Simple, 'dumb' question.... Is the kJ/mol number given in tables of bond strengths or bond dissociation energies , when it comes to double and triple bonds, just for the 'last' bond or for both (or all three) together?

  • 1
    $\begingroup$ The tabulated numbers are for dissociating the bond, i.e., breaking it, not just weakening it. $\endgroup$
    – Ed V
    Commented Mar 10, 2020 at 14:51
  • $\begingroup$ As for you are interested on this, you should have reasoned about this by considering the values, isn't? $\endgroup$
    – Alchimista
    Commented Mar 11, 2020 at 7:45
  • $\begingroup$ I did reason about this, Alchimista, I just wasn't sure... $\endgroup$
    – Kurt Hikes
    Commented Apr 14, 2020 at 21:49

1 Answer 1


They're for the entire bond (so for a triple bond, all 3).

From Wikipedia, it can be defined as

The standard enthalpy change when [a bond, be it single, double, or triple] is cleaved by homolysis to give fragments A and B, which are usually radical species

So you get two fragments as your final state.

  • 3
    $\begingroup$ The part about homolytic cleavage is also important because for some bonds (like HCl) under the right conditions, heterolytic cleavage is much easier. For one thing, it does not produce radicals. $\endgroup$
    – Karsten
    Commented Mar 10, 2020 at 16:04

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