1. The Mole Concept Goal: To develop the concept of the mole as a useful measurement and to apply this in calculations involving mass and volume.

2. Recall the Mole

3. Recall Computing Percent Composition

4. Molecular and Empirical Formulas Empirical Formula Empirical Formula The lowest common denominator molar ratio of all the elements contained in a compound The lowest common denominator molar ratio of all the elements contained in a compound E.g. CH 2 O is the empirical formula for a carbohydrate E.g. CH 2 O is the empirical formula for a carbohydrate Molecular Formula Molecular Formula The true molar ratio in which elements combine to form any unique compound The true molar ratio in which elements combine to form any unique compound E.g. C 6 H 12 O 6 is the molecular formula for glucose. E.g. C 6 H 12 O 6 is the molecular formula for glucose. Experimental analysis in the chemical laboratory yields data on percent composition Experimental analysis in the chemical laboratory yields data on percent composition Percent composition can be converted into a molar ratio Percent composition can be converted into a molar ratio That molar ratio represents the empirical formula That molar ratio represents the empirical formula

5. Calculating Empirical Formulas

6. Converting to Molecular Formulas

7. Practice Problems: 321 20. 5.00 mol Cl - 20. 5.00 mol Cl - 21. 7.50 mol C, 15.0 mol H, 7.50 mol O 21. 7.50 mol C, 15.0 mol H, 7.50 mol O 22. 9.00 mol SO 4 - 22. 9.00 mol SO 4 - 23. 25.0 mol O 23. 25.0 mol O 24. 23.0 mol H 24. 23.0 mol H

8. Practice Problems: 322 25. 40.00 g/mol NaOH 25. 40.00 g/mol NaOH 110.98 g/mol CaCl 2 110.98 g/mol CaCl 2