Ion–ion–solvent interactions in aqueous ionic cosolvent systems. II. Single-ion transfer free energies and entropies using tetraphenylarsonium tetraphenylborate reference electrolyte assumption in aqueous sodium nitrate solvent system

1987 ◽  
Vol 65 (11) ◽  
pp. 2595-2604 ◽  
Author(s):  
Sibaprasad Rudra ◽  
Himansu Talukdar ◽  
Kiron K. Kundu
Keyword(s):  
Solvent System ◽  
Mirror Image ◽  
Scaled Particle Theory ◽  
Free Energies ◽  
Emf Measurements ◽  
Solvent Interactions ◽  
Rational Explanation ◽  
Born Equation ◽  
Cavity Effects ◽  
Reference Electrolyte

Single-ion tranfer free energies [Formula: see text] and entropies [Formula: see text] of some electrolytes from water to 1, 2, and 4m aqueous NaNO3 solvents have been determined at 25 °C using the widely used tetraphenylarsonium tetraphenylborate (Ph4AsBPh4) reference electrolyte assumption, after due modification for this solvent system. The required [Formula: see text] and [Formula: see text] values of Ph4AsPi, KBPh4, KPi, AgPi, PbPi2, Ag2CrO4, and AgCl where Pi = picrate, were determined by measuring solubilities at 15–35 °C of the solutes except AgCl, the values of which were determined from emf measurements. Analysis of [Formula: see text] and [Formula: see text] values of the ions as well as their respective true interaction effects, [Formula: see text] and [Formula: see text] as obtained after correcting for their cavity effects [Formula: see text] and [Formula: see text] estimated by the scaled particle theory (SPT) and Born-type electrostatic effects, [Formula: see text] and [Formula: see text] computed by simple Born equation, reveals that the behaviour of the ions in this ionic cosolvent system is chiefly guided by one or several effects of ion–ion–solvent, Born and cavity forming interactions. Moreover, a rational explanation has been offered to explain the observed mirror-image entropie behaviour of simple cations and anions in light of Kundu etal.'s four-steps transfer process.

Single-ion transfer energetics of some ions using tetraphenylarsonium tetraphenylborate reference electrolyte assumption in aqueous mixtures of urea and glycerol

1989 ◽  
Vol 67 (2) ◽  
pp. 321-329 ◽  
Author(s):  
Himansu Talukdar ◽  
Sibaprasad Rudra ◽  
Kiron K. Kundu
Keyword(s):  
Mirror Image ◽  
Chemical Effect ◽  
Scaled Particle Theory ◽  
Ion Transfer ◽  
Aqueous Mixtures ◽  
Emf Measurements ◽  
Transfer Energetics ◽  
Born Equation ◽  
Different Temperatures ◽  
Reference Electrolyte

Single-ion transfer free energies [Formula: see text] and entropies [Formula: see text] of some ions from water to aqueous mixtures of urea and glycerol have been determined using the widely used tetraphenylarsonium tetraphenylborate reference electrolyte assumption from solubility and emf measurements of some appropriate electrolytes at five different temperatures (15 to 35 °C). Analysis of [Formula: see text] and [Formula: see text] values of the ions as well as their respective "chemical" effect, [Formula: see text] and [Formula: see text] as obtained after correcting for their cavity and Born-type electrostatic effects, estimated by the scaled particle theory (SPT) and simple Born equation, respectively, show a complex dependence upon solvent composition. Attempts have been made to explain the observed mirror-image entropie behaviour of simple cations and anions in the light of Kundu etal.'s four-step transfer process and to compare the results with those obtained in other aquo-ionic and nonionic systems. Keywords: single ion, transfer energetics, TATB assumption, aqueous glycerol, aqueous urea.

