Why do Air-Bags Contain Sodium Azide ?

Why do Air-Bags Contain Sodium Azide ?


Sodium Azide in Airbags


Purpose



  • Sodium azide (NaN₃) is used in airbags as a gas-generating compound.

  • On decomposition, it produces nitrogen gas (N₂), which inflates the airbag in milliseconds.


Working Process



  1. Crash Detection → Sensor sends an electric signal to igniter.

  2. Decomposition Reaction →


2NaN3(s)  →  2Na(s)+3N2(g)2 NaN₃ (s) \; → \; 2 Na (s) + 3 N₂ (g)2NaN3​(s)→2Na(s)+3N2​(g)




    • Nitrogen gas inflates the airbag almost instantly.

    • Sodium metal formed is neutralized by other chemicals (e.g., potassium nitrate, silica).


  1. Cushioning → Inflated airbag protects passengers by reducing impact.


Why Sodium Azide?



  • Very Fast Reaction → Gas released in <0.05 sec.

  • Compact & Stable → Solid, safe to store in airbags.

  • Controlled Activation → Only triggered during a crash.


Safety Measures



  • Toxic NaN₃ and reactive sodium are sealed inside.

  • Neutralizers ensure no harmful substances reach passengers.


Key Exam Points



  • Gas Produced → Nitrogen (N₂)

  • Formula → Sodium Azide (NaN₃)

  • Reason for Use → Rapid, controlled nitrogen generation

  • Hazard Note → Toxic if handled outside the sealed airbag system