Empirical Formula:
* Represents the simplest whole-number ratio of atoms in a compound.
* Shows the relative number of each type of atom present.
* Does not necessarily reflect the actual number of atoms in a molecule.
Molecular Formula:
* Represents the actual number of atoms of each element in a molecule of the compound.
* Is a multiple of the empirical formula.
Relationship:
* The molecular formula is always a whole-number multiple of the empirical formula.
* The multiple is determined by the molecular weight of the compound.
* If the molecular weight is known, the molecular formula can be calculated from the empirical formula.
Example:
Consider the compound glucose:
* Empirical Formula: CH₂O
* Molecular Formula: C₆H₁₂O₆
The molecular formula (C₆H₁₂O₆) is six times the empirical formula (CH₂O). This is because the molecular weight of glucose is 180 g/mol, which is six times the empirical formula weight of 30 g/mol.
In summary:
The empirical formula provides the basic building block of a compound, while the molecular formula gives the complete composition of a molecule. The molecular formula is always a multiple of the empirical formula, and the multiple is determined by the molecular weight.