Ion–ion–solvent interactions in aqueous ionic cosolvent systems. I. Transfer thermodynamics of hydrogen chloride in aqueous sodium nitrate solutions from emf measurements

1986 ◽  
Vol 64 (10) ◽  
pp. 1960-1965
Author(s):  
Sibaprasad Rudra ◽  
Himansu Talukdar ◽  
Bijoy P. Chakravarti ◽  
Kiron K. Kundu
Keyword(s):  
Scaled Particle Theory ◽  
Free Energies ◽  
Standard State ◽  
Emf Measurements ◽  
Solvent Interactions ◽  
Born Equation ◽  
Transfer Thermodynamics ◽  
The Individual ◽  
Cavity Effect ◽  
Nitrate Solutions

Standard potentials (E0) of the Ag–AgCl electrode have been determined in 1, 2, and 4 m NaNO3 + water mixtures at five equidistant temperatures ranging from 15–35 °C from the emf measurements of the cell: Pt, H2 (g, 1 atm)/HCl (m) NaNO3 +water/AgCl–Ag. These values have been used to evaluate the transfer energetics [Formula: see text] accompanying the transfer of 1 mole of HCl from the standard state in water to the standard state in each of the NaNO3 + water mixtures. Transfer free energies [Formula: see text] of HCl and that of the individual ions obtained from a separate study, and those obtained after correcting the "cavity effect" and Born-type electrostatic effect, as estimated tentatively by the scaled-particle theory (SPT) and simple Born equation respectively, have been discussed in the light of ion–ion–solvent interactions. The observed [Formula: see text]–composition profile as well as that obtained after correcting for the "cavity effect" were examined in the light of semiquantitative theory proposed by Kundu etal. earlier and are found to substantiate this theory.

Ion–ion–solvent interactions in aqueous ionic cosolvent systems. IV. Transfer energetics of water, p-nitroaniline, and benzoic acid from emf/solubility measurements at different temperatures in aqueous sodium nitrate solvent system

1988 ◽  
Vol 66 (3) ◽  
pp. 469-475
Author(s):  
Sibaprasad Rudra ◽  
Himansu Talukdar ◽  
Kiron K. Kundu
Keyword(s):  
Benzoic Acid ◽  
Sodium Nitrate ◽  
Solvent System ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Salting Out ◽  
Emf Measurements ◽  
Solvent Interactions ◽  
Different Temperatures ◽  
Composition Profiles

Autoionization constants (Ks) of aqueous mixtures of 1, 2, and 4 m sodium nitrate used as an ionic cosolvent system have been determined from emf measurements of the cell: Pt, H2 (g, 1 atm)/KOH (m1) KCl (m2), solvent/AgCl–Ag at five equidistant temperatures ranging from 15–35 °C. The standard free energies (ΔG0) and entropies (ΔS0) of autoionisation of the solvents were then evaluated from these data. Relative free energies (ΔG0) and entropies of (ΔS0)of autoionization of the solvents when coupled with the previously determined transfer free energies [Formula: see text] and entropies [Formula: see text] of H+ yielded [Formula: see text][Formula: see text],[Formula: see text] and [Formula: see text]. Values of [Formula: see text] and [Formula: see text] obtained after correcting for [Formula: see text], as well as [Formula: see text] and [Formula: see text]obtained after correcting the "cavity effect" and Born-type electrostatic effect suggests that while the "basicity" of the aqueous NaNO3 solutions decreases, the "acidity" more or less increases with NaNO3 concentration. The observed [Formula: see text]– and [Formula: see text]–composition profiles were also examined in the light of Kundu et al.'s four-step transfer process and the involved order–disorder phenomena, respectively, as proposed earlier.Standard free energies [Formula: see text] and entropies [Formula: see text] of transfer of p-nitroaniline (pNA) and benzoic acid (HBz) for the solvent system have also been determined from solubility measurements at different temperatures. The observed [Formula: see text]–and [Formula: see text]–composition profiles appear to reflect the salting-out effect of the salt and the [Formula: see text]–and [Formula: see text]–composition profiles confirm the applicability of either of these quantities rather than [Formula: see text], as a better structural probe both for aquo-ionic and aquo-organic solvents.

