Nitrogen, symbol N, is the chemical element of atomic number seven. At room temperature, it is a gas diatomic molecules and is colorless and odorless. Nitrogen is a common element in the universe, estimated at about seventh in total abundance in our galaxy and the Solar System. On Earth, the element is primarily found as the gas molecule; it forms about 78% of Earth's atmosphere. The element nitrogen was discovered as a separable component of air, by Scottish physidan Daniel Rutherford, in 1772.
Many industrially important compounds, such as ammonia, nitric add, organic nitrates_(propellants and explosives), and cyanides, contain nitrogen. The extremely strong bond in elemental nitrogen dominates nitrogen chemistry, causing difficulty for both organisms and industry in converting the N2 into useful compounds, but at the same time causing release of large amounts of often useful energy when the compounds bum, explode, or decay back into nitrogen gas. Synthetically produced ammonia and nitrates_are key industrial fertilizers and fertilizer nitrates are key pollutants in causing the eutrophication of water systems.
Nitrogen gas has a variety of applications, induding serving as an inert replacement for air where oxidation is undesirable
As a modified atmosphere, pure or mixed with carbon dioxide, to preserve the freshness of packaged or bulk foods (by delaying randdity and other forms ofoxidative damage). Pure nitrogen as food additive is labelled in fire European Union with the E number E941.
© In incandescent light bulbs as an inexpensive alternative to argon.
© In photolithography in deep ultraviolet, to avoid a strong oxygen absorption.
©Dried and pressurized, as a dielectric gas for high-voltage equipment.
©The manufacturing of stainless steel.
©Used in some aircraft fuel systems to reduce fire hazard, (see inerting system).
©On top of liquid explosives as a safety measure.
©Filling automotive and aircraft tires due to its inertness and lack of moisture or oxidative qualities, as opposed to air.
© Nitrogen is used to protect flammable raw materials from any contact with Oxygen. By substantially reducing the risks of fire or explosion, the use of Nitrogen makes the handling of these materials much safer.
© In the food industry, Nitrogen is used as a protective atmosphere, preventing from any contact between foodstuffs (chips, nuts, etc.) and Oxygen, since the latter could make them unfit for consumption.
© Liquid Nitrogen (-196°C) is used to freeze food that can be cooled dramatically, a process that durably preserves their taste and texture.
© The environment
© Inflating tires with Nitrogen rather than air maintains tire pressure for a longer period of time. This in turn reduces the risks associated with under-inflated tires and lowers fuel consumption.
© Worn down tires can be embrittled upon contact with liquid Nitrogen. Once they have been "cryocrushed", they are recycled instead of being burned.
© Liquid Nitrogen is also used to reduce the emissions of volatile organic compounds (VO C s), which spark off ozone pollution peaks. These substances are industrially used as solvents or scavengers. After being cooled, these gases can be liquefied and trapped, and then recycled, which enables to avoid their release into air.
© In medicine and research, liquid Nitrogen (-196°C) is used to freeze and preserve blood, sperm, embryos, bone marrow cells and other live tissue samples, over periods that are theoretically unlimited.
© Liquid Nitrogen is also used in dermatology, where it is one of the most effective ways to bum warts and small benign skin tumors that are nonetheless contagious.
Liquid nitrogen is nitrogen in a liquid state at an extremely low temperature. It is produced industrially byfractional distillation of liquid air. Liquid nitrogen is a colorless clear liquid with density of 0.807 g/ml at itsboiling point and a dielectric constant of 1.43.Liquid nitrogen is often referred to by the abbreviation, L N 2or "LIN " or "L N" and has the U N number 1977. Liquid nitrogen is a diatomic liquid meaning the diatomic character of the covalent N bonding in N2 gas is retained even after liquefaction. Liquid nitrogen is a compact and readily transported source of nitrogen gas without pressurization. Further, its ability to maintain temperatures far below the freezing point of water makes it extremely useful in a wide range of applications, primarily as an open-cycle refrigerant, including:
© in cryotherapy for removing unsightly or potentially malignant skin lesions such as warts and actinic keratosis © to store cells at low temperature for laboratory work © in cryogenics
© in a Cryophorus to demonstrate rapid freezing by evaporation © as a backup nitrogen source in hypoxic air fire prevention systems © as a source of very dry nitrogen gas
© for the immersion, freezing, and transportation of food products
© for the cryopreservation of blood, reproductive cells (sperm and egg), and other biological samples and materials © to preserve tissue samples from surgical excisions for future studies
© as a method of freezing water and oil pipes in order to work on them in situations where a valve is not available to block fluid flow to the work area, method known as "ice plug" - nowadays replaced by electrical heat pumps (for small pipe diameters)
© in the process of promession, a way to dispose of the dead © for cryonic preservation in hopes of future reanimation.
© to shrink-weld machinery parts together © as a coolant for CCD cameras in astronomy
6) for a high-temperature superconductor to a temperature sufficient to achieve superconductivity for vacuum pump traps and in controlled-evaporation processes in chemistry.
(D to increase the sensitivity of infrared homing seeker heads of missiles such as the Strela 3 $) to temporarily shrink mechanical components during machine assembly and allow improved interference fits for computers and extreme overclocking
© for simulation of space background in vacuum chamber during spacecraft thermal testing ® in food preparation, such as for making ultra-smooth ice cream. See also molecular gastronomy.
© in container inerting and pressurisation by injecting a controlled amount of liquid nitrogen just prior to sealing or capping.
© as a cosmetic novelty giving a smoky, bubbling "cauldron effect" to drinks. See liquid nitrogen cocktail.
© as an energy storage medium.
© branding cattle.