1. Percent Composition and Empirical and Molecular Formula

2. Mass percent of an element: For iron in iron(III) oxide, (Fe 2 O 3 ): Copyright © Cengage Learning. All rights reserved 2

3. Consider separate 100.0 gram samples of each of the following: H 2 O, N 2 O, C 3 H 6 O 2, CO 2 Rank them from highest to lowest percent oxygen by mass. H 2 O, CO 2, C 3 H 6 O 2, N 2 O Copyright © Cengage Learning. All rights reserved 3 EXERCISE!

4. Formulas Empirical formula = CH Simplest whole-number ratio Molecular formula = (empirical formula) n [n = integer] Molecular formula = C 6 H 6 = (CH) 6 Actual formula of the compound Copyright © Cengage Learning. All rights reserved 4

5. Analyzing for Carbon and Hydrogen Device used to determine the mass percent of each element in a compound. Copyright © Cengage Learning. All rights reserved 5

6. The composition of adipic acid is 49.3% C, 6.9% H, and 43.8% O (by mass). The molar mass of the compound is about 146 g/mol. What is the empirical formula? C3H5O2C3H5O2 What is the molecular formula? C 6 H 10 O 4 Copyright © Cengage Learning. All rights reserved 6 EXERCISE!