Water is an unusual substance that deserves detailed study. The Soviet academician I. V. Petryanov wrote a book about this amazing substance, The Most Unusual Substance in the World. What anomalies in the physical properties of water are of particular interest? Together we will look for the answer to this question.
Interesting facts
We rarely think about the meaning of the word "water". On our planet, more than 70% of the total area is occupied by rivers and lakes, seas and oceans, icebergs, glaciers, swamps, snow on mountain tops, as well as permafrost. Despite such a huge amount of water, only 1% is drinkable.
Biological significance
The human body is 70-80% water. This substance ensures the flow of all vital processes, in particular, thanks to it, toxins are removed from it, cells are restored. The main function of water in a living cellis structural and energy, with a decrease in its quantitative content in the human body, it “shrinks”.
There is no such system in a living organism that could function without H2O. Despite the anomalies of water, it is a standard for determining the amount of heat, mass, temperature, altitude.
Basic concepts
H2O - hydrogen oxide, which contains 11.19% hydrogen, 88.81% oxygen by mass. It is a colorless liquid that has neither smell nor taste. Water is an essential component of industrial processes.
For the first time this substance was synthesized at the end of the 18th century by G. Cavendish. The scientist exploded a mixture of oxygen and hydrogen with an electric arc. G. Galileo first analyzed the difference in the density of ice and water in 1612.
In 1830, a steam engine was created by French scientists P. Dulong and D. Arago. This discovery made it possible to study the relationship between saturation vapor pressure and temperature. In 1910, the American scientist P. Bridgman and the German G. Tamman discovered several polymorphic modifications in ice at high pressure.
In 1932, American scientists G. Urey and E. Washburn discovered heavy water. Anomalies in the physical properties of this substance were discovered due to the improvement of equipment and research methods.
Some contradictions in physical properties
Pure water is a clear, colorless liquid. Its density when transformed into a liquid fromsolid matter increases, this manifests an anomaly in the properties of water. Heating it from 0 to 40 degrees leads to an increase in density. High heat capacity should be noted as an anomaly of water. The crystallization temperature is 0 degrees Celsius and the boiling point is 100 degrees.
The molecule of this inorganic compound has an angular structure. Its nuclei form an isosceles triangle with two protons at its base and an oxygen atom at its apex.
Density anomalies
Scientists have been able to identify about forty features characteristic of H2O. Water anomalies deserve close consideration and study. Scientists are trying to explain the causes of each factor, to give it a scientific explanation.
The anomaly of water density lies in the fact that this substance has its maximum value of density begins at +3, 98°C. With subsequent cooling, transferring from a liquid to a solid state, a decrease in density is observed.
For other compounds, the density in liquids decreases with decreasing temperature, since an increase in temperature contributes to an increase in the kinetic energy of molecules (their speed of movement increases), which leads to increased friability of the substance.
Considering such anomalies of water, it should be noted that it also tends to increase in velocity with increasing temperature, but the density decreases only at elevated temperatures.
After reducing the density of ice, it will be on the surface of the water. This phenomenon can be explained by the fact that the molecules in the crystal have a regular structure, which has a spatial periodicity.
If ordinary compounds have molecules tightly packed in crystals, then after the substance melts, the regularity disappears. A similar phenomenon is observed only when the molecules are located at considerable distances. The decrease in density during the melting of metals is a negligible value, estimated at 2-4%. The density of water exceeds that of ice by 10 percent. Thus, this is a manifestation of the water anomaly. Chemistry explains this phenomenon with a dipole structure, as well as a covalent polar bond.
Compressibility anomalies
Let's continue talking about the features of water. It is characterized by unusual temperature behavior. Its compressibility, that is, the decrease in volume, as the pressure increases, may well be considered an example of an anomaly in the physical properties of water. What specific features should be noted here? Other liquids are much easier to compress under pressure, and water takes on such characteristics only at high temperatures.
Temperature behavior of heat capacity
This anomaly is one of the strongest for water. Heat capacity tells you how much heat is needed to raise the temperature by 1 degree. For many substances, after melting, the heat capacity of the liquid increases by no more than 10 percent. And for water after the melting of ice, this physical quantity doubles. None of the substancesno such increase in heat capacity was recorded.
In ice, the energy that is supplied to it for heating is spent mostly on increasing the speed of movement of molecules (kinetic energy). A significant increase in the heat capacity after melting indicates that other energy-intensive processes occur in water, which require heat input. They are the reason for the increased heat capacity. This phenomenon is typical for the entire temperature range in which water has a liquid state of aggregation.
As soon as it turns into steam, the anomaly disappears. Currently, many scientists are engaged in the analysis of the properties of supercooled water. It lies in its ability to remain liquid below the crystallization point of 0°C.
It is quite possible to supercool water in thin capillaries, as well as in a non-polar medium as tiny droplets. A natural question arises as to what is observed with the density anomaly in such a situation. As water becomes supercooled, the density of water decreases significantly, it tends to the density of ice as the temperature decreases.
Reasons for appearance
When asked: "Name the anomalies of water and describe their causes", it is necessary to associate them with the restructuring of the structure. The arrangement of particles in the structure of any substance is determined by the features of the mutual arrangement of particles (atoms, ions, molecules) in it. Hydrogen forces act between water molecules, which remove this liquid from the dependence between boiling and melting points,characteristic of other substances that are in a liquid state of aggregation.
They appear between the molecules of a given inorganic compound due to the peculiarities of the electron density distribution. Hydrogen atoms have a certain positive charge, while oxygen atoms have a negative one. As a result, the water molecule has the shape of a regular tetrahedron. A similar structure is characterized by a bond angle of 109.5°. The most favorable arrangement is the placement of oxygen and hydrogen in the same line, having different charges, therefore, the hydrogen bond is characterized by an electrostatic nature.
So, the unusual (anomalous) properties of water are a consequence of the special electronic structure of its molecule.
Memory of water
There is an opinion that water has a memory, can accumulate and transfer energy, feeding the body with virtual information. For a long time, the Japanese scientist Masaru Emoto de alt with this problem. Dr. Emoto published the results of his research in the book Messages from Water. The scientists conducted experiments in which he first froze a drop of water at 5 degrees, and then analyzed the structure of the crystals under a microscope. To record the results, he used a microscope in which a camera was built.
As part of the experiment, Masau Emoto affected water in various ways, then re-frozen it, and took photographs. He managed to get the relationship between the shape of ice crystals and music,which the water listened to. Surprisingly, the scientist recorded the most harmonious snowflakes using classical and folk music.
The use of modern music, according to Masau, "pollutes" the water, so they were fixed crystals of irregular shape. An interesting fact is the identification by a Japanese scientist of the relationship between the shape of crystals and human energy.
Water is the most amazing substance that is found in large quantities on our planet. It is difficult to imagine any sphere of activity of a modern person in which she would not take an active part. The versatility of this substance is determined by anomalies caused by the tetrahedral structure of water.
