A message about water around the world. The message “Water and its properties. Water balance in the body is a direct path to health

Water on our planet exists in three states - liquid, solid (ice, snow) and gaseous (steam). Currently water occupies 3/4.

Water forms the aquatic shell of our planet - the hydrosphere.

The hydrosphere (from the Greek words “hydro” - water, “sphere” - ball) includes three main components: the World Ocean, land waters and water in the atmosphere. All parts of the hydrosphere are interconnected by the process of the water cycle in nature, already known to you.

Explain how water from the continents enters the World Ocean.
How does water get into the atmosphere?
How does water get back onto land?

The World Ocean accounts for over 96% of all the water on our planet.

Continents and islands divide the World Ocean into separate oceans: Pacific, Atlantic, Indian,.

In recent years, maps have highlighted the Southern Ocean, the body of water surrounding Antarctica. The largest in area is the Pacific Ocean, the smallest is the Arctic Ocean.

Parts of the oceans that extend into the land and differ in the properties of their waters are called seas. There are a lot of them. The largest seas on the planet are the Philippine, Arabian, and Coral.

Water under natural conditions contains various substances dissolved in it. 1 liter of ocean water contains on average 35 g of salt (mostly table salt), which gives it a salty taste and makes it unsuitable for drinking and use in industry and agriculture.

Rivers, lakes, swamps, glaciers and groundwater are land waters. Most of the land's waters are fresh, but among lakes and groundwater there are also salty ones.

You know what a huge role rivers, lakes, and swamps play in nature and people’s lives. But here’s what’s surprising: in the total amount of water on Earth, their share is very small - only 0.02%.

Much more water is contained in glaciers - about 2%. They should not be confused with the ice that forms when water freezes. arise where more falls than has time to melt. Gradually, the snow accumulates, compacts and turns into ice. Glaciers cover approximately 1/10 of the land. They are located primarily on the mainland of Antarctica and the island of Greenland, which are covered with huge ice shells. Blocks of ice that break off along their shores form floating mountains - icebergs.

Some of them reach enormous sizes. Considerable areas are occupied by glaciers in the mountains, especially in such high ones as the Himalayas, Pamirs, and Tien Shan.

Glaciers can be called storehouses of fresh water. So far, it has hardly been used, but scientists have long been developing projects for transporting icebergs to arid areas to provide drinking water to local residents.

They also make up about 2% of all water on Earth. They are located in the upper part of the earth's crust.

These waters can be salty and fresh, cold, warm and hot. They are often saturated with substances beneficial to human health and are medicinal (mineral waters).

In many places, for example along the banks of rivers, in ravines, underground waters come to the surface, forming springs (they are also called springs and springs).

Groundwater reserves are replenished by precipitation, which seeps through some of the rocks that make up the earth's surface. Thus, groundwater participates in nature.

Water in the atmosphere

Contains water vapor, water droplets and ice crystals. Together they make up a fraction of a percent of the total amount of water on Earth. But without them the water cycle on our planet would be impossible.

What is the hydrosphere? List its components.
What oceans form the World Ocean of our planet?
What makes up the waters of land?
How are glaciers formed and where are they located?
What is the role of groundwater?
What is water in the atmosphere?
What is the difference between a river, lake and ?
What danger does an iceberg pose?
Are there salty bodies of water on our planet other than seas and oceans?

The water layer of the Earth is called the hydrosphere. It consists of the World Ocean, land waters and water in the atmosphere. All parts of the hydrosphere are interconnected by the process of the water cycle in nature. The World Ocean accounts for more than 96% of the planet's total water. It is divided into separate oceans. The parts of the oceans that extend into the land are called seas. Land waters include rivers, lakes, swamps, glaciers, and groundwater. The atmosphere contains water vapor, water droplets and ice crystals.

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PRINCIPAL ABSTRACT COMPILER

PETRUNINA

ALLA

BORISOVNA

MUNICIPAL EDUCATIONAL SCHOOL

SECONDARY SCHOOL №4

ABSTRACT

in chemistry on the topic:

“Water and its properties”

Performed :

student 11 "B" class

Petrunina Elena

PENZA 2001

Water- a substance familiar and unusual. The famous Soviet scientist Academician I.V. Petryanov called his popular scientific book about water “The Most Extraordinary Substance in the World.” And Doctor of Biological Sciences B.F. Sergeev began his book “Entertaining Physiology” with a chapter about water - “The Substance that Created Our Planet.”

Scientists are right: there is no substance on Earth more important for us than ordinary water, and at the same time, there is no other substance of the same type whose properties would have as many contradictions and anomalies as its properties.

