As soon as the water freezes, it is hot or cold. The mpembi effect, why does hot water freeze faster than cold water? Why does water freeze faster than cold or hot water?

Hello, dear lovers of facts. Today we will talk about. But I think that what is included in the title of the food may seem simply absurd - if only we should once again trust the unsparingly woeful “healthy gut”, and not the clumsily delivered verification evidence. Let's try to figure out why hot water freezes faster and is colder?

Historical background

That in a diet of frozen cold and hot water “not everything is pure” was already understood in the words of Aristotle, then similar notes were made by F. Bacon, R. Descartes and J. Black. In modern history, this effect has been given the name “Mpembi’s Paradox” - after the name of a student from Tanganyika, Erasto Mpembi, who put the same problem on a foreign physics professor.

The boy's nutrition was not lost on an empty machine, but because of special care in the process of cooling the freezer bags in the kitchen. Surprisingly, the present classmates and the school teacher made Mpemba laugh - after an experimental verification by especially Professor D. Osborne, the fear of making fun of Erasto “disappeared” from them. Moreover, Mpemba, together with Professor Roku, published a detailed description of this effect in Physics Education in 1969 - and from that time the name became entrenched in the scientific literature.

What is the essence of the appearance?

The setup is quite simple: for other equals, try new thin-walled vessels, they contain very equal amounts of water, which are affected by temperature. Place the dishes in the refrigerator, after which an hour will pass until the ice has dissolved in the skin. The paradox lies in the fact that in a vessel with a hotter environment, it appears faster.

How does everyday physics explain this?

There is no universal explanation for the paradox, since a number of parallel processes are constantly proceeding, the contributions of which can be subdivided from specific cob minds - but with the same result:

the age of the country before hypothermia - the water is initially cold until hypothermia, then. is deprived of rare food if the temperature is below the freezing point
accelerated cooling - steam from hot water is transformed into microcrystals of ice, which, when falling back, accelerate the process, acting as an additional “external heat exchanger”
insulation effect - when hot, cold water freezes the animal, which leads to a change in heat transfer by convection and vibration

Є є low explanatory (the rest of the rests on the stir on the gypotesis of the British Korolivskka XIMICHNYA, the partnership was unschyodally, 2012)-ale of unequivocal vipadkіv combinatical minds ...

The British Royal Chemical Partnership is donating 1 thousand pounds sterling to anyone who can scientifically explain why in some episodes of hot water freezes faster than cold.

“Current science is still unable to provide evidence on this simple nutrition at first glance. Freezer makers and bartenders use this effect in their daily work, but no one really knows what they are doing. This problem has been known for thousands of years, and philosophers such as Aristotle and Descartes have discussed it,” said the President of the British Royal Chemical Partnership, Professor David Phillips, as stated in the press release of the Partnership.

A British physics professor's success as a cook from Africa

This is not pepper-and-butter heat, but rather physical reality. No science, which easily operates with galaxies and black holes, which are giant scourges for the search for quarks and bosons, cannot explain how elemental water “works.” The school handbook clearly states that it takes more than an hour to cool a hot body, but less to cool a cold body. And the axis for water will not be adjusted forever. This phenomenon was brought to the attention of Aristotle in the 4th century BC. e. As the ancient Greek wrote in the book “Meteorologica I”: “The fact that the water is heated in advance melts away its freezing. There are many people who, if they want to cool hot water as quickly as possible, put it in the sun...” In the Middle Ages, Francis Bacon and Rene Descartes tried to explain this phenomenon. Unfortunately, neither the great philosophers nor the great scientists learned how to develop classical thermophysics, and they have long forgotten about such an inescapable fact.

It was only in 1968 that fate was “guessed” by schoolchildren Erasto Mpembe from the distant science of Tanzania. Having started at the school of cookery mysticism, in 1963 the 13th river Mpembe set aside the task of making frost. The technology required boiling the milk, grinding it into a bowl, cooling it to room temperature, and then putting it in the refrigerator to freeze. Obviously, Mpemba has not studied too hard and has gotten tired of it. Afraid that you wouldn’t finish the lesson, you put hot milk in the refrigerator. On this occasion, it was frozen earlier, and the milk of my comrades was prepared according to all the rules.

