“The simplest stable compound of hydrogen and oxygen,” is the definition of water given by the Concise Chemical Encyclopedia. But, if you look at it, this liquid is not so simple. It has many extraordinary, amazing and very special properties. A Ukrainian aquatic researcher told us about the unique abilities of water Stanislav Suprunenko.

High heat capacity

Water heats up five times slower than sand and ten times slower than iron. To heat a liter of water by one degree, 3300 times more heat is required than to heat a liter of air. Absorbing a huge amount of heat, the substance itself does not heat up significantly. But when it cools down, it gives off as much heat as it took in when heating up. This ability to accumulate and release heat makes it possible to smooth out sharp temperature fluctuations on the surface of the earth. But that's not all! The heat capacity of water decreases as the temperature rises from 0 to 370C, that is, within these limits it is easy to heat it, it will not take much heat and time. But after the temperature limit of 370C, its heat capacity increases, which means that more effort will have to be made to heat it. It has been established: water has a minimum heat capacity at a temperature of 36.790C, and this is the normal temperature of the human body! So it is this quality of water that ensures the stability of the temperature of the human body.

High surface tension of water

Surface tension is the force of attraction and cohesion between molecules. It can be visually observed in a cup filled with tea. If you slowly add water to it, it will not overflow immediately. Take a closer look: you can see a thin film above the surface of the liquid - it prevents the liquid from spilling out. It swells as it is added, and only at the “last drop” will this happen.
All liquids have surface tension, but it is different for everyone. Water has one of the highest surface tensions. Only mercury has more, which is why, when spilled, it immediately turns into balls: the molecules of the substance are tightly “attached” to each other. But alcohol, ether and acetic acid have much lower surface tension. Their molecules are less attracted to each other and, accordingly, that is why they evaporate faster and spread their odor.

High latent heat of vaporization

Photo by Shutterstock

It takes five and a half times more heat to evaporate water than to boil it. If it were not for this property of water - to evaporate slowly - many lakes and rivers would simply dry up in the hot summer.
Globally, a million tons of water evaporate from the hydrosphere every minute. As a result, a colossal amount of heat enters the atmosphere, equivalent to the operation of 40 thousand power plants with a capacity of 1 billion kW each.

Extension

As the temperature decreases, all substances contract. Everything, but not water. Until the temperature drops below 40C, the water behaves quite normally - becoming slightly denser, it reduces its volume. But after 3,980C it behaves, or rather, it begins to expand, despite the decrease in temperature! The process goes smoothly up to a temperature of 00C until the water freezes. As soon as ice forms, the volume of already solid water increases sharply by 10%.

One of the common problems in the toilet is that the toilet tank simply does not fill with water. This kind of malfunction must be promptly eliminated due to the fact that it can cause a significant decrease in bathroom hygiene, as well as the appearance of an unpleasant odor.

The sources of this problem can be a large number of different factors. To identify them, you first need to understand the design of the drain tank itself. Only after this will it be possible to talk about what needs to be done to fix this problem yourself.

General characteristics

The principle of operation of the cistern is entirely based on the law of gravity. It is due to this that the water collected in the tank, after pressing the release button, is released into the toilet at the required speed.

The mechanism that is responsible for the collection of water into the tank and the draining process is called shut-off valves. The largest element of this design is the float. It is he who is responsible for the flushing mechanism. It is necessary to control the water level.

After the release button is pressed, the amount of water inside the container decreases and the float lowers. Due to this, the shut-off valve opens, through which water is poured again.

At the same time, float valves vary in position in the tank. So, there are side and bottom options.

Also, such a device has a drain and overflow system, which is a whole complex of elements.

It does not allow water to accumulate more than the set value in order to prevent it from pouring out of the tank into the bathroom.

The drain mechanism works as follows:

1. First, the required water level is reached, after which the float floats up, and the rocker arm rises behind it.
2. During this, the rocker itself turns and presses the valve, which shuts off the flow of water. When the required amount is collected in the tank, the flow stops due to the tight blocking of the channel.

Take into account: To change the maximum level of liquid that will be collected in the drain system, simply bend the rocker arm a little.

The trigger mechanism is a button, most often located on the toilet lid, and in some models (especially old ones) it is a chain located in the body assembly. But the first option is more common, since it is both more convenient and compact.

There is also a third option, where the tank is built into the wall and a button simply peeks out of it. It looks very aesthetically pleasing and is economical in itself, but if it is necessary to carry out repairs, this option is extremely inconvenient.

Types of breakdowns

The most common reasons why water has stopped flowing into the toilet cistern are:

1. 1. No water supply. This is a very common reason when there is simply no water in the tap. Therefore, in this case, the tank mechanism will have nothing to do with it.
   2. Rust in the filter. The reason here is that over time, the filter in the system becomes clogged, after which the water flows more and more slowly, and then stops flowing altogether. This can be corrected simply by cleaning the filter, after which the water will flow again with the required force.
   3. Float misalignment. Most often it occurs in fairly old models due to the fact that the mechanism has already become loose and the float has moved to the side after flushing, thus, after the water has left, it does not go down. Here it will be enough to simply put it in its original place.

1. Exhaust valve wear. In cases where the age of the tank is significant, this may mean failure of the entire mechanism. To solve this problem, it is necessary to completely replace the exhaust valve.
2. Contamination of the mechanism. Over time, mucus and plaque form on the internal elements of the tank, which prevent them from properly performing their respective functions. To resume operation of the device, you need to remove the mechanism and completely clean it.
3. Setting up the intake tract. If, during the assembly of the system, the elements in it were fastened too tightly, the water will flow very slowly and for a long time. This issue can be resolved by simply loosening certain fasteners.

If you think that certain parts are faulty, there is no need to try to repair them or call repairmen. The fact is that shut-off valves are inexpensive, so by purchasing new ones, you can save a lot of money that would have been spent on the work of a plumber.

