5% greater than that between ice molecules. The remaining molecules are located at distances intermediate between the first and second adjacent distances. The distance of 4.1 Å is the distance between the O-H atoms in the H 2 O molecule. According to modern concepts, such a structure is largely determined by hydrogen bonds, which, uniting each molecule with its four neighbors, form a very openwork "tridymite-like" structure with voids larger than the molecules themselves. The main difference between the structure of liquid water and ice is a more diffuse arrangement of atoms in the lattice, a violation of long-range order. Thermal vibrations lead to bending and breaking of hydrogen bonds. The water molecules that have left their equilibrium positions fall into the neighboring voids of the structure and linger there for some time, since the voids correspond to relative minima of the potential energy. This leads to an increase in the coordination number and to the formation of lattice defects, the presence of which determines the anomalous properties of water. The coordination number of molecules (the number of nearest neighbors) varies from 4.4 at 1.5°C to 4.9 at 83°C. The unit cell of water is tetrahedra containing four (simple tetrahedron) or five H 2 O molecules (body-centered tetrahedron) linked by hydrogen bonds. At the same time, each of the water molecules in simple tetrahedra retains the ability to form hydrogen bonds. Due to their simple tetrahedra can be combined with each other by vertices, edges or faces, forming various clusters with a complex structure, for example, in the form of a dodecahedron. Ri
With. Possible water clusters Combining with each other, clusters can form more complex structures: Rice.
More complex associates of water clusters Rice.
Formation of a stable water cluster from 20 individual water molecules (Figure below) Professor Martin Chaplin calculated and suggested a different model of water, which is based on the icosahedron. Rice.
Giant icosahedron of water PICTURES BELOW RIGHT According to this model, water consists of 1820 water molecules, which is twice as many as in the Zenin model. The giant icosahedron, in turn, consists of 13 smaller structural elements. Moreover, just like in Zenin, the structure of the giant associate is based on smaller formations. Thus, now it is an obvious fact that water associates arise in water, which carry a very large energy and information of an extremely high density. Water quanta" can interact with each other due to free hydrogen bonds sticking out from the vertices of the "quantum" with their faces. In this case, the formation of two types of second-order structures is possible. Their interaction with each other leads to the appearance of higher-order structures. The latter consist of 912 water molecules, which, according to Zenin's model, are practically incapable of interaction due to the formation of hydrogen bonds.This explains, for example, the high fluidity of a liquid consisting of huge polymers.Thus, the aqueous medium is like a hierarchically organized liquid crystal. A change in the position of one structural element in this crystal under the influence of any external factor or a change in the orientation of the surrounding elements under the influence of added substances provides, according to Zenin's hypothesis, a high sensitivity of the water information system. If the degree of perturbation of the structural elements is insufficient to restructure the entire structure of water in a given volume, then after the removal of the perturbation, the system returns to its original state in 30-40 minutes. If the recoding, i.e., the transition to a different mutual arrangement of the structural elements of water, turns out to be energetically favorable, then the coding effect of the substance that caused this rearrangement is reflected in the new state [Zenin, 1994]. Such a model allows Zenin to explain the "memory of water" and its information properties [Zenin, 1997]. In addition, the structured state of water turned out to be a sensitive sensor of various fields. S. Zenin believes that the brain, itself consisting of 90% of water, can, nevertheless, change its structure. Rice.
Separate water cluster (computer simulation) The cluster model of water explains many of its anomalous properties. The first anomalous property of water is boiling point and freezing point anomaly: If water - oxygen hydride - H 2 O would be a normal monomolecular compound, such, for example, as its counterparts in the sixth group of the Periodic Table of Elements D.I. Mendeleev sulfur hydride H 2 S, selenium hydride H 2 Se, tellurium hydride H 2 Te, then in the liquid state water would exist in the range from minus 90 0 С to minus 70 0 С. Rice.
