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To manufacture a proper air bag, potassium nitrate and silica are added to remove the...

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ashweee09 | eNotes Newbie

Posted April 2, 2013 at 2:40 AM via web

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  1. To manufacture a proper air bag, potassium nitrate and silica are added to remove the sodium metal formed. Here is the overall unbalanced reaction in an automobile air bag:

 

NaN3 (s) +   SiO2 (s) +   KNO3 (s) à  Na4SiO4 (s) +  K4SiO4 (s) +  N2 (g)

 

  1. (1 points) Balance the equation.

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llltkl | College Teacher | Valedictorian

Posted April 4, 2013 at 5:07 PM (Answer #1)

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Considering the individual reactions, it is evident that one of the obvious products (Na2O) is missing here.  Hence the overall reaction should be:

NaN3 (s) +   SiO2 (s) +   KNO3 (s) = Na4SiO4 (s) + K4SiO4 (s) + Na2O (s) + N2 (g)

The complete atom balance can be done as follows:

NaN3 (s) + SiO2 (s) + KNO3 (s) = Na4SiO4 (s) + K4SiO4 (s) + + N2 (g)

The part-reactions are:

2NaN3 →2Na +3N2 ------(i) ×10

10Na + 2KNO3 →K2O + 5Na2O +N2 ------(ii) ×2

2K2O + 2Na2O + 2SiO2 →Na4SiO4 + K4SiO4 -----(iii)

8Na2O + 4 SiO2 = 4 Na4SiO4 (for balancing Na2O and SiO2)

--------------------------------------------------------------

Overall: 20NaN3 + 4 KNO3 + 6 SiO2 = 8 Na2O + 32 N2 + 5 Na4SiO4 + K4SiO4 .

This is the balanced chemical equation for the airbag reaction.

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