There are many factors that influence which water freezes faster, hot or cold, but the question itself seems a little odd. It is implied, and it is known from physics, that hot water still needs time to cool down to the temperature of comparable cold water to turn into ice. In cold water, this stage can be skipped, and, accordingly, it wins in time.
But the answer to the question of which water freezes faster - cold or hot - outside in frost, knows any resident northern latitudes... In fact, scientifically, it turns out that in any case, cold water simply must freeze faster.
The physics teacher, who was approached by schoolboy Erasto Mpemba in 1963 with a request to explain why the cold mixture of future ice cream freezes longer than a similar but hot one, thought the same way.
"This is not world physics, but some kind of Mpemba physics"
At that time, the teacher only laughed at this, but Deniss Osborne, a physics professor who at one time stopped by the same school where Erasto studied, experimentally confirmed the existence of such an effect, although there was no explanation for this then. In 1969 in the popular scientific journal a joint article was published by these two people who described this peculiar effect.
Since then, by the way, the question of which water freezes faster - hot or cold - has its own name - the effect, or paradox, of Mpemba.
The question arose for a long time
Naturally, such a phenomenon took place before, and it was mentioned in the works of other scientists. Not only the schoolboy was interested in this issue, but Rene Descartes and even Aristotle thought about it in their time.
Here are just approaches to solving this paradox began to look only at the end of the twentieth century.
Conditions for a paradox to occur
As with ice cream, it's not just ordinary water that freezes during the experiment. Certain conditions must be present in order to start arguing which water freezes faster - cold or hot. What influences the course of this process?
Now, in the 21st century, several options have been put forward that can explain this paradox. Which water freezes faster, hot or cold, may depend on the fact that it has a faster evaporation rate than that of cold water. Thus, its volume decreases, and with a decrease in volume, the freezing time becomes shorter than if we take a similar initial volume of cold water.
Defrost the freezer for a long time
Which water freezes faster, and why it happens, can be influenced by the snow lining that can be found in the freezer of the refrigerator used for the experiment. If you take two containers that are identical in volume, but one of them will contain hot water, and in the other - cold, container with hot water melts the snow underneath, thereby improving the contact of the thermal level with the wall of the refrigerator. Container with cold water he cannot do that. If there is no such lining with snow in the refrigerator compartment, cold water should freeze faster.
Top - Bottom
Also, the phenomenon of which water freezes faster - hot or cold, is explained as follows. Following certain laws, cold water begins to freeze from the upper layers, when hot water does it the other way around - it begins to freeze from bottom to top. In this case, it turns out that cold water, having a cold layer on top with ice already formed in places, thus worsens the convection processes and thermal radiation, thereby explaining which water freezes faster - cold or hot. Photo from amateur experiments is attached, and it is clearly visible here.
The heat goes out, tending upward, and there it meets a very cooled layer. There is no free path for heat radiation, so the cooling process becomes difficult. Hot water has no such obstacles on its way. Which one freezes faster - cold or hot, on which the probable outcome depends, you can expand the answer by the fact that any water has certain substances dissolved in it.
Impurities in water as a factor affecting outcome
If you do not cheat and use water with the same composition, where the concentrations of certain substances are identical, then cold water should freeze faster. But if a situation occurs when dissolved chemical elements available only in hot water, and cold water does not possess them, then there is an opportunity for hot water to freeze earlier. This is explained by the fact that solutes in water create crystallization centers, and with a small number of these centers, the transformation of water into a solid state is difficult. It is even possible overcooling of water, in the sense that at sub-zero temperatures it will be in liquid state.
But all these versions, apparently, did not completely suit the scientists and they continued to work on this issue. In 2013, a team of researchers in Singapore said they had solved an age-old mystery.
A group of Chinese scientists argues that the secret of this effect lies in the amount of energy that is stored between water molecules in its bonds, called hydrogen bonds.
