Bond Dissociation Energies

Formula

$\text{ΔH}=\sum {\mathrm{H}}_{\text{bonds broken}}-\sum {\mathrm{H}}_{\text{bonds formed}}$

Bond energies in common molecules

Molecule	Chemical Bond	Bond Dissociation Energy (kJ/mol)
Methane	CH3 – H	426.8
Ethane	CH3CH2 – H	405.8
Propane	CH3CH2CH2 – H	393.3
t-butane	(CH3)3C – H	374.5
Ethane	CH3 – CH3	341.1
Ethylene	CH2 = CH2	710
Ethylene	CH ≡ CH	710

Bond energies in diatomic molecules

Homonuclear

Name	Chemical Bond	Bond Dissociation Energy (kJ/mol)
Hydrogen gas	H – H	436
Deuterium gas	D – D	442
Nitrogen gas	N ≡ N	944
Oxygen gas	O = O	496
Phosphorous gas	P ≡ P	485
Sulfur gas	S = S	425
Fluorine gas	F – F	158
Chlorine gas	Cl – Cl	242
Bromine gas	Br – Br	193
Iodine gas	I – I	151

Heteronuclear

Name	Chemical Bond	Bond Dissociation Energy (kJ/mol)
Hydrogen fluoride (hydrofluoric acid)	H – F	562
Hydrogen chloride (hydrochloric acid)	H – Cl	431
Hydrogen bromide (hydrobromic acid)	H – Br	366
Hydrogen iodide (hydroiodic acid)	H – I	299
Carbon monoxide	C ≡ O	1077