Boiling and freezing point anomalies of water compared to other hydrogen compounds. With such properties of water, life on Earth would not exist. But fortunately for us, and for all living things in the world, water is anomalous. It does not recognize the periodic patterns characteristic of countless compounds on Earth and in space, but follows its own laws, not yet fully understood by science, which gave us wonderful world life. The "abnormal" melting and boiling points of water are far from the only anomaly of water. For the entire biosphere, an extremely important feature of water is its ability to increase, rather than decrease, its volume upon freezing, i.e. reduce density. This is the second anomaly of water, which is called density anomaly. G. Galileo was the first to pay attention to this special property of water. During the transition of any liquid (except gallium and bismuth) to a solid state, the molecules are arranged more closely, and the substance itself, decreasing in volume, becomes denser. Any liquid, but not water. Water is an exception here too. When cooled, water initially behaves like other liquids: gradually condensing, it reduces its volume. Such a phenomenon can be observed up to +4°С (more precisely, up to +3.98°С). It is at a temperature of +3.98°C that water has the highest density and the smallest volume. Further cooling of the water gradually leads not to a decrease, but to an increase in volume. The smoothness of this process is suddenly interrupted and at 0°C there is a sharp jump in the increase in volume by almost 10%! At that moment, the water turns into ice. The unique feature of the behavior of water during cooling and ice formation plays an extremely important role in nature and life. It is this feature of water that protects all water bodies of the earth - rivers, lakes, seas - from continuous freezing in winter, and thereby saves lives. Unlike fresh water, sea water behaves differently when cooled. It freezes not at 0°C, but at minus 1.8-2.1°C, depending on the concentration of salts dissolved in it. It has a maximum density not at + 4°C, but at -3.5°C. Thus, it turns into ice, without reaching the greatest density. If vertical mixing in fresh water stops when the entire mass of water is cooled to +4°C, then vertical circulation in sea water occurs even at temperatures below 0°C. The process of exchange between the upper and lower layers goes on continuously, creating favorable conditions for the development of animal and plant organisms. Especially favorable environment for the inhabitants of the seas and oceans are melt waters formed during the melting of glaciers and icebergs. In the vast expanses of the oceans, floating iceberg mountains are mostly hidden under water, but they can pose a serious danger to navigation. The tragedy of the century was called the death of the Titanic, which occurred as a result of a collision of a superliner with a huge iceberg on April 14, 1912. All thermodynamic properties of water differ markedly or sharply from other substances. The most important of them is specific heat anomaly. The anomalously high heat capacity of water makes the seas and oceans a giant regulator of the temperature of our planet, as a result of which there is no sharp temperature drop in winter and summer, day and night. Continents located near the seas and oceans have a mild climate, where temperature drops at different times of the year are insignificant. Powerful atmospheric currents containing a huge amount of heat absorbed in the process of vaporization, giant ocean currents play an exceptional role in creating weather on our planet. Heat capacity anomaly is as follows: When any substance is heated, the heat capacity invariably increases. Yes, any substance, but not water. Water is an exception, and here it does not miss the opportunity to be original: with an increase in temperature, the change in the heat capacity of water is anomalous; from 0 to 37°C it decreases and only from 37 to 100°C does the heat capacity increase all the time. Within temperatures close to 37°C, the heat capacity of water is minimal. It is these temperatures that are the area of temperatures of the human body, the area of our life. The physics of water in the temperature range of 35-41°C (the limits of possible, normally occurring physiological processes in the human body) states the probability of achieving a unique state of water, when the mass is quasi-crystalline www.aquaberd.nm.ru/data/books/voda-i-zdorovye.htm-ftn2 and bulk water are equal to each other and the ability of one structure to pass into another - variability - is maximum. This remarkable property of water predetermines the equal probability of the flow of reversible and irreversible bio chemical reactions in the human body and provides "easy management" of them. Others are well aware of the exceptional ability of water to dissolve any substance. And here the water shows anomalies unusual for a liquid, and first of all anomalies of the dielectric constant of water. This is due to the fact that its dielectric constant (or permittivity) is very large and amounts to 81, while for other liquids it does not exceed 10. In accordance with Coulomb's law, the force of interaction of two charged particles in water will be 81 times less, than, for example, in air, where this characteristic is equal to one. In this case, the strength of intramolecular bonds decreases by a factor of 81, and under the action of thermal motion, the molecules dissociate with the formation of ions. It should be noted that due to the exceptional ability to dissolve other substances, water is never perfectly pure. Another amazing anomaly of water should be mentioned - an exceptionally high surface tension. Of all known liquids, only mercury has a higher surface tension. This property is manifested in the fact that water always tends to reduce its surface. Uncompensated intermolecular forces of the outer (surface) layer of water, caused by quantum mechanical factors, create an external elastic film. Thanks to the film, many objects, being heavier than water, are not immersed in water. If, for example, a steel needle is carefully placed on the surface of water, the needle does not sink. But the specific gravity of steel is almost eight times that of water. Everyone knows the shape of a drop of water. The high surface tension allows water to be spherical in free fall. Surface tension and wetting are the basis of the special properties of water and aqueous solutions, called capillarity. Capillarity is of great importance for the life of the plant and animal world, the formation of structures of natural minerals and the fertility of the earth. In channels that are many times narrower than a human hair, water acquires amazing properties. It becomes more viscous, compacted by 1.5 times, and freezes at minus 80-70°C. Cause superanomalies of capillary water are intermolecular interactions, the secrets of which are still far from being disclosed. Scientists and experts know the so-called pore water. In the form of the thinnest film, it covers the surface of pores and microcavities of rocks and minerals. earth's crust and other objects of animate and inanimate nature. Associated by intermolecular forces with the surface of other bodies, this water, like capillary water, has a special structure. Thus, the anomalous and specific properties of water play a key role in its diverse interaction with living and inanimate nature. All these unusual features of the properties of water are so "successful" for all living things, which makes water an indispensable basis for the existence of life on Earth. K. x. n. O. V. Mosin Literary sources
