Bond strength free energy change

Experimental determinations undertaken prior to the discovery of electrospray as a source of ions have shown86 87 that the bond strength of H-bonded complexes XH —A" increases with the gas-phase acidity of XH and the gas-phase basicity of A-. This relation has been examined82 for the special case where A- were a variety of anions produced by electrospray and XH = OH2, on the basis of the hydration energy data (see Table 8) and gas-phase basicities AGj A-) = AG°cid (AH) corresponding to the free energy change for the gas-phase reaction ... 

The free energy change (AG ) depends on the enthalpy change (Aff°) and the entropy change (A5°). AH° indicates relative bond strength, but what does AS° measure ... 

The sequence of enthalpy changes where replacement of a condensed alkali metal counterion by a heavier alkali metal counterion is an exothermic process is now in the same sequence as the observed equilibrium data. (, ) For the interaction of alkali metal cations with sulphated polyelectrolytes this is K>Na>Li. Thus in the case of the sulphated polyanions the enthalpy change and the equilibrium, free energy change, follow the same sequence. The sequence of enthalpy changes seems to imply that the bond strength between the condensed alkali metal cation and the dextran sulphate increases in the sequence Li[Pg.360]

The free energy change is related to changes in bond strengths and the degree of energy dispersal in the system... 

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