Chemical structure of water. Characteristics of the main liquid on Earth: physical and chemical properties of water

Content: It is necessary to distinguish between, on the one hand, water and, on the other, the substances dissolved in it that determine the chemical composition and mineralization of water. The geological fates of the solvent and the dissolved substance can follow their own, separate paths. Water most often enters the earth's crust and from the atmosphere, and the dissolved substance is borrowed mainly from rocks and soils. Let's take water in its pure form, without salts, and consider those structural features and properties on which the dissolving ability of water depends.

Composition of water. Water - a chemical compound of oxygen and hydrogen, which is usually denoted by the formula H 2 O. In fact, water has a more complex composition. The usual molecular weight of water is 18, but there are molecules with molecular weights of 19, 20, 21, 22. These molecules consist of heavier hydrogen and oxygen atoms, having atomic weights greater than 1 and 16, respectively. Hydrogen has two stable isotopes: protium (H) and deuterium (D); ratio H: D =6800. In addition, tritium (T) is known, a radioactive isotope with a half-life of 12.5 years. Oxygen has three stable isotopes: O 16, O 17, O 18. Water molecules can consist of various stable isotopes H 2 O 16, HDO 16, D 2 O 16, H 2 O 18, HDO 18, D 2 O 18, H 2 О 17, НDO 18, D 2 О 17.

The isotopic variety of water in which protium is replaced by deuterium is called heavy water. However, neither light nor heavy water has yet been discovered in nature. Heavy water is currently prepared artificially in large quantities for various technical purposes. Heavy water differs from ordinary water not only in its physical properties, but also in its physiological effects on the body.

Deuterium (D) is of particular geochemical and practical interest. The electron shell of the deuterium atom, like protium, consists of one electron, but its nucleus - deuteron - is approximately twice as heavy and consists of two particles - a proton and a neutron. Deuterium is used in modern nuclear technology as an explosive. In the future, it will be used as fuel in thermonuclear power plants. The reserves of deuterium thermonuclear energy present in the water of the earth's oceans are approximately one hundred million greater than the energy reserves of fossil fuels (coal, oil, gas, peat).

Natural waters of different genesis have different isotopic compositions. One of the main reasons creating differentiation of isotopes in natural waters is the process of evaporation The vapor pressure of heavy water is somewhat lower than the vapor pressure of ordinary water, and since the evaporation process is the main factor in the water cycle, the enrichment of water with heavy isotopes in places of evaporation and depletion in them in places of condensation can cause a noticeable difference in the density of water.

The following pattern of distribution of hydrogen isotopes in surface and atmospheric waters has been established:

1. Fresh surface waters of rivers, lakes and other bodies of water, filled mainly by atmospheric precipitation, contain less deuterium than ocean waters.

2 The isotopic composition of fresh surface waters is determined by the physical and geographical conditions of their location.

The structure of water. Back in the twenties of our century, based on the doctrine of the polar structure of water molecules, the simplest ideas about the association of molecules in liquid water as a result of the interaction of dipoles were developed. These ideas are as follows.

One of the structural features of the water molecule is the asymmetrical arrangement of hydrogen atoms around the oxygen atom; they are not located in a straight line drawn through the center of the oxygen atom, but at a certain angle (Figure 1). The centers of the nuclei of hydrogen atoms are located at a distance of 0.95 A from the center of the oxygen atom. The angle between the lines connecting the centers of oxygen and hydrogen atoms is 105 0. The connection between oxygen and hydrogen atoms in a water molecule is carried out by electrons. Due to the asymmetry of the distribution of electrical charges, the water molecule has polarity, i.e. has two poles - positive and negative, which, like a magnet, create force zeros around it.

Thus, water molecules are characterized by a dipole structure (dipoles). They are depicted as ovals, the poles of which have electrical charges of opposite sign. When sufficiently close, water molecules begin to act on each other with their force fields . In this case, the positively charged pole of one molecule attracts the negatively charged pole of another. As a result, aggregates of two, three, and, apparently, more molecules can be obtained (Fig. 2).

Such groups of water molecules are called dihydrols (H 2 O) 2 and trihydrols (H 2 O). Consequently, single (monohydrols), double and triple molecules are simultaneously present in water . Their content varies depending on temperature. Ice is dominated by ternary molecules with the largest volume. As the temperature increases, the speed of the molecules increases, and the forces of attraction between the molecules are insufficient to keep them near each other . In the liquid state, water is a mixture of dihydrols, trihydrols and monohydrols. As the temperature increases, triple and double molecules disintegrate, and at 10°C water consists mainly of monohydrols.

Chemically pure water has a number of properties that sharply distinguish it from other natural bodies.