Almost ¾ of the surface of our planet is occupied by oceans and seas. Hard water - snow and ice - covers 20% of the land. Of the total amount of water on Earth, equal to 1 billion 386 million cubic kilometers, 1 billion 338 million cubic kilometers are the share of salty waters of the World Ocean, and only 35 million cubic kilometers are the share of fresh waters. The total amount of ocean water would be enough to cover the globe with a layer of more than 2.5 kilometers. For every inhabitant of the Earth there is approximately 0.33 cubic kilometers of sea water and 0.008 cubic kilometers of fresh water. But the difficulty is that the vast majority of fresh water on Earth is in a state that makes it difficult for humans to access. Almost 70% of fresh water is contained in the ice sheets of polar countries and in mountain glaciers, 30% is in aquifers underground, and only 0.006% of fresh water is contained in the beds of all rivers.

Water molecules have been discovered in interstellar space. Water is part of comets, most planets in the solar system and their satellites.

Isotopic composition. There are nine stable isotope species of water. Their average content in fresh water is as follows: 1 H216 O – 99.73%, 1 H218 O – 0.2%,

1 H217 O – 0.04%, 1 H2 H16 O – 0.03%. The remaining five isotopic species are present in water in negligible quantities.

Molecule structure. As is known, the properties of chemical compounds depend on what elements their molecules are made of and change naturally. Water can be thought of as either hydrogen oxide or oxygen hydride. The hydrogen and oxygen atoms in the water molecule are located at the corners of an isosceles triangle with an O–H bond length of 0.957 nm; bond angle H – O – H 104o 27’.

1040 27"

But since both hydrogen atoms are located on the same side of the oxygen atom, the electrical charges in it are dispersed. The water molecule is polar, which is the reason for the special interaction between its different molecules. The hydrogen atoms in a water molecule, having a partial positive charge, interact with the electrons of the oxygen atoms of neighboring molecules. This chemical bond is called water. It combines water molecules into unique polymers with a spatial structure. About 1% water dimers are present in water vapor. The distance between oxygen atoms is 0.3 nm. In the liquid and solid phases, each water molecule forms four hydrogen bonds: two as a proton donor and two as a proton acceptor. The average length of these bonds is 0.28 nm, the H – O – H angle tends to 1800. The four hydrogen bonds of the water molecule are directed approximately to the vertices of a regular tetrahedron.

The structure of ice modifications is a three-dimensional grid. In modifications that exist at low pressures, the so-called ice - I, the H - O - H bonds are almost straight and directed towards the vertices of a regular tetrahedron. But at high pressures, ordinary ice can be transformed into the so-called ice-II, ice-III, and so on - heavier and denser crystalline forms of this substance. The hardest, densest and most refractory so far are ice - VII and ice - VIII. Ice – VII was obtained under a pressure of 3 billion Pa, it melts at a temperature of + 1900 C. In modifications – ice – II – ice – VI – the H – O – H bonds are curved and the angles between them differ from the tetrahedral one, which causes an increase in density along compared to the density of ordinary ice. Only in the ice-VII and ice-VIII modifications is the highest packing density achieved: in their structure, two regular networks built from tetrahedra are inserted into one another, while maintaining a system of straight hydrogen bonds.

A three-dimensional network of hydrogen bonds, built from tetrahedra, also exists in liquid water throughout the entire range from the melting point to the critical temperature of + 3.980C. The increase in density during melting, as in the case of dense modifications of ice, is explained by the curvature of hydrogen bonds.

The curvature of hydrogen bonds increases with increasing temperature and pressure, which leads to an increase in density. On the other hand, when heated, the average length of hydrogen bonds becomes larger, resulting in a decrease in density. The combined effect of two facts explains the presence of a maximum density of water at a temperature of + 3.980C.

Physical properties waters are anomalous, which is explained by the above data on the interaction between water molecules.

Water is the only substance on Earth that exists in nature in all three states of aggregation - liquid, solid and gaseous.

Melting of ice at atmospheric pressure is accompanied by a decrease in volume by 9%. The density of liquid water at temperatures close to zero is greater than that of ice. At 00C, 1 gram of ice occupies a volume of 1.0905 cubic centimeters, and 1 gram of liquid water occupies a volume of 1.0001 cubic centimeters. And ice floats, which is why bodies of water usually do not freeze through, but are only covered with ice.

The temperature coefficient of volumetric expansion of ice and liquid water is negative at temperatures below - 2100C and + 3.980C, respectively.

The heat capacity during melting almost doubles and in the range from 00C to 1000C is almost independent of temperature.

Water has unusually high melting and boiling points in comparison with other hydrogen compounds of elements of the main subgroup of group VI of the periodic table.