Replacement

To replace fittings, it is advisable to first select the correct option. In this case, you need to take into account the features of your current mechanism and try to choose a similar one.

If you have any doubts, you should ask the seller for advice.

After purchasing all the parts, you can begin the installation process itself:

1. First you need to turn off the water either at the riser, or specifically at the pipe from which the hose goes to the toilet.
2. Next, the button is removed, and then the tank lid.
3. Now the liner and drain column are disconnected. All this needs to be done in parts.
4. After this, the tank itself is removed, to do this, its fasteners are unscrewed and taken to a convenient place where further work will be carried out on it.
5. Next, we remove all the insides of the old mechanism from it, clean the walls with hot water and install new elements.
6. At the end, we mount the tank back to the place where we connect it to the water supply and toilet.

It is worth noting: if the installation and connection of the new mechanism was carried out correctly, everything will work, otherwise you need to call a specialist, who will connect everything correctly himself.

Such malfunctions in the operation of the tank are far from a tragedy and a problem that requires large expenses to solve. However, if you do not have experience and skills in working with such mechanisms, you should not try to fix the system yourself; it is better to immediately call a plumber so as not to cause even more damage.

Watch the video in which an experienced user explains in detail what to do if water does not fill the toilet tank:

Why does water freeze? Water is an amazing miracle of nature. It is necessary for all life on earth. It was in water, according to scientists, that life originated. It is surprising that water can exist in three states: liquid, solid and gaseous. At the same time, it can move from one state to another. The vast majority of water on the planet is liquid. The solid state of water is ice.

Why does water freeze in the cold?

The ability of water to transform into different states is affected by its composition. Water molecules are weakly bonded to each other; they always move and group, but at the same time they cannot form a certain structure. Water takes the shape of the vessel in which it is placed, but on its own it cannot hold any particular model. For example, we pour water into a pan, and the liquid will take its shape, but will not be able to hold it outside the container.

When heated, water molecules begin to move relative to each other even faster and more chaotically, losing connection with each other to a greater extent. In this case, the water becomes steam.

When low temperatures influence water, the movement of molecules is inhibited, the connection between them is strengthened, and then they can build a structure - hexagonal crystals. The state of transformation of moisture into ice is called crystallization, solidification.

In such a strong state it can retain the various forms it acquires for a long time. Water begins to freeze at a temperature of 0 degrees Celsius. Thus, the transition of water from a liquid state to a solid state, to ice, is determined by the physical properties of water, its composition.

Why does hot water freeze faster than cold water?

Speaking about the “transformation” of water into ice, curious phenomena are observed. A hot one freezes faster than a cold one, no matter how unlikely this may seem. This fact has been known for a long time, but for a long time it was not possible to reveal the secret of the mysterious properties of water. Only in the twentieth century did scientists around the world try to explain the reason why hot water freezes faster than cold water.

In 1963, a boy named Mpemba from Tanzania noticed while making ice cream that the delicious delicacy hardened faster if it was made from warm rather than cold milk. They started making fun of him when he shared his observations with his teacher and friends. Only one person, Professor Dennis Osborne, whom Mpemba met as an adult, paid attention to this fact.

Many hypotheses have been put forward about hot water freezing faster than cold water, but they all remained assumptions. The “strange” behavior of water is called the “Mpemba Effect”. Research is still being carried out. Scientists from many countries are trying to prove the “Mpemba Effect”, but so far to no avail.

Many researchers consider this fact not worthy of attention, since ice cream has different properties compared to hard water. Physicists from Singapore in 2013 theoretically proved the mystery of the Mpemba effect, but confirmation of laboratory studies of the incomprehensible phenomenon still does not exist.

Water freezes from above, not from below

Almost everyone knows that on reservoirs at low temperatures, a thin ice crust first forms, which becomes thicker and stronger as frost intensifies. And if it were not for this amazing property of water, it is unlikely that anyone would be able to skate, since the ice would simply sink to the bottom of the reservoir.

Water, like most similar substances, contracts and decreases in volume when cooled, but to a temperature not lower than 3 degrees Celsius. At lower temperatures, water, on the contrary, expands and its density increases. Ice is lighter than water, and this keeps it on top.

Why doesn't distilled water freeze?

Distilled water is called pure; it is “freed” from all impurities and oxygen. Impurities are the fragments to which water molecules attach. When transitioning from a liquid state to ice, the impurities present in the water are compressed. Distilled water, due to the absence of other substances, expands, and the distance between the molecules increases.

The resulting ice will float on the surface because it is lighter than water. Still, distilled water can freeze, but its freezing point is much lower than ordinary water. At the same time, it was noticed that if you hit, for example, a bottle of distilled water or shake it, the water will immediately begin to freeze. This is explained by the adhesion of molecules upon impact.

Freezing point of mineral water

Mineral water is saturated with salts and chemicals that are beneficial to humans. The freezing point of mineral water is lower than that of ordinary water. Striking or shaking a container of water will speed up the freezing process in the same way as with distilled water. Water molecules will adhere to each other and structure into crystals, accordingly, the water will freeze.

Does salt water freeze?

There are people who believe that it does not freeze. This statement is not entirely true. Salt water also tends to freeze, but its freezing point is significantly below zero. The explanation for this lies in the molecular composition of water.

Salt, or rather its small crystals, does not allow water molecules to connect. The freezing of salt water depends on the concentration of salt it contains. The more salt in the water, the lower the freezing point. Why are Antarctic ice and icebergs reserves of fresh water? According to scientists, these are fragments of the continent that broke away millions of years ago. Their education was not facilitated by the place where they are located.

Sea water also freezes at very low temperatures. Ice crystals formed on the surface of the water push out salt crystals, so the deeper the brine becomes richer. If you take ice from the water surface of the sea and melt it, the melted water will be almost fresh.

Does Epiphany water freeze?

Epiphany water is called “holy”. There is an opinion that on Epiphany night and for the next three days, the water in all reservoirs becomes “holy”, possessing magical healing properties. It can indeed be stored for a long time without changing its taste, but it freezes. Anyone can verify this. Place in the cold 2 bottles filled with plain water collected on Epiphany night. The water will freeze equally in both bottles.

