Water is an unusual substance that deserves a detailed study. The Soviet academician I. V. Petryanov wrote about this amazing substance the book “The Most Extraordinary Substance in the World”. What anomalies in the physical properties of water are of particular interest? Together we will seek an 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 the tops of mountains, as well as permafrost. Despite such a huge amount of water, only 1% is suitable for drinking.
Biological significance
The human body is 70-80% water. This substance ensures the course of all vital processes, in particular, thanks to it, toxins are removed from it, and cells are restored. The main function of water in a living cell is structural and energetic, 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, height of the area.
Basic concepts
H2O - hydrogen oxide, which contains 11.19% hydrogen, 88.81% oxygen by weight. It is a colorless liquid that has no odor or taste. Water is an indispensable component of technological processes in industry.
This substance was first synthesized at the end of the 18th century by G. Cavendish. The scientist exploded a mixture of oxygen and hydrogen by an electric arc. For the first time, G. Galilei 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 allowed us to study the relationship between saturated vapor pressure and temperature. In 1910, the American scientist P. Bridgman and the German G. Tamman discovered several polymorphic modifications of ice at high pressure.
In 1932, heavy water was discovered by American scientists G. Urey and E. Washburn. Anomalies in the physical properties of this substance were discovered due to improved equipment and research methods.
Some contradictions in physical properties
Pure water is a clear, colorless liquid. Its density when converted into a liquid from a solid increases, this shows an anomaly in the properties of water. Heating it from 0 to 40 degrees leads to an increase in density. As an anomaly of water, it is necessary to note the high heat capacity. The crystallization temperature is 0 degrees Celsius, and the boiling point is 100 degrees.
The molecule of this inorganic compound has an angular structure. The nuclei that make up its composition form an isosceles triangle, at the base of which are two protons, and the apex is an oxygen atom.
Density anomalies
Scientists were able to identify about forty features characteristic of H2O. Anomalies of water deserve close consideration and study. Scientists are trying to explain the reasons for each factor, to give it a scientific explanation.
The anomaly in the density of water lies in the fact that a given substance has its maximum density value at + 3.98 ° C. With subsequent cooling, transferring from a liquid to a solid state, a decrease in density is observed.
For other compounds, the density in liquids decreases with decreasing temperature, since an increase in temperature promotes 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 even with an increase in temperature, an increase in speed is characteristic, but the density decreases only at elevated temperature values.
After decreasing 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 with spatial periodicity.
If the molecules of ordinary compounds are densely packed in crystals, then after melting the substance, regularity disappears. A similar phenomenon is observed only when molecules are located at considerable distances. The decrease in density during the melting of metals is negligible, estimated at 2-4%. The density of water exceeds that of ice by 10 percent. Thus, this is a manifestation of water anomalies. Chemistry explains this phenomenon by the dipole structure, as well as by the covalent polar bond.
Compressibility Anomalies
We continue the conversation about the features of water. It is characterized by unusual temperature behavior. Its compressibility, that is, a decrease in volume, with increasing pressure can be considered an example of an anomaly in the physical properties of water. Specifically, what features should be noted here? Other liquids are much easier to compress under pressure, and water acquires such symptoms only at high temperatures.
Temperature behavior of specific heat
This anomaly is one of the strongest for water. Heat capacity indicates how much heat must be used in order to increase 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 melting ice, this physical quantity doubles. Not a single substance has a similar increase in heat capacity.
In ice, the energy that is supplied to it for heating is spent mainly on the increase in the speed of movement of molecules (kinetic energy). Significant growth after melting of the heat capacity indicates that other energy-intensive processes take place in the water, for which heat must be supplied. They are the reason for the increased heat capacity. This phenomenon is characteristic of the entire temperature range at which water has a liquid state of aggregation.
As soon as it turns into steam, the anomaly disappears. Currently, many scientists are analyzing the properties of supercooled water. It lies in its ability to maintain a liquid state below the crystallization point of 0 ° C.
It is quite possible to supercool water in thin capillaries, as well as in non-polar medium as tiny droplets. A logical question arises as to what is observed with the density anomaly in a similar situation. As supercooling, the density of water decreases significantly, it tends to the density of ice with decreasing temperature value.
Reasons for the appearance
When asked: “Name the anomalies of water and describe their causes”, it is necessary to connect 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. Between the water molecules there are hydrogen forces that remove this liquid from the relationship between the boiling and melting temperatures, which is characteristic of other substances in the liquid state of aggregation.
They appear between the molecules of this inorganic compound due to the peculiarities of the electron density distribution. Hydrogen atoms have a certain positive charge, and oxygen has a negative charge. As a result, the water molecule has the shape of a regular tetrahedron. A similar structure is characterized by a valence angle of 109.5 °. The most advantageous arrangement is the placement of oxygen and hydrogen having a different charge on the same line; therefore, the hydrogen bond is characterized by an electrostatic nature.
So, the unusual (abnormal) properties of water are a consequence of the special electronic structure of its molecule.
"Memory" of water
There is an opinion that water has memory, can accumulate and transfer energy, nourishing the body with virtual information. For a long time, this problem was addressed by the Japanese scientist Masaru Emoto. Dr. Emoto published the results of his research in the book “Messages of Water”. Scientists conducted experiments in which he first froze a drop of water at 5 degrees, and then analyzed the crystal structure under a microscope. To fix the results, he used a microscope in which a camera was built.
As part of the experiment, Masau Emoto acted on water in different ways, then it was frozen again, and he was taking photographs. He managed to get a relationship between the shape of ice crystals and the music that the water “listened” to. Surprisingly, the scientist recorded the most harmonious snowflakes when 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 discovery by Japanese scientists of the relationship between the form 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 areas 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.