Why does hot water freeze faster than cold? Why is the rink poured with hot water?

Description of the paradox of mpemba.

Content

Many of us in childhood, as well as in youth, often experimented with physical phenomena, including freezing of water. Oddly enough, but many of us know that for some reason it is customary to fill the rollers with hot water, and not cold, because it freezes faster. In this article, we will tell you why hot water turns into ice faster than cold.

Hot water freezes faster or not?

In general, this fact was known for a very long time, since the time of Aristotle, as well as Descartes. However, there were no scientific evidence. Only in 1963 did significant works began, the main task of which is to find out why this is happening.

Hot water freezes faster or not:

According to physics, this contradicts the first law of thermodynamics, according to which one energy flows into another. According to the first beginning of thermodynamics, the heated liquid, before the cooling temperature should pass, respectively, and hardening time should be much larger.
However, in practice, it happens differently. The schoolboy thought about this, who asked his physics teacher the corresponding question. The boy prepared ice cream at home, and noticed that a glass with a warm liquid froze much faster than with a cool, with the same composition of the substance.
Then the teacher only laughed at the guy, saying that this contradicts the first law of thermodynamics, therefore it is impossible. After a visit to the school of the famous physicist Osborn, the boy asked him the same question, which interested the scientist.

What water freezes hot or cold faster?

Since 1963, Osborne, together with the boy, began to deal with this issue, as a result of which an article was published, in the journal Educiation. At the same time, the exact answer why the heated liquid hardens faster than the cold was not obtained.

What water freezes hot or cold:

According to some scientists, a warm solution in the refrigerator with a thermostat passes into a solid state much faster only for the reason that the refrigerator begins to freeze harder, when the signal about increasing temperature in the chamber.
This does not happen with chilled liquid, since its temperature is much lower, and the thermostat works as usual, without reducing the temperature of the refrigerant. However, this version did not receive confirmation for the reason that the heated liquid under ordinary conditions in the air also hardens much faster than cold.
Accordingly, the thermostat is not in ordinary street conditions, therefore, the cold does not occur.

Why does hot water freeze faster?

However, it was possible to find out that the heated liquid, due to the presence of a large number of flesh above the surface, hardens much faster due to the fact that pairs are formed on the surface, the volume of fluid in the container decreases. Thus, it is possible to freeze a smaller amount of liquid, which is much simpler than more. However, in practice, the loss of volume is insignificant, therefore, the process of hardening cannot be considered justified.

Why is hot water freezing faster:

Many scientists agree that the heated fluid, due to the presence of fumes, begins to turn into ice faster. Ice droplets above the surface fall into the water, which contributes to the formation of ice crust, which is why a quick process of turning into ice occurs.
Scientists have found out,what, If you put a container with a warm fluid on the snow, or an ice crust in the refrigerator, it begins to melt, as a result of which the contact between the container, water in it, as well as the refrigerator, increases, thereby increasing the area of \u200b\u200bcontact, as a result of which there is a rapid freezing of warm water .
Chilled water does not have such an effect due to the fact that under it the snow pillow does not melting, and the process of turning into ice is much slower. In addition, it was possible to find out that the cold liquid, when the temperature is reduced, begins to harden in the upper part. As a result of this, the processes of mixing water inside the water are worsened, therefore the process is delayed. The heated liquid begins to freeze from below, thereby enhancing convection processes, heat radiation.

Why is the rink poured with hot water?

Scientists have found that if you include additional mechanical averaging of water in hot and cold containers, then chilled water will freeze much faster. This is due to the fact that a dense ice crust will not form.

Why the rink is poured with hot water:

Chemists also tried to explain this paradox, by the fact that inside the heated liquid, there are dissolved substances that settled at the bottom, pure water is on top. Everyone knows that the salt solution hardens at a lower temperature than distilled water.
Thus, they tried to explain this paradox. Accordingly, chilled water is more rigid, it in it is pronounced ions contained in its entire volume. In this case, in hot liquid, dissolved salt is preferably in the lower part of the solution.
Thanks to this, the upper part hardens faster, transmitting the reduced temperature to the lower layers of the liquid.

Does cold or hot water freeze faster?

Scientists have found that if constant mixing of warm and cold water, then the cold liquid will turn into ice much faster.

Cold or hot water freezes faster:

Many scientists believe that in warm water the connections between the molecules are stretched, so the hydrogen molecule is also more voluminous in space. With sharp cooling of water, these connections are torn, with a very sharp decrease in temperature.
This is what causes the rapid freezing of warm water. It is believed that hot fluid contains less dissolved gases than in cold. It is due to a change in the composition of hot fluid that its rapid transformation into ice occurs.
There is still no clear and final answer about this paradox. Studies were conducted in 2012-2017, which confirmed the paradox or refuted it. In 2016, in the journal Scientific Reports, there is a link to materials that cold water goes into a solid state slower than heated.

They conducted peculiar studies according to which 400 ml of water with different temperatures were frozen. According to these studies, hot fluid cooled faster than cold. In 2017, a hypothesis was published, according to which the effect of MPEMBA, which concerns the heating of the chilled system, does not correspond to equilibrium. Therefore, all the basic laws of physics and thermodynamics are not suitable for this paradox.