Chemical and physical properties of water in a liquid state - terms, definitions and comments

All biochemical processes in humans are reduced to chemical reactions in aqueous solution. This is the metabolism in the body. In a liquid medium, food is digested and nutrients are absorbed into the blood, and harmful metabolites are removed from the body through water.

Water is the basis of our body. The cells of our body swim in the extracellular fluid like fish in an aquarium. A child in childhood is more saturated with water. In the biological sense, old age is the loss of moisture by cells and the depletion of water resources of the intercellular fluid. We "dry out", "get sour" and die. The greatest saturation of water in the brain, liver, parenchymal organs. Even bones are 20% water. Our arteries, veins, lymph nodes also move fluid. We are a system of communicating vessels, along which flows of various liquids interacting with each other are continuously moving.

Movement in the intercellular spaces does not stop for a second. All this is connected with the entry of nutrients into the cells through the intercellular fluid and the removal of waste products through the same spaces. These are like rivers that sometimes turn into standing swamps - and then there is stagnation and illness, and when the rivers accelerate, everything falls into place. We feel the state of these rivers through our well-being.

Water is an electrolyte. The parameters of our electrolyte are specific and are determined by minerals dissolved in water, which serve as carriers of electrical charges.

An adult consumes an average of 2.5 liters of water per day. Of this amount, 1.2 l is for drinking water, 1 l is for water that came from food, 0.3 l of water is formed in the body itself in the process of metabolism. The same amount of water is excreted from the body: 50% through the kidneys, 32% with sweat through the skin, 13% with exhaled air through the lungs, 5% through the intestines.

In nature, there are 48 varieties of water, each of which has its own form of liquid crystals. When water freezes under the influence of these crystals, all other water molecules turn into structured ice. It turns out that the structure of the cell's protoplasm and the structure of the ice are organized in a similar way. After the ice melts, the structure of the crystals is preserved, so the melt water is easily absorbed by the body. After water is heated to 42 ° C, the water loses its structure and becomes normal.

Water is inherent information memory. Each organism, including viruses and bacteria, has its own frequency of radiation. All these radiations are “recorded” on water molecules. The poisoned water "remembers" about all the poisonous processes, heavy metals, poisons, with which it had contact. If ingested such water sooner or later will cause a painful reaction.

It is very difficult to erase the previous information, but recently it became clear that the freezing process erases this information, and after thawing the water, it becomes clean in the information sense.

Ordinary water is biologically incompatible with the internal environment of the human body, therefore, for the use of such drinking water in metabolic processes, the body spends valuable energy of cell membranes to ensure biocompatibility. This energy can be saved by using water with certain properties.

To optimize biochemical processes in the human body, water must have the following qualities:

Water should be biologically accessible, easily digestible. The degree of surface tension should not be too large. For tap water, this figure is 73 dyn / cm while in intra- and extracellular water it is 43 dyn / cm. The cell requires a large amount of energy to overcome this surface tension.

Water should be of medium hardness. Very hard water, like very soft water, is equally unsuitable for cells.

Water should be neutral, and preferably slightly alkaline. Most body fluids have a slightly alkaline reaction.

The redox potential of water must correspond to the same potential of the extracellular fluid. In this case, the body will not need to spend energy on the alignment of potentials.

Water must be structured. All water in the body is structured. Structured water is found in intact fruits and vegetables.

Water should have as little negative information as possible. The transfer of such information to the cell violates its bio- and energy-information characteristics.

Water should be slightly mineralized to maintain the electrolyte composition of body fluids.

Consider how the properties of water change during its processing.

Boiling water - destroys bacteria, coagulates colloidal particles of dirt, water softens, volatile organic substances and part of free chlorine evaporate. The concentration of salts of heavy metals, pesticides, organic substances is increasing. Chlorine, associated with organic matter, when heated, turns into a strong poison - carcinogen-dioxin, belonging to the category of especially dangerous poisons. Dioxins are significantly more toxic than potassium cyanide. Thus, boiled water slowly kills us.

Settling water for 3 hours reduces the concentration of free chlorine, but does not remove iron ions, heavy metals, carcinogenic chlorine compounds, radionuclides and non-volatile organic substances.

Distillation of water deprives it of the necessary trace elements. The constant use of such water leads to disorders of the immune system, heart rate, digestive processes, and therefore distilled water is unsuitable for continuous use.

