In the modern world, a car without an airbag is unheard of. The goal of the airbag is to stop the momentum of the passenger, with as little damage to the person as possible. This life saving technology is a necessity, and believe it or not, it is based off of the Gas Laws of Chemistry.
The image above depicts what happens when an airbag is set off. http://auto.howstuffworks.com/car-driving-safety/safety-regulatory-devices/airbag1.htm
First off, an airbag works by inflating (duh!). More importantly, is how it inflates. The bag is made of a thin nylon attached to a sensor. When a collision force of 10-15 miles per hour or more occurs, a mechanical switch is flipped, and the sensor receives a message to inflate. The airbag’s inflation system then reacts sodium azide (NaN3) with potassium nitrate (KNO3) to produce nitrogen gas, which then fills the airbag. Quickly afterward, the gas diffuses, so that the passenger can get out of the car.
This whole process is based off of the Gas Laws. When the sensor turns on the electrical circuit and releases NaN3, the volume increases because the amount of substance increases. Previously, there was no gas in the airbag, so when gas is pumped in, it inflates. This is supported by Avogadro’s law, n1/V1=n2/V2. Essentially, this law states that an increase in the moles of substance present increases the volume, therefore effectively expanding the airbag. Who knew we had Chemistry to thank for such a useful device?!