hydrogen telluride hydrogen selenide hydrogen sulfide water

N 2 Those N 2 S e N 2 S H2 O

t melting - 510С - 640С - 820С 00С

_____________________________________________________

boiling point - 40C - 420C - 610C 1000C

_____________________________________________________

Additional energy must be supplied to loosen and then destroy hydrogen bonds. And this energy is very significant. This is why the heat capacity of water is so high. Thanks to this feature, water shapes the climate of the planet. Geophysicists claim that the Earth would have cooled long ago and turned into a lifeless piece of stone if it were not for water. When it heats up, it absorbs heat, and when it cools down, it releases it. Earth's water both absorbs and returns a lot of heat, and thereby “evens out” the climate. The formation of the climate of the continents is especially noticeably influenced by sea currents, forming closed circulation rings in each ocean. The most striking example is the influence of the Gulf Stream, a powerful system of warm currents running from the Florida Peninsula in North America to Spitsbergen and Novaya Zemlya. Thanks to the Gulf Stream, the average January temperature on the coast of Northern Norway, above the Arctic Circle, is the same as in the steppe part of Crimea - about 00C, i.e. increased by 15 - 200C. And in Yakutia at the same latitude, but far from the Gulf Stream - minus 400C. And those water molecules that are scattered in the atmosphere - in clouds and in the form of vapors - protect the Earth from cosmic cold. Water vapor creates a powerful “greenhouse effect”, which traps up to 60% of the thermal radiation of our planet and prevents it from cooling. According to M.I. Budyko’s calculations, if the water vapor content in the atmosphere was halved, the average temperature of the Earth’s surface would drop by more than 50C (from 14.3 to 90C). The mitigation of the earth's climate, in particular the equalization of air temperature in the transition seasons - spring and autumn, is noticeably influenced by the huge values of the latent heat of melting and evaporation of water.

But this is not the only reason why we consider water a vital substance. The fact is that the human body is almost 63–68% water. Almost all biochemical reactions in every living cell are reactions in aqueous solutions. With water, toxic wastes are removed from our body; Water secreted by sweat glands and evaporating from the surface of the skin regulates our body temperature. Representatives of the animal and plant world contain the same abundance of water in their bodies. Some mosses and lichens contain the least amount of water, only 5–7% of their weight. Most of the world's inhabitants and plants consist of more than half water. For example, mammals contain 60 – 68%; fish – 70%; algae – 90 – 98% water.

Most technological processes take place in solutions (mainly aqueous) at chemical industry enterprises, in the production of medicines and food products.

It is no coincidence that hydrometallurgy - the extraction of metals from ores and concentrates using solutions of various reagents - has become an important industry.

Water is an important source of energy resources. As is known, all hydroelectric power stations in the world, from small to large, convert the mechanical energy of the water flow into electrical energy exclusively with the help of water turbines with electric generators connected to them. At nuclear power plants, a nuclear reactor heats water, water steam rotates a turbine with a generator and generates electric current.

Water, despite all its anomole properties, is the standard for measuring temperature, mass (weight), amount of heat, and terrain altitude.

Swedish physicist Anders Celsius, a member of the Stockholm Academy of Sciences, created a centigrade thermometer scale in 1742, which is now used almost everywhere. The boiling point of water is designated 100, and the melting point of ice is 0.

During the development of the metric system, established by decree of the French revolutionary government in 1793 to replace various ancient measures, water was used to create the basic measure of mass (weight) - kilogram and gram: 1 gram, as is known, is the weight of 1 cubic centimeter (milliliter) pure water at the temperature of its highest density - 40C. Therefore, 1 kilogram is the weight of 1 liter (1000 cubic centimeters) or 1 cubic decimeter of water: and 1 ton (1000 kilograms) is the weight of 1 cubic meter of water.

Water is also used to measure the amount of heat. One calorie is the amount of heat required to heat 1 gram of water from 14.5 to 15.50C.

All heights and depths on the globe are measured from sea level.

In 1932, the Americans G. Urey and E. Osborne discovered that even the purest water that can be obtained in the laboratory contains a small amount of some substance, apparently expressed by the same chemical formula H2 O, but having a molecular weight of 20 instead of the weight of 18 inherent in ordinary water. Yuri called this substance heavy water. The large weight of heavy water is explained by the fact that its molecules consist of hydrogen atoms with double the atomic weight compared to ordinary hydrogen atoms. The double weight of these atoms, in turn, is due to the fact that their nuclei contain, in addition to the single proton that makes up the nucleus of ordinary hydrogen, one more neutron. The heavy isotope of hydrogen is called deuterium.

(D or 2 H), and ordinary hydrogen began to be called protium. Heavy water, deuterium oxide, is expressed by the formula D2 O.

Soon, a third, superheavy isotope of hydrogen with one proton and two neutrons in the nucleus was discovered, which was named tritium (T or 3H). When combined with oxygen, tritium forms superheavy water T2O with a molecular weight of 22.

Natural waters contain on average about 0.016% heavy water. Heavy water is similar in appearance to ordinary water, but differs from it in many physical properties. The boiling point of heavy water is 101.40C, the freezing point is + 3.80C. Heavy water is 11% heavier than ordinary water. The specific gravity of heavy water at a temperature of 250C is 1.1. It dissolves various salts worse (by 5–15%). In heavy water, the rate of occurrence of some chemical reactions is different than in ordinary water.

And physiologically, heavy water has a different effect on living matter: unlike ordinary water, which has life-giving power, heavy water is completely inert. Plant seeds, if watered with heavy water, do not germinate; tadpoles, microbes, worms, fish cannot exist in heavy water; If animals are given only heavy water to drink, they will die of thirst. Heavy water is dead water.

