The energetics of acid dissociation in aqueous solution

The right-hand side product is equal to the self-dissociation constant for water, K  

If pAa for the conjugate acid of PhNH2 is 4.63, what is pAj, for PhNH2 To what equilibria do A and A refer  

Hydrazine, N2H4, 6.5, is a weak Bronsted base (pAb = 6.05), weaker than NH3 it reacts with strong acids to give hydrazinium salts (equation 6.23). 

The value of pAb for hydroxylamine, NH2OH, is 8.04, showing it to be a weaker base than either NH3 or N2H4. 

The degree of dissociation of NH3 in aqueous solution can be described in terms of a value of either or fiTb. Deduce a relationship between the values of plTa and pfiTb. 

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Chapter 6 The energetics of acid dissociation in aqueous solution 169... 

The intracellular pH in the myocardial tissue during ischemia reportedly falls to 6.4 therefore, the PBN/ OH should be relatively more persistent under ischemic conditions as opposed to reperfusion. In aqueous solution, the decomposition of PBN/ OH is facilitated due to the ease with which the acidic (3-proton is dissociated. In contrast, the unimolecular decomposition of PBN/ OH becomes energetically difficult in non-protic solvents such as toluene and benzene. This may well account for the increased stability of PBN/ OH adduct in these solvents. 

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