Liquid nitrogen

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"LN2" redirects here. Liquid nitrogen_sentence_0

For the high-speed railway line in France, see LGV Atlantique. Liquid nitrogen_sentence_1

For the natural logarithm of 2, see Natural logarithm of 2. Liquid nitrogen_sentence_2

Liquid nitrogen—LN2—is nitrogen in a liquid state at low temperature (−195.79 °C (77 K; −320 °F) boiling point at sea level). Liquid nitrogen_sentence_3

It is produced industrially by fractional distillation of liquid air. Liquid nitrogen_sentence_4

It is a colorless, low viscosity liquid that is widely used as a coolant. Liquid nitrogen_sentence_5

Physical properties Liquid nitrogen_section_0

The diatomic character of the N2 molecule is retained after liquefaction. Liquid nitrogen_sentence_6

The weak van der Waals interaction between the N2 molecules results in little interatomic interaction, manifested in its very low boiling point. Liquid nitrogen_sentence_7

The temperature of liquid nitrogen can readily be reduced to its freezing point 63 K (−210 °C; −346 °F) by placing it in a vacuum chamber pumped by a vacuum pump. Liquid nitrogen_sentence_8

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 an insulating layer of nitrogen gas bubbles. Liquid nitrogen_sentence_9

This effect, known as the Leidenfrost effect, occurs when any liquid comes in contact with a surface which is significantly hotter than its boiling point. Liquid nitrogen_sentence_10

Faster cooling may be obtained by plunging an object into a slush of liquid and solid nitrogen rather than liquid nitrogen alone. Liquid nitrogen_sentence_11

Handling Liquid nitrogen_section_1

As a cryogenic fluid that rapidly freezes living tissue, its handling and storage require thermal insulation. Liquid nitrogen_sentence_12

It can be stored and transported in vacuum flasks, the temperature being held constant at 77 K by slow boiling of the liquid. Liquid nitrogen_sentence_13

Depending on the size and design, the holding time of vacuum flasks ranges from a few hours to a few weeks. Liquid nitrogen_sentence_14

The development of pressurised super-insulated vacuum vessels has enabled liquid nitrogen to be stored and transported over longer time periods with losses reduced to 2% per day or less. Liquid nitrogen_sentence_15

Uses Liquid nitrogen_section_2

Liquid nitrogen is a compact and readily transported source of dry nitrogen gas, as it does not require pressurization. Liquid nitrogen_sentence_16

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: Liquid nitrogen_sentence_17

Liquid nitrogen_unordered_list_0

Culinary use Liquid nitrogen_section_3

See also: Ice cream § Cryogenics Liquid nitrogen_sentence_18

The culinary use of liquid nitrogen is mentioned in an 1890 recipe book titled Fancy Ices authored by Mrs. Agnes Marshall, but has been employed in more recent times by restaurants in the preparation of frozen desserts, such as ice cream, which can be created within moments at the table because of the speed at which it cools food. Liquid nitrogen_sentence_19

The rapidity of chilling also leads to the formation of smaller ice crystals, which provides the dessert with a smoother texture. Liquid nitrogen_sentence_20

The technique is employed by chef Heston Blumenthal who has used it at his restaurant, The Fat Duck, to create frozen dishes such as egg and bacon ice cream. Liquid nitrogen_sentence_21

Liquid nitrogen has also become popular in the preparation of cocktails because it can be used to quickly chill glasses or freeze ingredients. Liquid nitrogen_sentence_22

It is also added to drinks to create a smoky effect, which occurs as tiny droplets of the liquid nitrogen come into contact with the surrounding air, condensing the vapour that is naturally present. Liquid nitrogen_sentence_23

History Liquid nitrogen_section_4

Nitrogen was first liquefied at the Jagiellonian University on 15 April 1883 by Polish physicists Zygmunt Wróblewski and Karol Olszewski. Liquid nitrogen_sentence_24

