This resource includes a video lecture covering empirical and molecular formulas.  The practice worksheet has 5 problems converting percentages into binary empirical formulas and 10 problems converting empirical formulas to molecular formulas.  An answer key is included. This resource corresponds to Chemistry Atoms First 2e section 6.2https://openstax.org/books/chemistry-atoms-first-2e/pages/6-2-determining-empirical-and-molecular-formulas