Applications
Because of the non-reactive properties of inert gases they are often useful to prevent undesirable chemical reactions from taking place. Food is packed in nitrogen to remove oxygen gas. This prevents bacteria from growing. Chemical oxidation by oxygen in air is avoided. An example is the rancidification of oil. In food packaging, inert gases are used as a passive preservative, in contrast to active preservatives like sodium benzoate (an antimicrobial) or BHT (an antioxidant).
Historical documents may also be stored under an inert gas to avoid degradation. For example, the U.S. Constitution is stored under humidified argon. Helium was previously used, but it was less suitable because it diffuses out of the case more quickly than argon.
Nitrogen is often used as an inert gas in the chemical industry. In a chemical manufacturing plant, reactions are routinely conducted under nitrogen even if they are not sensitive to air, to minimize fire hazards. In such plants and in oil refineries, transfer lines and vessels are purged with inert gas, to avoid residual solvents or process fluids catching fire. At the bench scale, chemists perform experiments on air-sensitive compounds using air-free techniques developed to handle them under inert gas.
Read more about this topic: Inert Gas