chem LyonFinal - Jiwani, Sabrina Final 1 Due: Dec 16 2006,...

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Unformatted text preview: Jiwani, Sabrina Final 1 Due: Dec 16 2006, 2:00 pm Inst: Donna C Lyon 1 This print-out should have 45 questions. Multiple-choice questions may continue on the next column or page find all choices before answering. The due time is Central time. 001 (part 1 of 1) 10 points The following reaction occurs during the pro- duction of metallic iron: 2 Fe 2 O 3 (s) + 3 C(graphite) 4 Fe(s) + 3 CO 2 (g) Calculate H for this reaction at 25 C and 1 atm. H f for CO 2 (g) =- 393 . 51 kJ/mol, and H f for Fe 2 O 3 (s) =- 824 . 2 kJ/mol. 1. Thereisinsufficientinformationtoanswer this question. 2.- 430.7 kJ 3. +467.9 kJ correct 4.- 467.9 kJ 5. +430.7 kJ Explanation: H rxn = H products- H reactants = (- 393 . 51)(3)- (- 824 . 2)(2) = 467 . 9 kJ Note : The enthalpy of a pure element is al- ways zero. 002 (part 1 of 1) 10 points Calculate the pressure of 4 g of nitrogen gas in a 1 L container at 20.0 C. 1. 0.469 atm 2. 96.2 atm 3. 0.235 atm 4. 3.44 atm correct 5. 6.87 atm Explanation: 003 (part 1 of 1) 10 points The 3 d sublevel has enhanced stability when it contains 1. 5 electrons. 2. 5 or 10 electrons and no 4 s electrons. 3. no 4 s electrons. 4. 5 or 10 electrons. correct 5. 5 or 10 orbitals. Explanation: 004 (part 1 of 1) 10 points Double bonds between two given elements are (stronger, weaker) and (longer, shorter) than single bonds between the same two elements. 1. weaker; longer 2. stronger; shorter correct 3. weaker; shorter 4. stronger; longer Explanation: Double bonds have higher bond orders and bond energies and thus are stronger and shorter. 005 (part 1 of 1) 10 points Which of the following is true of a general thermodynamic state function? 1. The change in the value of the state func- tion is always positive for endothermic pro- cesses. 2. The value of the state function remains constant. 3. The change in the value of a state func- tion is always negative for a spontaneous re- action. Jiwani, Sabrina Final 1 Due: Dec 16 2006, 2:00 pm Inst: Donna C Lyon 2 4. The change of the value of a state func- tion is independent of the path of a process. correct 5. The value of a state function does NOT change with a change in temperature of a process. Explanation: A change in a state function describes a difference between the two states. It is inde- pendent of the process or pathway by which the change occurs. 006 (part 1 of 1) 10 points Estimate the minimum temperature at which magnetite can be reduced to iron by graphite. Fe 3 O 4 (s) + 2C(s) 2CO 2 (g) + 3Fe(s) S r = +351 . 44 J/K and the standard mo- lar enthalpies of formation of magnetite and CO 2 (g) are- 1118 . 4 and- 393 . 51 kJ/mol, respectively....
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chem LyonFinal - Jiwani, Sabrina Final 1 Due: Dec 16 2006,...

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