Belaya M.L., Levadny V.G. Molecular structure of water. M.: Knowledge 1987. - 46 p. BernalJ.D.The geometry of structures made of water molecules. Advances in Chemistry, 1956, vol. 25, p. 643-660. Bulenkov N.A. On the possible role of hydration as a leading integration factor in the organization of biosystems at different levels of their hierarchy. Biophysics, 1991, vol. 36, v. 2, pp. 181-243. Zatsepina T.N. Properties and structure of water. M.: Moscow State University, 1974, - 280 p. Naberukhin Yu.I. Structural models of liquid. M.: Science. 1981 - 185 p. Water is an unusual substance that deserves detailed study. The Soviet academician I. V. Petryanov wrote a book about this amazing substance, The Most Unusual Substance in the World. What anomalies in the physical properties of water are of particular interest? Together we will look for the answer to this question. We rarely think about the meaning of the word "water". On our planet, more than 70% of the total area is occupied by rivers and lakes, seas and oceans, icebergs, glaciers, swamps, snow on mountain tops, as well as permafrost. Despite such a huge amount of water, only 1% is drinkable. The human body is 70-80% water. This substance ensures the flow of all vital processes, in particular, thanks to it, toxins are removed from it, cells are restored. The main function of water in a living cell is structural and energy, with a decrease in its quantitative content in the human body, its “drying out” occurs. There is no such system in a living organism that could function without H2O. Despite the anomalies of water, it is a standard for determining the amount of heat, mass, temperature, altitude. H2O is hydrogen oxide, which contains 11.19% hydrogen, 88.81% oxygen by mass. It is a colorless liquid that has neither smell nor taste. Water is a must technological processes in industry. For the first time this substance was synthesized at the end of the 18th century by G. Cavendish. The scientist exploded a mixture of oxygen and hydrogen with an electric arc. For the first time, G. Galileo analyzed the difference in the density of ice and water in 1612. In 1830, a steam engine was created by French scientists P. Dulong and D. Arago. This discovery made it possible to study the relationship between saturation vapor pressure and temperature. In 1910, the American scientist P. Bridgman and the German G. Tamman discovered several polymorphic modifications in ice at high pressure. In 1932, American scientists G. Urey and E. Washburn discovered heavy water. Anomalies in the physical properties of this substance were discovered due to the improvement of equipment and research methods. Pure water is a clear, colorless liquid. Its density when transformed into a liquid from solid increases, this manifests an anomaly in the properties of water. Heating it from 0 to 40 degrees leads to an increase in density. High heat capacity should be noted as an anomaly of water. The crystallization temperature is 0 degrees Celsius, and the boiling point is 100 degrees. The molecule of this inorganic compound has an angular structure. The nuclei that make up its composition form an isosceles triangle, at the base of which there are two protons, and the top is an oxygen atom. Scientists were able to identify about forty features characteristic of H2O. Water anomalies deserve close consideration and study. Scientists are trying to explain the causes of each factor, to give him a scientific explanation. The anomaly of water density lies in the fact that this substance has its maximum density value at +3.98°C. With subsequent cooling, transferring from a liquid to a solid state, a decrease in density is observed. For other compounds, the density in liquids decreases with decreasing temperature, since an increase in temperature contributes to an increase in the kinetic energy of molecules (their speed of movement increases), which leads to increased friability of the substance. Considering such anomalies of water, it should be noted that, with an increase in temperature, an increase in velocity is also characteristic of it, but the density decreases only at elevated temperature values. After the density of ice decreases, it will be on the surface of the water. This phenomenon can be explained by the fact that the molecules in the crystal have a regular structure, which has a spatial periodicity. If in ordinary compounds the molecules are tightly packed in crystals, then after the substance melts, the regularity disappears. A similar phenomenon is observed only when the molecules are located at considerable distances. The decrease in density during the melting of metals is a negligible value, estimated at 2-4%. The density of water exceeds that of ice by 10 percent. Thus, this is a manifestation of the water anomaly. Chemistry explains this phenomenon with a dipole structure, as well as a covalent polar bond. Let's continue talking about the features of water. It is characterized by unusual temperature behavior. Its compressibility, that is, the decrease in volume, as the pressure increases, may well be considered an example of an anomaly in the physical properties of water. What specific features should be noted here? Other liquids are much easier to compress under pressure, and water acquires such characteristics only when high temperatures. This anomaly is one of the strongest for water. Heat capacity tells you how much heat is needed to raise the temperature by 1 degree. For many substances, after melting, the heat capacity of the liquid increases by no more than 10 percent. And for water after the melting of ice, this physical quantity increases twice. None of the substances showed such an increase in heat capacity. In ice, the energy that is supplied to it for heating is spent for the most part on an increase in the speed of movement of molecules (kinetic energy). A significant increase in heat capacity after melting indicates that other energy-intensive processes occur in water, which require heat input. They are the reason for the increased heat capacity. This phenomenon is typical for the entire temperature range in which water has a liquid state of aggregation. As soon as it turns into steam, the anomaly disappears. Currently, many scientists are engaged in the analysis of the properties of supercooled water. It lies in