There is another type of water that differs in physical properties from ordinary water - this is magnetized water. Such water is obtained using magnets mounted in the pipeline through which the water flows. Magnetized water changes its physical and chemical properties: the rate of chemical reactions in it increases, the crystallization of dissolved substances accelerates, the aggregation of solid particles of impurities increases and their precipitation with the formation of large flakes (coagulation). Magnetization is successfully used at waterworks when the water taken in is highly turbid. It also allows for the rapid sedimentation of contaminated industrial wastewater.

From chemical properties water, the ability of its molecules to dissociate (decay) into ions and the ability of water to dissolve substances of different chemical nature are especially important.

The role of water as the main and universal solvent is determined primarily by the polarity of its molecules and, as a consequence, by its extremely high dielectric constant. Opposite electric charges, and in particular ions, are attracted to each other in water 80 times weaker than they would be attracted in air. The forces of mutual attraction between molecules or atoms of a body immersed in water are also weaker than in air. In this case, it is easier for thermal movement to break up the molecules. This is why dissolution occurs, including of many sparingly soluble substances: a drop wears away a stone.

Only a small fraction of molecules (one in 500,000,000) undergo electrolytic dissociation according to the following scheme:

H2 + 1/2 O2 H2 O -242 kJ/mol for steam

286 kJ/mol for liquid water

At low temperatures in the absence of catalysts it occurs extremely slowly, but the reaction rate increases sharply with increasing temperature, and at 5500C it occurs explosively. As pressure decreases and temperature increases, the equilibrium shifts to the left.

Under the influence of ultraviolet radiation, water photodissociates into H+ and OH- ions.

Ionizing radiation causes radiolysis of water with the formation of H2; H2 O2 and free radicals: H*; HE*; ABOUT* .

Water is a reactive compound.

Water is oxidized by atomic oxygen:

H2 O + C CO + H2

At elevated temperatures in the presence of a catalyst, water reacts with CO; CH4 and other hydrocarbons, for example:

6H2 O + 3P 2HPO3 + 5H2

Water reacts with many metals to form H2 and the corresponding hydroxide. With alkali and alkaline earth metals (except Mg), this reaction occurs already at room temperature. Less active metals decompose water at elevated temperatures, for example, Mg and Zn - above 1000C; Fe – above 6000С:

2Fe + 3H2 O Fe2 O 3 + 3H2

When many oxides react with water, they form acids or bases.

Water can serve as a catalyst, for example, alkali metals and hydrogen react with CI2 only in the presence of traces of water.

Sometimes water is a catalytic poison, for example, for an iron catalyst in the synthesis of NH3.

The ability of water molecules to form three-dimensional networks of hydrogen bonds allows it to form gas hydrates with inert gases, hydrocarbons, CO2, CI2, (CH2)2 O, CHCI3 and many other substances.

Until about the end of the 19th century, water was considered a free, inexhaustible gift of nature. It was only lacking in sparsely populated desert areas. In the 20th century, the view of water changed dramatically. As a result of the rapid growth of the world's population and the rapid development of industry, the problem of supplying humanity with clean fresh water has become almost the number one global problem. Currently, people use about 3,000 billion cubic meters of water annually, and this figure is continuously growing rapidly. In many densely populated industrial areas, clean water is no longer available.

The lack of fresh water on the globe can be compensated for in various ways: by desalinating sea water, and also replacing fresh water with it, where technically possible; purify wastewater to such an extent that it can be safely discharged into reservoirs and watercourses without fear of contamination, and reused; Use fresh water sparingly, creating a less water-intensive production technology, replacing, where possible, high-quality fresh water with lower-quality water, etc.

WATER IS ONE OF THE MAIN RICH TASTS OF HUMANITY ON THE EARTH.

BIBLIOGRAPHY:

1. Chemical encyclopedia. Volume 1. Editor I.L. Knunyants. Moscow, 1988.

2. Encyclopedic dictionary of a young chemist. Compiled by

V.A. Kritsman, V.V. Stanzo. Moscow, “Pedagogy”, 1982.

“Gidrometeoizdat”, 1980.

4. The most extraordinary substance in the world. Author

I.V. Petryanov. Moscow, “Pedagogy”, 1975.

P L A N.

I. Introduction.

Statements by famous scientists about water.

II .Main part.

1.Distribution of water on planet Earth, in space

space.

2. Isotopic composition of water.

3.Structure of the water molecule.

4. Physical properties of water, their anomalies.

a).Aggregative states of water.

b).The density of water in solid and liquid states.

c).Heat capacity of water.

d). Melting and boiling points of water compared to

other hydrogen compounds of elements

main subgroup YI group of the periodic table.

5. The influence of water on the formation of climate on the planet

6.Water as the main component of plant and

animal organisms.

7.Use of water in industry, production

electricity.

8.Use water as a standard.

a).To measure temperature.

b).To measure mass (weight).

c).To measure the amount of heat.

d).To measure the height of the terrain.

