Thermodynamics of silver—silver halide electrodes and thermodynamic solubility products of silver halides in glycerol + water mixtures at different temperatures

The standard potentials of silver—silver bromide and silver—silver iodide electrodes in glycerol+water mixtures containing 5, 10, 20 and 30 wt% glycerol were determined from electromotive force measurements of the cell Ag(s), AgX(s), KX(c)//KCl(c), AgCl(s), Ag(s), where X is Br or I, at seven different temperatures in the range 5–35°C. The standard potentials in each solvent are represented as a function of temperature. The standard thermodynamic functions for the electrode reactions, the primary medium effects of various solvents upon X⁻, and the standard thermodynamic quantities for the transfer of 1 g-ion of X⁻ from water to the respective glycerol + water media are evaluated and discussed in the light of ion—solvent interactions as well as the structural changes of the solvents. From the values of the Ag/Ag⁺ and Ag/AgX, X⁻ electrodes, the thermodynamic solubility product constants of silver chloride, silver bromide and silver iodide have been determined in glycerol + water solvent mixtures at different temperatures.     

Thermodynamics of the chlorides,bromides, nitrates,bromates, iodates and sulphates of potassium and sodium in dioxane—water mixtures from conductance data at different temperatures

Studies on electrolytic conductance in dioxane—water mixtures of varying compositions at 30, 35, 40 and 45°C were initiated, in which the variations in the Walden product with solvent composition and temperature were reported and discussed with respect to theories concerning solvent structure and ion—solvent interactions. In the present communication, attempts have been made to evaluate the thermodynamic function (ΔG⁰_t) for the transfer of KCl, KBr, KNO₃, KBrO₃, KIO₃, K₂SO₄, NaCl, NaBr, NaNO₃, NaBrO₃, NaIO₃ and Na₂SO₄ from water to respective dioxane + water media, which would give some information regarding ionic solvation.     

Standard potentials of the silver—silver tungstate,silver—silver phosphate,and silver—silver arsenate electrodes in water—dioxane and water—urea mixtures and related thermodynamic functions

The standard potentials of the silver—silver tungstate, silver—silver phosphate and silver—silver arsenate electrodes in four different compositions of water—dioxane and water—urea mixtures at seven different temperatures from 5 to 35°C have been determined from EMF measurements of cells of the type Ag(s), AgCl(s), NaCl(c)//Na_xZ(c/x), Ag_xZ(s), Ag(s), where x is 2 or 3, and Z is WO₄, PO₄ or AsO₄. These values have been used to evaluate the transfer thermodynamic quantities accompanying the transfer of 1 g ion of WO^2?₄. PO^3?₄ or AsO^3?₄ ion from the standard state in water to the standard state in water—dioxane or water—urea mixtures.     

Thermodynamics of ternary salts in dioxane—water mixtures from conductance measurements

Studies of electrolytic conductance in dioxane—water mixtures of varying dioxane content were initiated in 1978 [1]. In the present communication, an attempt has been made to evaluate the thermodynamic function ΔG⁰_t for the transfer of Mg(ClO₄)⁺, Mg(NO₃)⁺, BaCl⁺, BaBr⁺, Ba(ClO₄⁺, Ba(NO₃)⁺, SrCl⁺, Sr(NO₃)⁺, CaCl⁺ and Ca(NO₃)⁺ from water to dioxane—water media, which would give some information regarding ionic solvation.     

Thermodynamics of 1,10-phenanthrolinium ion and ferrous-1,10 phenanthroline complex in dioxane—water and ethanol—water at 25°c

Enthalpies of formation of 1,10-phenanthrolinium ion and ferrous-1,10-phenanthroline (tris) complex in dioxane—water and ethanol—water media at 25°C have been determined by calorimetry. Results are discussed in the light of ion—solvent and solvent—solvent interactions.     

Picosecond dynamics and microheterogenity of water+dioxane mixtures

Dielectric spectra from 200 MHz up to 3 THz were determined to study the fast dynamics of dilute water+1,4-dioxane. epsilon(nu) could be fitted by a collision induced oscillator at high frequencies plus two Debye relaxations in the microwave region. Isotope substitution was used to assign water and dioxane modes. The presence of the cooperative hydrogen-bond network relaxation down to a water mole fraction of 0.005 suggests a microheterogeneous structure of the mixtures even at low water content. The collision mode of dioxane at approximately 2 THz grows upon water addition, revealing the presence of H2O molecules in dioxane-rich domains.     

