Why is nitrogen used as an inert atmosphere in chemical reactions?

Nitrogen is used as an inert atmosphere in chemical reactions primarily because of its high chemical stability. Molecular nitrogen ($N_2$) possesses a very high bond energy, which results in a high activation energy for reactions under ordinary conditions, making it relatively unreactive toward most reagents.1

Because of this property, nitrogen is effectively used to create an environment that excludes oxygen and moisture, which might otherwise cause unwanted oxidation or other forms of deterioration in a chemical product. In the chemical industry, it serves several practical purposes:2

• Preventing degradation: It inhibits oxidation and other chemical reactions that could spoil or damage materials.2
• Safety: It acts as an inhibitor of fire or explosions and serves as an inert diluent for reactive gases.2
• Process utility: It is used as a carrier to remove heat or chemicals from a system.2

By maintaining this nonreactive atmosphere, nitrogen ensures that sensitive substances remain stable during processing, storage, or industrial applications.2