AS with all these problems, it is useful to ASSUME that there are
There are thus
Now, we still have a missing percentage, and this is assumed to be oxygen (note that this is a standard assumption; there are few ways to analyse oxygen gas by combustion in that we have to burn the organic compound in oxygen to oxidize it, and so typically the oxygen percentage is calculated by difference, i.e. it is the missing percentage).
So to get the empirical formula, we divide thru by the SMALLEST molar quantity (that of oxygen) to get:
And thus we get the
Now we further know that the