In accordance with the general definition, the freezing temperature is the temperature of the transition of a substance from a liquid to a solid state. This characteristic depends on which substance is cooled (composition) and at what pressure, because the higher the pressure, the higher the freezing temperature. The most famous substance, which is most often converted from a liquid to a solid state and vice versa, is water. It is known that ordinary water becomes ice at zero degrees Celsius, however, ultrapure H 2 O in a clean vessel can be liquid and in severe frost, as well as a sea containing many salts.
Other fluids have different levels of this characteristic. For example, the freezing point of alcohol is much lower than the same indicator for ordinary water. This is due to the fact that this substance has a lower density.
In total, there are several groups of alcohols, each of which has its own physical and chemical properties. Today, the following classes are distinguished:
- depending on the number of hydroxyl groups (from monohydric to polyhydric alcohols);
- depending on how saturated the hydrocarbon substituent (unsaturated, limiting, aromatic);
- depending on the cyclicity in the hydrocarbon substituent (alicyclic, cyclic);
- by the number of substituents at the alpha-carbon atom (primary - tertiary).
For example, the freezing point of methanol, related to monoatomic, is minus 97 degrees Celsius, and cyclohexanol is about minus 42 ° C. However, most often a query regarding the properties of the liquid that is part of alcoholic beverages appears in search engines. The freezing point of ethyl alcohol (ethanol) is minus 114 degrees Celsius. This property is used in everyday life to isolate the alcohol component from alcohol-containing drinks in order to "increase the degree", as well as for the manufacture of winter "frost-free" for cars. Some motorists add ethanol to glass-washing solutions of the summer type or mix with water in certain proportions.
Note that not all liquids of this class become solid only with very strong cooling. For example, the freezing point of phenylcarbinol alcohol (benzyl aromatic alcohol) is minus 15 ° C.
If you ever become interested in the classification of thermometers, you can find out that there are alcohol-based thermometers. Those. instead of an electronic mechanism or mercury, the device contains alcohol. Such thermometers are most often used where it is necessary to measure low temperatures in domestic conditions. For example, in Siberia, where frosts up to 50-60 degrees are not uncommon. Here, ordinary thermometers will not be able to work correctly, because the freezing temperature of mercury is about minus 38 ° C. You can find out what kind of thermometer you have by the color of the column in the thermometer. If it is silver, then inside is mercury. But the red bar indicates a tinted alcohol solution. Such thermometers are often used to measure external temperatures. Even if it is -45 ° C on the street, the device will not fail, because the freezing point of alcohol is much lower.