Nitrogen, whose chemical formula is N2, is usually a colorless and odorless gas, and generally has a lower density than air. Nitrogen accounts for 78.08% (volume fraction) of the total atmosphere and is one of the main components of air. Under standard atmospheric pressure, when nitrogen is cooled to -195.8 ° C, it becomes a colorless liquid, and when cooled to -209.8 ° C, liquid nitrogen becomes a snow-like solid. The chemical nature of nitrogen is inert and it is difficult to react with other substances at room temperature, so it is often used to make preservatives. However, under high temperature and high energy conditions, chemical changes can occur with certain substances to make new substances useful to humans.
The main purpose
The main way that humans can effectively use nitrogen is to synthesize ammonia, but the requirements are high. In recent years, people have tried to understand the mechanism of nitrogen fixation in plants, and strived to use chemical methods to simulate biological nitrogen fixation, so as to realize the development and utilization of nitrogen resources in the air under mild conditions. Nitrogen is mainly used for the synthesis of ammonia, and the reaction formula is (conditions are high pressure, high temperature, and catalyst. The reaction is reversible) or an important raw material for synthetic fibers (nylon, acrylic), synthetic resin, synthetic rubber, etc. Nitrogen is a nutrient that can also be used to make fertilizer. For example: ammonium bicarbonate NH4HCO3, ammonium chloride NH4Cl, ammonium nitrate NH4NO3 and so on.
Due to the chemical inertness of nitrogen, it is often used as a protective gas, such as: fruits, food, bulb filling gas. In order to prevent certain objects from being oxidized by oxygen when exposed to air, filling the grain silo with nitrogen can make the grains not moldy and germinate, and can be stored for a long time. Liquid nitrogen can also be used as a deep cryogen. It is often used as a cryopreservant in the hospital for removing plaques, bags, beans, etc., that is, to freeze off plaques, bags, beans, etc., but it is prone to scars and is not recommended. High-purity nitrogen is used as a carrier gas for chromatographs and other instruments. Used as a bright annealing protective gas for copper tubes. Used as laser gas for laser cutting machine together with high purity helium and high purity carbon dioxide. Nitrogen is also used as a food preservation gas. In the chemical industry, nitrogen is mainly used as a protective gas, replacement gas, scrubbing gas, and safety gas. Used as protective gas for aluminum products, aluminum profile processing, aluminum thin rolling. Used as shielding gas for reflow and wave soldering to improve soldering quality. Used as a protective gas in the production process of float glass to prevent oxidation of tin baths.