Browsing by Author "Kundu, K. K."

Filter results by typing the first few letters
Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Autoprotolysis constants of water + dimethyl sulphoxide mixtures at 25°C and the related free energies of transfer of OH–
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (4), 1973) Das, A. K.; Kundu, K. K.
    The autoprotolysis constants (Ks) of dimethyl sulphoxide (DMSO)+ water mixtures containing 10, 20, 40 and 60 percent of DMSO by weight have been determined at 25°C from e.m.f. measurements of the cell: Pt, H2(g, 1 atm)∣ NaOH(m1), NaCl(m2), solvent ∣ AgCl—Ag. These values were utilized to compute the standard free energy changes, ΔGt(H2O—H2O)sys accompanying the transfer of H2O molecules, acting as an acid as well as a base, from water to these mixed solvents, and thence ΔG°t(OH–)app values for these solvent mixtures using ΔG°t(H+) values reported in the literature. The observed increasingly positive values of ΔG°t(OH–)app and also of ΔG°t(OH–), as obtained by deducting the influence of the activity of H2O in the mixed solvents, i.e., RT ln (aH2O)sw, from ΔG°t(OH–)app, suggest that the acidity of the mixed solvents decreases with increasing proportion of DMSO, as is expected from the decreasing stabilization of OH– by H-bonding and the increasing desolvation of OH– due to weaker ion-dipole interactions in the resulting solvent mixtures.
  • No Thumbnail Available
    Item
    Standard potentials of silver–silver chloride electrode at different temperatures and transfer energetics of hydrochloric acid in urea + water mixtures
    (Journal of the Chemical Society : Faraday Transaction - I. The Chemical Society, London. 1973, 69 (4), 1973) Kundu, K. K.; Mazumdar, K.
    Standard potentials (E°) of the Ag–AgCl electrode in four different compositions of urea + water mixtures at seven different temperatures from 10 to 40°C have been determined from the e.m.f. measurements of cells of the type: Pt, H2(g, 1 atm)|HCl(m), urea + water mixtures|AgCl–Ag. These values have been utilized to evaluate the transfer energetics (ΔG°t, TΔS°t and ΔH°t) accompanying the transfer of 1 mol of HCl from the standard state in water to the standard state in urea + water mixtures. Attempts have been made to explain the transfer energetics in the light of ion-solvent interactions and the structural contributions of the solvents. A detailed analysis of entropy changes accompanying the transfer process indicates that at about 5–7 m of urea there is an enhancement of the structure of the urea + water mixtures possibly due to the formation of hydrogen-bonded urea-water complex.