I don't know if I am correct, but I think I realized that empirical formula mass is made up from empirical formula which is only a ratio of numbers of atoms, which means that "real" molecule is not CH2O but in this case, if molecular mass equals 180, it's actually C6H12O6.
Sounds OK to me.
But is CH2O and C6H12O6 same molecule? It's confusing.
No, it is not the same molecule. But CH2
O is the empirical formula of C6
To make things less confusing consider that: CH2
O is an empirical formula, but real formula of a real compound is (CH2
. It may happen that n=1, in which case CH2
O is a real formula of a compound.
This is not invented to make life harder, this is just reflecting the reality
Take two real and quite common compounds, one with a real, molecular formula CH2
O (formaldehyde AKA methanal) and the second with a real, molecular formula C2
(acetic acid). If you make the elemental analysis you will find what are ratios of C:H:O, and you will find out both compounds have the same empirical formula of (CH2
. If you determine molar masses separately you will find out it is 30 g/mol for the first compound and 60 g/mol for the latter, so in the first case n=1 and in the second n=2. You can't determine n without knowing the molar mass.