Car Air Bags

Becky DeJesus

What are air bags?

Air bags are a safety device inside a road vehicle, consisting of a cushion to inflate rapidly in the event of a collision and positioned to protect passengers from being ejected from the vehicle's structure.

How do they work?

Air bags are triggered by a sudden deceleration of a vehicle which causes a switch to be thrown and starts a chemical reaction. The decomposition equation that causes the air bag to inflate is 2 NaN3 --> 2 Na + 3 N2. The inorganic compound sodium azide (2 NaN3) creates this chemical reaction which then produces the substances sodium metal (2Na) and nitrogen gas (3 N2).

The energy source that ignites the reaction comes from sensors located in the front of a vehicle that are able to detect a collision. These sensors send an electric signal to the canister that contains the sodium azide and the signal detonates a small amount of an igniter compound. The heat from this ignition starts the decomposition of sodium azide and the generation of nitrogen gas to fill the air bag.



Air bags help reduce injuries and increase the amount of lives saved from accidents. From 1975 to 2001, air bags saved 8,369 lives. In 2012 alone it saved 2,213 lives. Air bags are an effective form of a safety technique but are more effective when combined with seatbelts.
How an Airbag works