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Unformatted text preview: Version 076 Final Exam Lyon (52380) 1 This print-out should have 60 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. PLEASE BE SURE TO BUBBLE YOUR NAME, EID, AND EXAM VERSION NUM- BER CORRECTLY. FAILURE TO DO SO COULD PREVENT YOU FROM RECEIV- ING YOUR COURSE GRADE FOR SEV- ERAL WEEKS. 001 10.0 points The electronic configurations of most ele- ments are correctly predicted by the standard order of energy of the orbitals. Which of the following statements explains several of the apparent exceptions to this general order (the Aufbau order) of filling? 1. Exceptions occur for those elements whose emission spectrum is a continuous spec- trum. 2. When the potential frequency times the Schrodinger quantum equals Plancks con- stant, paramagnetic multiplicity dominates the orbitals. 3. There is a special stability associated with half-filled or filled sets of equivalent orbitals. correct 4. When an electron has n , m lscript , and m s all equal to +1, a special stability results. 5. Sometimes it is possible for two electrons with the same spin to occupy the same or- bitals. Explanation: 002 10.0 points When a chemical reaction comes to equilib- rium, both the forward and the reverse reac- tions continue, but their rates are equal. For such a system at equilibrium at 300 K and 1.00 atm pressure, the change in Gibbs free energy as the forward reaction occurs must be 1. positive. 2. a maximum. 3. a minimum. 4. zero. correct 5. negative. Explanation: For processes at equilibrium G = 0. 003 10.0 points Which of the following experiments most di- rectly supports de Broglies hypothesis of the wave nature of matter? 1. electron diffraction by a crystal correct 2. the emission spectrum of the hydrogen atom 3. the photoelectric effect 4. blackbody radiation 5. alpha-particle scattering by a metal foil Explanation: de Broglies hypothesis is that all matter possesses wave-like properties. Waves also exhibit a property known as diffraction. Elec- trons are often described as particles, but when a beam of electrons is aimed at a crys- tal, it undergoes diffraction. The resulting pattern varies depending on the exact crystal structure. The scattering experiment showed that most of the mass of an atom was con- centrated in a small, positive center which repelled alpha particles, but it did not pro- vide any further structural information on the metal foil. 004 10.0 points Calculate the work for the reaction 16 CO 2 (g) + 18 H 2 O(g) 2 C 8 H 18 ( lscript ) + 25 O 2 (g) at 298 K. 1. +17 . 34 kJ/mol Version 076 Final Exam Lyon (52380) 2 2.- 22 . 30 kJ/mol 3. +9 . 00 kJ/mol 4.- 9 . 00 kJ/mol 5.- 17 . 34 kJ/mol 6. +22 . 30 kJ/mol correct Explanation: The number of moles is n = 25 mol- (16 mol + 18 mol) =- 9 mol Thus the work is w =- nRT =- (- 9 mol) (8 . 314 J / mol K) (298 K) = 22298 . 1 J / mol = 22 . 2981 kJ / mol 005 10.0 points Which type of orbital will be occupied by...
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This note was uploaded on 01/30/2010 for the course CH 301 taught by Professor Fakhreddine/lyon during the Spring '07 term at University of Texas at Austin.
- Spring '07