Question

The volume of an automobile air bag was 66.8 L when inflated at 25 °C with 77.8 g of nitrogen gas. What was the pressure in the bag in kPa?

Answer 1

We can use the ideal gas law equation assuming that nitrogen behaves as an ideal gas.
PV = nRT 
P - pressure 
V - volume - 66.8 x 10⁻³ m³
n - number of moles - 77.8 g/ 28 g/mol = 2.78 mol
R - universal gas constant - 8.314 Jmol⁻¹K⁻¹
T - temperature - 25 °C + 273 = 298 K
substituting these values into the equation 
P x 66.8 x 10⁻³ m³ = 2.78 mol x 8.314 Jmol⁻¹K⁻¹ x 298 K
P = 103.1 kPa