Practice Exam 1 Key

Practice Exam 1 Key - CHEM 6B Practice Exam 1-2 (Prof....

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Chem 6B Practice Exam 1-2 1 - A Prof. Crowell CHEM 6B Practice Exam 1-2 (Prof. Crowell) January 23, 2008 *** FILL IN YOUR STUDENT ID NUMBER , NAME , and TEST FORM = A *** MULTIPLE CHOICE Fill in the bubble on the scantron corresponding to the correct response (26 questions worth 4 points each) 1. The lattice enthalpy of calcium bromide is the energy change for the reaction a). CaBr 2 (s) Ca(g) + 2Br(g) *b). CaBr 2 (s) Ca 2+ (g) + 2Br (g) c). Ca(s) + Br 2 (l) CaBr 2 (s) d). CaBr 2 (s) Ca(g) + Br 2 (g) e). Ca(g) + 2Br(g) CaBr 2 (g) 2. The temperature of 2.00 mol Ne(g) is increased from 25 ° C to 200 ° C at constant pressure. Calculate the change in the entropy of neon. Assume ideal behavior. a). +7.68 J/K *b). +19.2 J/K c). 7.68 J/K d). 19.2 J/K e). +9.60 J/K 3. What is the total motional contribution to the molar internal energy of gaseous H 2 O at 25 ° C? a). 6.19 kJ/mol *b). 7.43 kJ/mol c). 3.72 kJ/mol d). 12.4 kJ/mol e). 2.48 kJ/mol 4. Knowing that S° is 57.85 and 153.61 J/K-mol, respectively, for Na (l) and Na (g), and H vap ° = 105.27 kJ/mol for Na, estimate the normal boiling point in ° C for Na: a) 1100 ° C b) 685 ° C c) 412 ° C d) 1186 ° C *e) 826 ° C 5. Which of the following ionic compounds has the largest lattice energy? a) KBr b) MgBr 2 c) NaCl *d) MgCl 2 e) LiF 6. Use Trouton's constant to estimate the enthalpy of vaporization of diethyl ether, which boils at 309K. a). +85 kJ/mol *b). +26 kJ/mol c). +275 kJ / mol d). 85 kJ/mol e). +3.6 kJ/mol 7. Which of the following would probably have a positive S value? a). He(g, 2 atm) He(g, 10 atm) * b). H 2 (g) + I 2 (s) 2HI(g) c). 2Ag(s) + Br 2 (l) 2AgBr(s) d). O 2 (g) O 2 (aq) e). 2NO 2 (g) N 2 O 4 (g) 8. Given the bond energy data given below, estimate the heat of reaction for the following reaction between acetylene and hydrochloric acid: H 2 CCH 2 + HCl CH 3 CH 2 Cl Bond Energies (in kJ/mol): C-C 348;
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Practice Exam 1 Key - CHEM 6B Practice Exam 1-2 (Prof....

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