Bond and Group Enthalpies
Bond Energies for Single Bonds (kJ/mole)
| Bond | Bond Energy | Bond | Bond Energy |
| H-H | 436 | H-F | 563 |
| C-C | 348 | H-Cl | 432 |
| N-N | 161 | H-Br | 366 |
| O-O | 139 | H-I | 299 |
| F-F | 153 | C-N | 292 |
| Cl-Cl | 243 | C-O | 351 |
| Br-Br | 193 | C-S | 259 |
| I-I | 151 | C-F | 441 |
| C-H | 413 | C-Cl | 328 |
| N-H | 391 | C-Br | 276 |
| S-S | 213 | C-I | 240 |
| O-H | 463 | S-H | 339 |
Heat of sublimation of graphite = 713.0 kJ/mole
Bond Energies for Multiple Bonds (kJ/mole)
| Bond | Bond Energy | Bond | Bond Energy |
| C=C | 615 | C=O | 728 |
| N=N | 418 | C=S | 477 |
| O=O | 495 | C C triple bond | 812 |
| C=N | 615 | N N triple bond | 946 |
| C=O | 686 (formaldehyde) 715 (other aldehydes) |
C N triple bond | 891 (nitriles) 866 (HCN) |
From: L. Pauling, The Nature of the Chemical Bond, 3rd ed., Cornell Univ. Press,
1960, p. 85
Group Contributions to Gas Phase Standard Enthalpies of Formation at 298.2 K (kJ/mole)
| Group | DHof, 298.2 K (kJ/mole) | Group | DHof, 298.2 K (kJ/mole) | |
| C(H)3(C) => - CH3 | - 42.17 | C(Br)(H)2(C) | - 22 | |
| C(H)2(C)2 | - 20.7 | C(I)(H)2(C) | + 37 | |
| C(H)(C)3 | - 6.19 | C(Cl)(H)(C)2 | - 60.2 | |
| C(C)4 | + 8.16 | C(Br)(H)(C)2 | - 9.7 | |
| C(Cl)(H)2(C) | - 65.7 | C(Cl)(C)3 | - 53.1 |
From: Benson, Sydney W., Thermochemical Kinetics, John Wiley & Sons, Inc., New York (1968)