Liquid nitrogen is formed by air fractionation and is extremely cold (-196℃). It is often used as a coolant to store food and medicine. It can not only make sweet ice cream but also be suitable for scientific experiments.
Improper use of liquid nitrogen also has certain hazards. Under normal pressure, the boiling point of liquid nitrogen is extremely low. When exposed to liquid nitrogen, liquid nitrogen will absorb heat from the skin and boil rapidly to expand, which will seriously damage the skin tissue.
The liquid-to-gas expansion ratio of nitrogen is 1: 694. This means that even a small amount of liquid nitrogen will boil into a dense cloud of nitrogen, which will soon fill the entire room with nitrogen. When converted to gas, the relative amount of oxygen will be reduced because nitrogen quickly fills the space, and low-temperature nitrogen is heavier than air, so people who use liquid nitrogen on the ground face the greatest risk of suffocation.
Therefore, liquid nitrogen needs to be stored in a special insulated container to reduce evaporation and store the liquid nitrogen tank in a cool and ventilated environment. When using, you need to wear appropriate safety protective clothing.
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