Empirical Formula for combustion:
The Ideal Gas Law is used to determine the molar mass and from that the molecular formula
$PV = nRT$ $n = \frac{PV}{RT}$
P = kPa V = L R = 8.314 T = K ($\degree C + 273.15$)
Given mass of substance, and by figuring out moles, you can find its molar mass.