1. When water is heated from 0 to 4°C, the volume of water does not increase, but decreases, and its maximum density is achieved not at the freezing point (0 0 C), but at 4 0 C (more precisely, 3.98 0).

2. When water freezes, it expands and does not contract, like all other bodies, its density decreases.

3. The freezing point of water decreases with increasing pressure, and does not increase, as one would expect.

4. The specific heat capacity of water is extremely high compared to the heat capacity of other bodies.

5. Due to its high dielectric constant, water has a greater dissolving and dissociating ability than other liquids.

6. Water has the highest surface tension of all liquids - 75 erg/cm2 (glycerol - 65, ammonia - 42, and all others are below 30 erg/cm2), with the exception of mercury - 436 erg/cm 2.

Surface tension and density determine the height to which a liquid can rise in a capillary system when filtered through porous media.

The reason for the listed anomalous properties of water lies in the structural features of its molecules.

Water as a solvent. If you place water in an external electric field, then its iodine molecules, under the influence of the field, tend to arrange themselves in space as shown in

This phenomenon is called orientational polarization, which is characteristic of substances with polar molecules. The high polarity of water molecules is one of the most important reasons for its high activity in many chemical interactions. It also causes electrolytic dissociation in water, salts, acids and bases. It is also related to the solubility of electrolytes in water.

Dissolution is not only a physical, but also a chemical process. Solutions are formed by the interaction of solute particles with solvent particles. Water has the ability to dissolve many substances, that is, to produce homogeneous physicochemical systems of variable composition (solutions) with them. Dissolved in natural waters, salts are found: mainly in a dissociated state, in the form of ions. In the solid crystalline state, ionic compounds consist of regularly arranged positive and negative ions. In this case there are no molecules. Thus, for example, in halite, as determined by X-ray structural analysis, each Na + ion is surrounded by six C1 - ions, and each non-C1 - ion is surrounded by six sodium ions. Ions interact with each other, they attract each other (ionic bond).

What is the dissolution mechanism? Water molecules, due to the peculiarities of their structure and the force field that arises around them because of this, have the ability to attract molecules of other substances . The dissolution process consists precisely in the interaction of particles of the dissolved substance with particles of water. When any salt comes into contact with water, the nones that form its crystal lattice will be attracted by the oppositely charged particles of water molecules. For example, when halite crystals are immersed in water, the sodium ion (cation) will be attracted by the negative pole, and the chlorine ion (anion) will be attracted by the positive pole of the water molecule (Fig. 4 ). In order for the ions of the crystal lattice to break away from each other and go into solution, it is necessary to overcome the force of attraction of this lattice. When dissolving salts, this force is the attraction of lattice ions by water molecules, characterized by the so-called hydration energy. If the hydration energy is sufficiently high compared to the energy of the crystal lattice, the ions will be torn off from the latter and go into solution.

Depending on the nature of the substance, when it dissolves, heat is usually released or absorbed. The ions of the dissolved substance attract and hold around themselves a certain number of water molecules, which form a shell called a hydrocarbon shell. Thus, in an aqueous solution, the ions are hydrated, i.e. chemically bonded to water molecules

During the crystallization of many salts, part of the hydration water is captured in the crystal lattices. Similar crystallization water contains gypsum CaSO 4 *2H 2 O, mirabilite Na 2 SO 4 * 10H 2 O, bischofite MgCl 2 *6H 2 O, astrakhanite Na 2 SO 4 *MgSO 4 *4H 2 O, soda Na 2 CO 3 *10H2O . Crystalline substances containing water molecules are called crystalline hydrates.

Strong electrolytes, when dissolved in water, completely dissociate into ions. These include almost all salts, many mineral acids, bases of alkali and alkaline earth metals. The dissociation of a strong electrolyte, for example NaCl, is represented by the equation

NaС1 Na + +С1 -

There are no NaCl molecules in a halite crystal. When dissolved, the crystal structure is destroyed and hydrated ions pass into solution. There are no molecules in the solution. Therefore, we can only conditionally talk about undissociated molecules of solutions of strong electrolytes. These will most likely be ion pairs (Na + +C1 -), i.e.

Oppositely charged ions located close to each other (approached to a distance equal to the sum of the ion radii). These are supposedly undissociated molecules, or, as they are called, quasi-molecules.

Weak electrolytes, when dissolved in water, only partially dissociate into ions. These include almost all organic acids, some mineral acids, for example H 2 CO, H 2 S, H 2 SiO 3, and many metal bases. Water is a weak electrolyte.

In addition to electrolytes, the solution also contains non-electrolytes, the molecules of which, although they have a hydration shell, are “so strong that they do not disintegrate into ions (O 2, N 2).