Does water in a well freeze?

People prefer to drink water from a well, considering it more beneficial and suitable for the body. Does well water freeze in winter? The answer to this question is obvious. If the well is deep enough, the water level does not rise above the freezing point of the ground, which means that the water in the well will not freeze. If the well is shallow, then the top layer of water may be covered with an ice crust or a significant layer of ice.

Water is an amazing substance that can change from one state to another due to its chemical composition. The freezing point of water varies. Water is probably the only exceptional substance that can expand at low temperatures.

frozen water

Everyone knows about the importance and benefits of water for life. It turns out that water thawed after freezing has healing properties on the human body. It changes its structure after freezing and thawing processes. Many people attribute the longevity of the mountaineers to their consumption of melt water from springs flowing in the mountains.

This is true, although it sounds incredible, because during the freezing process, preheated water must pass the temperature of cold water. Meanwhile, this effect is widely used. For example, skating rinks and slides are filled with hot rather than cold water in winter. Experts advise motorists to pour cold, not hot, water into the washer reservoir in winter. The paradox is known in the world as the “Mpemba Effect”.

This phenomenon was mentioned at one time by Aristotle, Francis Bacon and Rene Descartes, but only in 1963 did physics professors pay attention to it and try to study it. It all started when Tanzanian schoolboy Erasto Mpemba noticed that the sweetened milk he used to make ice cream froze faster if it was preheated and hypothesized that hot water froze faster than cold water. He turned to the physics teacher for clarification, but he only laughed at the student, saying the following: “This is not universal physics, but Mpemba physics.”

Luckily, Dennis Osborne, a physics professor from the University of Dar es Salaam, visited the school one day. And Mpemba turned to him with the same question. The professor was less skeptical, said that he could not judge something that he had never seen, and upon returning home he asked his staff to conduct appropriate experiments. They seemed to confirm the boy's words. In any case, in 1969, Osborne spoke about working with Mpemba in the English magazine. PhysicsEducation" That same year, George Kell of Canada's National Research Council published an article describing the phenomenon in English. AmericanJournalofPhysics».

There are several possible explanations for this paradox:

• Hot water evaporates faster, thereby reducing its volume, and a smaller volume of water at the same temperature freezes faster. Cold water should freeze faster in airtight containers.
• Availability of snow lining. A container with hot water melts the snow underneath, thereby improving thermal contact with the cooling surface. Cold water does not melt the snow underneath. If there is no snow liner, the cold water container should freeze faster.
• Cold water begins to freeze from above, thereby worsening the processes of heat radiation and convection, and hence heat loss, while hot water begins to freeze from below. With additional mechanical mixing of water in containers, cold water should freeze faster.
• The presence of crystallization centers in cooled water - substances dissolved in it. With a small number of such centers in cold water, the transformation of water into ice is difficult and even supercooling is possible, when it remains in a liquid state, having a subzero temperature.

Another explanation was recently published. Dr. Jonathan Katz from the University of Washington studied this phenomenon and concluded that substances dissolved in water, which precipitate when heated, play an important role in it.
By solutes, Dr. Katz means calcium and magnesium bicarbonates, which are found in hard water. When water is heated, these substances precipitate and the water becomes “soft.” Water that has never been heated contains these impurities and is “hard.” As it freezes and ice crystals form, the concentration of impurities in the water increases 50 times. Because of this, the freezing point of water decreases.

This explanation does not seem convincing to me, because... We must not forget that the effect was discovered in experiments with ice cream, and not with hard water. Most likely, the causes of the phenomenon are thermophysical, not chemical.

So far, no unambiguous explanation for Mpemba's paradox has been obtained. It must be said that some scientists do not consider this paradox worthy of attention. However, it is very interesting that a simple schoolboy achieved recognition of the physical effect and gained popularity due to his curiosity and perseverance.

Added February 2014

The note was written in 2011. Since then, new studies of the Mpemba effect and new attempts to explain it have appeared. So, in 2012, the Royal Society of Chemistry of Great Britain announced an international competition to solve the scientific mystery “Mpemba Effect” with a prize fund of 1000 pounds. The deadline was set on July 30, 2012. The winner was Nikola Bregovic from the laboratory of the University of Zagreb. He published his work in which he analyzed previous attempts to explain this phenomenon and came to the conclusion that they were not convincing. The model he proposed is based on the fundamental properties of water. Those interested can find a job at http://www.rsc.org/mpemba-competition/mpemba-winner.asp

The research did not end there. In 2013, physicists from Singapore theoretically proved the cause of the Mepemba effect. The work can be found at http://arxiv.org/abs/1310.6514.

Related articles on the site:

Other articles in this section

Comments:

Alexey Mishnev. , 06.10.2012 04:14

Why does hot water evaporate faster? Scientists have practically proven that a glass of hot water freezes faster than cold water. Scientists cannot explain this phenomenon for the reason that they do not understand the essence of the phenomena: heat and cold! Heat and cold are a physical sensation that causes the interaction of particles of Matter, in the form of counter compression of magnetic waves that move from space and from the center of the earth. Therefore, the greater the potential difference, this magnetic voltage, the faster the energy exchange occurs by the method of counter penetration of one wave into another. That is, by the diffusion method! In response to my article, one opponent writes: 1) “..Hot water evaporates FASTER, resulting in less of it, so it freezes faster” Question! What energy causes water to evaporate faster? 2) My article is about a glass, and not about a wooden trough, which the opponent cites as a counterargument. Which is not correct! I answer the question: “WHY DOES WATER EVAPORATE IN NATURE?” Magnetic waves, which always move from the center of the earth into space, overcoming the counter pressure of magnetic compression waves (which always move from space to the center of the earth), at the same time, spray water particles, since moving into space, they increase in volume. That is, they are expanding! If the magnetic compression waves are overcome, these water vapors are compressed (condensed) and under the influence of these magnetic compression forces, the water returns to the earth in the form of precipitation! Sincerely! Alexey Mishnev. October 6, 2012.

