# Problem: Average Bond Enthalpies (kJ/mol)C-H 413N-H 391O-H 463F-F 155C-C 348N-N 163O-O 146C=C 614N-O 201O=O 495Cl-F 253C-N 293N-F 272O-F 190Cl-Cl 242C-O 358N-Cl 200O-Cl 203Br-F 237C=O 799N-Br 243O-I 234Br-Cl 218C-F 485H-H 436Br-Br 193C-Cl 328H-F 567C-Br 276H-Cl 431I-Cl 208C-I 240H-Br 366I-Br 175H-I 299I-I 151(a) Use enthalpies of formation given in Appendix C to calculate ΔH for the reaction Br2(g) → 2Br(g), and use this value to estimate the bond enthalpy D(Br¬Br). (b) How large is the difference between the value calculated in Part A and the value given in the table to the left?

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###### Problem Details

 Average Bond Enthalpies (kJ/mol) C-H 413 N-H 391 O-H 463 F-F 155 C-C 348 N-N 163 O-O 146 C=C 614 N-O 201 O=O 495 Cl-F 253 C-N 293 N-F 272 O-F 190 Cl-Cl 242 C-O 358 N-Cl 200 O-Cl 203 Br-F 237 C=O 799 N-Br 243 O-I 234 Br-Cl 218 C-F 485 H-H 436 Br-Br 193 C-Cl 328 H-F 567 C-Br 276 H-Cl 431 I-Cl 208 C-I 240 H-Br 366 I-Br 175 H-I 299 I-I 151

(a) Use enthalpies of formation given in Appendix C to calculate ΔH for the reaction Br2(g) → 2Br(g), and use this value to estimate the bond enthalpy D(Br¬Br).

(b) How large is the difference between the value calculated in Part A and the value given in the table to the left?