Bond Dissociation Energy

The bond dissociation energy (enthalpy change) for a bond A B which is broken through the reaction AB : A B is defined as the standard-state enthalpy change for the reaction at a specified temperature, here at 298 K.

That is,

ΔHf ₂₉₈= ΔHf(A)₂₉₈ +ΔHf (A)₂₉₈ -ΔHf (AB)₂₉₈

All values refer to the gaseous state and are given at 298 K. Values of 0 K are obtained by subtracting 3⁄2RT from the value at 298 K.

To convert the tabulated values to kcal/mol, divide by 4.184.

Bond Dissociation Energies
Bond	Bond Energy (kj/mol)
H—H	432
H—F	565
H—Cl	427
H—Br	363
H—I	295
C—H	413
C—C	347
C—N	305
C—O	358
C—F	485
C—Cl	339
C—Br	276
C—I	240
C—S	259
N—H	391
N—N	160
N—F	272
N—Cl	200
N—Br	243
N—O	201
O—H	467
O—O	146
O—F	190
O—Cl	203
O—I	234
F—F	154
F—Cl	253
F—Br	237
Cl—Cl	239
Cl—Br	218
Br—Br	193
I—I	149
I—Cl	208
I—Br	175
S—H	347
S—F	327
S—Cl	253
S—Br	218
S—S	266
Si—Si	340
Si—H	393
Si—C	360
Si—O	452
C = C	614
C ≡ C	839
O = O	495
C = O	799
C ≡ O	1072
N = O	607
N = N	418
N ≡ N	941
C ≡ N	891
C = N	615