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nitrogen

The Columbia Encyclopedia, Sixth Edition | Date: 2008

nitrogen , gaseous chemical element; symbol N; at. no. 7; at. wt. 14.0067; m.p. -209.86°C; b.p. -195.8°C; density 1.25 grams per liter at STP; valence principally -3, +3, or +5. Nitrogen is a colorless, odorless, tasteless diatomic gas. It is found in Group 15 of the periodic table . It does not burn, does not support combustion, and is only slightly soluble in water. It is relatively inactive chemically, but many of its compounds display marked reactivity. At high temperatures it reacts with some of the other elements to form nitrides.

Nitrogen for industrial use is produced largely by the fractional distillation of liquid air. Nitrogen is used to some extent for filling light bulbs, in thermometers, and generally anywhere a relatively inert atmosphere is needed, as in the production of electronic parts such as transistors, diodes, and integrated circuits, and in food storage packaging to prevent spoilage. It is used in the manufacture of stainless steel and as a coolant for the immersion freezing of food products, for the transportation of foods, for the preservation of bodies and reproductive cells (sperm and eggs), and for the storage of biological samples. However, the chief importance of the element lies in its compounds, among them ammonia , nitric acid , and cyanide.

Nitrogen Tanks

from The New York Times F.Y.I.
By JESSE MCKINLEY
Published: August 20, 1995

"Nynex has many, many three-inch cables running under the streets, each of which contains 3,600 pairs of copper wires (each pair carries a conversation). Steam, created by subways and heating vents, sometimes gets inside these cables and causes crossed connections and corrosion of the copper wires, said Bob Varettoni, a spokesman for Nynex.

The tanks are actually more like glorified thermoses, keeping the nitrogen very, very cold. Nitrogen boils (that is, starts turning to gas) at about minus 320 degrees Fahrenheit. So when the nitrogen is pumped out of the tank into the tubing you see, it becomes a gas. The gas is compressed and then blown into the three-inch cables, sopping up moisture without otherwise affecting the copper wires, before escaping through a venting hole to dissipate in the air, like steam."