Depending on the size of the particles of the dissolved substance, true and colloidal solutions are distinguished. Solutions are called true when the dissolved substance is in an ionized state. According to the principle of electrical neutrality, an ionic solution always contains equal amounts of equivalent cations and anions. Under natural conditions, ionic solutions are formed by dissolving simple salts.

Colloidal solutions are those in which the substance is not in an ionized state, but in the form of groups of molecules, the so-called “colloidal particles”. The sizes of particles in colloidal solutions range approximately from 10 to 2000 A. In stable colloidal solutions, particles in most cases carry electrical charges of different magnitudes, but the same in sign for all particles of a given colloidal system. Colloidal solutions are called sols. Sols are capable of turning into gels, i.e. turn into gelatinous masses as a result of the enlargement of colloidal particles (coagulation process).

In nature, colloidal solutions can be organic and inorganic. The latter are formed mainly during the hydrolytic breakdown of various silicates. During hydrolysis, silicates release the bases they contain (alkali and alkaline earth metals), giving rise to true solutions. But, in addition, during hydrolysis, silicon, iron, aluminum and other metals pass into solution, forming, for the most part, colloidal solutions.

Many substances react with water in an exchange decomposition reaction called hydrolysis. During hydrolysis, a shift in the dissociation equilibrium of water H O H + OH occurs due to the binding of one of its ions by ions of the dissolved substance with the formation of a slightly dissociated or sparingly soluble product. Consequently, hydrolysis is the chemical interaction of dissolved salt ions with water, accompanied by a change in the reaction of the medium. Due to the reversibility of hydrolysis, the equilibrium of this process depends on all those factors that generally affect the equilibrium of ion exchange. In particular, it strongly (sometimes almost completely) shifts towards the decomposition of salt if the products of the latter (most often in the form of basic salts) are poorly soluble.

In nature, the phenomenon of hydrolysis plays an important role. For example, the main chemical form of weathering of magmatic minerals is hydrolysis.

Solubility of salts. Solid, liquid and gaseous substances can dissolve in water. Based on their solubility in water, all substances are divided into three groups: 1) highly soluble, 2) poorly soluble, and 3) practically insoluble. It must be emphasized that there are no absolutely insoluble substances.

Mineralization of natural waters is usually created by a few simple salts: chlorides, sulfides, bicarbonates of sodium, magnesium, calcium.

There are no NaCl molecules in a halite crystal. When dissolved, the crystalline structure is destroyed and hydrated ions pass into solution. There are no molecules in the solution. Therefore, we can only conditionally talk about undissociated molecules of solutions of strong electrolytes. These are ion pairs (Na + Cl), i.e. Oppositely charged ions located close to each other. These are not dissociated molecules, but quasi-molecules.

Weak electrolytes, when dissolved in water, partially dissociate into ions. These include almost all organic crystals, some mineral acids, for example H CO, H S, H SiO, and many metal bases. Water is a weak electrolyte.

In addition to electrolytes, the solution also contains non-electrolytes, the molecules of which, although they have a hydration shell, are so strong that they do not disintegrate into ions (O, N).

Depending on the size of the particles of the dissolved substance, true and colloidal solutions are distinguished. Solutions are called true when the dissolved substance is in an ionized state.

The solubility of solids in water depends not only on their chemical nature, but also on temperature, pressure and the presence of gases and impurities in it.

The solubility of sodium chloride changes little when the temperature increases from up to 60°C (the change in solubility is given in g per 100 mg of water). The solubility of sodium carbonate and sulfate increases greatly.

Temperature has a great influence on the solubility of silicic acid. In the silicic acid-water system studied in the range from 0 to 200°, the dependence of solubility on temperature is linear. Under normal conditions, the solubility of silicic acid is very low.

Among the salts that decrease their solubility with increasing temperature is Ca SO 4.

As is known, the solubility of a given salt decreases in the presence of another salt that has the same ion with it, and, conversely, increases if there are ions of different names in the solution. For example, the solubility limits of CaSO 4 in the presence of different salts vary greatly. If there is a large amount of sodium chloride in the solution (about 100 g/l), the solubility of CaSO 4 reaches 5-6 g/l

Of the major salts, carbonates of alkaline earths have the lowest solubility, but it increases several times if the water contains carbon dioxide (CO 2). Dissolution proceeds according to the following scheme:

CaCO 3 + H 2 O + CO 2 Ca(HCO 3) 2 Ca ++ +2HCO 3;

MgCO 3 + H 2 O + CO 2 Mg(HCO 3) 2 Mg ++ +2HCO 3.

