Learn all about nitrogen, the key nutrient essential for healthy plant growth and crop production.Nitrogen . It is the chemical element with atomic number 7 and symbol N. It is a colorless, odorless and tasteless gas that constitutes four-fifths of atmospheric air (in its molecular form N 2 ).
History
Nitrogen was recognized as an independent substance in 1772 by the Scottish physician , chemist , and botanist Daniel Rutherford of the University of Edinburgh, who showed that it was incapable of supporting life or combustion . The French chemist Antoine Laurent Lavoisier called it mephitic air and later ázoe (“lifeless”), and it is still known by this name in France (azote). The French physician and industrialist Jean Chaptal proposed the name nitrogen in 1790 , due to the presence of this element in nitre (saltpeter, KNO 3 ).
Natural state
Nitrogen is the main component of the Earth ‘s atmosphere , accounting for 78.1% of its volume. This concentration is the result of the balance between the fixation of atmospheric nitrogen by bacterial, electrical (lightning) and chemical (industrial) action and its release through the decomposition of organic matter by bacteria or by combustion. It also makes up 3% of the elemental composition of the human body and appears in animal remains. Scientists have detected some compounds from outer space that contain nitrogen.
This chemical element is an essential component of nucleic acids and amino acids. When hydrogen compounds have cyanide ions, they form salts that are toxic and can be fatal.
It is inert and acts as an oxygen-diluting agent in the processes of combustion and respiration. It is an important element in plant nutrition . Certain soil bacteria fix nitrogen and transform it (for example, into nitrates) so that it can be absorbed by plants, in a process called nitrogen fixation. In the form of protein , it is an important component of animal fibers. Nitrogen appears combined in minerals, such as saltpeter (KNO 3 ) and Chilean nitrate ( NaNO 3 ), two important commercial products.
Obtaining
It is obtained from the atmosphere by passing air through hot copper or iron ; oxygen is separated from the air, leaving nitrogen mixed with inert gases. Pure nitrogen is obtained by fractional distillation of liquid air. Since liquid nitrogen has a lower boiling point than liquid oxygen , nitrogen is distilled earlier, allowing them to be separated.
Applications
Nitrogen is used as a refrigerant and in the production of ammonia , which is then used to produce fertilizers , nitric acid , urea , hydrazine , amines and explosives.
Ammonia is also used to make nitrous oxide ( N2O ), a colorless gas popularly known as laughing gas. This gas, mixed with oxygen , is used as an anesthetic in surgery .
Liquid nitrogen
Liquid nitrogen is widely used in the field of cryogenics as a cooling agent. Its use has increased with the arrival of ceramic materials that become superconductors at the boiling point of nitrogen.
Liquid nitrogen is kept at a temperature equal to or lower than its boiling point (-195.8 ºC). It can be produced industrially by fractional distillation and is often used to seal water channels in public works.
Finally, the nitrogen cycle is known as the biological and abiotic processes that allow the supply of the element to living beings. The dynamic balance of the biosphere ‘s composition depends on these processes.
Compounds
Nitrogen compounds have been known since ancient times. The most important from an industrial point of view are: NH 3 , and HNO 3 .
The name ammonia derives from the name given to an Egyptian deity: Amon. The Egyptians prepared a compound, ammonium chloride , from animal urine in a temple dedicated to this god. When it was brought to Europe it kept that name in memory of the salt of Ammon. At room temperature it is a colorless gas with a strong and characteristic odor. It is easy to condense into liquid ammonia. The liquid is a good solvent for alkaline and alkaline earth metals as well as for fats and non-polar substances. It is the gas with the greatest solubility in water because it is capable of forming hydrogen bonds with it (1 L of H 2 O dissolves 727 L of NH 3 ).
The two common oxyacids of nitrogen are nitrous acid (HNO2 ) and nitric acid (HNO3 ) . The former is a much weaker acid than the latter. Nitric acid was known to alchemists as aqua fortis . It is the most important oxyacid of nitrogen and probably the second most important of all inorganic acids (after sulfuric acid) . It is an oily, colorless liquid which, when exposed to light, turns brown in color, more or less intense, due to its partial decomposition into NO2 ( its solutions should be kept in dark bottles).
Nitrogen forms a series of oxides in which the oxidation state of N can take any value in the range +1 to +5. Nitrogen oxides are not as common as other nitrogen compounds, but they are widely encountered. N2O has anesthetic properties and is used somewhat in dentistry ( “ laughing gas”). NO2 is used in the manufacture of nitric acid. N2O4 is widely used as an oxidizer in rocket fuels.
NO is the most biologically important oxide of nitrogen. In humans, it plays a role in maintaining blood pressure , aids in the immune response to eliminate foreign organisms, and is essential for maintaining long-term memory. In 1996 , scientists discovered that hemoglobin transports NO as well as O 2 . NO decreases the thickness of blood vessel walls, facilitating the transport of oxygen to surrounding tissues.