1. Empirical Formulas

2. Gives the lowest whole-number ratio of the elements in a compound. Example: Hydrogen Peroxide (H 2 O 2 ) Empirical Formula- HO

3. Steps Determine the number of moles for each element. Divide all elements by the smallest number of moles. You may need to multiply in order to get all elements in whole numbers.

4. Determining Empirical Formulas A compound is analyzed and found to contain 25.9% nitrogen and 74.1% oxygen. What is the empirical formula?

5. Calculate the empirical formulas: 94.1% O, 5.9% H

6. 67.6% Hg, 10.8% S, 21.6% O

7. Molecular Formulas Can be a multiple of the empirical formula. Example: H 2 O 2 can be divided by 2 to become HO.

8. Finding Molecular Formula of a Compound Calculate the molecular formula of a compound whose molar mass is 60.0 g/mole and the empirical formula is CH 4 N. CH 4 N has a empirical formula mass of 30.0 g/mole. So 60.0 g/ 30.0 g = 2 Molecular formula = C 2 H 8 N 2