Empirical Formula
The chemical formula giving the simplest whole-number ratio of atoms of each element in a compound.
Formula / equation
ratio = (mass % ÷ A_r), normalised
Unit
Dimensionless
In depth
It is derived directly from combustion analysis or percentage composition data by converting each element's mass to moles and dividing through by the smallest result. The empirical formula alone cannot distinguish compounds that differ only by a multiple, so a separate molar-mass measurement is required.
Examples in the real world
Both glucose (C₆H₁₂O₆) and formaldehyde (CH₂O) share the empirical formula CH₂O; benzene C₆H₆ reduces to CH.