1. Section 6.3 Formulas of Compounds 1.To understand the meaning of empirical formula 2.To learn to calculate empirical formulas 3.To learn to calculate the molecular formula of a compound Objectives

2. Section 6.3 Formulas of Compounds What is the Formula? mass spec If I analyze a compound by mass as 7.7% Hydrogen and 92.3 % Carbon what is its formula? If I have 100g of the compound how many grams do I have of each element? How many moles of each element do I have? What is the simple number ratio between the two numbers of moles? What is the formula? Is this the only possible formula?

3. Section 6.3 Formulas of Compounds A. Empirical Formulas The empirical formula of a compound is the simplest whole number ratio of the atoms present in the compound. What is the empirical formula of the following compounds? Sodium Peroxide Na 2 O 2 Terephthalic acid C 8 H 6 O 4 Phenobarbital C 12 H 12 N 2 O 3 1,4-dichloro-2-butene C 4 H 6 Cl 2

4. Section 6.3 Formulas of Compounds B. Calculation of Empirical Formulas

5. Section 6.3 Formulas of Compounds C. Calculation of Molecular Formulas The molecular formula is the exact formula of the molecules present in a substance. The molecular formula is always an integer multiple of the empirical formula. Molecular formula = (empirical formula) n where n is a whole number Empirical Formula: CH Molar Mass = 78 Molecular Formula?

6. Section 6.3 Formulas of Compounds Formula Summary For the sugar glucose