Here is a 9 minute video sequence talking about the basics of airbags:
Here is a CBS news article citing ammonium nitrate, NH4NO3, as the propellant in the airbag:
From http://www.thechemicalblog.co.uk/how-do-airbags-work/ the basic chemical reactions of the typical airbag are presented:
"Under room temperature, sodium azide is a stable compound. However, when heated by an impulse it disintegrates to produce sodium (Na) and nitrogen (N2). It only takes about 50-100 grams sodium azide to produce enough nitrogen gas to fill a normal air bag for the driver (it takes a little more for the passenger).
This, however, is not the only chemistry involved. Unfortunately, sodium will quickly react with water to form sodium hydroxide (NaOH), which can be toxic if inhaled. To minimize this danger, manufacturers add other chemicals, including potassium nitrate (KNO3) and silicon dioxide (SiO2), which can react with sodium, to eventually produce a safe and harmless compound, silicate glass (Na2O3Si).
(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)
Most car-manufactures prefer KNO3 and not NaNO3, as it’s less hygroscopic. To ensure the air bag is fully operational even in the presence of moisture, it’s essential to choose non-hygroscopic components, otherwise the reaction may fail."--
Takata is the only company producing airbags using ammonium nitrate. Here is a document discussing safety issues with ammonium nitrate:
Ammonium nitrate reacts with metal hydroxides, releasing ammonia and forming alkali metal nitrate:
NH4NO3 + MOH → NH3 + H2O + MNO3 (M = Na, K)
Ammonium nitrate gives ammonium chloride and nitric acid upon reaction with hydrochloric acid:
NH4NO3 + HCl → NH4Cl + HNO3
Ammonium nitrate leaves no residue when heated:
NH4NO3 → N2O + 2H2O
Here is a video showing an ammonium nitrate explosion:
*This might be a timely research project for your students. Also, students are always looking for extra credit opportunities.
Check out this website's Topic List to help you to find past Blog entries. It can help in finding other topics you need!
The holidays approach, so buy my lab book "Chemistry on a Budget" (or ask for it as a gift) -- it is available for $20 at amazon.com or $23 at lulu.com. It will take a few weeks to get to you, so order now!
This book contains 13 labs using consumable materials purchased from local stores. There are two versions of each lab, one with a ten-question conclusion and one with directions for a full lab report. This way the teacher has the option! Each lab is two pages to allow for one two-sided handout.
Have a good weekend!