AP® Chemistry

Free Version

Upgrade subject to access all content


Geometric Bond Dissociation


Given ethene $(C_2H_4)$ and ethyne $(C_2H_2)$, which of the following would be expected to have a higher sum of all bond dissociation energies for the substance based on the following bond enthalpies?

Bond Bond Energy
$C-H \quad$ 413 kJ/mol
$C-C$ 347 kJ/mol
$C=C$ 614 kJ/mol
$C≡C$ 839 kJ/mol

Ethene because there are two more $C-H$ bonds that can be broken, requiring more overall energy.


Ethyne because the $C≡C$ bond is very short so it is the strongest and requires more overall energy to break it.


The two compounds will have comparable bond dissociation energies.


The bond energies of the two compounds cannot be directly compared due to the differences in structure.