CAR AIR BAGS
BY: TAYLOR RABITZ
Air bags save lives every day by providing padding during a collision, but do you know how that padding comes to be?
What type of equation causes air bags to inflate?
The term “airbag” itself is misleading since there’s no significant “air” in these cushions. They are, instead, shaped and vented nylon-fabric pillows that fill, when deployed, with nitrogen gas. The crash sensors located in the front of the car detect the sudden deceleration and send an electrical signal activating an initiator. Often compared to a light bulb, an initiator contains a thin wire that heats up and penetrates the propellant chamber, causing the solid chemical propellant, sodium azide (NaN3) , in the inflator to undergo a rapid chemical reaction. This controlled reaction produces harmless nitrogen gas that fills the air bags. During deployment the expanding nitrogen gas(N2) undergoes a process that reduces the temperature and removes most of the combustion residue or ash.
What is the compound that creates the chemical reaction?
The sole compound that creates this chemical reaction is sodium azide (NaN3). The heat generated by the electrical signal sent to the ignitor causes the sodium azide to decompose into sodium metal and nitrogen gas, inflating the car's airbag.
What are the substances produced during the chemical reaction?
When NaN3 burns, it generates not only nitrogen gas that fills the airbag, but also numerous by-products. The by-products fall within two broad categories: gases and particulates. Gases that are produced can include those that have been linked to severe injuries, such as benzene and toluene. Particulates are small particles that are suspended in the air, which appear as smoke or dust. They are the reason that many people report seeing smoke in their car after an airbag deploys. This is because all airbags have venting, either through the porous fabric or through vent holes.
REACTION EQUATIONS:
(1) 2 NaN3 → 3 N2 + 2 Na
(2) 10 Na + 2 KNO3 → N2 + K2O + 5 Na2O
(3) K2O + 2 SiO2 + Na2O → K2O3Si + Na2O3Si (silicate glass)
What are some statistics on how airbags are beneficial?
Obviously the goal of an airbag is to protect the driver. Every new vehicle in the U.S. today is manufactured with airbags for safety. Essentially, an airbag is monitored by sensors in the vehicle and is programmed to deploy under specific conditions. Usually airbags found in vehicles are frontal airbags, but as newer editions of cars are produced, airbags are spread throughout the car. The U.S. Department of Transportation stated that as of 2013 over 30,000 lives have been saved because of airbags. If airbags weren't designed to inflate in moderate to severe frontal crashes, many many lives would be lost each year. As of 1998, airbags have been required in all passenger cars.
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