For each element, you divide the total mass of its atoms by the empirical formula mass and multiply by 100.
What is the percent composition of a compound with the empirical formula
Step 1: Find the masses of the individual atoms.
Step 2: Find the total mass of each atom in the formula.
Step 3: Find the total mass of all the atoms in the formula.
Step 4: Find the mass percent of each atom.
Step 5: Check that your answers add up to 100 %.