When Mpemba shared his words with the physics teacher, he made him laugh in front of the whole class. Mpemba is remembered in the image. Five years later, while a student at the university in Dar es Salaam, he attended a lecture by the famous physicist Denis G. Osborne. After the lecture, he asked the following question: “You will take two equal containers of water, one at 35 °C (95 °F), and the other at 100 °C (212 °F), and place them in the freezer nick, then The water in a hot container freezes faster. Why? You can see the reaction of the British professor to the nutrition of a young man from God-forsaken Tanzania. He mocked the student. However, Mpemba was ready for such a scenario and called for a mortgage. This super test ended with an experimental re-verification, which confirmed Mpembi’s correctness and Osborne’s defeat. Thus, the scientist-cook entered her name into the history of science, and from now on this phenomenon is called the “Mpembi effect”. Throw him out, shout him out, as if he were not going out. The reality is clear, and, as the writer sings, “I don’t set foot in the tooth.”

Winnie the powder and break up the speech?

Over the years, many people have tried to unravel the secret chamber of freezing water. A whole bunch of explanatory phenomena have been identified: evaporation, convection, infusion of dissolved substances - but from these factors it is not possible to recognize the residual. The low vchenih dedicated her entire life to the Mpemba effect. A scientist at the Department of Radiation Safety at the State University of New York, James Brownridge, has been studying the paradox for a decade now. Having conducted hundreds of experiments, studies confirm that hypothermia may be “to blame.” Brownridge explains that above 0°C the water becomes supercooled, and begins to freeze when the temperature drops lower. The freezing point is regulated by houses located near the water - they themselves change the fluidity of the formation of ice crystals. Houses, and therefore powders, bacteria and dissolved salts, exhibit their characteristic nucleation temperature when ice crystals are formed around the centers of crystallization. If the water contains several elements, the freezing temperature is determined by which of them will be the nucleation temperature.

To confirm, Brownridge took two samples of water at the same temperature and placed them in the freezer. It was discovered that one of the specimens always freezes before the other - most likely, through a different house.

Brownridge hardens that hot water reaches a greater difference between the temperatures of the water and the freezer - which helps it reach its freezing point first, the lower cold water reaches its natural freezing point, which is lower What, let’s say, at 5°C.

Meanwhile, the city of Brownridge is richly nourished. Those who are able to explain the Mpembi effect in their own way may have a chance to compete for a thousand pounds sterling from the British Royal Chemical Partnership.

When the water freezes, hot or cold, a lot of factors flow in, and the food itself turns out to be a little surprising. It is understandable, and it is clear from physics, that hot water still needs an hour to cool down to the temperature of poured cold water in order to turn into ice. This stage can be skipped, but, apparently, the hour will win.

Let’s talk about how water freezes whether it’s cold or hot – it’s frosty outside, you know, whatever the scumbag of the snowy latitudes is. In fact, in a scientific way, it turns out that in any case, cold water is simply to blame for the cold water.

Having thought the same way, the teacher of physics, to what extent the schoolboy Erasto Mpemba in 1963 went crazy to explain why the cold sum of the next frost freezes above, below the same, and then hot.

“This is not universal physics, but rather Mpembi physics”

That time, the reader just laughed at this, aka Denis Osborne, a professor of physics, who just arrived at the same school, where Erasto began, experimentally confirming the presence of such an effect, although there was no explanation yet Xia. In 1969, a popular scientific journal published a comprehensive article by two people who described this effect.

From now on, before speaking, the story is about how the water often freezes - hot or cold, it may be called a breeze - an effect, or a paradox, Mpembi.

Food has been going on for a long time

Naturally, such a phenomenon used to exist in the past, and in the works of other scientists. It was not only the schoolchildren who ate these meals, but also René Descartes and Aristotle who thought about it.

It was only until the end of the 20th century that people began to joke about this paradox.

Think about it so that there is a paradox

As with frost, it’s not just the original water that freezes during the experiment. It is up to you to sing your mind in order to begin to resist, as the water freezes either cold or hot. What does it mean to interrupt this process?

Now, in the 21st century, there are a number of options that can explain this paradox. Those whose water freezes sooner, hot or cold, can be stored due to the greater liquidity of evaporation in the lower cold. In this way, its volume changes, and with a changed volume, the freezing time becomes shorter than if you take the same volume of cold water.

