Empirical Formula

* Definition: The empirical formula represents the simplest whole-number ratio of atoms in a compound.

* Example: Glucose has a molecular formula of C₆H₁₂O₆. Its empirical formula is CH₂O, since the ratio of carbon, hydrogen, and oxygen atoms is 1:2:1.

Molecular Formula

* Definition: The molecular formula shows the actual number of atoms of each element in a molecule.

* Example: Glucose's molecular formula (C₆H₁₂O₆) tells us it contains 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.

Relationship

* Empirical formula is a simplified version of the molecular formula. It provides the basic ratio of atoms but doesn't necessarily tell you the actual number of atoms in a molecule.

* The molecular formula is a multiple of the empirical formula. To find the molecular formula from the empirical formula, you need to know the compound's molar mass. You calculate the empirical formula mass and divide the molar mass by the empirical formula mass. The result tells you how many times the empirical formula is repeated in the molecular formula.

Example:

1. Empirical formula: CH₂O

2. Molar mass: 180 g/mol

3. Empirical formula mass: 12 g/mol (C) + 2 g/mol (H) + 16 g/mol (O) = 30 g/mol

4. Multiple: 180 g/mol / 30 g/mol = 6

5. Molecular formula: (CH₂O)₆ = C₆H₁₂O₆

In summary:

* The empirical formula gives the simplest ratio of atoms in a compound.

* The molecular formula gives the actual number of atoms in a molecule.

* The molecular formula is a multiple of the empirical formula.