its ability to maintain a liquid state below the crystallization point of 0°C. It is quite possible to supercool water in thin capillaries, as well as in a non-polar medium as tiny droplets. A natural question arises as to what is observed with the density anomaly in such a situation. As the supercooling, the density of water decreases significantly, it tends to the density of ice when the temperature value decreases. When asked: "Name the anomalies of water and characterize their causes", it is necessary to associate them with the restructuring of the structure. The arrangement of particles in the structure of any substance is determined by the features relative position particles (atoms, ions, molecules) in it. Hydrogen forces act between water molecules, which remove this liquid from the dependence between boiling and melting points, which is characteristic of other substances that are in a liquid state of aggregation. They appear between the molecules of a given inorganic compound due to the peculiarities of the electron density distribution. Hydrogen atoms have a certain positive charge, while oxygen atoms have a negative one. As a result, the water molecule has the shape of a regular tetrahedron. Such a structure is characterized by a bond angle of 109.5°. The most favorable arrangement is the placement of oxygen and hydrogen in the same line, having a different charge, therefore, the hydrogen bond is characterized by an electrostatic nature. So, the unusual (anomalous) properties of water are a consequence of the special electronic structure of its molecule. There is an opinion that water has a memory, can accumulate and transfer energy, feeding the body with virtual information. For a long time, a Japanese scientist dealt with this problem. The results of his research, Dr. Emoto, published in the book “Messages of Water”. The scientists conducted experiments in which he first froze a drop of water at 5 degrees, and then analyzed the structure of the crystals under a microscope. To record the results, he used a microscope in which a camera was built. As part of the experiment, Masau Emoto affected water in various ways, then re-frozen it, and took photographs. He managed to get the relationship between the shape of ice crystals and the music that the water "listened to". Surprisingly, the scientist recorded the most harmonious snowflakes using classical and folk music. The use of modern music, according to Masau, "pollutes" the water, so he recorded irregularly shaped crystals. An interesting fact is the identification by Japanese scientists of the relationship between the shape of crystals and human energy. Water is the most amazing substance found in in large numbers on our planet. It is difficult to imagine any areas of activity modern man in which she would not take an active part. The versatility of this substance is determined by anomalies caused by the tetrahedral structure of water. People are accustomed to water and consider it an ordinary substance. They often take it for granted until a drought threatens crops and drinking water supplies, or a major flood threatens life and property. Many do not realize that the structure of water and its anomalous properties ensure the existence of life on Earth. One of the early Greek philosophers, Thales of Miletus (640-546 BC), explored the universal character of water. He considered it the main element from which everything is born. The abundance of water was obvious, but Thales noticed that it is the only substance naturally present on Earth at the same time in three different states: solid, liquid and gaseous. On a cold winter day, snow and ice cover the fields, a river flows nearby, and clouds float overhead. All substances exist in three different states, which depend on temperature and pressure. Solids have a definite shape and have a crystalline internal structure. By this definition, a substance like glass would be considered a highly viscous liquid because it does not have a crystalline structure. Solids tend to resist external influences. They can be converted to liquid by heating. The freezing point of water at a pressure of 1 atmosphere is 0 ° C, below which it exists in the form of ice. liquid, as opposed to solid body, does not have hardness and does not have a definite shape. It has volume, and it takes the form of the vessel in which it is stored. External influence forces it to flow. Water is a liquid between freezing and boiling points (100°C). Liquids can go into the gaseous phase when heated above the boiling point. A gas has neither a shape nor a definite volume. It takes the form and occupies the volume of the vessel in which it is located. A gas expands and contracts with changes in temperature and pressure and is able to easily diffuse into other gases. The anomalous properties of water are its unusually high boiling and freezing points compared to other compounds with a similar molecular structure. Other similar substances under normal conditions are gases. Water, with its lower molecular weight than similar compounds, is expected to have lower boiling and freezing points. However, due to the polar nature of its molecule and its hydrogen bonds, its boiling point is 100 °C and its freezing point is 0 °C. For comparison, the corresponding values for hydrogen sulfide H 2 S are -60 °C and -84 °C, for hydrogen selenide H 2 Se this figure is -42 °C and -64 °C and for hydrogen telluride -2 °C and -49 °C . As a rule, with decreasing temperature, substances become denser, and water is no exception. Its density at 25 °C is 0.997 g/mL and increases to a maximum (1 g/mL) at T = 4 °C. In the metric system, a kilogram is defined as the mass of 1 liter of water at its maximum density. Between 4 °C and the freezing point of 0 °C, an amazing thing happens, which is observed in a very small number of substances. Water gradually expands, becoming less dense. The density of ice at 0 °C is about 0.917 g/ml. Water molecules form crystals in the form of a tetrahedron (a four-sided figure, each face of which is an equilateral triangle). Since the density of the solid phase is less than that of the liquid phase, ice floats. When frozen, the volume of water increases by 1%. It is very important that the ice expands and floats on the surface. Because of this, water pipes burst in winter and potholes appear on the roads. The freezing and thawing of water is largely responsible for the destruction of rocks and the formation of soils. In addition, if lakes and streams were frozen from the bottom up, then aquatic life would cease to exist altogether, and climatic and weather conditions would change dramatically. Another anomalous property of water is its extremely high ability to absorb heat without a significant rise in temperature. For example, the summer sun on the beach heats up the sand to such an extent that it becomes impossible to walk on it. The water remains cold. Both substances absorb an equal amount of thermal energy, but the temperature of the sand is