Deprotonation and transfer energetics of glycine in aqueous mixtures of urea and glycerol from emf measurements at different temperatures

1989 ◽  
Vol 67 (2) ◽  
pp. 315-320 ◽  
Author(s):  
Himansu Talukdar ◽  
Sibaprasad Rudra ◽  
Kiron K. Kundu
Keyword(s):  
Scaled Particle Theory ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Emf Measurements ◽  
Transfer Energetics ◽  
Galvanic Cells ◽  
Aqueous Urea ◽  
Different Temperatures ◽  
Composition Profiles ◽  
Reference Electrolyte

Deprotonation constants, Ka(RH2+) and Ka(RH±), of glycine (RH±) have been determined at five equidistant temperatures ranging from 15 to 35 °C by measuring the emf of galvanic cells comprising Pt/H2 and Ag–AgCl electrodes in aqueous mixtures of protophilic protic urea (UH) and protophobic protic glycerol (GL). Medium effects on deprotonation of the acid: [Formula: see text] have been dissected into transfer free energies [Formula: see text] and entropies [Formula: see text] of the species involved as obtained by measuring the transfer energetics [Formula: see text] of RH± from solubility measurements at different temperatures and of H+ based on tetraphenylarsonium tetraphenylborate (TATB) reference electrolyte assumption determined earlier. The [Formula: see text] values obtained after due correction from the cavity effect based on scaled particle theory (SPT) and electrostatic effects including Born and ion–dipole effects for the charged species involved in the two deprotonation equilibria enable better understanding of the solvent effect on the deprotonation constants. Moreover, the [Formula: see text]–composition profiles are found to exhibit similar characteristic maxima and minima as for simple cations and anions in these solvent systems, thus providing useful information on the structural characteristic of these cosolvents. Keywords: deprotonation energetics, glycine, aqueous urea, aqueous glycerol, EMF measurements.

Ion–ion–solvent interactions in aqueous ionic cosolvent systems. III. Thermodynamics of hydrogen bromide and hydrogen iodide from water to aqueous solutions of sodium nitrate from emf measurements at different temperatures and the structuredness of the solvents

1987 ◽  
Vol 65 (12) ◽  
pp. 2843-2848
Author(s):  
Sibaprasad Rudra ◽  
Himansu Talukdar ◽  
Kiron K. Kundu
Keyword(s):  
Sodium Nitrate ◽  
Structural Changes ◽  
Hydrogen Bromide ◽  
Scaled Particle Theory ◽  
Relative Order ◽  
Emf Measurements ◽  
Solvent Interactions ◽  
Different Temperatures ◽  
Composition Profiles ◽  
The Individual

Standard free energies [Formula: see text] and entropies [Formula: see text] of transfer of hydrogen bromide and iodide from water to the aqueous 1, 2, and 4 m of sodium nitrate have been determined by measuring the emf's of the cell: Pt, H2(g, 1 atm)/KOH(m1), KX(m2), solvent/AgX–Ag where X = Br or I at five equidistant temperatures ranging from 15–35°C. [Formula: see text] values of HBr, HI as well as that of HCl obtained from earlier paper and particularly of the individual ions [Formula: see text](i), obtained by use of modified TATB assumption reported earlier and also [Formula: see text](i) obtained after correcting for "cavity" effect and Born-type electrostatic effect estimated tentatively by the scaled particle theory (SPT) and simple Bom equation, respectively, reveal the relative order of stabilisation of Cl−, Br−, and I− ions. Analysis of [Formula: see text]–composition profile (X = Cl, Br, and I) exhibits a characteristic "maxima" around 1.5 m NaNO3 with the relative order HI > HBr > HCl in the region of maxima. Moreover, dissection of [Formula: see text] values into the individual ion contributions by use of the modified TATB assumption reported earlier, results in the characteristic "maxima" around 1.5 m NaNO3 in [Formula: see text] or [Formula: see text]–composition profiles for H+ and "minima" for Cl−, Br−, and I−. The results are discussed in terms of ion–ion–solvent interactions as well as the structural changes of the solvents.

Transfer free energies of alkali metal chlorides and of some individual ions in glycerol and water mixtures

1980 ◽  
Vol 58 (1) ◽  
pp. 79-85 ◽  
Author(s):  
Indra N. Basumullick ◽  
Kiron K. Kundu
Keyword(s):  
Alkali Metal ◽  
Aqueous Mixtures ◽  
Free Energies ◽  
Dispersion Interactions ◽  
Native Conformation ◽  
Alkali Metal Chlorides ◽  
Metal Chlorides ◽  
Emf Measurements ◽  
Reference Electrolyte ◽  
Electrolyte Ph

