2005spring4key[1]

2005spring4key[1] - Chem. 121 Fourth Exam (04/27/05) Name_...

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Chem. 121 Fourth Exam (04/27/05) Name_____________________________________ Total points = 100 1. (36 pts) 1. If you count stereoisomers as different compounds, the reaction of 2-methylbutane with chlorine would yield how many monochloro derivatives ? A) 2 B) 3 C) 4 D) 5 E) 6 2. How many signals would be seen in the 13 C NMR spectrum of the following compound? CH 3 CH 3 H H CH 3 CH 3 A) 3 B) 4 C) 5 D) 8 E) 10 3. What is the relationship between the protons labelled a and b in the following cyclobutane? CH 3 H H a H b a) chemically equivalent b) enantiotopic c) diastereotopic d) mesotopic e) none of the above 4. Consider the bond dissociation energies listed below in kcal/mol. CH 3 -Br 70 CH 3 CH 2 -Br 68 (CH 3 ) 2 CH-Br 68 (CH 3 ) 3 C-Br 65 These data show that the carbon-bromine bond is weakest when bromine is bound to a ______________________. a) methyl carbon b) primary carbon c) secondary carbon d) tertiary carbon e) quaternary carbon 5. Given the bond dissociation energies below (in kcal/mol), estimate the Δ H° for the propagation step (CH 3 ) 2 CH• + Cl 2 -------> (CH 3 ) 2 CHCl + Cl•. CH 3 CH 2 CH 2 -H 98 (CH 3 ) 2 CH-H 95 Cl-Cl 58 H-Cl 103 CH 3 CH 2 CH 2 -Cl 81 (CH 3 ) 2 CH-Cl 80 A) -22 kcal/mol B) +22 kcal/mol C) -40 kcal/mol D) +45 kcal/mol E) +45 kcal/mol 6. Which of the following gas-phase reactions is a possible chain-terminating step in the light- initiated chlorination of methane? A) Cl–Cl
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This note was uploaded on 04/07/2008 for the course CHEM 121 taught by Professor Lever during the Spring '05 term at Missouri (Mizzou).

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2005spring4key[1] - Chem. 121 Fourth Exam (04/27/05) Name_...

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