1. E MPIRICAL AND M OLECULAR F ORMULA

2. M OLECULAR F ORMULAS A molecular formula tells exactly how many atoms of each element are in a molecule. It is a whole number multiple of the empirical formula.

3. E MPIRICAL /M OLECULAR F ORMULA Using ratios- think whole numbers Empirical FormulaMolecular Formula An empirical formula indicates the simplest whole-number ratio for a molecule **Not common** CH 2 A molecular formula tells exactly how many atoms of each element are in a molecule. Is a multiple of the empirical formula C 2 H 4 C 5 H 10

4. F IND THE EMPIRICAL FORMULA FOR … C 6 H 12 O 6 C 6 H 12 O 2 N 2 H 2 CH 4

5. D ETERMINING M OLECULAR F ORMULA F ROM E MPIRICAL F ORMULA

6. M OLECULAR F ORMULA E XAMPLE Find the molecular formula of a compound with empirical formula of CH 2 O and molar mass of 180.18g.

7. A brown gas has the empirical formula of NO 2. Its experimental molar mass is 46 g/mol. What is its molecular formula?

8. F INDING THE MOLECULAR FORMULA FROM THE PERCENT COMPOSITION Step 1: Find empirical formula Step 2: Divide the molar mass of the compound (given in the problem) by the molar mass of the empirical formula Step 3: Multiply each subscript by the answer to Step 2

9. A COMPOUND HAS A MOLAR MASS IS 30.0 GRAMS AND A COMPOSITION IS 20.0 % H AND 80.0% C? 1. What is the empirical formula? 2. What is the molecular formula?