higher. An empty iron pot hanging over a fire will quickly become red-hot, but if it is filled with water, then its heating occurs gradually. The high heat capacity of water makes it a good coolant in condensers and car radiators, preventing engines from overheating. Its value is 5 times the heat capacity of sand and about 10 times that of iron. The temperate climate in the coastal regions is the result of the absorption of solar thermal energy during the day by water and its slow release at night. Inland areas away from the coast generally experience much higher extreme temperatures. The vast oceans on Earth (about 75% of the surface area) are responsible for moderating the climate on our planet, supporting the existence of life. The heat of the phase transition is related to the heat capacity. This is the amount of thermal energy absorbed or released by a substance that changes in phase (from liquid to solid or vice versa, and from liquid to gaseous or vice versa) without a change in temperature. Extraordinarily high values of the specific heat of fusion (332.4 kJ/kg) and evaporation (2256.2 kJ/kg) are another anomalous physical properties water. When freezing, the same amount of heat is released that is absorbed during the melting process. A practical example of using the specific heat of fusion of water is the use of ice to cool drinks in an insulated cooler. As the ice melts, it absorbs thermal energy drinks, keeping them cool. A container with water in a greenhouse in a cold winter night will soften the room temperature due to the heat released during freezing. The condensation of steam releases the same amount of heat that is absorbed during the evaporation process. The specific heat of evaporation is 5 times the heat required to raise the temperature from 0 to 100 °C. The anomalous property of water to store a large amount of stored thermal energy makes steam heating efficient. During the condensation process, the steam releases the stored thermal energy. An afternoon thunderstorm on a hot summer day is another example of the release of thermal energy in upper layers atmosphere when hot, humid air condenses. Even a hurricane is an example of the redistribution effect of the vast amount of thermal energy absorbed by the tropical oceans. Evaporative cooling systems work the other way around. Water in the process of evaporation absorbs heat energy from the air, cooling it. A solvent is capable of dissolving another substance to form a homogeneous mixture (solution) on molecular level. Another anomalous property of water in chemistry due to its polar nature is its ability to dissolve other polar compounds - salts, alcohols, carboxyl compounds, etc. More substances dissolve in water than in any other solvent. More than half of the known chemical elements can be found in it, some in high concentrations and others only in trace amounts. For example, the saturation concentration of sodium chloride is about 36 g per 100 ml, and calcium carbonate is about 0.0015 g. The ability of water to dissolve a substance depends on its chemical composition, the strength of chemical bonds of elements, temperature and pH. Non-polar compounds, including most hydrocarbons, dissolve in low or trace amounts. For example, oils tend to float on the surface of water. The anomalous properties of water include its highest (after mercury) surface tension compared to any other liquid. This is the force of attraction between molecules located below the surface and those located at the liquid-air interface. It keeps water from spreading. Polar compounds tend to have a much higher surface tension than non-polar ones. And water is no exception. At 20 °C, this indicator is 0.07286 N/m (for ethyl alcohol it is 0.0228 N/m). Without external influence, the H 2 O drop takes the form of a sphere, since this figure has the smallest surface area per unit volume. Raindrops are tiny bullets that, when exposed for a long time, shatter rocks. For the same reason, objects heavier than water can be held on its surface. Insects can walk on it, and a razor blade can swim. The hydrogen bond determines the anomalous property of water to wet most surfaces. Such substances are considered hydrophilic. Water is able to rise along the walls of a glass and other containers. Other substances such as oils, fats, waxes and synthetics (polypropylene, etc.) do not get wet. They are hydrophobic. Membrane filter cartridges with a pore size of less than 1 micron are made from hydrophobic polymers with the help of wetting agents that reduce the surface tension of water so that the latter can penetrate and remain in them. This phenomenon is called the capillary effect. It is responsible for the movement of water in the soil and through the roots of plants and blood through the blood vessels. H 2 O is an integral component of the existence of all living things. This explains the recent interest in finding water in other parts of the universe. All known biochemical processes occur in the aquatic environment. Most living things contain 70-80% H 2 O by weight. In addition, water plays a significant role in the process of photosynthesis. Plants use the radiant energy of the sun to transform water and carbon dioxide into carbohydrates: 6CO 2 + 6H 2 O + 672 kcal → C 6 H 12 O 6 + 6O 2. Photosynthesis is the most basic and important chemical reaction on Earth. He supplies nutrients, directly or indirectly, to all living organisms and is the main source of atmospheric oxygen. The ability of elements to form compounds depends on the ability of their atoms to donate or accept electrons. Elements of the first type become positively charged ions (cations), and the second - negatively charged anions. The ability of an element to interact with other elements to form compounds is called valence. It corresponds to the number of received or given electrons. For inorganic compounds, the algebraic sum of the valence numbers of elements is zero. The electrostatic attraction of oppositely charged ions to form a compound is called ionic bonding. The elements that form water (hydrogen and oxygen) exist separately in H 2 and O 2 molecules, each containing two atoms. They are held together by the exchange of an electron pair in a chemical bond called a covalent bond. It is much stronger than ionic. Two atoms held together by a covalent bond form a much more stable molecule than its constituent parts. In it, hydrogen is combined with oxygen through common electron pairs. This unique distribution of electrons in the formed chemical compound causes the H atoms to be located in relation to O at an angle of 104.5 °. The anomalous physical properties of water are explained by its structure and chemical bond. The oxygen atom has a relatively strong effect on the shared pair of electrons, causing the hydrogen atoms to become electropositive and the oxygen atom to become electronegative. Since the positively and negatively charged regions are unevenly distributed with respect to the central point, the water