9.Heavy water, its properties.

10. Magnetized water, its properties.

11. Chemical properties of water.

a).Formation of water from oxygen and hydrogen.

b).Dissociation of water into ions.

c).Photodissociation of water.

d).Radiolysis of water.

d).Oxidation of water with atomic oxygen.

f).The interaction of water with non-metals, halogens,

hydrocarbons.

g).Interaction of water with metals.

h).Interaction of water with oxides.

i).Water as a catalyst and inhibitor of chemicals

III .Conclusion.

Water is one of the main resources of humanity on Earth.

INTRODUCTION

Water is the most abundant substance on our planet. Oceans, seas and rivers, glaciers and atmospheric water - this is not a complete list of water “storages” on Earth. Even in the depths of our planet there is water, and what can we say about the living organisms living on its surface! There is not a single living cell that does not contain water. The human body, for example, consists of more than 70% water.

Life on Earth is a combination of numerous complex processes, the main place among which is the cycle of heat, moisture and substances. The main role in this is played by water - the ancestor of life on Earth.
But is it accidental that our life is inseparable from water, and what are the reasons for this?

Unlike ordinary people, who are accustomed to considering water as something so ordinary and familiar that it is not worth much thought, much less surprise, scientists consider this liquid the most mysterious and amazing. For example, many properties of water are anomalous, that is, they differ significantly from the corresponding properties of compounds of a similar structure. Oddly enough, it was the anomalous properties of water that gave this liquid the opportunity to become the most important on Earth.

WATER IN NATURE

In a free state, the Earth contains a colossal amount of water - about one and a half billion cubic kilometers. Almost the same amount of water is in a physically and chemically bound state in crystalline and sedimentary rocks.
Most natural waters are solutions, the content of dissolved substances in which ranges from 0.01% (in fresh water) to 3.5% (in sea water).
Fresh water accounts for only about 3% of the planet's total water supply (approximately 35 million km3). A person can directly use only 0.006% of fresh water for his needs - this is the part that is contained in the beds of all rivers and lakes. The rest of the fresh water is difficult to access - 70% are polar ice sheets or mountain glaciers, 30% are underground aquifers.
Without exaggeration, we can say that our planet is saturated with water. It is thanks to this that the development of those forms of life that we see around us became possible on Earth.

PROPERTIES OF WATER,

WHO CONTRIBUTED TO THE APPEARANCE OF LIFE ON EARTH
Comparing the properties of water with the properties of analogous compounds, we come to the conclusion that many characteristics of water have anomalous values. As will be discussed below, it is this anomalous properties that will play the most important role for the origin and existence of life on Earth.

Boiling temperature

Let us consider the boiling temperatures of compounds of the H2El series, where El is an element of the main subgroup of group VI.

Compound H 2 0 H 2 S H 2 Se H 2 Te

t°c boil. +100 -60 -41 -2

As can be seen, the boiling point of water differs sharply from the boiling point of compounds of analogous elements and has an abnormally high value. It has been established that a similar anomaly is observed for all compounds of the H 2 El type, where El is a strongly electronegative non-metal (O, N, etc.).
If in the series H 2 Te-H 2 Se-H 2 S the boiling point decreases uniformly, then from H 2 S to H 2 0 it increases abruptly. The same is observed for the series HI -HBr-HCl-HF and H 3 Sb-H 3 As-H 3 P-H 3 N. It was assumed and subsequently proven that there are specific bonds between H 2 0 molecules, the breaking of which requires energy heating. These same bonds make it difficult for HF and H 3 N molecules to separate. This type of bond is called a hydrogen bond, let’s look at its mechanism.

The elements H and O have a large difference in electronegativity values (EO(H) = 2.1; EO(O) = 3.5), so the H-O chemical bond is highly differentiated. The electron density shifts towards oxygen, as a result of which the hydrogen atom acquires an effective positive charge, and the oxygen atom acquires an effective negative charge. A hydrogen bond is an image resulting from an electrostatic attraction between a positively charged hydrogen atom of one molecule and a negatively charged oxygen atom of another molecule:

The ability of water to form hydrogen bonds has important biochemical significance.

Density
All substances are characterized by an increase in density with decreasing temperature. However, water behaves somewhat unusually in this case.
The minimum temperature at which water can exist without freezing is 0 "C. It would be logical to assume that the highest density of water also corresponds to this temperature. However, it has been experimentally proven that the density of liquid water is maximum at 4 °C.
This fact is of enormous importance. Let's imagine that water obeys the laws characteristic of all other liquids. Then the change in its density would occur like other liquids. In the world around us, this would lead to a catastrophe: with the approach of winter and widespread cooling, the upper layers of liquid in reservoirs would cool and sink to the bottom. The warmer layers of liquid that rose in their place would also cool to 0 °C and sink. This would continue until all the water had cooled to 0°C. Then the water, starting from the upper layers, would begin to freeze. Being more dense, the ice would sink to the bottom, freezing would continue until all the water in natural reservoirs froze to the bottom. It is clear that in such conditions the flora and fauna of natural reservoirs could not exist.

