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|Title:||Standard potentials of Ag-AgX (X = Br and I) electrodes at different temperatures and the related transfer energetics of HX in quasi-isodielectric aqueous ethylene carbonate solvents|
Kundu, Kiron K
|Abstract:||Ag-AgI electrodes have been determined in quasiisodielectric aqueous mixtures of 10, 30, 50 and 70 (wt %) dipolar aprotic ethylene carbonate (EC) at 25°,30°,35°,40° and 45°C. These E0 values have been utilized to compute transfer free energies (∆G) and entropies (∆S) of HBr and HI. These values when coupled with previously determined transfer energetics of H+ yield the transfer energetics of Br- arid I-. The chemical parts of transfer free energies ∆G,ch (i), obtained after correcting the cavity effect and Born-type and ion-dipole type electrostatic effects, are found to be in accord with the dictates of increased destabilizing chemical effect of dipolar aprotic nature of EC and the superimposed soft-soft interactions on these large sized halide ions. The observed T∆S (i) versus composition profiles as well as those of T∆G,ch (i) versus composition, as obtained after correcting for the cavity effect and Born-type electrostatic effects, have been examined in the light of Kundu et al.'s semiquantitative theory based on a four-step transfer process, It is found that addition of cosolvent EC induces breakdown of three dimensional water structure due to possible formation of H-bonded EC-(H2O)x complexes and EC-EC aggregates and the packing imbalance in solvent mixtures containing higher proportion of EC.|
|Appears in Collections:||IJC-A Vol.30A(11) [November 1991]|
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