These reactions are reversible and proceed until a certain equilibrium is reached. As a result of these reactions, calcium and magnesium bicarbonates appear in water. It should be noted that neither calcium bicarbonates nor magnesium bicarbonates exist in solid form. The mineralization of hydrocarbonate magnesium-calcium waters, widespread in nature, usually reaches 500-600 mg/l. In the presence of large quantities of CO 2, the solubility of Ca(HCO 3) 2 and Mg(HCO 3) 2 can exceed 1 g/l (carbon dioxide mineral waters).

With increasing temperature, the solubility of calcium and magnesium bicarbonates decreases greatly and at 100° drops to 0. At high temperatures, these salts decompose with the release of CO 2 and the precipitation of carbonates

Ca(HCO 3) 2 → CaCO 3+H 2 O+CO 2;

Mg(HCO 3) 2 → MgCO 3+H 2 O+CO 2;

It follows that calcium and magnesium hydrocarbonate waters cannot exist in deep conditions, and, therefore, thermal waters of this composition do not exist.

The enrichment of waters with salts is accomplished not only through simple dissolution. Natural solutions are also formed during the hydrolytic breakdown of certain minerals. Minerals that are insoluble directly in water, but can be hydrolytically broken down, include various silicates - aluminosilicates, ferrosilicates, etc., which make up 75% of all minerals in the earth's crust. Under the influence of water and carbon dioxide during weathering, silicates release base Na +, K +, Ca ++, Mg ++ into solution. These bases form, when combined with CO 2, carbon dioxide and bicarbonate salts or, under appropriate conditions, sulfate and chloride salts.

Main literature: OL 1.

additional literature: DL 5.7.

Control questions:

1. What are the natural main isotopes?

2. What are the special qualities of water?

3. How does the process of halite dissolution occur?

4. How are substances divided and called based on solubility?

Water can be in three states of aggregation - gaseous, liquid and solid. In each of these states, the structure of water is not the same. Depending on the composition of the substances in it, water acquires new properties. The solid state of water also comes in at least two types: crystalline - ice and non-crystalline - glassy, ​​amorphous (vitrification state). When flash freezing using, for example, liquid nitrogen, the molecules do not have time to form a crystal lattice, and the water acquires a solid glassy state. It is this property of water that allows living organisms, such as unicellular algae, leaves of moss Mnium, consisting of two layers of cells, to be frozen without damage. Freezing with the formation of crystalline water leads to cell damage.

The crystalline state of water is characterized by a wide variety of forms. It has long been noted that the crystalline structures of water resemble radiolaria, fern leaves, and cysts. On this occasion, A. A. Lyubishchev suggested that the laws of crystallization are somewhat similar to the laws of the formation of living structures.

Physical properties of water. Water is the most anomalous substance, although it is taken as the standard measure of density and volume for other substances.

Density. All substances increase in volume when heated, while decreasing their density. However, at a pressure of 0.1013 MPa (1 atm.) in water in the range from 0 to 4 0 C, as the temperature increases, the volume decreases and the maximum density is observed (at this temperature, 1 cm 3 of water has a mass of 1 g). When freezing, the volume of water sharply increases by 11%, and when ice melts at 0°C, it also decreases sharply. With increasing pressure, the freezing point of water decreases every 13.17 MPa (130 atm.) by 1 0 C. Therefore, at great depths at subzero temperatures, water in the ocean does not freeze. With an increase in temperature to 100 0 C, the density of liquid water decreases by 4% (at 4 ° C its density is 1).

Boiling and freezing (melting) points. At a pressure of 0.1013 MPa (1 atm.), the freezing and boiling points of water are at 0°C and 100°C, which sharply distinguishes H20 from hydrogen compounds with elements of group VI of the periodic system of Mendeleev. In the series H2Te, H2Se, H2S, etc. As the relative molecular weight increases, the boiling and freezing points of these substances increase. If this rule were followed, water would have to have a freezing point between - 90 and - 120 ° C, and a boiling point between 75 and 100 ° C. The boiling point of water increases with increasing pressure, and the freezing (melting) point decreases (Appendix 1).

Heat of fusion. The latent heat of fusion of ice is very high - about 335 J/g (for iron - 25, for sulfur - 40). This property is expressed, for example, in the fact that ice at normal pressure can have a temperature from - 1 to - 7 ° C. The latent heat of vaporization of water (2.3 kJ/g) is almost 7 times higher than the latent heat of fusion.