Another anomaly in the density of water is that the density of ice is lower than the density of water, i.e., when water freezes, it does not compress like all other liquids, but rather expands.
From the point of view of the laws of physics, this is absurd, because a more ordered state of molecules (ice) cannot occupy a larger volume than a less ordered one (liquid water), provided that the number of molecules in both states is the same.
As already mentioned, in liquid water H 2 0 molecules are connected to each other by hydrogen bonds. The formation of ice crystals is accompanied by the formation of new hydrogen bonds, causing water molecules to form layers. The connection between the layers is also carried out due to hydrogen bonds. The resulting structure (the so-called ice structure) is one of the least dense - the voids present between the molecules in an ice crystal exceed the size of water molecules. Therefore, the density of water is more important than the density of ice.

Surface tension

As a rule, the surface tension of a liquid is understood as a force acting per unit length of the interface contour and tending to reduce this surface to a minimum. The value of surface tension for water has an abnormally high value - 7.3 .10 -2 N/m at 20 0 C (of all liquids, only mercury has a higher value - 51 10 -2 N/m).

The high value of surface tension of water is manifested in the fact that it tends to reduce its surface to a minimum. We can say that under the influence of this force, the molecules of the outer layer of water adhere, forming some kind of film on the surface. It is so strong and elastic that individual objects are able to float on the surface of the water without sinking into it, even if their density is greater than the density of water.

The presence of the film makes it possible for many insects to move on the surface of the water and even sit on it as if on a hard surface.
The inner side of the water surface is also actively used by living beings. Many of us have seen mosquito larvae hanging on it or small snails crawling in search of prey.
High surface tension also determines such an extremely important phenomenon in nature as capillarity (liquid rises through very thin tubes - capillaries). Thanks to this, plant nutrition is provided.
Quite complex physical laws have been derived to describe the behavior of water in capillaries. Layers of water located near a solid surface are structurally ordered. The thickness of such a layer can reach tens and hundreds of molecules. Now scientists are inclined to consider the structurally ordered state of water in capillaries as a separate state - capillary.

Capillary water is widespread in nature in the form of so-called pore water. With a thin but dense film, it covers the surfaces of pores and cracks in rocks and minerals of the earth’s crust. The density of this film is also due to the fact that the water molecules that make it up are connected to the particles that form the solid body by intermolecular forces. The structural ordering of pore water is the reason that its crystallization (freezing) temperature is noticeably lower than the temperature of free water. In addition, the properties of rocks with which pore water comes into contact significantly depend on the state of aggregation in which it is located.

Most of our planet - 79% - is occupied by water, and even if you delve deep into the thickness of the earth's crust, you can find water in cracks and pores. In addition, all minerals and living organisms known on Earth contain water.

The importance of water in nature is great. Modern scientific studies of water make it possible to consider it as a unique substance. It participates in all physical-geographical, biological, geochemical and geophysical processes occurring on Earth, and is the driving force behind many global processes on the planet.

Water caused such a phenomenon on Earth as The water cycle - a closed, continuous process of water movement, covering all the most important shells of the Earth. The driving force behind the water cycle is solar energy, which causes water to evaporate (6.6 times more from the oceans than from land). Water entering the atmosphere is transported horizontally by air currents, condenses and, under the influence of gravity, falls to the Earth in the form of precipitation. One part of them enters lakes and the ocean through rivers, and the other goes to moisten the soil and replenish groundwater, which takes part in feeding rivers, lakes and seas.

The annual cycle involves 525.1 thousand km 3 of water. On average, 1030 mm of precipitation falls on our planet per year and approximately the same amount evaporates (in volumetric units 525,000 km 3).

The equality between the amount of water arriving on the Earth's surface with precipitation and the amount of water evaporating from the surface of the World Ocean and land over the same period of time is called water balance of our planet (Table 19).

Table 19. Water balance of the Earth (according to M.I. Lvovich, 1986)

Evaporation of water requires a certain amount of heat, which is released when water vapor condenses. Consequently, the water balance is closely related to the heat balance, while moisture circulation evenly distributes heat between its spheres, as well as regions of the Earth, which is of great importance for the entire geographical envelope.

Water is also of great importance in economic activities. It is impossible to list all the areas of human activity in which water is used: domestic and industrial water supply, irrigation, electricity generation and many others.

Leading biochemist and mineralogist academician V. I. Vernadsky noted that water stands apart in the history of our planet. Only it can exist on Earth in three states of aggregation and move from one to another (Fig. 158).

Water, found in all states of aggregation, forms the water shell of our planet - hydrosphere.

Since water is contained in the lithosphere, atmosphere and in various living organisms, it is very difficult to determine the boundaries of the water shell. In addition, there are two interpretations of the concept “hydrosphere”. In a narrow sense, the hydrosphere is the intermittent water shell of the Earth, consisting of the World Ocean and inland water bodies. The second interpretation - broad - defines it as a continuous shell of the Earth, consisting of open bodies of water, water vapor in the atmosphere and groundwater.

