What is the empirical formula for a compound if a sample contains 3.72g of p and 21.28g of cl?-pcl5-pcl3-p2cl10-p2cl5

The empirical formula is PCl5. To solve this problem, convert the given masses to moles by dividing them by their respective atomic (molar) masses. There are 0.120 mol of P in 3.72 g of P and 0.600 mol of Cl in 21.28 g of Cl. Divide both mole values by 0.120 mol, the smallest number. The quotients, 1 for P and 5 for Cl, complete the chemical formula, PCl5.