# exam 3 - Garg Pallavi Exam 3 Due Dec 5 2007 11:00 pm Inst...

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Garg, Pallavi – Exam 3 – Due: Dec 5 2007, 11:00 pm – Inst: Donna C Lyon 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. The due time is Central time. 001 (part 1 oF 1) 10 points ±or an endothermic reaction, the sum oF the bond energies oF the reactants is 1. the same as that in the products. 2. greater than that oF the products. cor- rect 3. less than that in the products. 4. cannot tell From inFormation given. Explanation: 002 (part 1 oF 1) 10 points ±or the reaction H 2 (g) + Cl 2 (g) 2HCl(g) at constant temperature and pressure, we would expect 1. Δ H Δ E . 2. Δ H > Δ E . 3. Δ H = Δ E . correct 4. Δ H Δ E . 5. Δ H < Δ E . Explanation: The equation that relates Δ H to Δ E is Δ E = Δ H - n ) R T . As 2 moles oF gaseous reactants (1 mol oF H 2 and 1 mol oF Cl 2 ) become 2 moles oF gaseous product, Δ n must be 0. This means that the term (Δ n ) R T will become zero, and Δ H and Δ E will become equal. 003 (part 1 oF 1) 10 points All oF the Following are state Functions EX- CEPT 1. H 2. T 3. q correct 4. U Explanation: 004 (part 1 oF 1) 10 points Calculate the standard entropy oF vaporiza- tion oF ethanol at its boiling point 352 K. The standard molar enthalpy oF vaporization oF ethanol at its boiling point is 40.5 kJ · mol - 1 . 1. +513 J · K - 1 · mol - 1 2. - 40.5 kJ · K - 1 · mol - 1 3. - 115 J · K - 1 · mol - 1 4. +115 J · K - 1 · mol - 1 correct 5. +40.5 kJ · K - 1 · mol - 1 Explanation: 005 (part 1 oF 1) 10 points The sublimation oF solid carbon dioxide is a spontaneous process. Predict the sign (+, - , or 0) oF Δ G r , Δ H r , and Δ S r , respectively. 1. - , +, + correct 2. 0, +, + 3. - , - , - 4. - , 0, + 5. - , +, - Explanation: 006 (part 1 oF 1) 10 points Calculate the change in internal energy when

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Garg, Pallavi – Exam 3 – Due: Dec 5 2007, 11:00 pm – Inst: Donna C Lyon 2 2.50 kJ of energy is transferred as heat to 1.50 mol N 2 at 298 K and 1 atm at constant volume. 1. - 1 . 50 kJ 2. +1 . 00 kJ 3. +1 . 50 kJ 4. - 2 . 50 kJ 5. +2 . 50 kJ correct Explanation: 007 (part 1 of 1) 10 points Calculate the standard reaction enthalpy for the reaction N 2 H 4 (l) + H 2 (g) 2NH 3 (g) given N 2 H 4 (l) + O 2 (g) N 2 (g) + 2H 2 O(g) Δ H = - 543 kJ · mol - 1 2H 2 (g) + O 2 (g) 2H 2 O(g) Δ H = - 484 kJ · mol - 1 N 2 (g) + 3H 2 (g) 2NH 3 (g) Δ H = - 92 . 2 kJ · mol - 1 1. - 935 kJ · mol - 1 2. - 151 kJ · mol - 1 correct 3. - 1119 kJ · mol - 1 4. - 59 kJ · mol - 1 5. - 243 kJ · mol - 1 Explanation: 008 (part 1 of 1) 10 points For the reaction 2C(s) + 2H 2 (g) C 2 H 4 (g) Δ H r = +52.3 kJ · mol - 1 and Δ S r = - 53.07 J · K - 1 · mol - 1 at 298 K. This reaction will be spontaneous at 1. all temperatures. 2.
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exam 3 - Garg Pallavi Exam 3 Due Dec 5 2007 11:00 pm Inst...

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