Answer Happy

answer the following questions in the order A -F on your first appended page.
VII. [40 Points) We have learned that the bromination of ethene proceeds via a bromonium ion to give 1,2-dibromoethane. With light or a radical initiator, an alternative mechanism can be formulated, traversing a radical chain pathway: hu Br2 AH = ? kcal mol Br Br Answer the following questions in the order a-f on your first appended page, labelled "VII.". a. Using the bond dissociation energies in the Table below, the energy of the T bond, 65 kcal mol-, and the strength of the Br-Br bond, 46 kcal moll, calculate the AH of this reaction. Show your work. Label this part "a.". Table 3.1 Bond-Dissociation Energies of Various A-B Bonds in the Gas Phase [DH in kcal mol-' (kJ mol) B in A-B A in A-B -F -a -Br -1 -OH -NH H- 104 (435) 136 (569) 103 (431) 87 (364) 71 (297) 119 (498) 108 (452) CH- 105 (439) 110 (460) 85 (356) 70 (293) 57 (238) 93 (389) 84 (352) CH,CH, 101 (423) 111 (464) 84 (352) 70 (293) 56 (234) 94 (393) 85 (356) CH,CH,CH:- 101 (423) 110 (460) 85 (356) 70 (293) 56 (234) 92 (385) 84 (352) (CH),CH- 98.5 (412) 111 (464) 84 (352) 71 (297) 56 (234) 96 (402) 86 (360) (CH, C- 96.5 (404) 110 (460) 85 (356) 71 (297) 55 (230) 96 (402) 85 (356) Nowe (1) DN*- ar for the process A-B - A+B. () These numbers are being revised continually because of improved methods for their measurement. (e) The trends observed for A-H bonds are significantly altered for polar A-B bonds because of dipolar contributions to Dir. Write the radical chain mechanism for this reaction, the initiation and the two propagation steps, using electron-pushing fishhook arrows, and calculate the associated AH values. Label these parts "b", "c.", etc. b. Initiation and its AH value c. Propagation step 1 d. Propagation step 2 e. AH of propagation step 1 f. AH of propagation step 2