Staqndard free energies of transfer, ΔGt0, of alkali metal chlorides from water to aqueous mixtures of 10, 30, 50, and 70 wt.% glycerol have been determined from emf measurements of the double cell comprising Ag– AgCl and K(Hg) electrodes at 25°C. These values were divided into individual ion contributions by use of tetraphenyl arsonium tetraphenyl boride (Ph4AsBPh4) assumption, the required ΔGt0 values of the reference electrolyte (Ph4AsPh4B), obtained by measuring solubilities of KBPh4, Ph4AsPi, and KPi (Pi = picrate) in the solvents. The solvation behaviour of the involved ions, as dictated by their respective ΔGt0(i) values, in this as well as in systems of other similar co-solvents like ethanol, ethylene glycol, and urea, suggests that it is determined by one or several effects of acid-base, Born-type, and dispersion interactions. Moreover, comparable stability of PH4B–, particularly in aqueous glycerol and urea, suggests that "specific interactions" are possibly responsible for the well_known folding-unfolding phenomenon of native conformation of proteins in presence of co-solvents.

Free energies of transfer of some single ions from ethylene glycol to its isodielectric mixtures with acetonitrile at 25 °C

1979 ◽  
Vol 57 (18) ◽  
pp. 2476-2481 ◽  
Author(s):  
Kumardev Bose ◽  
Kiron K. Kundu
Keyword(s):  
Ethylene Glycol ◽  
Aprotic Solvent ◽  
Ion Solvation ◽  
Free Energies ◽  
Solvent Interactions ◽  
Free Energies Of Transfer ◽  
Isodielectric Mixtures ◽  
The Individual ◽  
Reference Electrolyte ◽  
Electrolyte Ph

Free energies of transfer (ΔGt0) of the reference electrolyte Ph4AsBPh4 (Ph = phenyl) from ethylene glycol to its approximately isodielectric mixtures with acetonitrile have been determined at 25 °C from the measurement of the solubilities of KPi, Ph4AsPi, and KBPh (Pi = picrate) in these solvents. Using the assumption [Formula: see text] values for the individual ions K+, Pi−, Ph4As+, and Ph4 s− have been estimated. These, in conjunction with previously determined values of ΔGt0 for MCl (M = Li, Na, K, Rb, Cs, and H), KBr and KI have provided ΔGt0 values for Cl−, Br−, I−, and M+ ions. Ionic ΔGt0's have been interpreted in terms of specific ion–solvent interactions. The contrasting behaviour of ethylene glycol and acetonitrile in ion-solvation is shown to be characteristic of the protic and dipolar aprotic solvent types respectively.

scholarly journals Use of scaled-particle theory in the assessment of the Ph4As+/Ph4B− assumption for single ions

1979 ◽  
Vol 57 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Michael H. Abraham ◽  
Asadollah Nasehzadeh
Keyword(s):  
Free Energy ◽  
Recent Work ◽  
Scaled Particle Theory ◽  
Cavity Formation ◽  
Energy Term ◽  
Free Energies ◽  
Particle Theory ◽  
Novel Method ◽  
Energy Of Interaction ◽  
Solvent Molecules

A novel method for the assessment of the Ph4As+/Ph4B− assumption for free energies of transfer of single ions has recently been suggested by Treiner, and used by him to deduce that the assumption is not valid for transfers between water, propylene carbonate, sulpholane, dimethylsulphoxide, N-methyl-2-pyrrolidone, and perhaps also dimethylformamide. The basis of the method is the estimation of the free energy of cavity formation by scaled-particle theory, together with the hypothesis that the free energy of interaction of Ph4As+ (or Ph4B−) with solvent molecules is the same in all solvents, ΔGt0(int) = 0. It is shown in the present paper that (a) whether or not the Ph4As+/Ph4B− assumption applies to transfer to a given solvent depends on which other solvent is taken as the reference solvent in Treiner's method, (b) the calculation of the cavity free energy term by scaled-particle theory and by the theory of Sinanoglu – Reisse – Moura Ramos (SRMR) yields values so different that the method cannot be considered reliable, (c) the calculation of cavity enthalpies and entropies for Ph4As+ or Ph4B− by scaled-particle theory yields results that are chemically not reasonable, (d) the hypothesis that ΔGt0(int) = 0 conflicts with SRMR theory, and (e) the conclusions reached by Treiner are not in accord with recent work that in general supports the Ph4As+/Ph4B− assumption for solvents that are rejected by Treiner.

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