What is freezing point?

What Does freezing point Mean

The freezing point , also called freezing point , is the temperature at which a substance in a liquid state becomes a solid state . In other words: the freezing point is the moment when a liquid solidifies .

In the case of the pure water ( H2O ), the freezing point is 0 ° C . This means that, as long as it is at a temperature above 0ºC and below 100ºC (since that is its boiling point ), the water will be in a liquid state. If the temperature falls below 0ºC , the water will freeze and turn into a solid (ice).

Continuing with the example of water , always taking the theoretical values ​​(since in practice the processes can occur at other temperatures), we can see how a substance changes state according to the different points.
Let's take the water at a room temperature of 20 ° C : the water will be a liquid. If the liquid is subjected to a cooling process , when it reaches 0 ° C it will reach its freezing point and will become a solid. On the other hand, if the water starts to heat up from 20ºC , when it reaches 100ºC it will meet its boiling point and will transform into steam .
Although this value, 0 ° C, is in effect the freezing point of water, this is only fulfilled if the atmospheric pressure conditions are normal and if the water does not contain a certain degree of impurities. If there are such impurities, then it is necessary to get them to freeze, to form small ice seeds or nuclei to help freeze the liquid. A water simulation study by researchers H. Eugene Stanley and Pradeep Kumar revealed that in some cases the freezing point can be below 47 degrees Celsius below zero , a huge difference from the traditional value mentioned above.
If we analyze the freezing point of a solution (for example, seawater, which is salt water), this will depend on the type of solvent and the molality of the solute in the solvent in question. The higher the molality, the lower the freezing point.
Molality, for its part, is expressed by the letter m and is the number of moles of solute found in one kilo of solvent. When the preparation of solutions of a particular molality is required, it is possible to carry it out in a beaker (a cylinder-shaped container that is frequently used in the laboratory, especially for heating or preparing substances, and also for the transfer of liquids) and use an analytical balance to weigh it, not forgetting to note the weight of the glass before pouring the substance to find the exact value.

In the case of molarity, a concept that is sometimes confused with it simply because of its similarity at the orthographic level, the preparation of a solution requires the use of a volumetric flask (volumetric material used to measure the volume of a liquid according to the capacity of the flask itself; it has a narrow and high neck, which increases the accuracy of measurements).
Continuing with molality, which directly affects the freezing point of certain solutions, the greatest benefit it provides as a measurement method is that it does not depend on pressure or temperature, since it is not a function of volume, and allows a calculation more accurate than others. The reason is that the temperature and pressure of a solution determine the volume, and that is why it changes if they do the former.

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