Heat capacity. The heat capacity of water (i.e., the amount of heat required to increase the temperature by 1 °C) is 5 to 30 times higher than that of other substances. Only hydrogen and ammonia have a higher heat capacity. In addition, only liquid water and mercury have specific heat capacity that decreases with increasing temperature from 0 to 35°C (then begins to increase). The specific heat capacity of water at 16°C is conventionally taken as unity, serving as a standard for other substances. Since the heat capacity of sand is 5 times less than that of liquid water, then with the same heating by the sun, the water in the reservoir heats up 5 times less than the sand on the shore, but retains heat the same times longer. The high heat capacity of water protects plants from a sharp increase in temperature at high air temperatures, and the high heat of vaporization is involved in thermoregulation in plants.

High melting and boiling points and high heat capacity indicate strong attraction between neighboring molecules, as a result of which liquid water has high internal cohesion.

Water as a solvent. The polarity of the water molecule determines its ability to dissolve substances better than other liquids. The dissolution of crystals of inorganic salts is carried out due to the hydration of their constituent ions. Organic substances, including carboxyl and hydroxyl, are highly soluble in water. Carbonyl and other groups with which water forms hydrogen bonds. (add. 1)

Water in a plant is found in both free and bound states (Appendix 2). Free water is mobile, it has almost all the physicochemical properties of pure water, and penetrates well through cell membranes. There are special membrane proteins that form channels inside the membrane that are permeable to water (aquaporins). Free water enters into various biochemical reactions, evaporates during transpiration, and freezes at low temperatures.

Bound water - has altered physical properties mainly as a result of interaction with non-aqueous components. Conventionally, bound water is taken as water that does not freeze when the temperature drops to - 10°C.

Bound water in plants is:

1) Osmotically bound

2) Colloid-bound

3) Capillary-connected

Osmotically bound water is bound with ions or low molecular weight substances. Water hydrates dissolved substances - ions, molecules. Water binds electrostatically and forms a monomolecular layer of primary hydration. Vacuolar sap contains sugars, organic acids and their salts, inorganic cations and anions. These substances retain water osmotically.

Colloidally bound water - includes water that is inside the colloidal system and water that is on the surface of colloids and between them, as well as immobilized water. Immobilization is the mechanical capture of water during conformational changes of macromolecules or their complexes, with water being enclosed in the confined space of the macromolecule. A significant amount of colloid-bound water is located on the surface of the cell wall fibrils, as well as in the biocolloids of the cytoplasm and the matrix of the membrane structures of the cell.

Water that hydrates colloidal particles (primarily proteins) is called colloidally bound, and solutes (mineral salts, sugars, organic acids, etc.) are called osmotically bound. Some researchers believe that all water in a cell is bound to one degree or another. Physiologists conventionally understand bound water as water that does not freeze when the temperature drops to -10 °C. It is important to note that any binding of water molecules (adding solutes, hydrophobic interactions, etc.) reduces their energy. This is what underlies the decrease in the water potential of the cell compared to pure water.

The water content in various plant organs varies within fairly wide limits. It varies depending on environmental conditions, age and type of plants. Thus, the water content in lettuce leaves is 93-95%, corn - 75-77%. The amount of water varies in different plant organs: sunflower leaves contain 80-83% water, stems - 87-89%, roots - 73-75%. The water content of 6-11% is typical mainly for air-dried seeds, in which vital processes are inhibited. Water is contained in living cells, dead xylem elements and intercellular spaces. In the intercellular spaces, water is in a vapor state. The main evaporative organs of the plant are the leaves. In this regard, it is natural that the largest amount of water fills the intercellular spaces of the leaves. In a liquid state, water is found in various parts of the cell: cell membrane, vacuole, protoplasm. Vacuoles are the most water-rich part of the cell, where its content reaches 98%. At the highest water content, the water content in the protoplasm is 95%. The lowest water content is characteristic of cell membranes. Quantitative determination of water content in cell membranes is difficult; it apparently ranges from 30 to 50%.

The forms of water in different parts of the plant cell are also different. The vacuolar cell sap is dominated by water retained by relatively low molecular weight compounds (osmotically bound) and free water. In the shell of a plant cell, water is bound mainly by high-polymer compounds (cellulose, hemicellulose, pectin substances), i.e. colloidally bound water. In the cytoplasm itself there is free water, colloidally and osmotically bound. Water located at a distance of up to 1 nm from the surface of the protein molecule is tightly bound and does not have a regular hexagonal structure (colloidally bound water). In addition, there is a certain amount of ions in the protoplasm, and, therefore, part of the water is osmotically bound.

The physiological significance of free and bound water is different. Most researchers believe that the intensity of physiological processes, including growth rates, depends primarily on the free water content. There is a direct correlation between the content of bound water and the resistance of plants against unfavorable external conditions. These physiological correlations are not always observed.