molecule is polar. This nature of it causes it to become electrostatically attractive to other H 2 O molecules, as well as ions and contact surfaces with charged sites. Electropositive hydrogen atoms are attracted to electronegative oxygen atoms of neighboring water molecules. This phenomenon is called hydrogen bonding. Its strength is only about 10% covalent, but it is responsible for most of the anomalous physical properties of water. These include high freezing and boiling points, heat capacity, specific heat of fusion and evaporation, solubility and surface tension. The hydrogen bond is responsible for maintaining the integrity of the H2O molecule during chemical reactions. While other compounds undergo ionization, water itself retains its chemical integrity. Only a relatively small number of molecules ionize into hydrogen and hydroxide ions. Therefore, H 2 O is a relatively poor conductor of electric current. The specific resistance of theoretically pure water is 18.3 MΩcm, while drinking water has a resistivity of less than 10,000 Ωcm. In this way, the purity of H 2 O can be easily checked. The anomalous properties of water are explained by the presence of hydrogen bonds, due to which there is a low density of ice. When freezing, molecules are located along them, which leads to the expansion of the substance. For this reason, ice floats on the surface of the water. Increased pressure lowers the melting point. The pressure generated by the skate blade melts the ice, creating a layer for graceful gliding. Even at extremely low temperatures, high pressure weakens the crystal lattice. This is the reason why huge ice masses, such as glaciers, gradually move. The polar nature of the water molecule causes it to orient itself in an electric or magnetic field. The electronegative oxygen atom lines up towards the positive pole, and the electropositive hydrogen atoms line up towards the negative pole. Water has an exceptionally large dipole moment, which is the product of the distance between charges multiplied by the magnitude of the charge. Dielectric constant is another property associated with dipole moment. Water molecules, by aligning themselves in an electric field, tend to neutralize it and create resistance to the transfer of an electrostatic charge. The permittivity of a substance is determined by ε in the equation F = Q1∙Q2/ε∙r 2 , where F is the force between two charges Q divided by the distance r in the medium. As the permittivity increases, the force between charges decreases. A high dielectric constant reduces the force of attraction of ions, which explains the anomalous chemical properties of water to dissolve a wide variety of substances. For humans, water is a common substance that is often taken for granted. Despite the fact that the anomalous properties of water are explained at the atomic level, its significance is indeed great. Obviously, it is necessary for the existence of life on Earth. The anomalous properties of water, in short, allow it to serve as a mediator of chemical and biochemical processes, shape our natural environment and participate in the creation of climate and weather. One of the explanations for the anomaly in water density is that it is attributed to a tendency for the association of its molecules, which form different groups [Н2О, (Н2О) 2, (Н2О) 3], the specific volume of which is different at different temperatures, the concentrations of these groups are also different, therefore, their total specific volume is also different. The first of these means that density anomalies due to movement do not create a heat flux through the lower ridge. At the upper boundary, the density is given, and on the shore (x 0), the normal component of the horizontal heat flux is assumed to be zero. The velocities and and and on the shore must vanish due to the impermeability and no-slip conditions. The hydrostatics approximation, however, simplifies the dynamics so much that the no-slip condition for and; cannot be fulfilled. Tertiary and secondary alcohols are characterized by an anomaly in vapor density at high temperatures (determination according to B. Tertiary alcohols (up to Cj2) give only half the molecular weight at the boiling point of naphthalene (218e), due to their decomposition into water and alkylenes; secondary alcohols (up to C9 ) exhibit the same anomaly, but. The positive sign of the work has to be attributed to the anomaly in the water density. If, as Grebe argues, the work of St. Clair Deville contributed, on the one hand, to the explanation of the observed anomalies in vapor densities and thereby, albeit indirectly, confirmed Avogadro's theory, then, on the other hand, On the other hand, these works served as a stimulus for the study of chemical affinity, since they contributed to the elucidation of the nature of certain reactions. For water, equation (64) gives correct results up to a temperature of 4, since it is known to have a density anomaly. At 4, the density of water is the highest; below 4, a complex density distribution is observed, which is not taken into account by this equation. By virtue of (8.3.56), the parameter X is a measure of the ratio (L / LH) 2 and the inequality (8.3.19 a) simply means that the density anomalies created by the pressure are mixed on a scale small compared to L. In the presence of the main stratification, the positive curl of the shear wind stress and the associated vertical movement in the inner region create a positive density anomaly in this entire region, to which is added the density anomaly due to the heat influx on the surface. If bonds within polyhedra are much stronger than between polyhedra, then only these latter will be disordered in the melt, so that units in the form of polyhedra will exist in the melt. Some density anomalies in liquid Al-Fe alloys seem to support this hypothesis. The problem formulation for the stability of such a ground state will be given for the case of a zonal flow in the atmosphere. The case of the ocean can be considered as a special case of the problem for the atmosphere in everything that concerns the formulation of the problem and is obtained by simply replacing the standard density profile ps (z) with a constant density value and replacing the atmospheric potential temperature anomaly in the ocean density anomaly taken with a minus sign. An increase in pressure shifts the maximum density of water towards lower temperatures. Thus, at 50 atm, the maximum density is observed near 0 C. Above 2000 atm, the water density anomaly disappears. Thus, in a wide temperature range, the most energetically stable compound of hydrogen and oxygen is water. It forms oceans, seas, ice, vapors and fog on Earth, is found in large quantities in the atmosphere, and in rock strata water is represented by capillary and crystalline hydrate forms. Such a prevalence and unusual properties (anomaly in the density of water and ice, the polarity of molecules, the ability to electrolytic dissociation, to form hydrates, solutions, etc.) make