Clue from Chinese Scientists
This is followed by information, for understanding which it is necessary to have some knowledge in chemistry in order to figure out which water freezes faster - hot or cold. As you know, it consists of two H (hydrogen) atoms and one O (oxygen) atom, held together by covalent bonds.
But also hydrogen atoms of one molecule are attracted to neighboring molecules, to their oxygen component. It is these bonds that are called hydrogen bonds.
It should be remembered that at the same time, water molecules are repulsive to each other. Scientists noted that when water heats up, the distance between its molecules increases, and this is due to the repulsive forces. It turns out that occupying one distance between the molecules in the cold state, one might say, they stretch, and they have a greater supply of energy. It is this store of energy that is released when water molecules begin to approach each other, that is, cooling occurs. It turns out that a greater supply of energy in hot water, and its greater release when cooled to subzero temperatures, occurs faster than in cold water, which has less such energy. So which water freezes faster - cold or hot? On the street and in the laboratory, the Mpemba paradox should occur, and hot water should turn into ice faster.
But the question is still open
There is only a theoretical confirmation of this clue - all this is written in beautiful formulas and seems plausible. But when the experimental data, which water freezes faster - hot or cold, are put in a practical sense, and their results are presented, then the question of the Mpemba paradox can be considered closed.
The good old formula H 2 O, it would seem, does not contain any secrets. But in fact, water - the source of life and the most famous liquid in the world - is fraught with many mysteries that sometimes even scientists cannot solve.
Here are the 5 most interesting facts about water:
1. Hot water freezes faster than cold water
Take two containers with water: pour hot water into one and cold water into the other, and place them in the freezer. Hot water will freeze faster than cold water, although logically, cold water should have been the first to turn into ice: after all, hot water must first cool down to cold temperature, and then turn into ice, while cold water does not need to cool down. Why is this happening?
In 1963, Erasto B. Mpemba, high school student high school in Tanzania, while freezing prepared ice cream mix, I noticed that hot mix solidifies faster in the freezer than cold mix. When the young man shared his discovery with the physics teacher, he only laughed at him. Fortunately, the student was persistent and convinced the teacher to conduct an experiment, which confirmed his discovery: certain conditions hot water does freeze faster than cold water.
Now this phenomenon of hot water freezing faster than cold water is called the "Mpemba effect". True, long before him this unique property water was noted by Aristotle, Francis Bacon and Rene Descartes.
Scientists still do not fully understand the nature of this phenomenon, explaining it either by the difference in hypothermia, evaporation, ice formation, convection, or by the effect of liquefied gases on hot and cold water.
Note from X.RU to the topic "Hot water freezes faster than cold water".
Since the issues of refrigeration are closer to us, refrigerators, we will allow ourselves to delve a little into the essence of this problem and give two opinions about the nature of such mysterious phenomenon.
1. A scientist from the University of Washington offered an explanation for a mysterious phenomenon known since the time of Aristotle: why hot water freezes faster than cold water.
The phenomenon called the Mpemba effect is widely used in practice. For example, experts advise motorists to pour cold, not hot, water into the washer reservoir in winter. But what lies at the heart of this phenomenon, for a long time remained unknown.
Dr. Jonathan Katz of the University of Washington investigated this phenomenon and concluded that important role substances dissolved in water play in it, which precipitate when heated, reports EurekAlert.
Under the dissolved substances dr Katz refers to the calcium and magnesium bicarbonates found in hard water. When the water is heated, these substances are deposited, forming scale on the walls of the teapot. Water that has never been heated contains these impurities. As it freezes and ice crystals form, the concentration of impurities in the water increases 50 times. This lowers the freezing point of water. "And now the water must still be cooling to freeze," explains Dr. Katz.
There is a second reason that prevents unheated water from freezing. Lowering the freezing point of water reduces the temperature difference between the solid and liquid phases. “Because the rate at which water loses heat is dependent on this temperature difference, water that has not been heated cools worse,” says Dr. Katz.
