Question #98436

1 Answer
Feb 5, 2016

Oxygen Atom #~~ 16#
Oxygen Gas (that we inhale) #~~32#


This question is quite confusing considering that we tend to refer to oxygen (the element with symbol O) and to the oxygen (the gas we inhale #O_2#) using the same term.

Since oxygen the element consist only of 1 atom of Oxygen, then we will use the atomic weight of oxygen for this mass (#mass_O ~~ 16#). However since oxygen rarely exists as purely a single atom, we say that the molar mass of oxygen is 32 or #mass_(O_2) = 32 g/(mol)#.

Now when computing for empirical formula sample problems, use #16 g/(mol)# since it corresponds to the mass of 1 atom of oxygen. Just remember to multiply the value to the subscript of Oxygen when you need to determine the molar masses of the compounds you need to compute for.