Alexey Mishnev. , 06.10.2012 04:19

What is temperature? Temperature is the degree of electromagnetic tension of magnetic waves with compression and expansion energy. In the case of an equilibrium state of these energies, the temperature of the body or substance is in a stable state. When the equilibrium state of these energies is disturbed, towards the energy of expansion, the body or substance increases in the volume of space. If the energy of magnetic waves exceeds in the direction of compression, the body or substance decreases in the volume of space. The degree of electromagnetic voltage is determined by the degree of expansion or compression of the reference body. Alexey Mishnev.

Moiseeva Natalia, 23.10.2012 11:36 | VNIIM

Alexey, you are talking about some article that sets out your thoughts on the concept of temperature. But no one read it. Please give me a link. In general, your views on physics are very unique. I've never heard of "electromagnetic expansion of a reference body."

Yuri Kuznetsov, 04.12.2012 12:32

A hypothesis is proposed that this is due to intermolecular resonance and the ponderomotive attraction between molecules it generates. In cold water, molecules move and vibrate chaotically, at different frequencies. When water is heated, with an increase in the frequency of vibrations, their range narrows (the difference in frequencies from liquid hot water to the point of vaporization decreases), the vibration frequencies of the molecules approach each other, as a result of which resonance occurs between the molecules. During cooling, this resonance is partially preserved and does not fade away immediately. Try pressing one of the two guitar strings that are in resonance. Now let go - the string will begin to vibrate again, the resonance will restore its vibrations. Likewise, in frozen water, the external cooled molecules try to lose the amplitude and frequency of vibrations, but the “warm” molecules inside the vessel “pull” the vibrations back, acting as vibrators, and the external ones as resonators. Ponderomotive attraction* arises between vibrators and resonators. When the ponderomotive force becomes greater than the force caused by the kinetic energy of the molecules (which not only vibrate, but also move linearly), accelerated crystallization occurs - the "Mpemba Effect". The ponderomotive connection is very unstable, the Mpemba effect strongly depends on all related factors: the volume of water to be frozen, the nature of its heating, freezing conditions, temperature, convection, heat exchange conditions, gas saturation, vibration of the refrigeration unit, ventilation, impurities, evaporation, etc. Possibly even from lighting... Therefore, the effect has a lot of explanations and is sometimes difficult to reproduce. For the same “resonance” reason, boiled water boils faster than unboiled water - resonance retains the intensity of vibrations of water molecules for some time after boiling (the loss of energy during cooling is mainly due to the loss of kinetic energy of the linear movement of molecules). During intense heating, vibrator molecules change roles with resonator molecules in comparison with freezing - the frequency of the vibrators is less than the frequency of the resonators, which means that not attraction, but repulsion occurs between the molecules, which accelerates the transition to another state of aggregation (pair).

Vlad, 12/11/2012 03:42

Broke my brain...

Anton, 02/04/2013 02:02

1. Is this ponderomotive attraction really so great that it affects the heat transfer process? 2. Does this mean that when all bodies are heated to a certain temperature, their structural particles enter into resonance? 3. Why does this resonance disappear when cooled? 4. Is this your guess? If there is a source, please indicate. 5. According to this theory, the shape of the vessel will play an important role, and if it is thin and flat, then the difference in freezing time will not be large, i.e. you can check this.

Gudrat, 03/11/2013 10:12 | METAK

In cold water there are already nitrogen atoms and the distances between water molecules are closer than in hot water. That is, the conclusion: Hot water absorbs nitrogen atoms faster and at the same time it freezes quickly than cold water - this is comparable to the hardening of iron, since hot water turns into ice and hot iron hardens with rapid cooling!

Vladimir, 03/13/2013 06:50

or maybe this: the density of hot water and ice is less than the density of cold water, and therefore the water does not need to change its density, losing some time and it freezes.

Alexey Mishnev, 03/21/2013 11:50

Before talking about resonances, attractions and vibrations of particles, we need to understand and answer the question: What forces cause particles to vibrate? Since, without kinetic energy, there can be no compression. Without compression, there can be no expansion. Without expansion, there can be no kinetic energy! When you start talking about the resonance of strings, you first make an effort so that one of these strings begins to vibrate! When talking about attraction, you must first of all indicate the force that makes these bodies attract! I claim that all bodies are compressed by the electromagnetic energy of the atmosphere and which compresses all bodies, substances and elementary particles with a force of 1.33 kg. not per cm2, but per elementary particle. Since atmospheric pressure cannot be selective! Not to be confused with the amount of force!

Dodik, 05/31/2013 02:59

It seems to me that you have forgotten one truth - “Science begins where measurements begin.” What is the temperature of the "hot" water? What is the temperature of the “cold” water? The article doesn't say a word about this. From this we can conclude - the whole article is bullshit!

Grigory, 06/04/2013 12:17

Dodik, before calling an article nonsense, you need to think about learning, at least a little. And not just measure.

Dmitry, 12/24/2013 10:57

Hot water molecules move faster than in cold water, because of this there is closer contact with the environment, they seem to absorb all the cold, quickly slowing down.

Ivan, 01/10/2014 05:53

It is surprising that such an anonymous article appears on this site. The article is completely unscientific. Both the author and commentators vying with each other in search of an explanation for the phenomenon, without bothering to find out whether the phenomenon is observed at all and, if observed, under what conditions. Moreover, there is not even an agreement on what we are actually observing! Thus, the author insists on the need to explain the effect of rapid freezing of hot ice cream, although from the entire text (and the words “the effect was discovered in experiments with ice cream”) it follows that he himself did not conduct such experiments. From the options for “explanation” of the phenomenon listed in the article, it is clear that completely different experiments are being described, carried out under different conditions with different aqueous solutions. Both the essence of the explanations and the subjunctive mood in them suggest that even a basic check of the ideas expressed was not carried out. Someone accidentally heard a funny story and casually expressed his speculative conclusion. Sorry, but this is not a physical scientific study, but a conversation in a smoking room.