According to the scientist, his theory can be verified experimentally, since the Mpemba effect becomes more pronounced for harder water.
2. Oxygen plus hydrogen plus cold makes ice. At first glance, this transparent substance seems very simple. In reality, the ice is fraught with many mysteries. The ice created by the African Erasto Mpemba did not dream of fame. It was hot days. He wanted fruit ice... He would take a pack of juice and put it in the freezer. He did this more than once and therefore noticed that the juice freezes especially quickly, if you hold it in the sun beforehand - it’s really hot! This is strange, thought the Tanzanian schoolboy, who was acting contrary to worldly wisdom. Really, in order for the liquid to turn into ice faster, it must first be ... heated? The young man was so surprised that he shared his guess with the teacher. He reported this curiosity in the press.
This story happened back in the sixties of the last century. Now the "Mpemba effect" is well known to scientists. But for a long time this seemingly simple phenomenon remained a mystery. Why does hot water freeze faster than cold water?
It wasn't until 1996 that physicist David Auerbach found a solution. To answer this question, he conducted an experiment for a whole year: he heated water in a glass and cooled it again. So what did he find out? When heated, air bubbles dissolved in water evaporate. Water devoid of gases freezes more easily on the walls of the vessel. "Of course, water with a high air content will freeze too," says Auerbach, "but not at zero degrees Celsius, but only at minus four or six degrees." Obviously, the wait will take longer. So, hot water freezes before cold water, this is a scientific fact.
There is hardly a substance that would appear before our eyes with the same ease as ice. It consists only of water molecules - that is, elementary molecules containing two hydrogen atoms and one oxygen. However, ice is arguably the most mysterious substance in the universe. Scientists have not yet been able to explain some of its properties.
2. Supercooling and "instant" freezing
Everyone knows that water always turns to ice when cooled down to 0 ° C ... except in some cases! Such a case, for example, is "overcooling", which is a property of very pure water remain liquid even when cooled to below freezing point. This phenomenon becomes possible due to the fact that environment does not contain centers or nuclei of crystallization that could provoke the formation of ice crystals. And therefore, water remains in liquid form, even when cooled to temperatures below zero degrees Celsius. The crystallization process can be triggered, for example, by gas bubbles, impurities (contaminants), or an uneven surface of the container. Without them, water will remain liquid. When the crystallization process starts, you can observe how supercooled water instantly turns into ice.
Watch the video (2 901 Kb, 60 sec) from Phil Medina (www.mrsciguy.com) and see for yourself >>
Comment. Superheated water also remains liquid, even when heated to a temperature above the boiling point.
3. "Glass" water
Quickly and without hesitation, name how much different conditions does the water have?
If you answered three (solid, liquid, gaseous), then you are wrong. Scientists distinguish at least 5 different states of liquid water and 14 states of ice.
Remember the conversation about supercooled water? So, no matter what you do, at a temperature of -38 ° C, even the purest supercooled water suddenly turns into ice. What happens with a further decrease
temperature? At -120 ° C, something strange begins to happen to water: it becomes super-viscous or viscous, like molasses, and at temperatures below -135 ° C, it turns into "glass" or "glassy" water - a solid that lacks crystalline structure.
4. Quantum properties of water
At the molecular level, water is even more surprising. In 1995, a neutron scattering experiment conducted by scientists gave an unexpected result: physicists found that neutrons aimed at water molecules "see" 25% fewer hydrogen protons than expected.
It turned out that an unusual quantum effect takes place at a speed of one attosecond (10 -18 seconds), and chemical formula water instead of the usual - H 2 O, becomes H 1.5 O!
5. Does water have a memory?
Homeopathy, an alternative to mainstream medicine, claims that diluted solution medicinal product can have a therapeutic effect on the body, even if the dilution factor is so great that nothing but water molecules is left in the solution. Proponents of homeopathy explain this paradox by a concept called "memory of water", according to which water at the molecular level has a "memory" of a substance that was once dissolved in it and retains the properties of a solution of its original concentration after not a single molecule of an ingredient remains in it.
