Air and Atmosphere - Properties and Uses of Oxygen and Nitrogen

Air is a mixture of gases, primarily consisting of Nitrogen ($N_2$) at approximately $78\%$ and Oxygen ($O_2$) at approximately $21\%$ by volume.

Oxygen ($O_2$) is a colorless, odorless, and tasteless gas. It is slightly heavier than air and is sparingly soluble in water, which allows aquatic life to breathe.

Oxygen is a strong supporter of combustion (burning). It does not burn itself but is necessary for other substances to burn.

Respiration is the biological process where living organisms use $O_2$ to break down glucose ($C_6H_{12}O_6$) to release energy, producing $CO_2$ and $H_2O$ as byproducts.

Nitrogen ($N_2$) is an inert or chemically inactive gas. Its primary role in the atmosphere is to dilute the effect of oxygen and slow down the process of combustion and oxidation.

Nitrogen is essential for living organisms to produce proteins. Although plants cannot absorb $N_2$ directly from the air, it is converted into nitrates in the soil through nitrogen fixation.

Uses of Oxygen: For artificial respiration in hospitals and by divers/mountaineers, in welding (oxy-acetylene flame), and as an oxidizer in rocket fuels.

Uses of Nitrogen: Used in food packaging (like potato chips) to prevent rancidity by displacing $O_2$, and in liquid form as a refrigerant ($Liquid \ N_2$) to store biological samples.