Ivan, 01/10/2014 06:10

Regarding the comments in the article about filling the rollers with hot water and the windshield washer reservoirs with cold water. Everything is simple here from the point of view of elementary physics. The skating rink is filled with hot water precisely because it freezes more slowly. The skating rink must be level and smooth. Try to fill it with cold water - you will get bumps and “swells”, because... The water will freeze _quickly_ without having time to spread out in an even layer. And the hot one will have time to spread in an even layer, and will melt the existing ice and snow tubercles. The washer is also not difficult: there is no point in pouring clean water in cold weather - it freezes on the glass (even hot); and a hot non-freezing liquid can lead to cracking of cold glass, plus the glass will have an increased freezing point due to the accelerated evaporation of alcohols on the way to the glass (is everyone familiar with the principle of operation of a moonshine still? - the alcohol evaporates, the water remains).

Ivan, 01/10/2014 06:34

But in essence of the phenomenon, it is stupid to ask why two different experiments under different conditions proceed differently. If the experiment is carried out purely, then you need to take hot and cold water of the same chemical composition - we take pre-cooled boiling water from the same kettle. Pour into identical vessels (for example, thin-walled glasses). We do not place it on the snow, but on an equally flat, dry base, for example, a wooden table. And not in a micro-freezer, but in a fairly voluminous thermostat - I conducted an experiment a couple of years ago at the dacha, when the weather outside was stable and frosty, about -25C. Water crystallizes at a certain temperature after releasing the heat of crystallization. The hypothesis boils down to the statement that hot water cools faster (this is true, in accordance with classical physics, the rate of heat transfer is proportional to the temperature difference), but retains an increased cooling rate even when its temperature becomes equal to the temperature of cold water. The question is, how does water that has cooled to a temperature of +20C outside differ from exactly the same water that has cooled to a temperature of +20C an hour before, but in a room? Classical physics (by the way, based not on chatter in the smoking room, but on hundreds of thousands and millions of experiments) says: nothing, the further dynamics of cooling will be the same (only the boiling water will reach the +20 point later). And the experiment shows the same thing: when a glass of initially cold water already had a strong crust of ice, the hot water didn’t even think about freezing. P.S. To the comments of Yuri Kuznetsov. The presence of a certain effect can be considered established when the conditions for its occurrence are described and it is consistently reproduced. And when we have unknown experiments with unknown conditions, it is premature to build theories to explain them and this does not give anything from a scientific point of view. P.P.S. Well, it’s impossible to read Alexei Mishnev’s comments without tears of tenderness - a person lives in some kind of fictional world that has nothing to do with physics and real experiments.

Gregory, 01/13/2014 10:58

Ivan, I understand that you are refuting the Mpemba effect? It doesn't exist, as your experiments show? Why is it so famous in physics, and why are many trying to explain it?

Ivan, 02/14/2014 01:51

Good afternoon, Gregory! The effect of an impure experiment exists. But, as you understand, this is not a reason to look for new laws in physics, but a reason to improve the skill of an experimenter. As I already noted in the comments, in all the mentioned attempts to explain the “Mpemba effect,” the researchers cannot even clearly formulate what exactly and under what conditions they measure. And you want to say that these are experimental physicists? Do not make me laugh. The effect is known not in physics, but in pseudo-scientific discussions on various forums and blogs, of which there are now a sea. It is perceived as a real physical effect (in the sense as a consequence of some new physical laws, and not as a consequence of an incorrect interpretation or just a myth) by people far from physics. So there is no reason to speak of the results of different experiments conducted under completely different conditions as a single physical effect.

Pavel, 02/18/2014 09:59

hmm, guys... article for "Speed ​​Info"... No offense... ;) Ivan is right about everything...

Grigory, 02/19/2014 12:50

Ivan, I agree that there are now a lot of pseudo-scientific sites publishing unverified sensational material.? After all, the Mpemba effect is still being studied. Moreover, scientists from universities are researching. For example, in 2013, this effect was studied by a group from the University of Technology in Singapore. Look at the link http://arxiv.org/abs/1310.6514. They believe they have found an explanation for this effect. I will not write in detail about the essence of the discovery, but in their opinion, the effect is associated with the difference in the energies stored in hydrogen bonds.

Moiseeva N.P. , 02/19/2014 03:04

For everyone interested in research into the Mpemba effect, I have slightly supplemented the material in the article and provided links where you can familiarize yourself with the latest results (see text). Thanks for your comments.

Ildar, 02/24/2014 04:12 | there's no point in listing everything

If this Mpemba effect really takes place, then the explanation must be sought, I think, in the molecular structure of water. Water (as I learned from popular science literature) exists not as individual H2O molecules, but as clusters of several molecules (even dozens). As the temperature of the water increases, the speed of movement of the molecules increases, the clusters break up against each other and the valence bonds of the molecules do not have time to assemble large clusters. The formation of clusters takes a little more time than the reduction in the speed of molecular movement. And since the clusters are smaller, the formation of the crystal lattice occurs faster. In cold water, apparently, large, fairly stable clusters prevent the formation of a lattice; it takes some time to destroy them. I myself saw on TV a curious effect when cold water standing calmly in a jar remained liquid for several hours in the cold. But as soon as the jar was picked up, that is, slightly moved from its place, the water in the jar immediately crystallized, became opaque, and the jar burst. Well, the priest who showed this effect explained it by the fact that the water was blessed. By the way, it turns out that water greatly changes its viscosity depending on temperature. This is imperceptible to us, as large creatures, but at the level of small (mm or smaller) crustaceans, and even more so bacteria, the viscosity of water is a very significant factor. This viscosity, I think, is also determined by the size of the water clusters.