An international team of scientists led by Professor Madeleine Ennis of Queen's University of Belfast, who criticized the principles of homeopathy, conducted an experiment in 2002 to refute this concept once and for all. which, the scientists said that they were able to prove the reality of the effect of "memory of water." However, experiments conducted under the supervision of independent experts have not yielded results.Disputes about the existence of the phenomenon of "memory of water" continue.
Water has many others unusual properties, which we did not talk about in this article.
Literature.
1.5 Really Weird Things About Water / http://www.neatorama.com.
2. The mystery of water: the theory of the Aristotle-Mpemba effect has been created / http://www.o8ode.ru.
3. Nepomnyashchy N.N. Secrets of inanimate nature. The most mysterious substance in the universe / http://www.bibliotekar.ru.
Many researchers have put forward and are putting forward their own versions as to why hot water freezes faster than cold water. It would seem a paradox - after all, in order to freeze, hot water first needs to cool down. However, the fact remains, and scientists explain it in different ways.
Major versions
On the this moment There are several versions that explain this fact:
- As hot water evaporates faster, its volume decreases. Less water of the same temperature freezes faster.
- The freezer compartment of the refrigerator has a snow pad. The hot water container melts the snow underneath. This improves the thermal contact with the freezer.
- The freezing of cold water, unlike hot water, starts from the top. In this case, convection and heat radiation, and, consequently, heat loss, worsen.
- In cold water there are crystallization centers - substances dissolved in it. With a small content of them in water, icing is difficult, although at the same time, it may be overcooled - when at sub-zero temperatures it has a liquid state.
Although in fairness it can be said that this effect is not always observed. Very often cold water freezes faster than hot water.
At what temperature does water freeze
Why does water freeze at all? It contains a certain amount of mineral or organic particles. These, for example, can be very fine particles of sand, dust or clay. When the air temperature drops, these particles are centers around which ice crystals form.
The role of crystallization nuclei can also be played by air bubbles and cracks in a container containing water. The speed of the process of turning water into ice is largely influenced by the number of such centers - if there are many of them, the liquid freezes faster. Under normal conditions, with normal atmospheric pressure, the water goes into solid state from liquid at a temperature of 0 degrees.
The essence of the Mpemba effect
The Mpemba effect is understood as a paradox, the essence of which is that under certain circumstances hot water freezes faster than cold water. This phenomenon was noticed by Aristotle and Descartes. However, it was not until 1963 that a student from Tanzania, Erasto Mpemba, determined that hot ice cream freezes in more than a short time than cold. This is the conclusion he made while carrying out a cooking assignment.
He had to dissolve sugar in boiled milk and, after cooling it, place it in the refrigerator to freeze. Apparently, Mpemba did not differ in special zeal and began to perform the first part of the assignment with a delay. Therefore, he did not wait for the milk to cool, and put it in the refrigerator hot. He was very much surprised when it froze even faster than his classmates, who performed the work in accordance with the given technology.
The young man was very interested in this fact, and he began experiments with plain water. In 1969, Physics Education published the research results of Mpemba and Professor Dennis Osborne of the University of Dar es Salaam. The effect they described was named Mpemba. However, even today there is no clear explanation for the phenomenon. All scientists agree that the main role in this difference between the properties of chilled and hot water belongs, but it is not known exactly which one.
Singapore version
Physicists from one of the Singapore universities were also interested in the question, which water freezes faster - hot or cold? A team of researchers led by Xi Zhang explained this paradox precisely by the properties of water. Everyone still knows the composition of water from school - an oxygen atom and two hydrogen atoms. Oxygen to some extent pulls electrons away from hydrogen, so the molecule is a kind of "magnet".
As a result, certain molecules in water are slightly attracted to each other and are united by a hydrogen bond. Its strength is many times lower than the covalent bond. Singaporean researchers believe that the explanation for the Mpemba paradox lies in hydrogen bonds. If the water molecules are very densely placed among themselves, then such a strong interaction between the molecules can deform the covalent bond in the middle of the molecule itself.
