Question

What is the empirical formula of $ {C_2}{H_4}{O_2} $ ?

Answer 1

Hint :Empirical formula of a compound depicts the simplest whole number ratio of the atoms present in a compound while molecular formula depicts the number of every atom present in a molecule. On the other hand, the structural formula depicts how atoms present in a molecule are being bonded to one another.

Complete Step By Step Answer:
Molecular formula represents the exact number of all of the atoms present in a molecule or compound. But, empirical formula represents the ratio of those atoms in a molecule or compound. Thus we can say that the relationship that exists between the molecular formula and the empirical formula can be represented as follows:
 $ Molecular{\text{ }}formula = {(Empirical{\text{ }}formula)_n} $
Where n refers to an integer
In the given question, we are provided with the molecular formula of the compound (acetic acid) and we have to find out the empirical formula of this compound. In order to find out the empirical formula from the molecular formula, we will divide the subscripts by the same integer to attain the smallest whole number. Let us find the empirical formula of the given compound:
 $ {C_2}{H_4}{O_2} $ : The ratio of $ C:H:O $ is $ 2:4:2 $ . The empirical formula will be $ {C_{\dfrac{2}{2}}}{H_{\dfrac{4}{2}}}{O_{\dfrac{2}{2}}} = C{H_2}O $ (also formula of formaldehyde) which will be obtained by dividing each subscript by 2 as shown.
Hence, $ C{H_2}O $ is the empirical formula of $ {C_2}{H_4}{O_2} $ .

Note :
If we know the molar mass of any unknown compound, we can find the molecular formula of that compound from its empirical formula by comparing the empirical formula mass with the molar mass of the compound.