Acetylene (C2H2) and nitrogen (N2) both contain a triple bond, but they differ greatly in their chemical properties.
(a) Write the Lewis structures for the two substances.
(b) By referring to Appendix C, look up the enthalpies of formation of acetylene and nitrogen and compare their reactivates.
(c) Write balanced chemical equations for the complete oxidation of N2 to form N2O5 (g) and of acetylene to form CO2 (g) and H2O (g).
(d) Calculate the enthalpy of oxidation per mole of N2 and C2H2 (the enthalpy of formation of N2O5 (g) is 11.30kJ / mol). How do these comparative values relate to your response to part (b)? Both N2 and C2H2 possess triple bonds with quite high bond enthalpies (Table 8.4). What aspect of chemical bonding in these molecules or in the oxidation products seems to account for the difference in chemical reactivates?

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TABLE 8.4 Average Bond Enthalples (kJ/mol) Single Bonds 413 348 293 358 485 328 276 240 259 391 163 201 O-F 272 -Cl 200 0-1 243 463 146 190 203 234 155 C-H C-C C-N N-H N-N Cl-F Cl-Cl 253 242 C-F C-Cl C-Br N-Cl N-Br 237 218 193 339 327 253 218 266 Br-Cl Br Br H-H H-F H-Cl 43 S-Br 436 C--S 567 S-Cl I-CI I-Br 208 175 151 Si -H Si Si Si-C si-o Si-Cl 323 226 301 368 464 366 299 Multiple Bonds 495 C-N 615 891 799 1072 523 418 607 C O