Water, bond energy terms dissociation

The dynamic NMR technique allows investigations on the rate of exchange between 3-substituted quinuclidinium ions and water. The rate of dissociation of amine/water (or amine/alcohol) complexes is determined71 by the free energy contribution from the pKa-dependent hydrogen bond breaking, and from dispersion forces between acceptor and donor which may be at the most 40% of the activation energy of the dissociation of the complex. Similar importance may be attributed to a term for the formation of a cavity prior to the dissociation of the complexes. 

What energy terms are important in determining AH° for the dissociation of HX in water (Keep in mind that large, positive contributions to the value of AH° will tend to make AG° more highly positive, K3 smaller, and the acid weaker.) One important factor is certainly the H—X bond strength. Note from Table 19.8 that the H—F bond is much stronger than the other H—X bonds. This factor tends to make HF a weaker acid than the others. 

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