The temperature of liquid nitrogen
Liquid nitrogen is a transparentsubstance whose specific gravity is 0.808 g / cm³. This is one of the aggregate states in which nitrogen can be present, its boiling point is -195.75 ° C. Liquid nitrogen is not toxic and explosive.
A feature of the operation and storage of liquidNitrogen is that when heated, it expands very much, for example, when the temperature is raised to only 20 C, about 700 liters of gas are formed from one liter of the substance. Therefore, for storage and transportation it is used special containers, the so-called Dewar vessels, which provide vacuum isolation.
Liquid nitrogen has found wide application inthe most diverse areas of human activity, in many ways, this breadth of use is due to a property such as the temperature of liquid nitrogen. It is used in industry where it is necessary to apply the technology of cryogenic metal cutting. The very low temperature of liquid nitrogen allows it to be used in deep freezing, and in this sphere it is suitable for both inorganic materials and organic, including living organisms.
There are other uses: fire fighting and cooling of various units and technical devices, cryopreservation of cells, overclocking.
At atmospheric pressure, the temperature of liquid nitrogen is below the oxygen condensation temperature by 10 degrees, therefore, as a rule, a sediment of the substance condensate can be observed on the walls of the vessels.
Due to the fact that the boiling point of nitrogen inliquid state is -195.8 ° C, which is lower than that for liquid oxygen, in which it is -183 ° C, as a result of their interaction, liquid air is very rapidly enriched in oxygen. The same temperature difference explains the more intensive evaporation of liquid nitrogen, in comparison with liquid oxygen.
Virtually any temperature that exceedsthe indicator for liquid nitrogen can be observed in the following experiment. Required for this aluminum block, cooling, if it gradually dripped with liquid air.
In modern technologies, the temperature of liquidnitrogen, as the main property of this substance, has caused widespread use in the electronic and electrical industry of semiconductors, which due to this, are reliably cooled.
The same principle is based on the application ofsubstance as a component of various fire-fighting mixtures. In the process of fire extinguishing, nitrogen evaporates very quickly and, thereby, displaces oxygen, as a result of stopping access to oxygen to the fire, the fire is localized and stops altogether. Due to this effect, nitrogen fire extinguishing is now recognized as more effective than carbon dioxide. With the use of such technologies, a high degree of preservation of material values is achieved.
In general, the effect of liquid nitrogen hasthe opportunity to observe almost everyone, if you turn your attention to the movie effects used in the filming of modern films. For example, in the movie "Terminator", the effects obtained with the help of liquid nitrogen (frames, on which instantaneous freezing of objects are shown) are widely used. But this effect can have a much more familiar embodiment. For example, the low temperature of nitrogen allows it to be used for quick freezing of anesthetic character. This we can often observe during sports competitions, when an athlete is injured, and he is given first aid by local aerosol anesthesia.
More exotic, if not to saythe use of a substance as a means of freezing living beings, with a view to their subsequent defrosting, and the preservation of biological properties, now appears.
At the same time, in the US and Russia, there are already companies that are engaged in cryogenic freezing of people and animals on a commercial basis.