But when the water is heated, the bound molecules move slightly away from each other. As a result, in the middle of the molecules, relaxation of covalent bonds occurs with the release of excess energy and a transition to a lower energy level... This leads to the fact that hot water begins to rapidly cool. By at least, as shown by theoretical calculations carried out by Singaporean scientists.
Instant freezing of water - 5 incredible tricks: Video
Mpemba effect(Mpemba paradox) - a paradox that says that hot water freezes faster under certain conditions than cold water, although it must pass the temperature of cold water during the freezing process. This paradox is an experimental fact that contradicts the usual concepts, according to which, under the same conditions, a more heated body to cool to a certain temperature takes longer than a less heated body to cool to the same temperature.
This phenomenon was noticed at the time by Aristotle, Francis Bacon and Rene Descartes, but it was not until 1963 that a Tanzanian schoolboy Erasto Mpemba found that a hot ice cream mixture freezes faster than a cold one.
As a student at Magamba High School in Tanzania, Erasto Mpemba did practical work on the cookery business. He needed to make homemade ice cream - boil milk, dissolve sugar in it, cool it to room temperature and then refrigerate to freeze. Apparently, Mpemba was not a particularly diligent student and he delayed completing the first part of the assignment. Fearing that he would not be in time by the end of the lesson, he put the hot milk in the refrigerator. To his surprise, it froze even earlier than the milk of his comrades, prepared according to a given technology.
After that, Mpemba experimented not only with milk, but also with ordinary water. In any case, already being a student of the Mkvavskaya high school, he asked a question to Professor Dennis Osborne from university college in Dar-es-Salaam (invited by the headmaster to give the students a lecture on physics) specifically about water: "If we take two identical containers with equal volumes of water so that in one of them the water has a temperature of 35 ° C, and in the other - 100 ° C, and put them in the freezer, then in the second the water will freeze faster. Why? " Osborne became interested in this issue and soon in 1969 he and Mpemba published the results of their experiments in the journal "Physics Education". Since then, the effect they discovered is called Mpemba effect.
Until now, no one knows exactly how to explain this strange effect. Scientists do not have a single version, although there are many. It's all about the difference in the properties of hot and cold water, but it is not yet clear which properties play a role in this case: the difference in supercooling, evaporation, ice formation, convection, or the effect of liquefied gases on water at different temperatures.
The paradox of the Mpemba effect is that the time during which a body cools down to ambient temperature should be proportional to the difference in temperatures between this body and the environment. This law was established by Newton and since then has been confirmed many times in practice. In this effect, water with a temperature of 100 ° C cools down to a temperature of 0 ° C faster than the same amount of water with a temperature of 35 ° C.
However, this does not yet suggest a paradox, since the Mpemba effect can be explained within the framework of well-known physics. Here are some explanations for the Mpemba effect:
Evaporation
Hot water evaporates faster from the container, thereby reducing its volume, and a smaller volume of water with the same temperature freezes faster. Water heated to 100 C loses 16% of its mass when cooled to 0 C.
Evaporation effect - double effect. First, the amount of water required for cooling is reduced. And secondly, the temperature decreases due to the fact that the heat of vaporization of the transition from the water phase to the vapor phase decreases.
Temperature difference
Due to the fact that the temperature difference between hot water and cold air is greater - therefore, heat exchange in this case is more intense and hot water cools faster.
Hypothermia
When water is cooled below 0 C, it does not always freeze. Under some conditions, it can undergo hypothermia, continuing to remain liquid at temperatures below the freezing point. In some cases, water can remain liquid even at a temperature of -20 C.
The reason for this effect is that in order for the first ice crystals to begin to form, centers of crystal formation are needed. If they are not present in liquid water, then hypothermia will continue until the temperature drops so much that crystals begin to form spontaneously. When they begin to form in a supercooled liquid, they will begin to grow faster, forming an ice slush, which, freezing, will form ice.
