Question

Automotive air bags inflate when a sample of sodium azide, NaN3, is very rapidly decomposed.

2NaN₃(s) --> 2Na(s) + 3N₂(g)

What mass of sodium azide is required to produce 2.6 ft³ (73.6 L) of nitrogen gas with a density of 1.25 g/L?

Answer 1

Volume of nitrogen gas produced = 73.6 L; the density of nitrogen gas = 1.25 g/L.

Therefore, mass of nitrogen gas produced = (73.6 L)*(1.25 g/1 L) = 92 g

Now write the balanced chemical equation:

2 NaN₃ (s) -------> 2 Na (s) + 3 N₂ (g)

As per the balanced equation, the molar ratio of nitrogen gas and NaN₃ = 3:2.

Molar mass of nitrogen gas = 28.0134 g/mol.

Therefore, moles of N₂ produced in the reaction = (92 g)/(28.0134 g/mol) = 3.284 mole.

Now, moles of NaN₃ required = (3.284 mole N₂)*(2 mole NaN₃/3 mole N₂) = 2.189 Mole NaN₃.

Molar mass of NaN₃ = 65.0099 g/mol.

Therefore, mass of NaN₃ required = (2.189 mole)*(65.0099 g/1 mole) = 142.3067 g ≈ 142.307 g (ans).