Nitrogen

As more and more uses for the element have been found, the demand for nitrogen has increased dramatically over the past few decades. In 1988, for example, it was the second most widely produced chemical in the United States, with a production of 52.1 billion lbs (23.7 billion kg).

The most important applications of nitrogen depend on the element's inertness. For example, it is used as a blanketing atmosphere in metallurgical processes where the presence of oxygen would be harmful. In the processing of iron and steel, for example, a blanket of nitrogen placed above the metals prevents their reacting with oxygen, forming undesirable oxides in the final products.

The purging of tanks, pipes, and other kinds of containers with nitrogen can also prevent the possibility of fires. In the petroleum industry, for example, the processing of organic compounds in the presence of air creates the possibility of fires, a possibility that can be avoided by covering the reactants with pure nitrogen.

Nitrogen is also used in the production of electronic components. Assembly of computer chips and other electronic devices can take place with all materials submerged in a nitrogen atmosphere, preventing oxidation of any of the materials in use. Nitrogen is often used as a protective agent during the processing of foods so that decay (oxidation) does not occur.

Another critical use of nitrogen is in the production of ammonia by the Haber process, named after its inventor, the German chemist Fritz Haber. The Haber process involves the direct synthesis of ammonia from its elements, nitrogen and hydrogen. The two gases are combined at temperatures of 932–1,292°F (500–700°C) under a pressure of several hundred atmospheres over a catalyst such as finely divided nickel. One of the major uses of the ammonia produced by this method is in the production of synthetic fertilizers.

About a third of all nitrogen produced is used in its liquid form. For example, liquid nitrogen is used for quick-freezing foods and for preserving foods in transit. Materials can also be processed at the very low temperatures of liquid nitrogen in ways that they can not be handled at room temperature. For example, most forms of rubber are too soft and pliable for machining at room temperature. They can, however, first be cooled in liquid nitrogen and then handled in a much more rigid form.