(a) Compare the bond enthalpies (Table 8.4) of the carbon-carbon single, double, and triple bonds to deduce an average -bond contribution to the enthalpy. What fraction of a single bond does this quantity represent?
(b) Make a similar comparison of nitrogen-nitrogen bonds. What do you observe?
(c) Write Lewis structures of N2H4, N2H2, and N2, and determine the hybridization around nitrogen in each case.
(d) Propose a reason for the large difference in your observations of parts (a) and (b).

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TABLE 8.4 Average Bond Enthalpies (kJ/mol) Single Bonds C-H C-C C-N N-H N-N 391 163 201 OF 272 200 O 243 463 146 190 203 234 F-F 155 413 348 293 358 485 328 276 240 259 O-H O-O ClF ClCI 253 242 N-F N CI N Br OCl C-F C CI C Br 237 218 193 SH 339 327 253 218 266 Br Br H-H H-F H Cl H Br H-I 436 SF 567 SC 431 366 299 C S I CI S-Br S-S 208 175 151 SiH SiSi SiC Si-O Si-Cl 323 226 301 368 464 Multiple Bonds 614 839 615 891 799 1072 N-N 418 941 607 495 523 418 C O