1. Assume a 100 g Sample
This makes the calculations easier because the percentages directly translate to grams:
* Calcium (Ca): 20 g
* Bromine (Br): 80 g
2. Convert Grams to Moles
* Moles of Ca = (20 g Ca) / (40.08 g/mol Ca) = 0.499 mol Ca
* Moles of Br = (80 g Br) / (79.90 g/mol Br) = 1.00 mol Br
3. Find the Simplest Mole Ratio
Divide each mole value by the smallest mole value (0.499 mol Ca):
* Ca: 0.499 mol / 0.499 mol = 1
* Br: 1.00 mol / 0.499 mol = 2
4. Write the Empirical Formula
The empirical formula represents the simplest whole-number ratio of atoms in the compound. The ratio of Ca to Br is 1:2. Therefore, the empirical formula is CaBr₂.