Strictly speaking, in this material we will briefly consider not only chemical and physical properties of water in a liquid state,but also properties inherent in it in general as such.

For more information on the properties of water in the solid state, you can find in the article.

As noted above, in this material we will list the basic physical and chemical properties of water and make brief comments on some of them.

Physical properties of water

PHYSICAL PROPERTIES - these are properties that manifest themselves outside chemical reactions.

Clean water

The purity of water depends on the presence of impurities, bacteria, salts of heavy metals in it ..., in order to get acquainted with the interpretation of the term PURE WATER according to the version of our site, it is necessary to read the article.

Water color

Water color - depends on chemical composition and mechanical impurities.

For example, we give the definition of “Colors of the Sea” given by the “Great Soviet Encyclopedia”.

The color of the sea. The color perceived by the eye when the observer looks at the surface of the sea, the color of the sea depends on the color of sea water, the color of the sky, the number and nature of clouds, the height of the sun above the horizon and other reasons.

The concept of the color of the sea should be distinguished from the concept of the color of sea water. Under the color of sea water understand the color perceived by the eye when sheer inspection of sea water over a white background. From the surface of the sea only a small part of the light rays incident on it is reflected, the rest of them penetrate deep into, where it is absorbed and scattered by water molecules, suspended particles and tiny bubbles of gases. The scattered rays reflecting and emerging from the sea create the central axis. The water molecules scatter most are the blue and green rays. Suspended particles scatter all rays almost equally. Therefore, sea water with a small amount of suspended matter seems to be blue-green (the color of the open parts of the oceans), and with a significant amount of suspended matter - yellowish-green (for example, the Baltic Sea). The theoretical side of the theory of the central metropolitan area was developed by V. V. Shuleikin and C. V. Raman.

Great Soviet Encyclopedia. - M .: Soviet encyclopedia. 1969-1978

Smell of water

Smell of water - clean water is usually odorless.

Water clarity

The transparency of water depends on the mineral substances dissolved in it and the content of mechanical impurities, organic substances and colloids:

TRANSPARENCY OF WATER - the ability of water to transmit light. Usually measured by a Secchi disc. It depends mainly on the concentration of suspended and dissolved in water, organic and inorganic substances. May decrease sharply as a result of anthropogenic pollution and eutrophication of water bodies.

Ecological encyclopedic dictionary. - Chisinau I.I. Dedu. 1989

TRANSPARENCY OF WATER - the ability of water to transmit light rays. It depends on the thickness of the water that the rays pass, the presence of suspended impurities, dissolved substances, etc. in it. The red and yellow rays are absorbed more strongly in the water, and violet penetrate deeper. According to the degree of transparency, in order to reduce it, water is distinguished:

transparent;

slightly opalescent;

opalescent;

slightly turbid;

muddy;

very muddy.

Dictionary of hydrogeology and engineering geology. - M .: Gostoptekhizdat. 1961

Taste of water

The taste of water depends on the composition of the substances dissolved in it.

Dictionary of hydrogeology and engineering geology

The taste of water is a property of water, depending on the salts and gases dissolved in it. There are tables of taste-tangible concentrations of salts dissolved in water (in mg / l), for example, the following table (according to Staff).

Water temperature

Water melting point:

MELTING TEMPERATURE - the temperature at which a substance transitions from a SOLID CONDITION to a liquid. The melting point of a solid is equal to the freezing point of a liquid, for example, the melting point of ice, O ° C, is equal to the freezing point of water.

Water boiling point : 99.974 ° C

Scientific and Technical Encyclopedic Dictionary

BOILING TEMPERATURE, the temperature at which a substance changes from one state (phase) to another, i.e. from liquid to vapor or gas. The boiling point increases with increasing external pressure and decreases with decreasing it. It is usually measured at a standard pressure of 1 atmosphere (760 mmHg). The boiling point of water at a standard pressure is 100 ° C.

Scientific and technical encyclopedic dictionary.

Triple point water

Triple water point: 0.01 ° C, 611.73 Pa;

Scientific and Technical Encyclopedic Dictionary

TRIPLE POINT, temperature and pressure at which all three states of matter (solid, liquid, gaseous) can exist simultaneously. For water, the triple point is at a temperature of 273.16 K and a pressure of 610 Pa.

Scientific and technical encyclopedic dictionary.

