• Question: what is liquid nitrogen

    Asked by elsa to Angela, Claire, Ian, Robert, Sarah on 19 Nov 2014.
    • Photo: Ian Cade

      Ian Cade answered on 19 Nov 2014:

      it is nitrogen… that is a liquid

      …

      It is a general property of matter that if you raise the temperature you tend to convert solids to liquids and then to gasses. These changes in the ‘phases’ of matter is also affected by pressure (raising the pressure will usually encourage liquids to solidify and gasses to condense into liquids).

      So to make liquid nitrogen you just have to liquefy gaseous nitrogen… which may be done by cooling it or pressurising it, or both.

      Its really no different than the relationship between water and water vapour, only that you are more familiar with liquid water then liquid nitrogen because at 25C and 1 atmosphere water is a liquid and nitrogen is a gas.

    • Photo: Angela Stokes

      Angela Stokes answered on 19 Nov 2014:

      It is nitrogen gas that has been cooled to below minus 196 degrees centigrade so it becomes liquid. As it warms it becomes a gas once more as it boils at minus 196 degrees centigrade.

      Doctors can use it to freeze of warts and other skin tag type things from patients arms and necks., it can also be used in food preservation.

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