Hot water is most susceptible to hypothermia because heating it removes dissolved gases and bubbles, which in turn can serve as centers for the formation of ice crystals.
Why does hypothermia cause hot water to freeze faster? In the case of cold water, which is not supercooled, the following occurs. In this case, a thin layer of ice will form on the surface of the vessel. This layer of ice will act as an insulator between the water and cold air and will prevent further evaporation. The rate of formation of ice crystals in this case will be slower. In the case of hot water subject to supercooling, supercooled water does not have a protective surface layer of ice. Therefore, it loses heat much faster through the open top.
When the hypothermia process ends and the water freezes, much more heat is lost and therefore more ice forms.
Many researchers of this effect consider hypothermia to be the main factor in the case of the Mpemba effect.
Convection
Cold water begins to freeze from above, thereby worsening the processes of heat radiation and convection, and hence the loss of heat, while hot water begins to freeze from below.
This effect is explained by the water density anomaly. Water has a maximum density at 4 C. If you cool water to 4 C and put it at a lower temperature, the surface layer of water will freeze faster. Because this water is less dense than water at 4 ° C, it will remain on the surface, forming a thin, cold layer. Under these conditions, a thin layer of ice will form on the surface of the water for a short time, but this layer of ice will serve as an insulator protecting the lower layers of water, which will remain at a temperature of 4 C. Therefore, the further cooling process will be slower.
In the case of hot water, the situation is completely different. The surface layer of water will cool faster due to evaporation and more difference temperatures. In addition, the cold water layers are denser than the hot water layers, so the cold water layer will sink down, raising the layer warm water to the surface. This circulation of water ensures a rapid drop in temperature.
But why does this process fail to reach an equilibrium point? To explain the Mpemba effect from this point of view of convection, it should be assumed that cold and hot layers of water are separated and the convection process itself continues after the average water temperature drops below 4 C.
However, there is no experimental data that would support this hypothesis that cold and hot layers of water are separated by convection.
Gases dissolved in water
Water always contains gases dissolved in it - oxygen and carbon dioxide... These gases have the ability to reduce the freezing point of water. When the water is heated, these gases are released from the water, since their solubility in water at high temperature below. Therefore, when hot water is cooled, there is always less dissolved gases in it than in unheated cold water. Therefore, the freezing point of heated water is higher and it freezes faster. This factor is sometimes considered as the main one in explaining the Mpemba effect, although there are no experimental data confirming this fact.
Thermal conductivity
This mechanism can play a significant role when water is placed in a refrigerator compartment in small containers. Under these conditions, it was noticed that the container with hot water melts the ice of the freezer under it, thereby improving thermal contact with the freezer wall and thermal conductivity. As a result, heat is removed from a container with hot water faster than from cold water. In turn, the container with cold water does not thaw snow under it.
All these (as well as others) conditions have been studied in many experiments, but an unambiguous answer to the question - which of them provide one hundred percent reproduction of the Mpemba effect - has not been obtained.
For example, in 1995 the German physicist David Auerbach studied the effect of supercooling of water on this effect. He found that hot water, reaching a supercooled state, freezes at a higher temperature than cold water, which means faster than the latter. But cold water reaches a supercooled state faster than hot water, thereby compensating for the previous lag.
In addition, Auerbach's results contradicted earlier findings that hot water can achieve greater hypothermia due to fewer crystallization centers. When water is heated, gases dissolved in it are removed from it, and when it is boiled, some salts dissolved in it precipitate.
So far, only one thing can be asserted - the reproduction of this effect essentially depends on the conditions in which the experiment is carried out. Precisely because it is not always reproduced.
Water- a fairly simple substance from a chemical point of view, but at the same time it has a number of unusual properties that never cease to amaze scientists. Below are some facts that few people know about.
