What is the density of methyl chloride gas, #CH_3Cl#, at STP?
If you assume it behaves as an ideal gas, then
If you assume that it behaves as an ideal gas then it's simple enough, and will give you a fair estimate:
One mole of an ideal gas at STP occupies
Then simply divide the molar mass by the molar volume which gives you a density in
If you want a more accurate figure you will need to use the full form of the gas equation incorporating a virial expansion, but that's a lot more complicated!