+895 A compound has an empirical formula of C2H4O and a molar mass of 88 grams per mole. What is the molecular formula of this compound?
A compound's empirical formula tells you the smallest whole number ratio that exists between the elements that make up a compound.
In your case, the unknown compound has an empirical formula of C2H4O, which means that it contains carbon, C, hydrogen, H, and oxygen, O, in a 2:4:1 ratio.
In other words, one mole of this compound will contain carbon, hydrogen, and oxygen in a 2:4:1 mole ratio.
All you have to do now is determine the mass of the empirical formula and compare it with the molar mass of the compound. You will have
2×12.011 g mol−1+4×1.00794 g mol−1+1×15.9994 g mol−1=44.053 g mol−1
The molar mass of the compound essentially tells you the mass of one mole of the compound. This means that you will have
44.053g mol−1×n=88g mol−1
Rearrange to get
n=88 / 44.053=1.9976≈2
Therefore, the molecular formula of the compound, which tells you the exact number of atoms of each element present in one molecule of the compound, will be:
(C2H4O)2 =C4H8O2
