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Intro—Airbags. How do airbags work in your car?. There is a Nylon bag inside your steering wheel That bag contains solid sodium azide (NaN 3 ) which is ignited with electricity when a crash sets off a trigger 2 NaN 3 (s) 2 Na (s) + 3 N 2 (g)
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How do airbags work in your car? • There is a Nylon bag inside your steering wheel • That bag contains solid sodium azide (NaN3) which is ignited with electricity when a crash sets off a trigger • 2 NaN3 (s) 2 Na (s) + 3 N2 (g) • The nitrogen gas created in this reaction then fills the airbag!! How Does An Airbag Work??? Watch this!
Problems with this reaction? • It produces sodium metal, which reacts with water to form hydrogen gas & it also produces enough heat to ignite the hydrogen gas • The reaction produces heat, so the gas is very hot inside of the airbag • NaN3 is very toxic What Solutions did we see in the video???
Why do we use it? • It produces the gas very quickly, but not so quick that it’s more of a hazard • Reactants are small and easier to store before needed • The amount of dangerous chemical is minimal • Heat from the reaction is absorbed, in part, by the physical components of the airbag system (nylon bag, steering wheel etc.)
Solids: • Particles are closely packed together • Particles vibrate in place – in fixed positions • Particles can’t switch places • Have a definite shape • Have a definite volume
Liquid • Particles more spread out than solid • Particles are free to move past each other – fluid • Slightly compressible • Definite volume • No definite shape – take shape of container
Gas • Particles very spread out – they can be poured • Rapid, random motion • Highly compressible • No definite volume—they will fill container • No definite shape—take shape of container
Sublimation Boiling or Evaporating Gas Increasing molecular motion (temperature) Liquid Melting Condensing Freezing Solid Deposition Changes in State
Temperature of state changes • Freezing point = melting pint • Boiling point = condensation point Example: Water will freeze or melt at 0°C – it just depends upon the direction of heat flow. If we are adding heat at 0°C then it will melt. If we take away heat at 0°C it will freeze!
What’s between the particles? ? Nothing! There is absolutely nothing between the particles!