Water surface tension

Marine dictionary

WATER HARDNESS (Stiffness of Water) is a property of water, exsanguinated by the content of alkaline earth metal salts dissolved in it, ch. arr. calcium and magnesium (in the form of bicarbonate salts - bicarbonates), and salts of strong mineral acids - sulfuric and hydrochloric. Zh. V. is measured in special units, the so-called. degrees of rigidity. The degree of hardness is called the weight content of calcium oxide (CaO), equal to 0.01 g in 1 liter of water. Hard water is unsuitable for powering the boilers, as it contributes to the strong formation of scale on their walls, which can cause the boiler tubes to burn out. Boilers of high capacity and especially high pressures should be fed with completely purified water (condensate from steam engines and turbines, purified by means of filters from oil impurities, and also distillate prepared in special evaporator units).

Samoilov KI. Maritime Dictionary. - M.L.: State Naval Publishing House of the USSR NKVMF, 1941

Scientific and Technical Encyclopedic Dictionary

HARDNESS OF WATER, inability of water to form foam with soap due to dissolved salts, mainly calcium and magnesium.

Scale in boilers and pipes is formed due to the presence of dissolved calcium carbonate in water, which enters the water upon contact with limestone. In hot or boiling water, calcium carbonate enters the sediment in the form of solid calcareous deposits on the surfaces inside the boilers. Calcium carbonate also does not allow soap to foam. The ion exchange container (3) is filled with granules coated with sodium-containing materials. with whom water comes in contact. Sodium ions as more active, replace calcium ions. Since sodium salts remain soluble even when boiled, scale does not form.

Scientific and technical encyclopedic dictionary.

Water structure

Under the structure of water refers to a specific location of water molecules with respect to each other. This concept is actively used in theory.

Water salinity :

Ecological Encyclopedic Dictionary

WATER MINERALIZATION - Inorganic water saturation. (mineral) substances in it in the form of ions and colloids; the total amount of inorganic salts contained predominantly in fresh water, the degree of mineralization is usually expressed in mg / l or g / l (sometimes in g / kg).

Ecological encyclopedic dictionary. - Chisinau: The main editorial board of the Moldavian Soviet Encyclopedia. I.I. Dedu. 1989

Water viscosity - characterizes the internal resistance of fluid particles to its movement:

Geological dictionary

The viscosity of water (liquid) is a property of a fluid that causes the onset of frictional force during movement. It is a factor that transmits motion from water layers moving at high speed to the layers with lower speed. V. c. depends on the temperature and concentration of the solution. Physically, it is estimated coefficient. viscosity, which is included in a number of formulas for the movement of water.

Geological dictionary: in 2 volumes. - M .: Nedra. Edited by C. N. Paffenholz and others. 1978

There are two types of water viscosity:

The dynamic viscosity of water is 0.00101 Pa s (at 20 ° C).

The kinematic viscosity of water is 0.01012 cm 2 / s (at 20 ° C).

Water point

A critical point of water is its state at a certain ratio of pressure and temperature, when its properties are the same in the gaseous and liquid state (gaseous and liquid phase).

Critical point of water: 374 ° C, 22.064 MPa.

Water dielectric constant

The dielectric constant, in general, is a coefficient indicating how much the interaction force between two charges in a vacuum is greater than in a certain medium.

In the case of water, this indicator is unusually high and equals 81 for static electric fields.

Heat capacity of water - water has a surprisingly high heat capacity:

Ecological dictionary

Heat capacity is the property of substances to absorb heat. It is expressed in the amount of heat absorbed by the substance when it is heated by 1 ° C. The heat capacity of water is about 1 cal / g, or 4.2 J / g. The heat capacity of the soil (at 14.5-15.5 ° C) varies (from sandy to peaty soils) from 0.5 to 0.6 cal (or 2.1-2.5 J) per unit volume and from 0.2 up to 0.5 cal (or 0.8-2.1 J) per unit mass (g).

Ecological dictionary. - Alma-Ata: "Science". B.A. Bulls. 1983

Scientific and Technical Encyclopedic Dictionary

SPECIFIC HEAT CAPACITY (designation c), heat required to raise the temperature of 1 kg of a substance by 1K. Measured in j / ck (where j is joule). Substances with a high specific heat capacity, such as water, require more energy to raise the temperature than substances with a low specific heat capacity.

