Some airbags in cars contain a mixture of sodium azide (NaN3), sodium nitrate (N

Question

Some airbags in cars contain a mixture of sodium azide (NaN3), sodium nitrate (NaNO3 or potassium nitrate in some cases) and silicone dioxide (Si0). When the car undergoes a collision, a series of three chemical reactions produce N2 gas to fill the airbag and convert highly toxic NaNg (The maximum concentration of NaN3 allowed in the workplace is 0.2 mg/m3 air), to harmless glass. Even sodium oxide (Na2O) is toxic. The reactions are 2NaNgå 2Na +3N2 Na2O +10 SiO2 à glass NaN3 can decompose at 300°C to produce sodium metal (Na) and nitrogen gas (N2). In one preparation, 150 g of NaNg are used in an airbag. If all of the sodium in the system can be safely sequestered as glas then grams of NaNO3 and SiO2 must be included aregm andgm O 0.462 and 13.85 39.3 and 831 0.462 and 39.3 39.3 and 83.1

Explanation / Answer

150 gram NaN3 = 150 g/(65 g/mol) = 2.308 mol

This gives 2.308 mol Na metal.

Now, 10 mol Na combines with 2 mol NaNO3.

Thus, 2.308 mol Na combines with 2.308/5 = 0.4615 mol NaNO3 = 0.4615 x 85 g/mol = 39.23 g NaNO3

This produces 0.4615 x 3 = 1.3845 mol Na2O.

1.3845 mol Na2O will require 13.845 mol SiO2 = 13.845 x 60.1 g/mol = 832 g SiO2

Thus, correct answer: second option

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