What is liquid nitrogen

Liquid nitrogen (LN2) is the cryogenic liquid form of nitrogen gas (N2) at extremely low temperatures. Nitrogen is a colourless, odorless and tasteless gas that makes up a significant portion of the Earth's atmosphere. In its liquid state, nitrogen becomes a clear, colorless liquid that is extremely cold and has various practical applications because of its unique properties.

What is liquid nitrogen

Liquid nitrogen is obtained by cooling nitrogen gas to a temperature of approximately −196 °C (−321 °F) at atmospheric pressure. At this temperature, nitrogen undergoes a phase transition from a gas to a liquid. Here are some important features of liquid nitrogen:

  • Extreme cold: Liquid nitrogen is one of the coldest substances on Earth, and materials exposed to it can freeze rapidly. It is commonly used as a coolant in various applications.

  • Boiling Point: Liquid nitrogen boils at −196 °C (−321 °F) at atmospheric pressure. This low boiling point means that it vaporizes easily when exposed to high temperatures, producing large amounts of nitrogen gas.

  • Non-toxic: Nitrogen gas is non-toxic, and liquid nitrogen is also considered non-toxic. However, its extremely cold temperature can cause frostbite or tissue damage if it comes into direct contact with skin or other materials.

  • Preservation and cryopreservation: Liquid nitrogen is used in various fields to preserve biological materials, such as cells, tissues and even reproductive cells (sperm and eggs) for research and medical purposes. The low temperature effectively halts metabolic processes and preserves ingredients for extended periods.

  • Cryogenic Storage: Many scientific and industrial applications involve the storage of materials at very low temperatures. Liquid nitrogen is often used as a cryogenic coolant to maintain these low temperatures.

  • Cryotherapy: In medical applications, liquid nitrogen can be used in cryotherapy, a technique that involves applying an extremely cold substance to freeze and destroy abnormal tissue, such as warts or certain skin lesions.

  • Food and Beverage Industry: Liquid nitrogen is sometimes used in the culinary world to make frozen desserts like ice cream with a unique texture or to quickly freeze certain ingredients.

Due to the extreme cold and potential hazards, handling liquid nitrogen requires proper training and safety precautions. It should only be used in well-ventilated areas, and protective gear, such as gloves and safety glasses, should be worn to prevent direct contact with skin and eyes.