Distribution in nature
In the air there is about 78.09% of free nitrogen by volume, by weight - 75.6%, if we ignore the minor impurities in the form of oxides and ammonia.As the prevalence of the solar system, it occupies the fourth place, following the hydrogen, helium and oxygen.
Translated from the Greek "nitrogen" means "lifeless that does not support life," in fact this chemical element necessary for the life of organisms.Protein animals and humans by 16-17% nitrogen, it is formed by the consumption of the substances present in living organisms and herbivores in plants.In nature, it constantly runs the cycle, the main role is played by microorganisms capable of converting free atmospheric nitrogen into compounds, which are then absorbed by plants.
Physical and chemical properties
diatomic molecule at the nitrogen triple bond, its dissociation becomes noticeable only at very high temperatures.Nitrogen is lighter than air, the water in the gas is less soluble than oxygen.It is hardly liquefied, while it has a low critical temperature (-147 ° C).
This gas has a very low reactivity, the cause of which is a large dissociation energy of the molecule.Nitrogen oxides are formed in air at atmospheric discharges, they can also be prepared by the action of ionizing radiation on a mixture of nitrogen and oxygen.
nitrogen reacts upon heating to relatively low temperatures only with active metals such as calcium, magnesium and lithium, with most other chemical elements it reacts at a high temperature in the presence of catalysts.Since it does not react with halogens, all nitrogen halides can be obtained only indirectly, most of them are malostoykimi compounds.
Most of the resulting free nitrogen goes into the production of ammonia, which is then processed into fertilizer, nitric acid and explosives.Nitrogen is used as inert medium in various chemical and metallurgical processes, it is used for pumping flammable liquids, and also to fill the free space in the Mercury thermometers.Liquid nitrogen finds application in various refrigeration systems as a refrigerant.It is stored in steel containers, and nitrogen gas - in cylinders.
- HiMiK.ru, Nitrogen