The temperature of liquid nitrogen is-196℃ at normal pressure; 1 m3 liquid nitrogen can be expanded into 696 m3 2 1℃ pure gaseous nitrogen. Liquid nitrogen is a colorless and odorless liquid, and it is a cryogenic gas under high pressure. Liquid nitrogen (often written as LN2) is a liquid form formed by nitrogen at low temperature.

In industry, liquid nitrogen is fractionated from air. After air is purified, it is liquefied in a pressurized cooling environment, and separated by using the difference of boiling points of each component in the air. There is no problem for human skin to contact liquid nitrogen directly, and it will be frostbitten for more than 2 seconds, which is irreversible.

Danger:

1, health hazard: skin contact with liquid nitrogen can cause frostbite. If there is too much nitrogen produced by vaporization under normal pressure, the partial pressure of oxygen in the air will decrease, and in extreme cases, it will cause hypoxia and suffocation.

2. Explosion hazard: This product is not flammable and explosive.

Extended data:

A, the safe use of liquid nitrogen:

In general, when liquid nitrogen is stored in a sealed tank, attention should be paid to keeping a certain gap at the mouth of the liquid nitrogen tank, otherwise the gas cannot be discharged in time when liquid nitrogen is gasified, which may easily lead to an explosion accident. Generally, the cover plug of liquid nitrogen tank has a certain gap, so don't block it artificially when using it.

Second, the use of liquid nitrogen matters needing attention:

1, liquid nitrogen is a low-temperature product, and frostbite should be prevented during use.

2. When operating and accessing frozen articles in liquid nitrogen, the speed should be fast, and care should be taken to handle them gently, so as to avoid unnecessary damage caused by thawing articles.

3. Keep good ventilation in the room where liquid nitrogen is used and stored, so as to avoid suffocation due to lack of oxygen in the space.

4. Because liquid nitrogen doesn't sterilize, we should pay attention to the disinfection of instruments that come into contact with liquid nitrogen.

5. The liquid nitrogen tank must be fixed during transportation to prevent vibration and overturning.

6, liquid nitrogen tank storage items for a long time, should pay attention to timely supplement of liquid nitrogen.

Application of liquid nitrogen

1, quickly transport food by freezing, or make ice products;

2. Carry out low-temperature physics research;

3. Demonstrate the low temperature state in science education. Soft objects at room temperature will be as fragile as glass if immersed in liquid nitrogen;

4. Provide the temperature required for high-temperature superconductors to show superconductivity, such as YBCO；;

5. It can be used as refrigerant to quickly freeze biological tissues and prevent them from being destroyed;