Molecular Formula

Molecular Formula tutorial

A molecular formula is the formula for a compound as it exists in nature. For example: the molecular formula for hydrogen peroxide is H2O2. These formulas should not be reduced. A reduced version of a molecular formula is called the empirical formula.

How to Calculate a Molecular Formula from an Empirical Formula

Example: For a compound with an empirical formula C4H9 , determine its molecular formula if its molecular formula mass is 114.0 g/mol.

Description of Action	Action
1. Determine the gram formula mass of the empirical formula.	C: 4 x 12.0 = 48.0 H: 9 x 1.0 = 9.0 48.0 + 9.0 = 57.0 g/mol
2. Divide the molecular formula mass by the empirical formula mass.	114.0 ÷ 57.0 = 2
3. Multiply each subscript in your empirical formula by your result.	C4H9 becomes C8H18