1. Assume a 100g Sample
* This makes the calculations easier. We'll have 13g of Mg and 87g of Br.
2. Convert Grams to Moles
* Divide the mass of each element by its molar mass:
* Mg: 13g / 24.31 g/mol = 0.53 mol
* Br: 87g / 79.90 g/mol = 1.09 mol
3. Find the Mole Ratio
* Divide each mole value by the smallest mole value (in this case, 0.53 mol):
* Mg: 0.53 mol / 0.53 mol = 1
* Br: 1.09 mol / 0.53 mol = 2.06 (approximately 2)
4. Write the Empirical Formula
* The mole ratio tells you the simplest whole-number ratio of atoms in the compound.
* The empirical formula is MgBr₂
