Stoichiometry Airbag

Question

solve the following problem using stoichiometry and the ideal gas law. Incorporate the answer in your infographic: A standard airbag has a volume of 65 L. Under standard temperature and pressure, what mass of sodium azide is needed for the reaction? In your calculation, you can assume that the first reaction (the decomposition of sodium azide) is the primary reaction for the production of nitrogen.

Answer 1

PV = nRT

1 Determine what information is given in the original question.

V = 65 L

T = 273 K (Standard temp)

P = 1 atm (standard pressure)

R = .0821 (constant)

2 Solve for n (# of moles) using the ideal gas law equation: PV = nRT

PV = nRT

n = (1 atm x 65 L) / (.0821 x 273 K) = 2.90 mol N2

3 Determine decomposition equation that produces N2 (nitrogen naturally exists in diatomic form in the gas phase, so we know this is the ideal gas in this problem)

2NaN3 (sodium azide) -> 3N2 (g) + 2Na (l)

4 Solve for moles NaN3

2.9 mol N2 x 2 mol NaN3 / 3 mol N2 = 1.93 mol NaN3