Scientific and technical encyclopedic dictionary.

The thermal conductivity of a substance implies its ability to conduct heat from its hotter parts to cooler parts.

Heat transfer in water occurs either at the molecular level, i.e. it is transmitted by water molecules, or due to the movement / movement of any volumes of water — turbulent thermal conductivity.

Water compressibility

Water compressibility is negligible.

The electrical conductivity of water largely depends on the amount of salts dissolved in them.

Water radioactivity

The radioactivity of water depends on the content of radon in it, the emanation of radium.

Physical and chemical properties of water

Dictionary of hydrogeology and engineering geology

PHYSICAL AND CHEMICAL PROPERTIES OF WATER - parameters that determine the physico-chemical characteristics of natural waters. These include indicators of the concentration of hydrogen ions (pH) and the redox potential (Eh).

Dictionary of hydrogeology and engineering geology. - M .: Gostoptekhizdat. Compiled by: A. A. Makkaveev, editor O. K. Lange. 1961

Acid-base water balance

Redox potential of water

The redox potential of water (ORP) - the ability of water to engage in biochemical reactions.

Chemical properties of water

CHEMICAL PROPERTIES of a SUBSTANCE are properties that are manifested as a result of chemical reactions.

Below are the chemical properties of water in the textbook “Fundamentals of Chemistry. Internet-textbook ”by the authors A. V. Manuilov, V. I. Rodionov.

The interaction of water with metals

When water interacts with most metals, a reaction occurs with the release of hydrogen:

2Na + 2H2O = H2 + 2NaOH (rapidly);
2K + 2H2O = H2 + 2KOH (rapidly);
3Fe + 4H2O = 4H2 + Fe3O4 (only when heated).

Not all, but only sufficiently active metals can participate in redox reactions of this type. Alkali and alkaline-earth metals of groups I and II react most easily.

The interaction of water with non-metals

For example, carbon and its hydrogen compound (methane) react with water from non-metals. These substances are much less active than metals, but still capable of reacting with water at high temperature:

C + H2O = H2 + CO (with strong heating);
CH4 + 2H2O = 4H2 + CO2 (with strong heating).

The interaction of water with electric current

When exposed to an electric current, water decomposes into hydrogen and oxygen. It is also a redox reaction, where water is both an oxidizing agent and a reducing agent.

Interaction of water with non-metal oxides

Water reacts with many non-metal oxides and some metal oxides. These are not redox reactions, but compound reactions:

SO2 + H2O = H2SO3 (sulfurous acid)

SO3 + H2O = H2SO4 (sulfuric acid)

CO2 + H2O = H2CO3 (carbonic acid)

The interaction of water with metal oxides

Some metal oxides can also react with water. Examples of such reactions we have already met:

CaO + H2O = Ca (OH) 2 (calcium hydroxide (slaked lime)

Not all metal oxides can react with water. Some of them are practically insoluble in water and therefore do not react with water. For example: ZnO, TiO2, Cr2O3, from which water resistant paints are prepared, for example. Iron oxides are also insoluble in water and do not react with it.

Hydrates and crystalline hydrates

Water forms compounds, hydrates and crystalline hydrates, in which the water molecule is completely preserved.

For example:

CuSO4 + 5 H2O = CuSO4.5H2O;
CuSO4 - a white substance (anhydrous copper sulphate);
CuSO4.5H2O - crystalline hydrate (blue vitriol), blue crystals.

Other examples of hydrate formation are:

H2SO4 + H2O = H2SO4. H2O (sulfuric acid hydrate);
NaOH + H2O = NaOH.H2O (caustic soda hydrate).

Compounds that bind water to hydrates and crystalline hydrates are used as desiccants. With their help, for example, water vapor is removed from humid atmospheric air.

Biosynthesis

Water participates in bio-synthesis as a result of which oxygen is formed:

6n CO 2 + 5n H 2 O = (C 6 H 10 O 5) n + 6n O 2 (under the action of light)

We see that the properties of water are diverse and cover almost all aspects of life on Earth. As one of the scientists formulated ... it is necessary to study water in a complex, and not in the context of its individual manifestations.

In preparing the material information was used from the books - Yu. P. Rasadkina “Water is ordinary and extraordinary”, Yu. Ya. Fialkova “Unusual properties of ordinary solutions”, Textbook “Basics of Chemistry. Internet-tutorial ”authors A. V. Manuylova, V. I. Rodionov and others.