Water is a very complex and poorly understood system. The structure of water is dynamic. Weak hydrogen bonds combine into chains. In water, molecular associates easily form, disintegrate and transform into each other. At the same time, they are exposed to many factors that were not previously taken into account or studied by traditional science.

Memory of water

Water is a source of weak and ultra-weak electromagnetic radiation. This radiation of structured water is the least chaotic, which sometimes leads to the induction of a certain electromagnetic field. The field affects the structural and information characteristics of “living” biological objects, spreading the charge along the molecular chain of water dipoles.

Physical fields of various natures can act as information carriers. Scientists have found that the structure of water is capable of interacting at the information level using acoustic, electromagnetic and other fields with objects that have various natural properties.

The structure of water exposed to a magnetic field improves. It becomes more structured. The crystallization of dissolved substances in the liquid increases, adsorption processes become more intense, and the precipitation of impurities improves. Most likely, the healing biological effect that structured water has on the human body is due to the fact that the pumps of tissues and organs pass molecules of “living” water at a higher speed, because the structure of water, in this case, resembles the structure of the cell membrane itself, those. highly structured organelle.

In the water molecule, the main character is the oxygen atom.

Since hydrogen atoms noticeably repel each other, the angle between the chemical bonds (lines connecting the nuclei of atoms) hydrogen - oxygen is not straight (90°), but slightly larger - 104.5°.

The chemical bonds in a water molecule are polar, since oxygen attracts negatively charged electrons, and hydrogen attracts positively charged electrons. As a result, an excess negative charge accumulates near the oxygen atom, and a positive charge accumulates near the hydrogen atoms.

Therefore, the entire water molecule is a dipole, that is, a molecule with two opposite poles. The dipole structure of the water molecule largely determines its unusual properties.

A water molecule is diamagnetic.

If you connect the epicenters of positive and negative charges with straight lines, you get a three-dimensional geometric figure - a tetrahedron. This is the structure of the water molecule itself.

When the state of the water molecule changes, the length of the sides and the angle between them change in the tetrahedron.

For example, if a water molecule is in the vapor state, then the angle formed by its sides is 104°27". In the water state, the angle is 105°03". And in ice condition the angle is 109.5°.

Geometry and dimensions of the water molecule for various states
a - for the vapor state
b - for the lowest vibrational level
c - for a level close to the formation of an ice crystal, when the geometry of the water molecule corresponds to the geometry of two Egyptian triangles with an aspect ratio of 3: 4: 5
g - for ice condition.

If we divide these angles in half, we get the angles:
104°27": 2 = 52°13",
105°03": 2 = 52°31",
106°16": 2 = 53°08",
109.5°: 2 = 54°32".

This means that among the geometric patterns of water and ice molecules there is the famous Egyptian triangle, the construction of which is based on the relationships of the golden proportion - the lengths of the sides are in the ratio 3:4:5 with an angle of 53°08".

A water molecule acquires the golden ratio structure along the way when water turns into ice, and vice versa when ice melts. Obviously, melt water is valued for this condition, when its structure in construction has the proportions of the golden section.

Now it becomes clear that the famous Egyptian triangle with an aspect ratio of 3:4:5 was “taken” from one of the states of the water molecule. The very geometry of the water molecule is formed by two Egyptian right triangles, having a common leg equal to 3.

The water molecule, based on the golden ratio, is a physical manifestation of Divine Nature, which participates in the creation of life. That is why the earthly nature contains the harmony that is inherent in the entire cosmos.

And therefore, the ancient Egyptians deified the numbers 3, 4, 5, and considered the triangle itself sacred and tried to incorporate its properties, its harmony into any structure, houses, pyramids, and even in the marking of fields. By the way, Ukrainian huts were also built using the golden ratio.

In space, a water molecule occupies a certain volume and is covered with an electron shell in the form of a veil. If you imagine a hypothetical model of a molecule in a plane, it looks like the wings of a butterfly, like an X-shaped chromosome in which the life program of a living creature is written. And this is an indicative fact that water itself is an essential element of all living things.

If you imagine the appearance of a hypothetical model of a water molecule in volume, then it conveys the shape of a triangular pyramid, which has 4 faces, and each face has 3 edges. In geometry, a triangular pyramid is called a tetrahedron. This structure is characteristic of crystals.

Thus, the water molecule forms a strong angular structure, which it retains even when it is in the vapor state, on the verge of becoming ice, and when it turns into ice.

If the “skeleton” of a water molecule is so stable, then its energy “pyramid” - the tetrahedron - also stands unshakable.

Such structural properties of the water molecule under various conditions are explained by strong bonds between two hydrogen atoms and one oxygen atom. This bond is approximately 25 times stronger than the bond between neighboring water molecules. Therefore, it is easier to separate one water molecule from another, for example, by heating, than to destroy the water molecule itself.