Rice. 158. Physical states of water

Water vapor in the atmosphere is called diffuse hydrosphere, and groundwater is called buried hydrosphere.

As for the hydrosphere in the narrow sense, most often the surface of the globe is taken as its upper boundary, and the lower boundary is drawn along the groundwater level, which is located in the loose sedimentary layer of the earth's crust.

When considering the hydrosphere in a broad sense, its upper boundary is located in the stratosphere and is very uncertain, that is, it lies above the geographical envelope, which does not extend beyond the troposphere.

Scientists claim that the volume of the hydrosphere is approximately 1.5 billion km 3 of water. The vast majority of the area and volume of water falls on the World Ocean. It contains 94% (according to other sources 96%) of the volume of all water contained in the hydrosphere. About 4% is buried hydrosphere (Table 20).

When analyzing the volumetric composition of the hydrosphere, one cannot limit oneself to one quantitative aspect. When assessing the component parts of the hydrosphere, its activity in the water cycle should be taken into account. For this purpose, the famous Soviet hydrologist, Doctor of Geographical Sciences M.I. Lvovich introduced the concept water exchange activity, which is expressed by the number of years required to completely restore the volume.

It is known that in all rivers on our planet the simultaneous volume of water is small and amounts to 1.2 thousand km 3. At the same time, channel waters are completely renewed on average every 11 days. Almost the same activity of water exchange is characteristic of the dispersed hydrosphere. But underground waters, the waters of polar glaciers and the oceans require millennia to be completely renewed. The water exchange activity of the entire hydrosphere is 2800 years (Table 21). The lowest water exchange activity at the polar glaciers is 8000 years. Since in this case slow water exchange is accompanied by the transition of water into a solid state, the masses of polar ice are preserved hydrosphere.

Table 20. Distribution of water masses in the hydrosphere

Parts of the hydrosphere	Share in world reserves, %
Parts of the hydrosphere	from total water reserves	from fresh water reserves
World Ocean
The groundwater
Glaciers and permanent snow cover
including in Antarctica
Groundwater in the permafrost zone



including fresh lakes
Water in the atmosphere
Total fresh water reserves
Total water reserves

Table 21. Water exchange activity of the hydrosphere (but to M.I. Lvovich, 1986)

* Taking into account underground flow into the ocean, bypassing rivers: 4200 years.

Table 21. Water exchange activity of the hydrosphere (according to M.I. Lvovich, 1986)

The hydrosphere has gone through a long path of evolution, repeatedly changing in mass, the ratio of individual parts, movement, the ratio of dissolved gases, suspended matter and other components, changes in which are recorded in the geological record, which is far from completely deciphered.

When did the hydrosphere appear on our planet? It turns out that it existed already at the very beginning of the geological history of the Earth.

As we already know, the Earth arose approximately 4.65 billion years ago. The oldest rocks found are 3.8 billion years old. They retained the imprints of single-celled organisms that lived in bodies of water. This allows us to judge that the primary hydrosphere appeared no later than 4 billion years ago, but it accounted for only 5-10% of its modern volume. According to one of the most widespread hypotheses today, water during the formation of the Earth appeared by melting and degassing of mantle matter(from Latin negative particles de and French gas- gas) - removal of dissolved gases from the mantle. Most likely, the impact (catastrophic) degassing of mantle matter caused by the fall of large meteorite bodies to the Earth initially played a major role.

Initially, the increase in the volume of the surface hydrosphere proceeded very slowly, since a significant part of the water was spent on other processes, including the addition of water to mineral substances (hydration, from the Greek. hydro- water). The volume of the hydrosphere began to grow rapidly after the rate of release of water bound in rocks exceeded the rate of their accumulation. At the same time, there was an entry into the hydrosphere. juvenile waters(from lat. juvenilis- young) - rich waters formed from oxygen and hydrogen released from magma.

Water is still released from magma, falling onto the surface of our planet during volcanic eruptions, during the formation of the oceanic crust in stretching zones of lithospheric plates, and this will continue to happen for many millions of years. The volume of the hydrosphere now continues to increase at a rate of about 1 km 3 of water per year. In this regard, it is expected that the volume of water in the World Ocean will increase by 6-7% over the next billion years.

Based on this, until quite recently, people were confident that water supplies would last forever. But in fact, due to the rapid pace of consumption, the quantity of water is sharply reduced, and its quality has also decreased sharply. Therefore, one of the most important problems today is the organization of rational use of water and its protection.

None of us doubts that water is the source of life. Ordinary water is the most amazing substance in nature.
The surface of the Earth occupied by water is 2.5 times larger than the land surface. There is no pure water in nature; it always contains impurities. Composition of water (by mass): 11.19% hydrogen and 88.81% oxygen.
Chemically pure water is a colorless, odorless and tasteless liquid.
Natural water is always a solution of various chemical compounds, mostly salts. In addition to various salts, gases are also dissolved in water. Modern methods of analysis have found two thirds of the chemical elements of the periodic table in sea water and, presumably, with the growth of technical capabilities, the remaining third will be discovered.