Water has unusual properties. Its highest density is observed at a temperature of 4 ° C. When fresh water bodies cool in winter, as the temperature of the surface layers decreases, the denser masses of water descend, and warm and less dense ones rise in their place. This happens until the water in the deep layers reaches a temperature of 4 ° C. In this case, the transfer of heat stops, since there will be heavier water below. Further cooling of the water occurs only from the surface, which explains the formation of ice in the surface layer of water bodies. Because of this, life under the ice does not stop.

Vertical mixing sea water carried out by the action of wind, tides and changes in density in height. The mixing of water by wind occurs from top to bottom, tidal - from bottom to top. Density mixing occurs due to cooling of surface waters. Wind and tidal mixing spread to a depth of 50 m, at great depths only the effect of density mixing can affect.

The intensity of mixing of bottom and surface waters contributes to their refreshment, enrichment with oxygen and nutrients necessary for the development of life. Air dissolved in water is always richer in oxygen than atmospheric air. The oxygen present in water has a beneficial effect on the development of life processes in it.

When freezing clean water expands, sea - to a smaller value. As freezing water expands, an increase in external pressure reduces its freezing temperature; ice melting temperature, on the contrary, increases with pressure. In laboratory conditions with a pressure of more than 40 thousand. atmospheres you can get ice, which will melt at a temperature of 175 ° C. Heat capacity and heat melting of ice decrease with temperature, thermal conductivity almost does not depend on temperature. When the ice thickness on the surface of the reservoir reaches 15 cm, it becomes a reliable tester between water and air. .

Sea water freezes at a temperature of -1.91 ° C. With a further decrease in temperature, sodium sulfate begins to settle, and only at a temperature of -23 ° C sodium chloride drops out of solution. Since part of the brine during crystallization leaves ice, its salinity is less than the salinity of sea water. The long-term sea ice is so desalted that it is possible to get drinking water from it. The temperature of the maximum density of seawater is below freezing. This is the reason for sufficiently rapid heat transfer, which penetrates a considerable "thickness of seawater and impedes freezing. The heat capacity of seawater is in third place after the heat capacity of hydrogen and liquid ammonia.

Sometimes the water freezes at a positive temperature. This phenomenon is observed in pipelines and soil capillaries. In pipelines, water can freeze at a temperature of + 20 ° C. This is explained by the presence of methane in water. Since methane molecules occupy about 2 times more volume than water molecules, they "push apart" water molecules, increase the distance between them, which leads to a decrease in internal pressure and an increase in freezing temperature. In soil moisture, protein molecules play a similar role. Due to the influence of protein molecules, the freezing point of water in soil capillaries can increase to + 4.4 ° С.

The salinity of water depends on the concentration of salts dissolved in it, therefore the salinity of water is different in different seas and oceans. The average salinity of the ocean is 35%; Salinity of sea water can vary from zero near the confluence of large rivers to 40% in tropical seas. Drinking water should contain less than 0.05% dissolved salts. For watering plants in the water should not contain more than 0.25% salt, otherwise the plants will die.

Existing in nature, fluids can be divided into normal and associated. Normal are those fluids in which molecules are not combined into groups (associations). Fluids that do not comply with this condition are called associated. Water is one of the associated liquids. If water were non-associated liquid, the ice melting point would normally be + 1.43 ° C, and the boiling point of water would be 103 ° C. As a rule, the heat capacity of liquids increases with temperature, but when water approaches the temperature of + 35 ° C, the heat capacity drops to a minimum after growth and then gradually grows again. This is due to the fact that at such a temperature molecular bonds are destroyed. The simpler the molecular structure, the lower the heat capacity of the substance. The temperature of the highest water density decreases with increasing pressure and at a pressure of 150 atmospheres reaches 0.7 ° C. This is also explained by a change in the structure of molecular associations.

Among the liquids existing in nature, water has the greatest heat capacity. Its quality has a significant impact on climate. The main thermostat climate are the waters of the oceans and seas: accumulating heat in the summer, they give it in the winter. The absence of reservoirs on the ground usually leads to the formation of a sharply continental climate. Due to the influence of the oceans on a significant part of the Earth’s pair, land on Earth’s evaporation over evaporation is provided, and plant and animal organisms obtain the amount of water they need for life. The water and air shells of the Earth constantly exchange carbon dioxide with rocks, flora and fauna, which also contributes to stabilizing the climate.