Due to orientational, inductive, dispersion interactions (van der Waals forces) and hydrogen bonds between the hydrogen and oxygen atoms of neighboring molecules, water molecules are able to form as random associates, i.e. not having an ordered structure, and clusters are associates having a certain structure.

According to statistics, in ordinary water there are random associates - 60% (destructured water) and clusters - 40% (structured water).

As a result of research conducted by Russian scientist S.V. Zenin, stable, long-lived water clusters were discovered.

Zenin found that water molecules initially form a dodecahedron. Four dodecahedrons combine to form the main structural element of water - a cluster consisting of 57 water molecules.

In a cluster, dodecahedrons have common faces, and their centers form a regular tetrahedron. This is a volumetric compound of water molecules, including hexamers, which has positive and negative poles.

Hydrogen bridges allow water molecules to join together in a variety of ways. Due to this, there is an infinite variety of clusters in water.

Clusters can interact with each other due to free hydrogen bonds, which leads to the appearance of second-order structures in the form of hexahedrons. They consist of 912 water molecules, which are practically incapable of interaction. The lifetime of such a structure is very long.

This structure, similar to a small sharp ice crystal of 6 rhombic faces, was created by S.V. Zenin called it “the main structural element of water.” Numerous experiments have confirmed that there are myriads of such crystals in water.

These ice crystals hardly interact with each other, therefore they do not form more complex stable structures and easily slide their faces relative to each other, creating fluidity. In this sense, water resembles a supercooled solution that cannot crystallize.

The main substance that allows life to exist on the planet is water. It is necessary in any condition. The study of the properties of liquids led to the formation of an entire science - hydrology. The subject of study of most scientists is physical and chemical properties. They understand by these properties: critical temperatures, crystal lattice, impurities and other individual characteristics of a chemical compound.

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Water formula known to every schoolchild. These are three simple signs, but they are contained in 75% of the total mass of everything on the planet.

H2O- these are two atoms and one - . The structure of the molecule has an empirical form, which is why the properties of the liquid are so diverse, despite its simple composition. Each of the molecules is surrounded by neighbors. They are connected by one crystal lattice.

Simplicity of structure allows a liquid to exist in several states of aggregation. Not a single substance on the planet can boast of this. H2O is very mobile; in this property it is second only to air. Everyone is aware of the water cycle, that after it evaporates from the surface of the earth, rain or snow falls somewhere far away. Climate controlled precisely due to the properties of the liquid, which can give off heat, while itself practically does not change its temperature.

Physical properties

H2O and its properties depend on many key factors. The main ones:

• Crystal cell. The structure of water, or rather its crystal lattice, is determined by its state of aggregation. It has a loose but very strong structure. Snowflakes show a lattice in a solid state, but in the usual liquid state, water does not have a clear crystal structure, they are mobile and changeable.
• The structure of the molecule is a sphere. But the influence of gravity causes water to take the shape of the vessel in which it is located. In space it will be geometrically correct in shape.
• Water reacts with other substances, including those that have unshared electron pairs, including alcohol and ammonia.
• Has high heat capacity and thermal conductivity, heats up quickly and does not cool down for a long time.
• It has been known since school that the boiling point is 100 degrees Celsius. Crystals appear in the liquid when it drops to +4 degrees, but ice forms at an even greater decrease. The boiling point depends on the pressure under which H2O is placed. There is an experiment in which the temperature of a chemical compound reaches 300 degrees, and the liquid does not boil, but melts lead.
• Another important property is surface tension. The water formula allows it to be very durable. Scientists have found that to break it, a force with a mass of more than 100 tons will be required.

Interesting! H2O, purified from impurities (distilled), cannot conduct current. This property of hydrogen oxide appears only in the presence of salts dissolved in it.

Other Features

Ice is unique condition, which is characteristic of hydrogen oxide. It forms loose bonds that are easily deformed. In addition, the distance between particles increases significantly, making the density of ice much lower than liquid. This allows reservoirs not to freeze completely in winter, preserving life under a layer of ice. Glaciers are a large supply of fresh water.

Interesting! H2O has a unique condition called the triple point phenomenon. This is when she is in three of her states at once. This condition is possible only at a temperature of 0.01 degrees and a pressure of 610 Pa.