The excess volumes of bicyclohexyl+cyclohexane, + cycloheptane,and + cyclooctane at three different temperatures

The excess volumes of bicyclohexyl + cyclohexane, + cycloheptane, and + cyclooctane have been measured over the whole composition range at 288.15, 298.15, and 308.15 K.     

Thermodynamics and ion—solvent interactions of trichloroacetic acid in 50% dioxane—water

The thermodynamics of ion-association in aqueous solutions was reviewed by Noncollas [1] in 1960. The ion-pairs of nitrates [2], halides [3–5], hydroxides [5–8], sulphates [9], acetates [2] and malonates [10] of some metal ions were studied and the thermodynamic parameters were reported. Similarly, the association data of some organic and inorganic acids [11–14] were also studied. From these studies it was concluded that the association constants may decrease or increase or may pass through a minimum with increase in temperature, but no explanation was given for the deviations observed. Hence, we have studied the thermodynamics of ion-pair formation of trichloroacetic acid in 50% (w/w) dioxane—water mixtures at different temperatures and the deviations are explained in terms of the changes in ion—solvent interactions with temperature.     

Thermodynamics of the silver—silver thiocyanate electrode in urea—water mixtures

E.m.f. measurements on cells of the type Ag(s), AgCNS(s), KCNS(c)//KCl(c), AgCl(s), Ag(s) in four different composition of urea—water mixtures at seven different temperatures from 5 to 35°C have been made to determine the standard potentials of the silver—silver thiocyanate electrode in these media. These values have been used to evaluate the transfer thermodynamic quantities accompanying the transfer of 1 g ion of CNS^? ion from the standard state in water to the standard state in urea—water mixtures.     

Thermodynamics of binary mixtures: excess gibbs free energies of 1,2-Dibromoethane mixtures with benzene,cyclohexane, carbon tetrachloride and dioxane at 20°C

The excess Gibbs free energies of 1,2-dibromoethane mixtures with benzene, cyclohexane, carbon tetrachloride and dioxane have been determined by a static vapour pressure method at 20°C. The results have been analysed in the light of the current theories of solutions due to Prigogine and Flory. Both the theories fail to fit the results with useful accuracy.     

Thermodynamics of binary liquid mixtures of cyclopentane with 2-propanol, 1-butanol and 2-butanol at different temperatures

Densities and speeds of sound of the cyclopentane with 2-propanol, 1-butanol and 2-butanol are measured over the whole composition range at different temperatures in the range 288.15–308.15 K and atmospheric pressure using Anton Paar DSA 5000 densimeter. The experimental densities and speeds of sound have been used to calculate excess molar volumes, excess molar isentropic compressibilities and excess intermolecular free length. The partial molar volumes and apparent molar volumes at infinite dilution have also been calculated. The mixing quantities like (∂V _m^E/∂T)_P and (∂H _m^E/∂P)_T have been calculated at T = 298.15 K and these values are compared with the values calculated from Flory’s theory at equimolar composition.     

Thermodynamics of the hydrogen-silver chloride cell in ethanol-water mixtures from −10 to +40°C

From emf E measurements of the reversible cell $$Pt|H_2 (g,1 atm)|HCl(m)|AgCl|Pt$$ at 0.01?1 in 70% (w/w) ethanol-water solvent mixtures over the temperature range from ?10 to +40°C, the standard emf E° of the cell with the related thermodynamic functions of the cell reaction and the mean molal activity coefficients of hydrochloric acid have been determined. The present E data at 70% (w/w) ethanol have been combined with earlier data at ≤50% (w/w) ethanol to be analyzed critically by a one-stage multilinear regression method leading to an optimized set of E° values for the range 0–70% (w/w) ethanol which are essential for the assessment of pH standards in these solvent media.     

B-DNA structural determination of Na+ counterions at different humidities,ionic concentrations,and temperatures

Seventeen different computer experiments are presented and analyzed. In each experiment a three-turn B-DNA double helix fragment interacts with a variable number of water molecules (from 60 to 1200), with a variable number of sodium ions (from 30 to 63), at one or more temperatures (280, 300, 320 K). The experiments are performed with the Monte Carlo method using quantum-mechanically derived potentials. In the analysis of the experiments we partition the water molecules (and the corresponding interactions) as being either bound or in the first solvation shell or in the groove regions relative to DNA; for the former two cases, the number of water molecules and the water interaction energy are reported for selected atoms or groups of atoms. The entire study is condensed into eight tables. The use of these tables is exemplified by considering, in detail, some of the trends emerging from these experiments. The analyses are complemented by graphical representations presented either to elucidate the very complex pattern of hydrogen bonded water molecules, or to show the statistical distributions of the oxygen and hydrogen atoms of the water molecules.