It is known that molecules that are on the surface of a liquid have an excess of potential energy and therefore tend to be drawn inwards so that with: - a small number of molecules remain on the surface. Due to this, a force always acts along the surface of the liquid, trying to reduce the surface. This phenomenon in physics has been called the surface tension of a fluid.

Among the liquids that exist in nature, the surface tension of water is second only to mercury. Its highly wetting action (the ability to “stick” to the surface of many solids) is connected with the surface tension of water. In addition, water is a universal solvent. The heat of its evaporation is higher than the heat of evaporation of any other liquids, and the heat of crystallization is inferior only to ammonia.

A water molecule consists of two hydrogen atoms and one oxygen atom. In the composition of ordinary water H2O there is a small amount of heavy water D2O and a very small amount of super-heavy water T, O. Instead of ordinary hydrogen H - protium, the heavy water isotope D - deuterium is included in the heavy water molecule, and the heavier isotope T - tritium is contained in the super heavy water molecule. In natural water, for 1000 molecules of H, 0 there are two molecules of D2O and for one molecule of T, 0 - 1019 molecules of H2O.

Heavy water D2O is colorless, has no smell, no taste and is not digested by living organisms.i. Its freezing temperature is 3.8 ° C, the boiling point is 101.42 ° C, and the temperature of greatest density is 11.6 ° C. In terms of its ability to absorb heavy water, it is close to sulfuric acid. Its density is 10% more than the density of natural water, and the viscosity exceeds the viscosity of natural water by 20%. The solubility of salts in heavy water is about 10% less than in ordinary water. Since D2O evaporates more slowly than light water, it is more in tropical seas and lakes than in the waters of polar latitudes.

INTRODUCTION

One of the most acute problems facing humanity today is the shortage of clean drinking water. Millions of people are already feeling the shortage of water resources today, this problem is particularly acute in some countries of Asia and Africa. However, the latest developments in nanotechnology scientists can help humanity solve this problem and provide millions of people with clean drinking water.

A person consumes a huge amount of drinking water, and for drinking it is necessary to clean, fresh and fresh drinking water. It is also necessary to take into account the fact that more than 97% of the water on the globe is unsuitable for us. The remaining percentages of water resources are constantly polluted by agriculture, industry and are lost in the form of inefficient use. At the same time, the world's population is growing rapidly and according to experts, by 2030, 3.9 billion people (47% of the population) will not have access to clean drinking water. Some futurologists are already predicting future wars, which will be fought by countries for sources of clean drinking water.

However, scientists can now offer a “tiny”, but very effective solution to this global problem. We are talking about nanotechnology. Nanomaterials are already being developed that can effectively clean contaminated water from toxic metal compounds or toxic organic substances, and most importantly can turn salty seawater into fresh water.

While the productivity of such systems is low, however, the technology is very young and scientists promise it a great future. Already, there is interest in such materials from serious investors who are willing to invest in such research. According to experts, nanotechnologies will be able to play a major role in water purification in the next 5 or 10 years.

However, cleaning and disinfecting fresh water is only one task that nanotechnology can help solve. The second, probably even more important task that needs to be solved, for the “quenching” of the future global thirst is the desalination of salt water. Indeed, the vast majority of the water reserves on our planet is unsuitable for drinking. We are talking about the salty water of the seas and oceans. Scientists who work in the field of nanotechnology are ready to “lend a shoulder” and offer a more efficient and less expensive way to desalinate salt water.

Basic requirements for drinking water

One of the main environmental problems of mankind is the quality of drinking water, which is directly related to the state of public health, the ecological purity of food, and the resolution of medical and social problems. According to the World Health Organization (WHO) - 85% of all diseases in the world are transmitted by water. Every year 25 million people die from these diseases. In the New Sanitary Rules and Norms (San PiN 2.1.4.559-96) “Drinking Water”, virus indicators were defined, requirements for the presence of pesticides were tightened, and standards for chlorine-containing substances were increased more than three times. This is due to the forced choice of one of the two evils for water treatment: disinfect water with abundant chlorination and violate the chlorine standard or accept bacteria in the water. Chlorinated toxic, mutagenic and carcinogenic substances, trihalomethanes, are formed during the chlorination of natural waters. It should be noted that in the above-mentioned Sanitary Standards, the content of lead and aluminum, respectively, is 3-10 times higher than that provided for in the WHO standards. It should be borne in mind that lead and aluminum belong to the class of highly hazardous substances.

