All Chapters Video 1.3 Molecular Formulas and Percent Composition (Solution, Pt. 2) Chapter OutlineChapter Quiz Question? Ask Dr. Mike! Lesson Summary 1. The empirical formula of a compound with molecules containing 12 carbon atoms, 14 hydrogen atoms, and 6 oxygen atoms is __________. A. C12H14O6 B. C6H7O3 C. CHO D. CH2O E. C2H4O 2. Calculate the percent composition, by mass, of carbon in the following compounds: Cocaine, C17H21NO4 Vancomycin, C55H75Cl2N9O24 3. What is the molecular formula of each of the following compounds? Empirical formula CH2, molar mass = 84 g/mol Empirical formula HCO2, molar mass = 90.0 g/mol 4. What is the empirical formula of a compound with 9.5% C, 12.7% O, and 56.3% Cl? A. COCl B. COCl2 C. C2OCl D. CO2Cl E. ClCO4 5. Which of the following ores containing Cu (63.5 g/mol) has the highest percentage of Cu by mass? (The molar masses are given inside the parenthesis.) A. Chalcopyrite, CuFeS2 (183.5 g/mol) B. Chalcocite, Cu2S (159 g/mol) C. Covellite, CuS (95.6 g/mol) D. Cuprite, Cu2O (143 g/mol) E. Tenorite, CuO (79.5 g/mol) 6. An ore containing gold was processed so that all of the gold is converted to AuCl3 (303 g/mol). If a 4.0 g sample of an ore produced 3.03 g of AuCl3, what is the percentage of Au (197 g/mol) in the ore? A. 10.0 % B. 49.3 % C. 75.8 % D. 98.5 % E. 24.6 % Lesson 1.3 Molecular Formulas and Percent Composition (Solution, Pt. 2) 1.1 The Mole and Molecular Weights 1.1 Quiz Video Solution (Pt. 1) 1.1 Quiz Video Solution (Pt. 2) 1.2 Balancing Reactions 1.2 Quiz Video Solution (Pt. 1) 1.2 Quiz Video Solution (Pt. 2) 1.3 Molecular Formulas and Percent Composition 1.3 Quiz Video Solution (Pt. 1) 1.3 Quiz Video Solution (Pt. 2) 1.4 Product and Reactant Amounts 1.4 Quiz Video Solution 1.5 Limiting Reactants 1.5 Quiz Video Solution 1.6 Theoretical and Percent Yields 1.6 Quiz Video Solution (Pt. 1) 1.6 Quiz Video Solution (Pt. 2) Instructor Dr. Mike Christiansen Dr. Christiansen is a chemistry professor at Utah State University and has a PhD in organic chemistry. He's been teaching students chemistry for nearly 12 years.