An empirical formula is the simplest chemical formula of a compound that shows the smallest whole-number ratio of atoms of each element present in it.
Key points:
- It does not show the actual number of atoms in a molecule, only the simplest ratio.
- Different compounds can have the same empirical formula but different molecular formulas.
- It is determined from experimental data, such as the percent composition of a compound.
- The empirical formula is useful because it gives the basic combining ratio of elements, which is important in identifying and analyzing substances.
Examples:
- Hydrogen peroxide has the molecular formula H₂O₂, but its empirical formula is HO (1:1 ratio).
- Glucose has the molecular formula C₆H₁₂O₆, but its empirical formula is CH₂O (1:2:1 ratio).
In short: The empirical formula is the simplest expression of the relative number of atoms of each element in a compound.