Air bags are activated when a severe impact causes a steel ball to compress a spring and electrically ignite a detonator cap. This action causes sodium azide (NaN3) to decompose explosively according to the following reaction. 2 NaN3(s) → 2 Na(s) + 3 N2(g) What mass of NaN3(s) must be reacted to inflate an air bag to 70.6 L at STP?

136 g of   must be reacted to inflate an air bag to 70.6 L at STP.

Explanation:

Using ideal gas equation:

P= pressure of nitrogen gas = 1 atm (at STP)

V =volume of nitrogen gas = 70.6 L

n = number of moles of nitrogen gas = 1 atm (at STP)

R = gas constant = 0.0821 Latm/Kmol

T = temperature of nitrogen gas = 273 K (at STP)

For the balanced chemical reaction:

3 moles of nitrogen are produced by = 2 moles of

3.14 moles of nitrogen are produced by = moles of

Mass of = Moles × Molar mass = 2.09 mole × 65 g/mol = 136 g

the number of valence electrons for each molecule or ion is shown beneath the structure. remember hydrogen will not have more than two electrons. this hydrogen is part of a covalent bond (sharing two electrons). a double bond here would cause hydrogen to share four electrons with phosphorus.