The freezer has been frozen for a long time

If the water freezes sooner, and why not, you can insert a snow lining, which can be placed in the refrigerator that is being used for the experiment. If you take two containers that are identical, but in one of them there will be hot water, and in the other - cold, melt the snow under the container with hot water, thereby reducing the contact of the thermal surface with the wall of the refrigerator. We can’t make a container like this with cold water. Since there is no such lining due to snow in the refrigerator compartment, cold water is responsible for the increase.

Top - bottom

It is also a phenomenon that water freezes more often - hot or cold, it is explained as follows. Following the same laws, cold water starts to freeze from the top, and when it gets hot, it starts to freeze from the bottom up. When it turns out that the water is cold, looming for the beast a cold bowl of ice, which has already settled in places, is absorbed in this process of convection and thermal vibration, this explains how water freezes either cold or hot. Photos from amateur experiments are included and are clearly visible.

The heat comes out, rushes uphill, and there it meets with the evenly cooled ball. There is no good way for heat transfer, so the cooling process becomes complicated. Hot water does not harm such people on their way. Whether it freezes or is cold or hot, where possible results can be obtained, we can expand the idea that whether the water has a song or a speech, it will be disturbed.

Houses near the water storage as a factor that influences the result

If you do not shake and vikorize the water from the same storage, where the concentrations of the active substances are identical, then the cold water is liable to freeze faster. If there is a situation when chemical elements are broken down in hot water, and cold water does not contain water, then there is a possibility of hot water freezing earlier. It is explained that the dissolution of the substances in water creates crystallization centers, and for a small number of these centers, the transformation of water in solids becomes more difficult. It is possible to cause supercooling of the water, because at sub-zero temperatures it is rarely possible.

But all these versions, perhaps, were not completely followed and they continued to work on these foods. In 2013, a team of investigators near Singapore announced that they had solved an age-old mystery.

A group of Chinese studies confirm that the secret of this effect lies in the amount of energy stored between water molecules in their bonds, which are called water molecules.

The solution to Chinese legends

Below you will find information that requires some knowledge of chemistry to understand how water freezes whether it is hot or cold. Apparently, it consists of two H atoms (water) and one atom (acid), which are bonded together by covalent bonds.

Also, the water atoms of the same molecules are attracted to the liquid molecules, to their acid storage. Such connections themselves are called water connections.

Remember that at the same time the water molecules are the same. It has already been shown that when the water is heated, the formation between the molecules increases, and this creates a force that acts as a force. It turns out that when you occupy one space between the molecules in a cold state, you can say they stretch out, and they have a larger supply of energy. This energy reserve itself changes when water molecules begin to approach one another, and cooling occurs. It turns out that hot water has a greater reserve of energy, and its greater intensity when cooled to sub-zero temperatures is observed sooner than that of cold water, which has a smaller reserve of such energy. So how does water freeze sooner - cold or hot? On the street and in the laboratory, Mpembi's paradox may occur, and hot water may turn into ice.

Ale food still open

There is no theoretical confirmation of this solution - everything is written in beautiful formulas and seems believable. If the data from experiments on how water often freezes - hot or cold, will be put into practical sense, and their results will be presented, then it will be possible to close the nutritional paradox of Mpemby.

In this article we will look at why hot water freezes faster than cold water.

Heated water freezes faster, lower cold! The power of water is amazing, and no one can really explain it until recently. For example, even in Aristotle there is a description of winter fishing: fishermen inserted rods into openings in the ice, and so that the stinks froze more quickly, they poured warm water on the ice. The name of this discovery was named after Erasto Mpembi in the 60s of the 20th century. The membrane noted a wonderful effect when cooked frosty, and went on an explanation to his contribution to physics - Dr. Denis Osborne. Mpemba and Dr. Osborne experimented with water at different temperatures and developed a concept: some boiling water begins to freeze faster, and some water is at room temperature. Others have carried out similar experiments in the past and have soon found similar results.

