Chemistry Behind Airbags

How chemistry is in the process of an Airbag!!

Info on Airbags Today

The airbag was developed to restrain drivers and passengers from getting into a terrible accident. Airbags were invented in the 1950's but became patented in 1953. Although they has spent many years perfecting the airbag, it still causes a higher percentage of head injuries and deaths. People that have airbags and seat belts have 26% lower death percentage than just a seat belt alone. The airbag today inflates and deploys at a rate of 40 milliseconds. That's Fast! The first component of the airbag is a sensor that can detect a collision and it immediately deploys the airbag. The airbag has a magnet with a ball on top, if the balls moves slow (a pothole or speed bump) the airbag will not deploy, but if the ball takes a big dramatic jump the airbag will automatically deploy.

Chemical Components of an Airbag

Inside the bag is a gas generator enclosing a mixture of Sodium Azide, Potassium Nitrate, and Silicone Dioxide. When the driver experiences a head-on collision these three chemical reactions form a gas. The gas is toxic so to make it harmless Nitrogen is introduced. Sodium Azide is decomposed to make a sodium metal and nitrogen gas. The signal from the sensor in the airbag sends an electric pulse which decomposes the chemicals and introduces nitrogen to inflate the airbag. The purpose of the Potassium Nitrate and Silicone Dioxide is to make the gas in the airbag harmless. The ending produce is Silicate glass which is harmless and stable.

Gas-Generator Reaction

Initial Reaction Triggered by Sensor

Reactant:

  • NaN3
Product:

  • Na
  • N2 (g0


Second Reaction

Reactant:

  • Na
  • KNO3
Product:

  • K2O
  • NA2O
  • N2 (g)


Final Reaction

Reactant:

  • K2O
  • Na2O
  • SiO2
Product:

  • Alkaline Silicate (glass)


Facts about Airbags!!

  • Airbags have deployed approximately 800,000 times saving more that 1,700 lives
  • Fatal injuries have been reduced by 11%
  • Hospital injuries have been reduces by 24%
  • Airbag inflates at speeds as much as 200 miles per hour
  • With airbags Injury is most often very minor, abrasions and/or bloody noses.