water an active chemical agent, in relation to which the properties of a large number of other compounds are usually considered. Liquids tend to expand noticeably when heated. For some substances (for example, water) there is a characteristic anomaly in the values of the isobaric expansion coefficient. At higher pressures, the maximum density (minimum specific volume) shifts towards lower temperatures, and at pressures above 23 MPa, the density anomaly near water disappears. This estimate is encouraging, since Ba is in good agreement with the observed thermocline depth, which varies from 800 m in the middle latitudes to 200 m in the tropical and polar zones. Since the depth 50 is much less than the depth of the ocean, it seems reasonable to consider the thermocline as a boundary layer; in accordance with this, when setting the boundary condition at the lower boundary, we can assume that the temperature at depths greater than BO tends asymptotically to some horizontally homogeneous distribution. Since the scale r is already equal to D, it is convenient to move the origin to the surface and measure r from the ocean surface. Thus, at z - - the density anomaly should decay and should tend to an as yet unknown asymptotic value, just as the vertical velocity created at the lower boundary of the Ekman layer cannot be given a priori. Permanent UE must be determined from the conditions on the hill. In the hydrostatic layer, due to the large density gradients created by the vertical movement (La S / E), the value of vc is much greater than vj. At the same time, v must satisfy the no-slip condition as f x 0. Vn are equal to zero and, consequently, to itself. This difficulty is resolved if we remember that in the inner region the vertical mixing of density counterbalances the effect of the vertical motion, while in the hydrostatic layer the density anomaly created by the vertical motion is balanced only by the effect of the horizontal mixing. Thus, there must be an intermediate region between the inner region and the hydrostatic layer, in which vertical and horizontal diffusion are equally important. As (8.3.20) shows, this area has a horizontal scale Lff, so that calculated with this scale A is equal to one. As you know, water, when heated from zero temperature, contracts, reaching the smallest volume and, accordingly, the highest density at a temperature of 4 C. Researchers from the University of Texas proposed an explanation that takes into account not only the interaction of the closest water molecules, but also more distant ones. In all 10 known forms of ice and in water, the interaction of the closest molecules occurs in the same way. The situation is different with the interaction of more distant molecules. In the liquid phase, in the temperature range where there is an anomaly in density, the state with a higher density is more stable. The curve of density versus temperature that the scientists calculated is similar to that observed for water. Pure water is clear and colorless. It has no smell or taste. The taste and smell of water is given by impurities dissolved in it. Many physical properties and the nature of their change in pure water are anomalous. This applies to the melting and boiling points, enthalpies and entropies of these processes. The temperature variation of water density is also anomalous. Water has a maximum density at 4 C. Above and below this temperature, the density of water decreases. During solidification, a further sharp decrease in density occurs, so the volume of ice is 10% larger than the volume of water equal in mass at the same temperature. All these anomalies are explained by structural changes in water associated with the formation and destruction of intermolecular hydrogen bonds with temperature changes and phase transitions. The anomaly of water density is of great importance for the life of living creatures inhabiting freezing water bodies. The surface layers of water at temperatures below 4 C do not sink to the bottom, because when cooled they become lighter. Therefore, the upper layers of water can solidify, while the temperature of 4 C remains in the depths of the reservoirs. Under these conditions, life continues. (characteristic of abnormally high information content of water) In the periodic table of elements D.I. Mendeleev oxygen forms a separate subgroup. Oxygen, sulfur, selenium and tellurium included in it have much in common in physical and chemical properties. The commonality of properties can be traced, as a rule, for the same type of compounds formed by members of the subgroup. However, water is characterized by a deviation from the rules. Of the lightest compounds of the oxygen subgroup (and they are hydrides), water is the lightest. The physical characteristics of hydrides, as well as other types of chemical compounds, are determined by the position in the table of elements of the corresponding subgroup. So, the lighter the element of the subgroup, the higher the volatility of its hydride. Therefore, in the oxygen subgroup, the volatility of water, oxygen hydride, should be the highest. The same property is very clearly manifested in the ability of water to "stick" to many objects, that is, to wet them. When studying this phenomenon, it was found that all substances that are easily wetted by water (clay, sand, glass, paper, etc.) certainly have oxygen atoms in their composition. To explain the nature of wetting, this fact turned out to be key: energetically unbalanced molecules of the surface layer of water get the opportunity to form additional hydrogen bonds with “foreign” oxygen atoms. Due to surface tension and wetting ability, water can rise in narrow vertical channels to a height greater than that allowed by gravity, that is, water has the property of capillarity. Capillarity plays an important role in many natural processes occurring on Earth. Due to this, water wets the soil layer, which lies much higher than the groundwater table, and delivers nutrient solutions to plant roots. Capillarity determines the movement of blood and tissue fluids in living organisms. But water is characterized by some features of its properties. For example, water has the highest characteristics that should have been the lowest: boiling and freezing points, heats of vaporization and melting. Boiling and freezing temperatures of hydrides of elements of the oxygen subgroup are graphically presented in fig. 1.7. The heaviest of the hydrides The associativity of water also affects the very high specific heat of its vaporization. To evaporate water already heated to 100°C, six times more heat is required than to heat the same mass of water by 80°C (from 20 to 100°C). Every minute, a million tons of hydrosphere water evaporates from solar heating. As a result, a colossal amount of heat constantly enters the atmosphere, equivalent to that which would be produced by 40,000 power plants with a capacity of 1 billion kilowatts each. When ice melts, a lot of energy is spent on overcoming