Density and Moles

We told you how to convert from mass to moles and from moles to molecules, we event told you how to convert from mass to molecules. You thought you were finally finished, well you're not!
There's also Density.
Density or is measured in g/L or other variations such as kg/mL
well that's it for the non-gas density notes, how about a few example
How many moles are contained when the density of Li₂ O is 3.5 g/mL and the mass is 15 mL
15 mL  x           1 mol            = 29.9 mol
                 (2x6.94)+16.00

Thus you can now add this on to your growing number of possible conversions, exciting right?
Density of Gases
it's slightly different, you get a new formula (because we all love more new formulas)
molar mass over molar volume
  MMg/mol    = density g/L
22.4 L/mol

Oh boy, more examples!
Flourine gas at STP, find the density
2(19.00)g/mol  = 1.70 g/L
  22.4 L/mol

Now I want you to find the density of one Flourine at STP
1.70g/l  = 0.850 g/L (ridiculously simple)
    2

And so I leave you with a comic, so you can sit in your chair laughing while I go to sleep.
But remember conversions are important.