Bond Energy Calculator
Calculate enthalpy of reaction (delta H) using bond dissociation energies for reactants and products.
Bonds Broken (Reactants)
Bonds Formed (Products)
Enthalpy Change (Delta H)
-242.50 kJ/mol
Reaction is: Exothermic
Formula:
Delta H = Sum(Bond Energies Broken) - Sum(Bond Energies Formed)
Calculation:
Bonds broken: 1 x H-H + 0.5 x O=O = 683.50 kJ
Bonds formed: 2 x H-O = 926.00 kJ
Delta H = 683.50 - 926.00 = -242.50 kJ/mol
Common Bond Energies (kJ/mol)
H-H
436 kJ/mol
H-C
413 kJ/mol
H-N
391 kJ/mol
H-O
463 kJ/mol
H-F
567 kJ/mol
H-Cl
431 kJ/mol
H-Br
366 kJ/mol
H-I
298 kJ/mol
C-C
348 kJ/mol
C=C
614 kJ/mol
C≡C
839 kJ/mol
C-N
293 kJ/mol
C=N
615 kJ/mol
C≡N
891 kJ/mol
C-O
358 kJ/mol
C=O
799 kJ/mol
Understanding Bond Energy
Bond energy (or bond dissociation energy) is the amount of energy required to break one mole of bonds in gaseous molecules. Breaking bonds requires energy (endothermic), while forming bonds releases energy (exothermic). The enthalpy change of a reaction can be estimated by comparing the total energy needed to break all bonds in reactants with the total energy released when forming all bonds in products.