Lead is deposited in the bones, leads to changes in the central nervous system (polyneuritis, cerebral arteriosclerosis), blood (decrease in hemoglobin, decrease in the number of red blood cells), the gastrointestinal tract (spastic chronic colitis), as well as metabolic disturbances, “inhibition” of many enzymes and hormones. Even a small amount of lead causes kidney damage.

Aluminum paralyzes the nervous and immune systems, it has a particularly destructive effect on the children's body and contributes to the development of Alzheimer's disease.

Prolonged use of drinking water in violation of hygienic requirements for chemical composition causes the development of various diseases in the population. The adverse biological effects of excessive intake of a number of chemicals are manifested not only in an increase in the general or specific morbidity, but also in a change in individual health indicators indicating initial pathological or prepathological changes in the body.

Increasing the concentration of copper in drinking water causes damage to the mucous membranes of the kidneys and liver; nickel - skin lesions; zinc - the kidneys; arsenic - the central nervous system.

Thus, drinking water - the most important factor in human health. Almost all of its sources are subject to anthropogenic and man-made effects of varying intensity. Studies indicate a deterioration in water quality since 1995 and that in some regions the level of chemical and microbiological contamination of water bodies remains high, mainly due to the discharge of untreated industrial and domestic wastewater. Despite the relative protection of groundwater from pollution, so that they tend to use it for drinking water supply, about 1,800 centers of pollution have been found to date, 78% of which are in the European part of the Russian Federation. Due to the lack of facilities for cleaning and disinfecting water in most of the water pipes with water intake from open reservoirs, the condition of sources of centralized water supply in the whole country is extremely unfavorable.

Physical and chemical properties of water

In the nineteenth century, the chemical formula of this compound H 2 O was discovered, which, as it seemed, gives full information about water, but in 1932 a new sensational fact was discovered - in addition to ordinary water, there is also the concept of "heavy" water, and today Up to 135 isotopic water species are already known per day. The composition of a single drop of water, subject to its complete purification from impurities of mineral and organic substances, is always unique, and its properties vary depending on the physical nature of its constituent atoms, the way a molecule is formed, and the combination of these molecules into a chemical compound.

One of the most remarkable and at the same time difficult to study water properties is the ability of water to act as a universal solvent. Any substance, be it in a solid, liquid or gaseous state, is necessarily to some extent soluble in water, so water is always a solution that has a very complex chemical composition. And even when the chemical composition of water taken in different places is completely identical, it turns out that water has completely different effects on the body, since the conditions of water formation also determine its properties.

It should be noted that in nature there is no absolutely pure water, and rain water is the closest to this concept, although even it contains a certain amount of impurities that enter it from the air. And the most characteristic solvent is sea water, since it can dissolve almost any substance, and its composition can include up to 70 elements of the periodic table, starting with chlorine, magnesium, sodium, sulfur, calcium and potassium, bromine, carbon, strontium and boron which are contained in sea water in large quantities, and ending with the rarest of radioactive elements in very small proportions.

Depending on the content in water of various impurities, it can be divided into several classes: fresh water, salt water, and brines. The color of the water depends on it. At first glance, any water is a clear, colorless liquid that has neither taste nor smell, but the deep waters of the sea or ocean look blue, and the water of mountain rivers looks green, it is the presence of various impurities in the water that gives it a different color. It would seem that with modern equipment and technology, today we know everything about water, but new and new facts are revealed that show that water has an undisclosed potential that humankind has yet to learn.

It turns out that water, not only from ancient times, serves to satisfy domestic and industrial human needs, but also protects the Earth in the summer from overheating, and in the winter, giving it its heat from freezing. The excess carbon dioxide produced in the process of human life, could lead to catastrophic consequences if it were not absorbed by the waters of the world's oceans.

