nitrogenoxygen

Nitrogenoxygen is a term used to describe a binary gas mixture composed primarily of nitrogen (N2) and oxygen (O2). In practice, the phrase is most often used to refer to the composition of Earth's atmosphere or to engineered blends that adjust the relative amounts of nitrogen and oxygen for specific purposes. The concept is not a distinct chemical compound but a combination of two diatomic gases.

In Earth's atmosphere, nitrogen and oxygen together account for about 99% of the gas by volume, with about 78% nitrogen and 21% oxygen; the remainder includes argon, carbon dioxide, neon, helium, and other minor gases. The N2:O2 ratio is approximately 3.7:1.

Both gases are colorless, odorless, and non-toxic under normal conditions. They are diatomic molecules at room temperature. The mixture's density is close to that of air, and its physical behavior is determined by temperature and pressure; higher oxygen content increases the propensity for combustion and supports aerobic respiration in organisms.

While ordinary air is a nitrogen-oxygen mix, engineered blends adjust the O2 fraction for applications such as medical or diving gas, industrial inerting, and electronics manufacturing. Enriched air nitrox (EANx) is a well-known example in diving, where higher O2 levels (often 32–40%) aid decompression but require careful management of oxygen toxicity risk.

Safety considerations depend on the mixture: reducing the oxygen fraction below normal air can cause hypoxia in enclosed spaces, while increasing oxygen concentration raises fire and oxidation risks. The nitrogen-oxygen pair is ubiquitous as the main constituent of air and is encountered in many industrial, scientific, and environmental contexts.

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