Explanation of the physical phenomenon

There is still no clear explanation of why this is so exciting. Many followers assume that everything on the right is in the supercooled middle, which is expected when its temperature drops below the freezing temperature. Otherwise, if water freezes at a temperature below 0°W, then supercooled water can reach a temperature of, for example, -2°W, which will result in the rare possibility of turning into ice. If we try to freeze cold water, it is likely that it will become too cold right away, and it will harden within an hour. Heated water undergoes other processes. This mixture is quickly transformed into ice due to convection.

Convection- This is a physical phenomenon in which the lower balls of the middle rise, and the upper ones, when cool, fall.

A short explanation of why hot water freezes faster

It turns out that the middle of the sky itself mixes and settles. When the convection process in the heated water is active, the ice crystals from the surface sink quickly and cool the warm water at the bottom.

Many of the followers hung and hung their versions so that hot water freezes sooner than cold. It would seem like a phenomenon - even in order to freeze, hot water is needed to cool the cob. However, the fact is deprived of the fact, and it will continue to be explained in different ways.

At the moment, there are a number of versions that explain this fact:

Residues evaporated in hot water become faster and must change. And if less water freezes, the temperature rises faster.
The freezer compartment of the refrigerator is covered with snow. The container containing the hot water melts the snow underneath it. This causes the thermal contact with the freezer to decrease.
Cold water freezing when hot water begins to freeze. In this case, convection and heat transfer, therefore, the thermal decline will worsen.
Cold water has crystallization centers - its speech is disrupted. When the temperature is low, freezing in the water is more difficult, although at the same time hypothermia is possible – if at sub-zero temperatures it becomes rare.

For the sake of fairness, we can say that this effect cannot be avoided forever. Most often, cold water freezes faster than hot water.

At what temperature does water freeze?

Why does water freeze? This warehouse contains a large number of mineral and organic particles. This, for example, can be even smaller particles of sand, saw or clay. At low temperatures, these particles become centers around which crystal crystals are formed.

The role of crystallization nuclei can be played by wind bulbs and cracks in the container where water is placed. During the process of converting water into ice, a large number of such centers flow into the fluid - since there are a lot of them, the center freezes sooner. For the most extreme minds, with normal atmospheric pressure, water passes from a solid state to a rare one at a temperature of 0 degrees.

The essence of the Mpembi effect

Under the effect of Mpembi, one understands the paradox, the essence of which is that hot water freezes faster than cold water. This phenomenon was first noted by Aristotle and Descartes. Prote in 1963, a schoolboy from Tanzania, Erast Mpemba, noted that the hotter freezes in a shorter hour, the colder it is. Having acquired such a mastery, we signed off on the kitchen's certificate.

You should chop up the zukor in the boiled milk and, after cooling it, place it in the refrigerator to freeze. Respecting everything, Mpemba, with special diligence, did not give up and began to wrap up the first part of the task. Therefore, without bothering to cool the milk, it was placed in the refrigerator while it was hot. He was already worried that it had frozen even more, and among his classmates, they were making a robot according to the given technology.

The young man was already intrigued by this fact, and experiments with plain water began. In 1969, the journal Physics Education published the results of research by Mpembi and Professor Dennis Osborne at the University of Dar es Salaam. The described effect was given by the name Mpembi. However, today’s phenomenon lacks a clear explanation. Everyone always agrees on the Duma that the main role belongs to the authorities of cold and hot water, which is unknown.

Singapore version

Physicists at one of the Singapore universities were also concerned about how soon water freezes - hot or cold? A team of investigators under the leadership of Si Zhang explained this phenomenon to the water authorities themselves. There is also a warehouse of water in the school lava – an acid atom and two water atoms. Kisen like a song draws electrons into the water, so the molecule is a kind of “magnet”.

Through the war, the molecules in the drinking water are attracted to each other and form a bond of water. Its value is often lower due to the covalent bond. Singaporean descendants appreciate that the Mpembi paradox is explained just in the water connections. Since water molecules are located very closely together, such strong interactions between molecules cause deformation of the covalent bond in the middle of the molecule itself.

And when the water is heated, the bound molecules are easily removed one after another. As a result, in the middle of the molecules, relaxation of covalent bonds occurs due to the release of energy and the transition to a lower energy level. This leads to the point where the hot water begins to cool down. It is better to show in this way the theoretical developments that were carried out at the Singapore ceremonies.