Exam 4 - Version 041 Exam 4 Lyon (52370) This print-out...

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Version 041 – Exam 4 – Lyon – (52370) 1 This print-out should have 30 questions. Multiple-choice questions may continue on the next column or page – fnd all choices beFore answering. PLEASE BUBBLE YOUR NAME, EID AND EXAM VERSION NUMBER COR- RECTLY ON YOUR ANSWER SHEET. ±AILURE TO DO WILL PREVENT ±INAL EXAM EXEMPTIONS ±OR STUDENTS WHO QUALI±Y A±TER THIS EXAM IS GRADED. 001 10.0 points Which oF the Following statements regarding intermolecular Forces (IM±) is/are true? I) Intermolecular Forces are not a²ected by the distance between two molecules. II) Water molecules do not exhibit disper- sion Forces. III) Bonds within a molecule are usually one or two orders oF magnitude stronger than intermolecular Forces. 1. I and III 2. II and III 3. I and II 4. II only 5. I, II, and III 6. III only correct 7. I only Explanation: Statement III is true; with a Few no- table exceptions in the ion-ion category, IM± are much weaker than the bonds within a molecule. Statements I and II are False; all IM± are the result oF Coulombic attraction, which diminishes greatly over even very short distances; all molecules have dispersion Forces. 002 10.0 points The heat oF combustion oF butane (C 4 H 10 ) is - 2878 kJ/mol. Assume a typical cigarette lighter holds about 1.75 g oF butane. How much heat energy would be released iF ALL oF the butane in the lighter were combusted? 1. 95.59 kJ 2. 86.63 kJ correct 3. 40.61 kJ 4. 1.05 kJ Explanation: MW butane = 58.14 g/mol ? kJ = - 2878 kJ mol · (1 . 75 g) · 1 mol 58 . 14 g = - 86 . 6271 kJ 003 10.0 points Which oF the Following molecules A) CH 3 CH 2 OH C) CH 3 OCH 3 B) CH 3 CHO D) CH 3 COOH are likely to Form hydrogen bonds? 1. C and D only 2. B and C only 3. A and C only 4. Another combination oF compounds 5. All are likely to Form hydrogen bonds. 6. None Forms hydrogen bonds. 7. B and D only 8. A and D only correct 9. A and B only Explanation: Only molecules with H attached to the electronegative atoms N, O, and ± can hy- drogen bond. OF the molecules given, only CH 3 COOH and CH 3 CH 2 OH have hydrogen attached to oxygen, so these are the only ones that can undergo hydrogen bonding.
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Version 041 – Exam 4 – Lyon – (52370) 2 004 10.0 points According to thermodynamics, which of the following would BEST describe a spontaneous reaction? 1. Δ H is positive and Δ S is negative. 2. Δ G is positive and Δ S is positive. 3. Δ H is negative. 4. Δ G is positive and Δ H and Δ S are neg- ative. 5. Δ G is negative and Δ H is positive. cor- rect Explanation: Δ G must be negative for a spontaneous process. 005 10.0 points Note: Enthaply of evaporation is enthaply of vaporization. The speciFc heat for liquid argon Ar( ) is 25 . 0 J mol · C and gaseous Ar(g) is 20 . 8 J mol · C . The enthalpy of evaporation is 6506 J/mol. How much energy is required to convert 1 mole of liquid Ar from 5 C below its boiling point to 1 mole of gaseous Ar 5 C above its boiling point? 1.
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This note was uploaded on 10/26/2010 for the course CH 52370 taught by Professor Lyon during the Spring '09 term at University of Texas at Austin.

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Exam 4 - Version 041 Exam 4 Lyon (52370) This print-out...

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