Liquid nitrogen

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Liquid nitrogen

Liquid nitrogen is a liquefied atmospheric gas

Gas

In physics, a gas is a state of matter, consisting of a collection of particles without a definite shape or volume that are in more or less random motion....
produced industrially in large quantities by fractional distillation

Fractional distillation

Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compound by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate....
of liquid air

Liquid air

Liquid air is air that has been cooled to very low temperatures so that it has condensed to a liquid. At room temperature, it must be kept in a Dewar flask....
. It is pure nitrogen

Nitrogen

Nitrogen is a chemical element that has the symbol N and atomic number 7 and atomic mass 14.00674?. Elemental nitrogen is a colorless, odorless, tasteless and mostly inert diatomic gas at standard conditions, constituting 78% by volume of Earth's atmosphere....
in a liquid state at very low temperature. Liquid nitrogen is a colourless clear liquid with density at its boiling point

Boiling point

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Liquid nitrogen is a liquefied atmospheric gas

Gas

Fractional distillation

Liquid air

Liquid air is air that has been cooled to very low temperatures so that it has condensed to a liquid. At room temperature, it must be kept in a Dewar flask....
. It is pure nitrogen

Nitrogen

Boiling point

The boiling point of a liquid is the temperature at which the vapor pressure of the liquid equals the environmental pressure surrounding the liquid....
of 0.807 g/mL and a dielectric constant of 1.4. Liquid nitrogen is often referred to by the abbreviation, LN₂ and has the UN number

UN number

UN numbers or UN IDs are four-digit numbers that identify hazardous substances, and articles in the framework of international transport....
1977.

At atmospheric pressure

Atmospheric pressure

Atmospheric pressure is sometimes defined as the force per unit area exerted against a surface by the weight of air above that surface at any given point in the Earth's atmosphere....
, liquid nitrogen boils at and is a cryogenic

Cryogenics

In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. Rather than the familiar temperature scales of Fahrenheit and Celsius, cryogenicists use the Kelvin scales....
fluid which can cause rapid freezing

Freezing

In physical science, freezing or solidification is the process in which a liquid turns into a solid when cold enough. The Melting point is the temperature at which this happens....
on contact with living tissue, which may lead to frostbite

Frostbite

Frostbite is the medical condition wherein localized damage is caused to skin and other biological tissue due to extreme cold.Frostbite is most likely to happen in body parts farthest from the heart and those with large exposed areas....
. When appropriately insulated

Thermal insulation

The term thermal insulation can refer to materials used to reduce the rate of heat transfer, or the methods and processes used to reduce heat transfer....
from ambient heat

Heat

In physics and thermodynamics, heat is any transfer of energy from one body or thermodynamic system to another due to a difference in temperature....
, liquid nitrogen can be stored and transported, for example in vacuum flasks. Here, the very low temperature is held constant at 77 K by slow boiling of the liquid, resulting in the evolution of nitrogen gas. Depending on the size and design, the holding time of vacuum flasks ranges from a few hours to a few weeks.

Liquid nitrogen can easily be converted to the solid by placing it in a vacuum chamber pumped by a rotary vacuum pump. Liquid nitrogen freezes at . Despite its reputation, liquid nitrogen's efficiency as a coolant is limited by the fact that it boils immediately on contact with a warmer object, enveloping the object in insulating nitrogen gas. This effect, known as the Leidenfrost effect

Leidenfrost effect

The Leidenfrost effect is a phenomenon in which a liquid, in near contact with a mass significantly hotter than its boiling point, produces an insulating vapor layer which keeps that liquid from boiling rapidly....
, applies to any liquid in contact with an object significantly hotter than its boiling point. More rapid cooling may be obtained by plunging an object into a slush of liquid and solid nitrogen than into liquid nitrogen alone.

Applications

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

Freezing Point

Freezing Point is a news journal in the People's Republic of China which has been the subject of controversy over its criticism of Communist Party officials and the sympathetic ear it lent to a Chinese historian who had criticized official history textbooks....
of water makes it extremely useful in a wide range of applications, primarily as an open-cycle refrigerant

Refrigerant

A refrigerant is a compound used in a heat engine that undergoes a phase change from a gas to a liquid and back. The two main uses of refrigerants are refrigerators/freezers and air conditioners ....
, including:

in cryogenics
Cryogenics

In physics, cryogenics is the study of the production of very low temperature and the behavior of materials at those temperatures. Rather than the familiar temperature scales of Fahrenheit and Celsius, cryogenicists use the Kelvin scales....
as a source of very dry nitrogen gas
the immersion freezing and transportation of food
Food

Food is any substance, usually composed of carbohydrates, fats, proteins and water, that can be Eating or Drinking by an animal or human for nutrition or pleasure....
products
the cryopreservation
Cryopreservation

Cryopreservation is a process where cell or whole Biological tissue are preserved by cooling to low sub-zero temperatures, such as 77 K or -196 ?C ....
of blood
Blood

Blood is a specialized bodily fluid that delivers necessary substances to the body's Cell s ? such as nutrients and oxygen ? and transports waste products away from those same cells....
, reproductive cells (sperm
Sperm

The term sperm is derived from the Greek word sperma and refers to the male reproductive Cell . In the types of sexual reproduction known as anisogamy and oogamy, there is a marked difference in the size of the gametes with the smaller one being termed the "male" or sperm cell....
and egg
Ovum

An ovum is a haploid female reproductive cell or gamete. Both animals and embryophytes have ova. The term ovule is used for the young ovum of an animal, as well as the plant structure that carries the female gametophyte and egg cell and develops into a seed after fertilization....
), and other biological
Biology

