Derive the simplest whole-number formula from percentage composition.
Assuming a 100 g sample turns mass percentages into grams directly. Dividing by atomic masses gives moles, and normalising by the smallest gives the atom ratio — 1:2:1 for glucose, hence CH₂O. The empirical formula is a ratio only; the molecular formula is a whole-number multiple of it, which requires the molar mass to determine.
Empirical Formula
Divide each mass percent by its atomic mass, then divide all results by the smallest
Divide each mass percent by its atomic mass, then divide all results by the smallest Assuming a 100 g sample turns mass percentages into grams directly. Dividing by atomic masses gives moles, and normalising by the smallest gives the atom ratio — 1:2:1 for glucose, hence CH₂O.
The empirical formula is a ratio only; the molecular formula is a whole-number multiple of it, which requires the molar mass to determine.
This calculator takes 6 inputs: Mass percent of element 1, Atomic mass of element 1, Mass percent of element 2, Atomic mass of element 2, Mass percent of element 3, Atomic mass of element 3. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.