Answer to Question #182097 in General Chemistry for Madison

Question

Air bags are activated when a severe impact causes a steel ball to compress a spring and electrically ignite a detonator cap. This causes sodium azide (NaN3) to decompose explosively according to the following reaction:

 

2 NaN3 (s) à  2 Na (s) + 3 N2 (g)

 

What mass of sodium azide must be reacted to inflate an air bag to 70.0 L at STP?  

Answer 1

70 L of N₂ at STP corresponds to 3.125 moles of N₂.

3.125 mole of N₂ corresponds to 2.083 moles of NaN₃ as per stoichiometric coefficients in the balanced reaction.

2.083 moles of NaN₃ correspond to 135.42 g NaN₃ as per molar mass of 65.0099.