Biology is a branch of the natural sciences concerned with the study of living organisms and their interaction with each other and their environment ....
samples and materials
as a coolant
Coolant

A coolant is a fluid which flows through a device in order to prevent its overheating, transferring the heat produced by the device to other devices that utilize or dissipate it....
for overclocking
Overclocking

Overclocking is the process of running a computer hardware at a higher clock rate than it was designed for or was specified by the manufacturer, usually practiced by personal computer enthusiasts seeking an increase in the performance of their computers....
a central processing unit
Central processing unit

A central processing unit is an electronic circuit that can execute computer programs. This broad definition can easily be applied to many early computers that existed long before the term "CPU" ever came into widespread usage....
, a graphics processing unit
Graphics processing unit

A graphics processing unit or GPU is a dedicated graphics rendering device for a personal computer, workstation, or game console. Modern GPUs are very efficient at manipulating and displaying computer graphics, and their highly parallel structure makes them more effective than general-purpose Central processing unit for a range of com...
, or another type of computer hardware
Computer hardware

A personal computer is made up of computer hardware, multiple physical components onto which can be loaded into a multitude of software that perform the functions of the computer....
as a method of freezing water pipes in order to work on them in situations where a valve is not available to block water flow to the work area.
in cryotherapy
Cryotherapy

Cryotherapy is the local or general use of low temperatures in medical therapy or the removal of heat from a body part. Its goal is to decrease cellular metabolism, increase cellular survival, decrease inflammation, decrease pain and spasm, promote vasoconstriction, and when using extreme temperatures, to destroy cells by crystalizing the cy...
for removing unsightly or potentially malignant skin lesions
Skin cancer

Skin cancer is a malignant growth on the skin which can have many causes. The most common skin cancers are basal cell cancer, squamous cell cancer, and melanoma....
such as wart
Wart

A wart is generally a small, rough tumor, typically on hands and feet but often other locations, that can resemble a cauliflower or a solid blister....
s and actinic keratosis
Actinic keratosis

Actinic keratosis is a premalignant condition of thick, scaly, or crusty patches of skin. It is more common in fair-skinned people. It is associated with those who are frequently exposed to the sun, as it is usually accompanied by Sun damage....
.
in the process of promession, a way to dispose of the dead.
cooling a high-temperature superconductor to a temperature sufficient to achieve superconductivity
Superconductivity

Superconductivity is a phenomenon occurring in certain materials generally at very low temperatures, characterized by exactly zero electrical resistance and the exclusion of the interior magnetic field ....
.
the cryonic preservation of humans and pets
Cryonics

Cryonics is the low-temperature Preserve of humans and animals that can no longer be sustained by contemporary medicine until resuscitation may be possible in the future....
in the hope of future reanimation.
as a coolant for vacuum pump
Vacuum pump

A vacuum pump is a device that removes gas molecules from a sealed volume in order to leave behind a partial vacuum. The vacuum pump was invented in 1650 by Otto von Guericke....
traps and in controlled-evaporation processes in chemistry.
as a coolant to increase the sensitivity of infrared homing
Infrared homing

Infrared homing refers to a Missile guidance#Passive homing which uses the light emission from a target of electromagnetic radiation in the infrared part of the Electromagnetic spectrum to track it....
seeker heads of missiles such as the Strela 3.
as a coolant to temporarily "shrink" mechanical components during machine assembly and allow improved interference fits.

Safety

Since the liquid to gas expansion ratio

Expansion ratio

The expansion ratio of a Liquification and cryogenic substance is the volume of a given amount of that substance in liquid form compared to the volume of the same amount of substance in gaseous form, at a given temperature....
of this substance is 1:694, a tremendous amount of force can be generated when liquid nitrogen boils off for whatever reason. In an incident in 2006 at Texas A&M University

Texas A&M University

Texas A&M University, often called A&M or TAMU, is a coeducational public university research university located in College Station, Texas, Texas....
, the pressure-relief devices of a tank of liquid nitrogen were sealed with brass plugs. As a result, the tank failed catastrophically, and exploded. The force of the explosion was sufficient to propel the tank through the ceiling immediately above it.

Due to its extremely low temperature, careless handling of liquid nitrogen may result in cold burns. As liquid nitrogen evaporates it will reduce the oxygen

Oxygen

Oxygen no O2 produced; 2) O2 produced, but absorbed in oceans & seabed rock; 3) O2 starts to gas out of the oceans, but is absorbed by land surfaces and formation of ozone layer; 4-5) O2 sinks filled and the gas accumulates]]...
concentration in the air

AIR

Air is the part of Earth's atmosphere that humans breath and as such Air .Air may also refer to:...
and might act as an asphyxiant, especially in confined spaces. Nitrogen is odourless, colourless and tasteless, and may produce asphyxia without any sensation or prior warning.

Vessels containing liquid nitrogen can condense oxygen from air

Liquid oxygen

Liquid oxygen is a form of the element oxygen. It has a pale blue color and is strongly paramagnetism. Liquid oxygen has a density of 1.141 g/cm? and is moderately cryogenics ...
. The liquid in such a vessel becomes increasingly enriched in oxygen (boiling point = 90 K) as the nitrogen evaporates, and can cause violent oxidation of organic material.

Cost

The cost of liquid nitrogen depends on the distance from related facilities and the price of energy; the actual cost tends to range between US$0.10 and US$0.50 per liter.

External links

- How liquid nitrogen is used in restaurants for cooking and cocktails

Liquid nitrogen

Applications

Safety

Cost

See also

External links