Water has specific properties that are not inherent in more than one chemical compound, for example, when water passes from a liquid to a solid state, it does not increase its density, but increases its volume. This is due to the molecular structure of ice: when freezing, the molecules are located at a considerable distance from each other, forming a loose ice structure, thereby increasing the volume, but maintaining the mass, thus, the water in the solid state (ice) is lighter than in the liquid. Do not have water with this property, the occurrence of life on Earth would not be possible, since the ice that arose on the surface of the reservoir immediately sank and the rivers, seas and even oceans would have frozen to the very bottom. So, one of the factors determining the properties of water is its molecular composition. The water molecule is an isosceles triangle at the base of which are hydrogen atoms, and the top is an oxygen atom, the valence angle of this triangle HON is 104.31 °, and the hydrogen atoms are so closely adjacent to the oxygen atom that at first glance the molecule has a spherical shape . The water molecule has weak hydrogen bonds, which allows water to evaporate, that is, if you put water in an open vessel, then gradually all the water molecules will move into the air. If the vessel is closed, the water will evaporate until a certain equilibrium is reached, which is explained by the pressure exerted by the molecules of water vapor that has accumulated between the lid of the vessel and the remaining water. Evaporation occurs even in the solid state of water, that is, from the surface of ice or snow. At the same time, the viscosity of water directly depends on its temperature; the higher the temperature, the lower the viscosity, when reaching the boiling point of water, the viscosity decreases by a factor of 8 than at its freezing point. Water is almost impossible to compress, and its density is maximum at 4 ° C.

The physical characteristics of water are such that it changes from a solid to a liquid state and vice versa (it melts and freezes) at the same temperature of 0 ° C. The boiling point of water is 100 ° C, although here the water exhibits very interesting properties: this rule is observed only at normal pressure, which is 760 mm Hg. Art., with a decrease in pressure decreases and the boiling point of water, so at an altitude of 2900 m above sea level, where the atmospheric pressure is 525 mm Hg. Art., the boiling point of water is 90 ° C.

The earth is 75% covered with water, and the natural cycle of water is constantly maintained by nature: it evaporates from the surface of water bodies and then falls as rain: snow or snow, but even with such a reasonable decision, some regions of the globe constantly suffer from a lack of fresh water. That is why it is worth remembering that water is the greatest wealth given to us by nature, and its every drop is precious, because human life is impossible without water.

Three states of water

Water is one of the most common chemical compounds on Earth. It surrounds us everywhere, even natural phenomena that we observe daily — cloudiness, fog, rain, snow — are just different states of water that are liquid, gaseous, and solid. After all, a cloud is nothing but an accumulation of many tiny water droplets or ice crystals that fall in the form of sediments — rain (liquid state of water) or snow (solid state of water). If you look at a snowflake under a microscope, you can see that this beautiful natural work of art is made of very small ice crystals. The gaseous state of the water is called steam. In nature, the concept of humidity means the content of water vapor in the air (high content of vapor - high humidity). At a temperature of 0 ° C and below and at normal atmospheric pressure, water passes into a solid state — ice. Ice is very poorly compressed, and the density of ice, due to its molecular structure, is less than the density of water, so ice is on the surface of the water and always protrudes 1/5 of its volume at 0 ° C.

WATER

A water molecule consists of an oxygen atom and two hydrogen atoms attached to it at an angle of 104.5 °.

An angle of 104.5 ° between the bonds in the water molecule causes the looseness of ice and liquid water and, as a consequence, the anomalous dependence of density on temperature. That is why large water bodies do not freeze to the bottom, which makes life possible in them.

Physical properties

WATER, ICE AND STEAM,respectively, liquid, solid and gaseous state of a chemical compound of molecular formula H 2 O.

Due to the strong attraction between the molecules, water has high melting points (0С) and boiling points (100С). A thick layer of water has a blue color, which is caused not only by its physical properties, but also by the presence of suspended particles of impurities. The water of mountain rivers is greenish due to suspended particles of calcium carbonate contained in it. Clear water is a poor conductor of electricity. The density of water is maximum at 4C; it is equal to 1 g / cm 3. Ice has a lower density than liquid water and floats on its surface, which is very important for inhabitants of water bodies in winter.

The water has an exceptionally large heat capacity, so it slowly heats up and slowly cools. Due to this, water basins regulate the temperature on our planet.

Chemical properties of water

Water is a very reactive substance. Under normal conditions, it interacts with many basic and acid oxides, as well as with alkali and alkaline earth metals. Water forms numerous compounds - crystalline hydrates.

Under the action of an electric current, water decomposes into hydrogen and oxygen:

2 H 2 O electricity = 2 H 2 + O 2

Video "Water Electrolysis"