Calculate the empirical formula of a mineral having the following composition :
CaO = 48.0% ; P2O5 = 41.3% ; CaCl2 = 10.7 %
Once the preliminary investigation on an unknown sample is done and the elements and their weights are obtained, the next step is to evaluate their ratio. This is done in four steps (shown below).

After the ratio is obtained, it becomes important to write the elements in an established order to obtain a correct, universally acceptable formula. This arrangement of elements is taught using the Hill nomenclature.
Using this knowledge, the empirical formula of the compound is written as 9CaO. 3P2O5. CaCl2.
Related reading -
Molecular Formula (subscribers only premium article)
Empirical Formula (subscribers only premium article)
How to calculate Empirical Formula from percentage composition and atomic masses (subscribers only premium article)
Difference between empirical and molecular formula (free)
Hill nomenclature (free)
