how does one apply the ideal gas law when not given the mole value?

Question

ex. quest. ----what is the density of oxygen at STP?
where do you begin??

Answer 1

is n/v the same thing as density? then just plug in standard t and p, and the r whatever that was.

Answer 2

use MM=(grams) (R) (T) / PV

since g/V = Density, use MM=DRT/P

rearrange it.

D=PMM/RT

recall that STP is 273K and 1.00atm and that oxygen weighs 32

D=(1)(32) / (.0821) (273)

D=1.43 grams per Liter