GRAY, 03/15/2014 05:30

everything around us that we see are superficial characteristics (properties) so we accept as energy only what we can measure or prove its existence in any way, otherwise it’s a dead end. This phenomenon, the Mpemba effect, can only be explained by a simple volumetric theory that will unite all physical models into a single interaction structure. it's actually simple

Nikita, 06/06/2014 04:27 | car

But how can you make sure that the water stays cold rather than warm when you’re driving in the car?

Alexey, 03.10.2014 01:09

Here's another "discovery" on the way. Water in a plastic bottle freezes much faster with the cap open. For fun, I performed the experiment many times in severe frost. The effect is obvious. Hello theorists!

Evgeniy, 12/27/2014 08:40

The principle of an evaporative cooler. We take two hermetically sealed bottles with cold and hot water. We put it in the cold. Cold water freezes faster. Now we take the same bottles with cold and hot water, open them and put them in the cold. Hot water will freeze faster than cold water. If we take two basins with cold and hot water, then the hot water will freeze much faster. This is due to the fact that we are increasing contact with the atmosphere. The more intense the evaporation, the faster the temperature drops. Here we must mention the humidity factor. The lower the humidity, the stronger the evaporation and the stronger the cooling.

gray TOMSK, 03/01/2015 10:55

GRAY, 03/15/2014 05:30 - continued What you know about temperature is not everything. There's something else there. If you correctly construct a physical model of temperature, it will become the key to describing energy processes from diffusion, melting and crystallization to such scales as an increase in temperature with an increase in pressure, an increase in pressure with an increase in temperature. Even the physical model of the Sun's energy will become clear from the above. I'm in winter. . in the early spring of 20013, looking at temperature models, I compiled a general temperature model. A couple of months later, I remembered the temperature paradox and then I realized... that my temperature model also describes the Mpemba paradox. This was in May - June 2013. I'm a year late, but it's for the best. My physical model is a freeze frame and it can be rewound both forward and backward and it contains motor activity, the same activity in which everything moves. I have 8 years of school and 2 years of college with a repetition of the topic. 20 years have passed. So I cannot attribute any kind of physical models to famous scientists, nor can I attribute formulas. So sorry.

Andrey, 08.11.2015 08:52

In general, I have an idea about why hot water freezes faster than cold water. And in my explanations everything is very simple, if you are interested, write to me by email: [email protected]

Andrey, 08.11.2015 08:58

I'm sorry, I gave the wrong email address, here's the correct email: [email protected]

Victor, 12/23/2015 10:37

It seems to me that everything is simpler, snow falls here, it is evaporated gas, cooled, so maybe in cold weather the hot one cools down faster because it evaporates and immediately crystallizes without rising far, and water in the gaseous state cools down faster than in the liquid state)

Bekzhan, 01/28/2016 09:18

Even if someone had revealed these laws of the world that are associated with these effects, he would not have written here. From my point of view, it would not be logical to reveal its secrets to Internet users when he can publish it in famous scientific journals and prove it himself personally before the people. So, what will be written here about this effect, most of it is not logical.)))

Alex, 02/22/2016 12:48

Hello Experimenters You are right when you say that Science begins where... not Measurements, but Calculations. “Experiment” is an eternal and indispensable argument for those deprived of Imagination and Linear thinking. It offended everyone, now in the case of E= mc2 - does everyone remember? The speed of molecules flying out of cold water into the atmosphere determines the amount of energy they carry away from the water (cooling is a loss of energy). The speed of molecules from hot water is much higher and the energy carried away is squared (the rate of cooling of the remaining mass of water) That's all, if you get away from " experimentation" and remember the Basic Fundamentals of Science

Vladimir, 04/25/2016 10:53 | Meteo

In those days when antifreeze was rare, water from the cooling system of cars in an unheated garage was drained after a working day so as not to defrost the cylinder block or radiator - sometimes both together. In the morning hot water was poured. In severe frost, the engines started without problems. Somehow, due to the lack of hot water, water was poured from the tap. The water immediately froze. The experiment was expensive - exactly as much as it costs to buy and replace the cylinder block and radiator of a ZIL-131 car. Whoever doesn’t believe it, let him check it. and Mpemba experimented with ice cream. In ice cream, crystallization occurs differently than in water. Try biting off a piece of ice cream and a piece of ice with your teeth. Most likely it did not freeze, but thickened as a result of cooling. And fresh water, whether it is hot or cold, freezes at 0*C. Cold water is quick, but hot water takes time to cool down.

Wanderer, 05/06/2016 12:54 | to Alex

"c" - the speed of light in vacuum E=mc^2 - a formula expressing the equivalence of mass and energy

Albert, 07/27/2016 08:22

First, an analogy with solids (there is no evaporation process). I recently soldered copper water pipes. The process occurs by heating a gas burner to the melting temperature of the solder. The heating time for one joint with a coupling is approximately one minute. I soldered one joint to the coupling and after a couple of minutes I realized that I had soldered it incorrectly. It was necessary to rotate the pipe a little in the coupling. I started heating the joint again with a burner and, to my surprise, it took 3-4 minutes to heat the joint to the melting temperature. How so!? After all, the pipe is still hot and it would seem that much less energy is needed to heat it to the melting temperature, but everything turned out to be the opposite. It's all about thermal conductivity, which is significantly higher in an already heated pipe and the boundary between the heated and cold pipe has managed to move far from the joint in two minutes. Now about the water. We will operate with the concepts of a hot and semi-heated vessel. In a hot vessel, a narrow temperature boundary is formed between hot, highly mobile particles and slow-moving, cold particles, which moves relatively quickly from the periphery to the center, because at this boundary fast particles quickly give up their energy (cooled) by particles on the other side of the boundary. Since the volume of external cold particles is larger, fast particles, giving up their thermal energy, cannot significantly warm up the external cold particles. Therefore, the process of cooling hot water occurs relatively quickly. Semi-heated water has much lower thermal conductivity and the width of the boundary between semi-heated and cold particles is much wider. The shift to the center of such a wide boundary occurs much more slowly than in the case of a hot vessel. As a result, the hot vessel cools faster than the warm one. I think we need to track the dynamics of the cooling process of water of different temperatures by placing several temperature sensors from the middle to the edge of the vessel.

