liquidnitrogen

Liquid nitrogen is the liquid form of the element nitrogen. It is produced by Fractional distillation of liquid air and is stored and transported in insulated dewars. It boils at −196 °C (−321 °F) at one atmosphere, so it exists as a cold liquid with a continuous vapor cloud when exposed to room temperature. It is colorless, odorless, and non-toxic, but it is not inert in all respects: it can displace oxygen in enclosed spaces and pose asphyxiation and cryogenic-frostbite hazards. It is non-flammable and does not react readily with most materials at room temperature.

Properties commonly cited include a density of about 0.807 g/mL near its boiling point and a large expansion ratio: roughly 700 units of liquid nitrogen vaporize to one unit of liquid at room temperature. This rapid vaporization can generate high pressures if confined, which is a key safety consideration.

Uses span multiple fields. In science and industry, liquid nitrogen is used for cryogenics and cooling of superconducting magnets, detectors, and laboratory equipment. It is employed in cryopreservation of biological samples, including cells and reproductive material. In food and beverage production, LN2 is used for rapid freezing and for creating fog effects in culinary applications. In medicine, it is used for cryosurgery to destroy diseased tissue.

Safety and handling require proper ventilation, protective equipment such as cryogenic gloves and eye protection, and avoidance of sealed containers. Liquid nitrogen can cause cold burns and asphyxiation if released in insufficiently ventilated areas, emphasizing the need for trained handling practices and appropriate storage.