What is the volume of 80 g #O_2# at STP?
At standard temperature and pressures, a molar quantity of an ideal gas has a volume of
So, all you have to do is calculate how many moles of oxygen you have (and oxygen like most gases save the Noble gases is diatomic), and multiply this by the molar volume at
If you look in the literature, you will find that the molar volume of oxygen is slightly different than that predicted by the ideal gas equation. It will be close, and that is why the ideal gas equation is widely used.