What are the uses of nitrogen gas

At room temperature, nitrogen is a colorless and odorless gas that is slightly less dense than air. It is usually in the form of diatomic N2Molecules. When it cools down to −195.82 ° C, the gas condenses to a colorless liquid. Nitrogen is less soluble in water than oxygen. One liter of water dissolves about 23.2 ml of nitrogen at 0 ° C. In contrast, 49.1 ml of oxygen are dissolved.
Liquid nitrogen

Liquid nitrogen is poured into a dewar container.

If substances or objects are kept in liquid nitrogen, they change their properties when they cool down. A frozen rose can be smashed, a solid rubber ball loses its elasticity. If you pour liquid nitrogen into a wide metal bowl filled with hot water, a vapor layer forms on which the nitrogen is carried and which spreads over the whole table. This phenomenon, which can also be observed when pouring water onto a hot stove, is called the “Leidenfrost phenomenon” after the German doctor Johann Gottlieb Leidenfrost (1715–1794).

Leidenfrost phenomenon

In the Leidenfrost phenomenon, a vapor layer forms on which the nitrogen is carried.

If you pour liquid nitrogen into a metal container, liquid air, which is enriched with liquid oxygen, condenses on the lower part of the container. If you hold a smoldering cigarette to such a drop, it flares up brightly. If you immerse balloons filled with carbon dioxide or air in liquid nitrogen, the balloons contract with a crackling sound. When heated, the balloons regain their original shape. When using carbon dioxide as the filling gas, dry ice forms in the balloon, which can be felt when the balloon is shaken.
Air balloon in liquid nitrogen

The balloon shrinks in liquid nitrogen with a loud crackling sound.
When exposed to warmth, it regains its original shape.

Like carbon dioxide, nitrogen does not sustain combustion. Due to its inertia, it forms chemical compounds only with difficulty. At room temperature, nitrogen only reacts with a few substances, for example it reacts with lithium to form lithium nitride:
6 Li + N2  2 li3N ΔHR. = −395 kJ / mol    
2 NH3  N2 + 3 H.2    ΔHR. = +92 kJ / mol 
At very high temperatures, nitrogen reacts with oxygen to form nitrogen monoxide:
N2 + O2  2 NO ΔHR. = −180 kJ / mol