the associative bonds of ice crystals, although six times less than when water evaporates. molecules The specific heat of melting of ice is higher than that of many substances, it is equivalent to the amount of heat consumed when 1 g of water is heated by 80°C (from 20 to 100°C). When water freezes, the corresponding amount of heat enters the environment, and when ice melts, it is absorbed. Therefore, ice masses, in contrast to the masses of vaporous water, are a kind of heat sinks in an environment with a positive temperature. Abnormally high values of the specific heat of vaporization of water and the specific heat of melting of ice are used by man in production activities. Knowledge natural features these physical characteristics sometimes prompt bold and effective technical solutions. Thus, water is widely used in production as a convenient and affordable coolant in a wide variety of technological processes. After use, water can be returned to a natural reservoir and replaced with a fresh portion, or it can be sent back to production, having previously been cooled in special devices - cooling towers. In many metallurgical industries, not cold water, but boiling water is used as a coolant. Cooling is due to the use of the heat of vaporization - the efficiency of the process increases several times, moreover, there is no need to build bulky cooling towers. Of course, boiling water-cooler is used where it is necessary to cool objects heated above 100°C. The widespread use of water as a coolant is explained not only and not so much by its availability and cheapness. The real reason must also be sought in its physical features. It turns out that water has another remarkable ability - high heat capacity. Absorbing a huge amount of heat, the water itself does not heat up significantly. The specific heat capacity of water is five times that of sand and nearly ten times that of iron. The ability of water to accumulate large reserves of thermal energy makes it possible to smooth out sharp temperature fluctuations on the earth's surface at different times of the year and in different time days. Due to this, water is the main regulator of the thermal regime of our planet. Interestingly, the heat capacity of water is anomalous not only in its value. The specific heat capacity is different at different temperatures, and the nature of the temperature change in the specific heat capacity is peculiar: it decreases as the temperature increases in the range from 0 to 37°C, and increases with a further increase in temperature. The minimum value of the specific heat capacity of water was found at a temperature of 36.79 ° C, which corresponds to the normal temperature human body. The normal temperature of almost all warm-blooded living organisms is also near this point. It turned out that at this temperature, microphase transformations are also carried out in the “liquid-crystal” system, that is, “water-ice”. It has been established that when the temperature changes from 0 to 100°C, water successively undergoes five such transformations. They called them microphase, since the length of the crystals is microscopic, no more than 0.2 ... 0.3 nm. The temperature limits of the transitions are 0, 15, 30, 45, 60, and 100°C. The temperature range of life of warm-blooded animals is within the boundaries of the third phase (30...45°C). Other types of organisms have adapted to other temperature ranges. For example, fish, insects, soil bacteria reproduce at temperatures close to the middle of the second phase (23...25°C), the effective temperature of spring awakening of seeds falls in the middle of the first phase (5...10°C). It is characteristic that the phenomenon of the passage of the specific heat capacity of water through a minimum with a temperature change has a peculiar symmetry: at negative temperatures, a minimum of this characteristic is also found. It falls at -20°C. If water below 0°C retains an unfrozen state, for example, being finely dispersed, then about -20°C its heat capacity increases sharply. This was established by American scientists, investigating the property of aqueous emulsions formed by water droplets with a diameter of about 5 microns.
According to the hypothesis of our scientist compatriot S.V. Zenin's water is a hierarchy of regular volumetric structures of "associates" (clathrates), which are based on a crystal-like "quantum of water", consisting of 57 of its molecules, which interact with each other due to free hydrogen bonds. At the same time, 57 water molecules (quanta) form a structure resembling a tetrahedron. The tetrahedron, in turn, consists of 4 dodecahedrons (regular 12-sided). 16 quanta form a structural element consisting of 912 water molecules. Water is 80% composed of such elements, 15% - quanta-tetrahedra and 3% - classical H 2 O molecules. Thus, the structure of water is associated with the so-called Platonic solids (tetrahedron, dodecahedron), the shape of which is associated with the golden ratio. The oxygen nucleus also has the form of a Platonic solid (tetrahedron).
Rice. Formation of the icosahedron of water
The ordinal number of such water structures is as high as the ordinal number of crystals (the structure with the highest ordering that we know), therefore they are also called "liquid crystals" or "crystal water". Such a structure is energetically favorable and is destroyed with the release of free water molecules only at high concentrations of alcohols and similar solvents [Zenin, 1994].
Rice.
Dependence of the specific volume of ice and water on temperature.Rice.
Temperature dependence of the specific heat capacity of water.
biological significance
Basic concepts
Some contradictions in physical properties
Density anomalies
Compressibility anomalies
Temperature behavior of heat capacity
Reasons for the appearance
"Memory" of water
Forms of matter
Boiling and freezing points
solid phase
Heat capacity
Heat of fusion and evaporation
Universal solvent
Surface tension
Anomalous properties of water and their significance for life
Anomalous properties of water and their causes
Dipole moment
Conclusion
Anomalies of physical and chemical properties water
they are negative: above 0°C this compound is gaseous. As we move to lighter hydrides ( 
,
) the boiling and freezing points are decreasing more and more. If this regularity continued, one would expect that water should boil at -70°C and freeze at -90°C. In this case, under terrestrial conditions, it could never exist in either solid or liquid states. The only possible would be a gaseous (vaporous) state. But on the plot of the dependence of critical temperatures for hydrides as a function of their molecular weight, there is an unexpectedly sharp rise - the boiling point of water is +100°C, the freezing point is 0°C. This is a clear advantage of associativity - a wide temperature range of existence, the ability to implement all phase states in the conditions of our planet.
actually remain in the same environment, only changes phase state water.
