The Chemistry Behind The Airbag System

Airbag is additional feature in car to prevent the passengers from serious injury caused by crash. The airbag has bag which will expanded by nitrogen gas resulted from sodium azide, NaN₃. Sodium azida very sensitive with crash. When the crash happened, the sensor will tell ECU to activate the sodium azide. It will produce nitrogen to expand the safety bag and by-product sodium. The reaction is:

NaN₃ → Na + N₂

Sodium is by-product that dangerous in car. With the presence of water, sodium can result hydrogen gas and sodium hydroxide. Hydrogen gas easily explode in high temperature. Sodium hydroxide is harm for metal unit in car, because of its corrosive character. So the presence of sodium in car may cause short circuit and car firing. By-product, sodium resulted from sodium azide must be neutralized with potassium nitrate. The reaction of this neutralization is:

Na + KNO₃ → Na₂O + K₂O + N₂

Sodium oxide and potassium oxside are residual that still harm in car and for environment. They are need to be treated. These residual must be treated with silicon oxide, SiO₂. After treat with silicon oxide, they will become silica as shown:

Na₂O + K₂O + 4SiO₂ → Na₂K₂Si₄ + 5O₂

May this information give you little bit imagination about chemistry process behind the airbag system.