A standard airbag is approximately 60. L in volume when inflated at 22ºC. How many moles of nitrogen gas must be produced to inflate this airbag to a pressure of 2.00 atm?

Question

What mass, in grams, of sodium azide must react to produce that amount of nitrogen gas? Excess sodium azide can pose a serious risk if it comes into contact with other substances such as heavy metals, so airbags are designed for this to be the limiting reactant. What is the *minimum* mass of potassium nitrate needed, in grams, for this to be true? *

Answer 1

In order to answer this question you need to use the equation PV=nRT where R is the ideal gas constant. Rearrange the equation to n=PV/RT

where n is moles of gas. To make things simpler, for R you can use 0.08205 L•atm/(mol•K) and convert 22C into 295K. Plugging it all in:

n = 2 atm • 60L /(R • 295K) which gives an answer in units of moles.

After calculating the number of moles nitrogen, the second part of the problem requires the balanced equation of the reaction between sodium azide and potassium nitrate to produce potassium oxide, sodium oxide and nitrogen gas.

10 NaN3 + 2 KNO3 => K2O + 5 Na2O + 16 N2

the rest is just converting the moles to masses