1. Which water freezes faster - cold or hot?
Take two containers with water: pour hot water into one and cold water into the other, and place them in the freezer. Hot water will freeze faster than cold water, although logically, cold water should have been the first to turn into ice: after all, hot water must first cool down to cold temperature, and then turn into ice, while cold water does not need to cool down. Why is this happening?
In 1963, a Tanzanian student named Erasto B. Mpemba, while freezing a prepared ice cream concoction, noticed that the hot concoction hardened faster in the freezer than the cold concoction. When the young man shared his discovery with the physics teacher, he only laughed at him. Fortunately, the student was persistent and convinced the teacher to conduct an experiment, which confirmed his discovery: under certain conditions, hot water really freezes faster than cold water.
Now this phenomenon of hot water freezing faster than cold water is called “ Mpemba effect". True, long before him this unique property of water was noted by Aristotle, Francis Bacon and Rene Descartes.
Scientists still do not fully understand the nature of this phenomenon, explaining it either by the difference in hypothermia, evaporation, ice formation, convection, or by the effect of liquefied gases on hot and cold water.
2. She is able to freeze instantly
Everybody knows that water always turns to ice when cooled to 0 ° C ... except in some cases! Such a case, for example, is supercooling, which is the property of very pure water to remain liquid even when cooled to below freezing point. This phenomenon becomes possible due to the fact that the environment does not contain centers or nuclei of crystallization, which could provoke the formation of ice crystals. And therefore, water remains in liquid form, even when cooled to temperatures below zero degrees Celsius.
Crystallization process can be triggered, for example, by gas bubbles, impurities (dirt), an uneven surface of the container. Without them, water will remain liquid. When the crystallization process starts, you can observe how supercooled water instantly turns into ice.
Note that "superheated" water also remains liquid, even when heated to temperatures above its boiling point.
3.19 states of water
Without hesitation, name how many different states water has? If you answered three: solid, liquid, gaseous, then you are mistaken. Scientists distinguish at least 5 different states of water in liquid form and 14 states in frozen form.
Remember the conversation about supercooled water? So, whatever you do, at a temperature of -38 ° C, even the purest supercooled water will suddenly turn into ice. What happens if the temperature drops further? At -120 ° C, something strange begins to happen to water: it becomes super-viscous or viscous, like molasses, and at temperatures below -135 ° C, it turns into "glass" or "glassy" water - a solid that lacks crystalline structure.
4. Water surprises physicists
At the molecular level, water is even more surprising. In 1995, a neutron scattering experiment conducted by scientists gave an unexpected result: physicists found that neutrons aimed at water molecules "see" 25% fewer hydrogen protons than expected.
It turned out that at a speed of one attosecond (10 -18 seconds) an unusual quantum effect takes place, and the chemical formula of water instead of H2O, becomes H1.5O!
5. Memory of water
Alternative to mainstream medicine homeopathy states that a diluted solution of a drug can have a healing effect on the body, even if the dilution factor is so high that nothing but water molecules is left in the solution. Homeopathic proponents attribute this paradox to a concept called “ memory of water", According to which water at the molecular level has a" memory "of a substance that was once dissolved in it and retains the properties of a solution of its original concentration after not a single molecule of an ingredient remains in it.
An international group of scientists, led by Professor Madeleine Ennis of Queen's University of Belfast, who criticized the principles of homeopathy, conducted an experiment in 2002 to refute this concept once and for all. The result was the opposite. After that, the scientists said that they were able to prove the reality of the effect " memory of water". However, experiments carried out under the supervision of independent experts did not yield any results. Disputes about the existence of the phenomenon " memory of water"Continue.
Water has many other unusual properties that we haven't covered in this article. For example, the density of water changes with temperature (ice is less dense than water); water has a fairly high surface tension; in a liquid state, water is a complex and dynamically changing network of water clusters, and it is the behavior of the clusters that affects the structure of water, etc.
About these and many other unexpected features water can be read in the article “ Abnormal properties of water"By Martin Chaplin, professor at the University of London.