Chemical properties

Basic chemical properties:

• Water is divided according to hardness, from soft and medium to hard. This indicator depends on the content of magnesium and potassium salts in the solution. There are also those that are constantly in the liquid, and some can be gotten rid of by boiling.
• Oxidation and reduction. H2O affects processes studied in chemistry that occur with other substances: it dissolves some, and reacts with others. The outcome of any experiment depends on the correct choice of conditions under which it takes place.
• Influence on biochemical processes. Water the main part of any cell, in it, as in an environment, all reactions in the body occur.
• In a liquid state, it absorbs gases that are inactive. Their molecules are located between H2O molecules inside the cavities. This is how clathrates are formed.
• With the help of hydrogen oxide, new substances are formed that are not associated with the redox process. We are talking about alkalis, acids and bases.
• Another characteristic of water is its ability to form crystalline hydrates. Hydrogen oxide remains unchanged. Among the common hydrates, copper sulfate can be distinguished.
• If an electric current is passed through the connection, then the molecule can be broken down into gases.

Importance for a person

A very long time ago, people realized the invaluable importance of liquid for all living things and the planet as a whole. . Without her a person cannot live and weeks . What is the beneficial effect of this most common substance on Earth?

• The most important application is its presence in the body, in the cells where all the most important reactions take place.
• The formation of hydrogen bonds has a beneficial effect on living beings, because when the temperature changes, the liquid in the body does not freeze.
• People have long been using H2O for everyday needs, in addition to cooking, such as washing, cleaning, bathing.
• No industrial plant can operate without fluid.
• H2O – source of life and health, she is medicine.
• Plants use it at all stages of their development and life. With its help, they produce oxygen, a gas so necessary for the life of living beings.

In addition to the most obvious beneficial properties, there are many more.

The importance of water for humans

Critical temperature

H2O, like all substances, has a temperature, which called critical. The critical temperature of water is determined by the method of heating it. Up to 374 degrees Celsius, the liquid is called vapor; it can still turn back into its usual liquid state, at a certain pressure. When the temperature is above this critical point, then water, as a chemical element, turns into gas irrevocably.

Application in chemistry

H2O is of great interest to chemists due to its main property - the ability to dissolve. Scientists often use it to purify substances, thereby creating favorable conditions for conducting experiments. In many cases it provides an environment in which pilot testing can be carried out. In addition, H2O itself participates in chemical processes, influencing one or another chemical experiment. It combines with non-metallic and metallic substances.

Three states

Water appears to people in three states, called aggregates. These are liquid, ice and gas. The substance is the same in composition, but different in properties. U

The ability to reincarnate is a very important characteristic of water for the entire planet, thus its circulation occurs.

Comparing all three states, a person more often sees the chemical compound in liquid form. Water has no taste or smell, and what is felt in it is due to the presence of impurities, substances dissolved in it.

The main properties of water in a liquid state are: enormous power, which allows you to sharpen stones and destroy rocks, as well as the ability to take any shape.

When small particles freeze, they reduce their speed and increase their distance, so ice structure is porous and lower in density than liquid. Ice is used in refrigeration units for various household and industrial purposes. In nature, ice only causes destruction, falling in the form of hail or an avalanche.

Gas is another condition that is formed when the critical temperature of water is not reached. Usually at temperatures greater than 100 degrees, or evaporating from the surface. In nature, these are clouds, fogs and vapors. Artificial gas formation played a major role in technological progress in the 19th century, when steam engines were invented.

Amount of substance in nature

75% - such a figure will seem huge, but this is all the water on the planet, even that which is in different states of aggregation, in living beings and organic compounds. If we take into account only liquid, that is, water found in the seas and oceans, as well as solid water - in glaciers, then the percentage becomes 70.8%.

Percentage distribution something like this:

• seas and oceans – 74.8%
• H2O from fresh sources, distributed unevenly across the planet, is 3.4% in glaciers, and only 1.1% in lakes, swamps and rivers.
• Underground sources account for approximately 20.7% of the total.

Characteristics of heavy water

Natural substance - hydrogen occurs as three isotopes, oxygen also exists in the same number of forms. This makes it possible to isolate, in addition to ordinary drinking water, deuterium and tritium.

Deuterium has the most stable form, it is found in all natural sources, but in very small quantities. A liquid with this formula has a number of differences from a simple and light one. Thus, the formation of crystals in it begins already at a temperature of 3.82 degrees. But the boiling point is slightly higher - 101.42 degrees Celsius. It has a higher density and the ability to dissolve substances is significantly reduced. It is also designated by a different formula (D2O).

Living systems react such a chemical compound is bad. Only some types of bacteria were able to adapt to life in it. The fish did not survive such an experiment at all. In the human body, deuterium can remain for several weeks, and then is eliminated without causing harm.

Important! Drinking deuterium water is prohibited!

Unique properties of water. - Just.

Conclusion

Heavy water is widely used in the nuclear and nuclear industries, and ordinary water is used everywhere.