Safety Liquid nitrogen_section_5

Because the liquid-to-gas expansion ratio of nitrogen is 1:694 at 20 °C (68 °F), a tremendous amount of force can be generated if liquid nitrogen is vaporized in an enclosed space. Liquid nitrogen_sentence_25

In an incident on January 12, 2006 at Texas A&M University, the pressure-relief devices of a tank of liquid nitrogen were malfunctioning and later sealed. Liquid nitrogen_sentence_26

As a result of the subsequent pressure buildup, the tank failed catastrophically. Liquid nitrogen_sentence_27

The force of the explosion was sufficient to propel the tank through the ceiling immediately above it, shatter a reinforced concrete beam immediately below it, and blow the walls of the laboratory 0.1–0.2 m off their foundations. Liquid nitrogen_sentence_28

Because of its extremely low temperature, careless handling of liquid nitrogen and any objects cooled by it may result in cold burns. Liquid nitrogen_sentence_29

In that case, special gloves should be used while handling. Liquid nitrogen_sentence_30

However, a small splash or even pouring down skin will not burn immediately because of the Leidenfrost effect, the evaporating gas thermally insulates to some extent, like touching a hot element very briefly with a wet finger. Liquid nitrogen_sentence_31

If the liquid nitrogen manages to pool anywhere, it will burn severely. Liquid nitrogen_sentence_32

As liquid nitrogen evaporates it reduces the oxygen concentration in the air and can act as an asphyxiant, especially in confined spaces. Liquid nitrogen_sentence_33

Nitrogen is odorless, colorless, and tasteless and may produce asphyxia without any sensation or prior warning. Liquid nitrogen_sentence_34

Oxygen sensors are sometimes used as a safety precaution when working with liquid nitrogen to alert workers of gas spills into a confined space. Liquid nitrogen_sentence_35

Vessels containing liquid nitrogen can condense oxygen from air. Liquid nitrogen_sentence_36

The liquid in such a vessel becomes increasingly enriched in oxygen (boiling point 90 K; −183 °C; −298 °F) as the nitrogen evaporates, and can cause violent oxidation of organic material. Liquid nitrogen_sentence_37

Ingestion of liquid nitrogen can cause severe internal damage, due to freezing of the tissues which come in contact with it and to the volume of gaseous nitrogen evolved as the liquid is warmed by body heat. Liquid nitrogen_sentence_38

In 1997, a physics student demonstrating the Leidenfrost effect by holding liquid nitrogen in his mouth accidentally swallowed the substance, resulting in near-fatal injuries. Liquid nitrogen_sentence_39

This was apparently the first case in medical literature of liquid nitrogen ingestion. Liquid nitrogen_sentence_40

In 2012, a young woman in England had her stomach removed after ingesting a cocktail made with liquid nitrogen. Liquid nitrogen_sentence_41

Production Liquid nitrogen_section_6

Main article: Air separation Liquid nitrogen_sentence_42

Liquid nitrogen is produced commercially from the cryogenic distillation of liquified air or from the liquefication of pure nitrogen derived from air using pressure swing adsorption. Liquid nitrogen_sentence_43

An air compressor is used to compress filtered air to high pressure; the high-pressure gas is cooled back to ambient temperature, and allowed to expand to a low pressure. Liquid nitrogen_sentence_44

The expanding air cools greatly (the Joule–Thomson effect), and oxygen, nitrogen, and argon are separated by further stages of expansion and distillation. Liquid nitrogen_sentence_45

Small-scale production of liquid nitrogen is easily achieved using this principle. Liquid nitrogen_sentence_46

Liquid nitrogen may be produced for direct sale, or as a byproduct of manufacture of liquid oxygen used for industrial processes such as steelmaking. Liquid nitrogen_sentence_47

Liquid-air plants producing on the order of tons per day of product started to be built in the 1930s but became very common after the Second World War; a large modern plant may produce 3000 tons/day of liquid air products. Liquid nitrogen_sentence_48

See also Liquid nitrogen_section_7

Liquid nitrogen_unordered_list_1

Credits to the contents of this page go to the authors of the corresponding Wikipedia page: nitrogen.