Here we can use the equation PV = nRT, where n could stand for m / M, considering M = Molar Mass. Now we can rearrange this equation to isolate M, as we have to determine the " molar mass " of this vapor,
PV = ( m / M )RT,
density = mass / volume = PM / RT -
M = dRT / P
First convert celcius to kelvins and torr to " standard atmosphere " before plugging in the known values,