Max, 11/19/2016 05:07

It has been verified: in Yamal, when it’s cold, the pipe with hot water freezes and you have to warm it up, but the cold one doesn’t!

Artem, 09.12.2016 01:25

It’s difficult, but I think that cold water is denser than hot water, even better than boiled water, and here there is an acceleration in cooling, etc. hot water reaches the cold temperature and overtakes it, and if you take into account the fact that hot water freezes from below and not from the top, as written above, this speeds up the process a lot!

Alexander Sergeev, 21.08.2017 10:52

There is no such effect. Alas. In 2016, a detailed article on the topic was published in Nature: https://en.wikipedia.org/wiki/Mpemba_effect From it it is clear that with careful experiments (if the samples of warm and cold water are the same in everything except temperature) the effect is not observed .

Zavlab, 08/22/2017 05:31

Victor , 10/27/2017 03:52

"It really is." - if at school you didn’t understand what heat capacity and the law of conservation of energy are. It’s easy to check - for this you need: desire, head, hands, water, refrigerator and alarm clock. And the skating rinks, as experts write, are frozen (filled) with cold water, and the cut ice is leveled with warm water. And in winter you need to pour antifreeze liquid into the washer reservoir, not water. The water will freeze in any case, and cold water will freeze faster.

Irina, 01/23/2018 10:58

Scientists all over the world have been struggling with this paradox since the time of Aristotle, and Victor, Zavlab and Sergeev turned out to be the smartest.

Denis, 02/01/2018 08:51

Everything is written correctly in the article. But the reason is somewhat different. During the boiling process, the air dissolved in it evaporates from water; therefore, as the boiling water cools, its density will eventually be less than that of raw water at the same temperature. There are no other reasons for different thermal conductivity other than different densities.

Zavlab, 03/01/2018 08:58 | Head of Lab

Irina:), “scientists around the world” do not struggle with this “paradox”; for real scientists this “paradox” simply does not exist - it is easily verified under well-reproducible conditions. The “paradox” appeared due to the irreproducible experiments of the African boy Mpemba and was inflated by similar “scientists” :)

miroland, 03/23/2019 07:20

a Tanzanian boy living in the very heart of Africa, who, very likely, has never seen snow... ;-D am I not confusing anything???)))

Sergey, 04/14/2019 02:02

We take two elastic bands, stretch both, one more than the other (analogy with the internal energy of cold and warm water) and simultaneously release one end of the elastic bands. Which rubber band will shrink faster?

Artanis , 05/08/2019 03:34

I just went through this experience myself. I put two completely identical cups of hot and cold water in the freezer. The cold one froze much faster. The hot one was still a little warm. What's wrong with my experience?

Zavlab, 05/09/2019 06:21 |

Artanis, With your experience, “everything is so” :) - “The Mpemba effect” does not exist with a correctly performed experiment, which ensures identical cooling conditions for identical volumes of water only with different initial temperatures. Congratulations to you - you have crossed over to the side of light, reason and the triumph of basic physical laws and began to move away from the “Mpemba sect” and fans of YouTube videos in the style of “what they lied to us about in physics lessons”... :)

Moiseeva N.P. , 05/16/2019 04:30 | Ch. editor

You are right, a lot depends on the experimental conditions. But if the effect had not been observed at all, then there would have been no research and no publications in serious journals. Did you read the note to the end? There is no talk about YouTube videos here.

Zavlab, 08/06/2019 05:26 | SlavNeftGas-YuzhNorthZapEast-SintezWhatever

Natalya Petrovna, we live in an era of “reproducibility crisis” in science, when, in order to increase the citation index under the slogan “publish or perish,” “miserable scientists” prefer to compete in inventing crazy theories to substantiate obviously dubious experimental data instead of spending a little time and resources to check this data before sitting down to a purely theoretical article. An example of such “miserable scientists” is precisely the “physicists from Singapore” whom you mentioned in the article - their publication does not contain their own experimental data, but only bare theoretical reasoning about the possible influence of the abstruse phenomenon “O:H-O Bond Anomalous Relaxation” on the process of anomalous freezing of water, which was observed by Francis Bacon and Rene Descartes and even Aristotle as early as 350 BC. ... And personally, I am very glad that Nikola Bregovic from the University of Zagreb received his prize money of 1000 pounds from the Royal Society of Chemistry of Great Britain after using good equipment under reproducible conditions he himself measured quite physically explainable results without any anomalies and questioned how clumsy the measurements were the boy Mpemba and his followers and the adequacy of those who tried to provide a “theoretical basis” for these clumsy experiments.

In modern conditions, the human body experiences water starvation: for the most part this is due to the characteristics of the artificial environment in which we live, the dehydrating effect of air-conditioned air and the food we eat. We are accustomed to not only quenching thirst, but also extracting some additional effect from drinking: the pleasant taste of soft drinks, the tonic properties of coffee or tea. We have forgotten how to simply drink water.

My drink

DRINK ROOM TEMPERATURE WATER OFTEN AND SLOWLY, WITHOUT WAITING TO FEEL STRONGLY THIRSTY

Sodas often contain corn syrup, which contains high levels of fructose, which is converted directly into triglycerides (the building blocks of fat) rather than glucose, which is the fuel for brain function. Now about milk: its protein takes a long time to digest, and the breakdown of lactose (milk sugar) requires the enzyme lactase, which not all people produce. Freshly squeezed juices are healthier, but this is also a kind of super-concentrated artificial drink - it would be much healthier to eat the whole fruit, along with the fiber and ballast substances it contains. In short, no other liquids - even those that we are accustomed to consider healthy and natural - can replace ordinary drinking water.