Water is the only liquid on Earth for which the dependence of specific heat capacity on temperature has a minimum. This minimum is realized at a temperature of +35 0 C. At the same time, the normal temperature of the human body, which consists of two-thirds (and even more at a young age) of water, is in the temperature range of 36-38 0 C.

The heat capacity of water is abnormally high. To heat a certain amount of it by one degree, it is necessary to expend more energy than when heating other liquids.

This results in the unique ability of water to retain heat. The vast majority of other substances do not have this property. This exceptional feature of water helps maintain a person’s normal body temperature at the same level both during a hot day and a cool night.

Water is the strongest universal solvent. If given enough time, it can dissolve almost any solid substance. It is precisely because of the unique dissolving ability of water that no one has yet managed to obtain chemically pure water - it always contains dissolved material from the vessel.

Only water is the only substance on the planet that can be in three states - liquid, solid and gaseous.

Sources of water and its types.

There is approximately 1,500 million km3 of water on Earth, with fresh water accounting for about 10% of the total planetary water supply. Water on the globe is located:
- in the world's oceans (salt waters),
- in the atmosphere,
- The groundwater,
- soil waters,
- in glaciers,
- in lakes and rivers,
- in plants and animals.
The main supply of fresh water consumed by humans is concentrated in lakes and rivers. We receive fresh water from the atmosphere (about 13 thousand km3) in the form of precipitation - rain and snow.
The world's oceans contain large reserves of water, which can be desalinated using various physicochemical methods.
Another source of water is living organisms. Plants and animals, which are two-thirds water, contain 6 thousand km3 of water.

Water and health.

Everyone knows the truth from childhood that water is the source of life. However, not everyone realizes and accepts the fact that water is the key to health and well-being. Everyone knows about the importance of water in our body. , these are not just words.
Present in all cells and tissues, playing a major role in all biological processes from digestion to blood circulation, water performs many important functions. Since a person consists of 65% (in old age) and 75% (in childhood) of water, naturally, it is absolutely necessary for all key human life support systems. It is found in human blood (79%) and promotes the dissolved transport of thousands of substances necessary for life through the circulatory system. Water is contained in lymph (96%), which carries nutrients from the intestines to the tissues of a living organism.
Adults lose 3.5 liters of water every day: half a liter of sweat, two liters of urine and a liter in the process of breathing. Therefore, our body constantly needs to replenish its supply of clean water.
Water is the most key ingredient for us to have a healthy body and well-being. Nothing affects our health more than water consumption. Water is necessary for digestion, for the functioning of the kidneys and liver. It removes toxins produced daily.
Lack of water in the body reduces immunity, and therefore the body’s resistance to various diseases. Dehydration can cause headaches, constipation, arthritis, and your skin will look dry and lose color and elasticity. And that is not all. Lack of water also causes apathy and we become vulnerable to stress.
A person can survive without water for no more than 3 days. Without moisture, both flora and fauna quickly wither and die.

Water is everywhere. It will not be difficult to consume it in any required quantities. A glass of water in the morning is especially important, since while we were sleeping, our body was deprived of an influx of water for several hours, so you should not start the day with strong tea or coffee, but rather start it with a glass of clean water.

How much water should you drink per day? Let's do the math... A person loses at least 10 glasses of liquid per day; with increased activity, consumption can increase to 1 liter per hour. It turns out that in order to feel great, our body needs to consume at least 8 glasses of water a day.

For water to provide maximum benefits, you need to drink it correctly. Moreover, there are both options for everyday use and for illnesses. By following simple rules, you can maintain your health and look great at any age.

You need to drink water before meals. The optimal time is 30 minutes before meals. This will prepare the digestive tract, especially for those who suffer from gastritis, duodenitis, heartburn, ulcers, colitis or other digestive disorders.
You should drink water whenever you feel thirsty, even while eating.
Water should be drunk 2.5 hours after eating to complete the digestion process and eliminate dehydration caused by the breakdown of food.
Water should be drunk in the morning immediately after waking up to eliminate dehydration caused by long sleep.
You should drink water before exercising to create a supply of free water for sweating.
Those who are prone to constipation and do not consume enough fruits and vegetables should drink water. Two or three glasses of water in the morning immediately after waking up act as the most effective laxative.”

Did you know that in the old days, young girls maintained skin tone in a very simple and cheap way. At a time when plastic surgery was unheard of, the “blooming appearance” (blood and milk) could be preserved for many years.
They were just not lazy, and in the morning they first washed their faces with hot water, and then immediately with ice water from the well. And so on several times. But then they didn’t wipe the face, but let it dry naturally.
Well water was considered “living water” and had unique properties of preserving youth and beauty.

Water is the source of life, the source of all life on our planet.