Molecular and empirical formula

Molecular formula
the molecular formula of a compound shows the number of atoms of each element in one molecule of a substance
for example the molecular formula of glucose is C6H12O6 ,this means each molecule contains six carbon atoms , 12 hydrogen atoms and six oxygen atoms.


Empirical formula
It is the simplest whole number ratio of the atoms of each element in the substance

in the last example the empirical formula of glucose is CH2O

This means this ratio can be repeated x number of times to generate different molecular formula


So the Molecular formula can be (CH2O)X

Where x is the number of times empirical formula is repeated
If the molecular formula is repeated twice it will generate the following molecular formula
(CH2O)2 = C2H4O2


First we calculate the empirical formula mass. If it is the same value as the molar mass of the compound the molecular formula and empirical formula are the same

If the numerical values are not the same divide the molar mass by the empirical mass to find X

If x =2, the molecular formula is twice the empirical formula

If x =3, the molecular formula is 3 times the empirical formula and so on




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