720 yuan a liter.

1, liquid nitrogen:liquid nitrogen. It is inert, colorless, odorless, non-corrosive, non-flammable, and has an extremely low temperature. Nitrogen makes up most of the atmosphere (78.03% by volume, 75.5% by weight). Nitrogen is inactive and does not support combustion. Vaporization with large amounts of heat absorption contact causes frostbite.

2, at atmospheric pressure, the temperature of liquid nitrogen is -196 ° C; 1 cubic meter of liquid nitrogen can be expanded to 696 cubic meters 21 ° C of pure gaseous nitrogen. Liquid nitrogen is a colorless, odorless, low-temperature liquid and gas under high pressure.

3. Liquid nitrogen (often written as LN2), is a liquid form of nitrogen formed at low temperatures. The boiling point of nitrogen is -196 ° C, in normal atmospheric pressure temperature if below this will form liquid nitrogen; if pressurized.

4, according to the purity of liquid nitrogen use classification, often divided into food-grade liquid nitrogen, industrial-grade liquid nitrogen. Food-grade liquid nitrogen purity is higher, because we have to take into account the safety of human consumption, the purity of 5 9 that is 99.999%. The purity of industrial grade liquid nitrogen is not as high as that of food grade liquid nitrogen, and different industries have different requirements for the purity of liquid nitrogen.

5, food-grade liquid nitrogen applications such as liquid nitrogen ice cream, liquid nitrogen cookies, medical aspects of liquid nitrogen freezing, anesthesia also need high purity liquid nitrogen. Other industries such as chemical, electronics, metallurgy, etc. have different requirements for liquid nitrogen purity.