One water

Many people's chemistry lessons left in their memory only the formula of water, H2O, as well as the belief that without water, life would not have arisen on our planet at all. This is true: with its direct participation, almost all biochemical reactions occur. After all, water is a universal solvent. The building material for constant renewal of the body (that is, for the synthesis of proteins) and energy sources (carbohydrates), oxygen, hormones and enzymes circulate in the intercellular space and enter the cells, being dissolved in water. And metabolic products are removed from cells and from the body also in solution.

Water “enters and leaves” through special water channels located in the plasma membrane of cells and called “aquaporins” (for their discovery, two American scientists, Peter Agree and Roderic McKinnon, were awarded the Nobel Prize in 2003 in chemistry). If other substances are added to the water molecule - after all, the dissolution process is accompanied by complex interactions with salts, sugars, acids, alcohol, chemicals that arise during the absorption of drugs or food additives - then these bulky formations are not able to pass through the small water pore. There seems to be water in the body (sometimes there is even too much of it, and we call this fluid retention, edema), but it does not penetrate into the cells, as a result of which metabolic processes are inhibited and toxins are not eliminated. Naturally, a person feels an incomprehensible malaise and fatigue, the cause of which is literally dissolved in water.

Choose a good filter

With all the variety of water filters, they perform the same task: they purify water from mechanical contaminants (sand, scale, rust), partly from chemical contaminants (chlorine, heavy metal salts, herbicides, pesticides, oil products), as well as from bacteria and viruses . The principle of operation is also similar: water passes through replaceable cartridges with filter media. Most of them “work” with a universal adsorbent - activated carbon and ion exchange resins, which are different for each manufacturer. The slower the water passes through the filter, the cleaner it is. For those who want to be sure that the water will be 97-99% purified, there are filters based on a reverse osmosis system. There, purification occurs by passing water through a multilayer membrane under a pressure of 3.5–4 atmospheres. The dimensions of the cells in the membrane are so small that only molecules of H2O and hydrogen and oxygen dissolved in water can pass through them. The advantage of such water is that you can really be sure of its purity. Disadvantages: it has no taste, it can be considered close to distilled, from which the body has no benefit.

From tap and from bottle

Tap water may not be healthy (after all, it passes through kilometers of pipes), but at least it is safe - primarily thanks to the chlorine ions that are used to disinfect it. The effect of chlorine is detrimental to any living cell - from bacteria to the cells of our body, therefore, before drinking tap water, it is better to filter it. “In principle, there are two options: filter tap water or buy bottled water, but I haven’t decided for myself which would be better,” admits Valery Sergeev. – On the one hand, bottled water is expensive, and there is not always confidence in its quality: did they slip us filtered tap water instead of artesian water? On the other hand, filtered water becomes unbalanced, “idle”. During the filtration process, it is deprived of almost all salts, including essential ones, such as calcium salts (which can lead to brittle bones), as well as essential microelements.”

According to therapist Sergei Stebletsov, even spring water from the foothills of the Alps or obtained as a result of melting glaciers does not always bring guaranteed benefits: it is better to drink local water, to the electrolyte composition of which a person has adapted. The most reasonable compromise option seems to be: do not be afraid of filtered tap water, but make it a rule to drink high-quality bottled water when outside the home.

Quantity and quality

When and how, and most importantly, how much water to drink – experts have differing opinions on this matter. According to Ayurveda, you should drink two to three liters of water per day, and its temperature should be as high as you can tolerate. “If you drink a lot of water at once, the main goal – cleansing the body – will not be achieved,” explains Mohammed Ali, a doctor from the Kerala Ayurvedic center. “Therefore, you need to drink constantly, but little by little: two or three sips every 10–15 minutes.” The morning, he says, should start with a glass of water at room temperature. Like medicine, it must be taken on an empty stomach without getting out of bed. Moreover, the water should not sit in the glass overnight - in this case it becomes “dead” - and should not be tap water. According to Mohammed Ali, ancient Ayurvedic teachers advised drinking rainwater, but now this should not be done for obvious reasons - it is too polluted. It's probably best to drink water from a freshly opened bottle in the morning.

A FEELING OF COMFORT IS THE MAIN SIGN THAT WILL LET YOU UNDERSTAND HOW MUCH WATER THE BODY NEEDS

When we drink water during the day, according to Ayurveda, it is worth taking into account: if we want to lose weight, it is better to drink it before meals, and if we want to gain weight, then after. Accordingly, those who want to keep their kilograms intact can drink water during meals.

A representative of another eastern school, professor of Chinese medicine Gao Yan, believes that it is best to drink water at room temperature. “It’s a little cooler than body temperature and starts the body’s cleansing processes,” he explains. European experts also believe that we need two to three liters of water per day – especially in the summer, when it’s hot. “It should be slightly mineralized, with a predominance of chlorine anions and calcium, magnesium, and potassium cations,” explains Valery Sergeev. “This replenishes the natural loss of salts during increased sweating.” So you can drink water like “Slavyanovskaya”, “Smirnovskaya”, “Kashinskaya”, “Novoterskaya” without restrictions. But highly mineralized waters, such as “Essentuki-17”, are a remedy for diseases of the gastrointestinal tract, which stimulates the secretion of gastric juice and intestinal motility. “If you like carbonated mineral water, then it’s good for your health,” says Valery Sergeev. – It quenches thirst better and stimulates the gastrointestinal tract. But if there are any disturbances in the functioning of the stomach, heartburn and discomfort, it is better to switch to still water.”

Trust feelings

So, drinking about two liters of water a day is considered a physiological norm. But, if we have not yet developed the habit of drinking water, should we count the glasses we drink, as if we were following a doctor’s order? “The body itself knows how much water it needs,” says Sergei Stebletsov. – For some, one and a half liters a day is enough, for others, two and a half is not enough. It all depends on the mode in which the kidneys, lungs, skin and gastrointestinal tract work, through which water leaves the body. The main indicator that you should focus on is a feeling of comfort.”