Solvent effect on standard electrode potential: Part IV. Silver-silver chloride electrode in glycerol-water mixtures

Standard potentials of the silver-silver chloride electrode in eighteen glycerol-water mixtures containing up to 90% by weight glycerol, have been determined from e.m.f. measurements of cells of the type Pt, H₂ (gas, 1 atm); HCl (m), X% glycerol, Y% water; AgCl, Ag, at nine different temperatures in the range 15 to 55°C. The standard molal potential in the various solvent mixtures has been expressed as a function of temperature. Standard thermodynamic quantities for cell reaction and the primary medium effects of various solvents upon HCl were also calculated. The temperature variation of the standard potential was utilized to calculate the thermodynamic quantities for the transfer of one mole of HCl from water to glycerol-water media. The results have been interpreted in regard to the acid-base properties and the structure of the solvent.     

Solvent effect on standard electrode potential: Part V. Silver-silver chloride electrode in tert-butyl alcohol + water mixtures

The electromotive force measurements of the cell Pt, H₂ (gas, 1 atm); HCl (m), X % Bu ^tOH, Y% H₂O; AgCl, Ag, at nine different temperatures ranging from 15 to 55°C at 5° intervals, have been used to determine the standard potentials of the silver-silver chloride electrode in eighteen tert-butyl alcohol+water solvent mixtures containing up to 90 wt. % alcohol. The standard molal potentials in each solvent have been represented as a function of temperature. The standard thermodynamic functions for the cell reaction, the primary medium effects of various solvents upon HCl, and the standard thermodynamic quantities for the transfer of one mole of HCl from water to tert-butyl alcohol+water media have been evaluated. The results have been discussed in the light of ion-solvent interactions as well as the structural changes of the solvents.     

Solvent effect on standard electrode potential: Part II. Silver-silver bromide electrode in methanol-water mixtures

The standard potentials of the silver-silver bromide electrode have been determined over a broad range of methanol concentrations from e.m.f. measurements of the cell Pt, H₂(g, 1 atm); HBr(m), X% methanol, Y% water; AgBr, Ag at eight temperatures ranging from 20 to 55°C. The standard e.m.f. has been expressed as a function of temperature. Thermodynamic functions of cell process, the primary medium effect of various media on hydrobromic acid, and thermodynamics of transfer of HBr from water to methanolic media have been computed and discussed in the light of ion-solvent interactions as well as the structural changes of the solvents.     

Thermodynamic properties of the silver ion in alcohol + water solvent mixtures from electromotive force measurements and thermodynamic solubility product constants of AgX (X = Cl,Br, I or CNS) at different temperatures

The standard potentials of the silver-silver ion electrode in alcohol+water solvent mixtures containing 10 and 20 wt% methanol, ethanol, 1-propanol and 2-propanol have been determined from the electromotive force measurements of the cell Ag(s), AgCl(s), NaCl(c), NaNO₃(c)// NaNO₃(c), AgNO₃(c), Ag(s) at seven different temperatures in the range 5–35°C. The standard potentials in each solvent have been represented as a function of temperature. The standard thermodynamic functions for the electrode reaction, the primary medium effects of various solvents upon Ag⁺, and the standard thermodynamic quantities for the transfer of 1 g-ion of Ag⁺ from water to the respective alcohol + water media have been evaluated and discussed in the light of ion-solvent interactions as well as the structural changes of the solvents. From the values of the standard potentials of the Ag/Ag⁺ and Ag/AgX, X^? electrodes, the thermodynamic solubility product constants of silver chloride, silver bromide, silver iodide and silver thiocyanate have been determined in alcohol + water solvent mixtures at different temperatures.     

Thermodynamic studies of hydriodic acid in ethylene glycol-water mixtures from electromotive force measurements

The standard potentials of the Ag—AgI electrode in twenty ethylene glycol—water mixtures covering the whole range of solvent composition have been determined from the e.m.f. measurements of the cell Pt¦H₂(g, 1 atm)¦HOAc (m ₁), NaOAc (m ₂), KI(m ₃), solvent¦AgI¦Ag at nine different temperatures ranging from 15 to 55°C. The temperature variation of the standard e.m.f. has been utilized to compute the standard thermodynamic functions for the cell reaction, the primary medium effects of various solvents upon HI, and the standard thermodynamic quantities for the transfer of HI from the standard state in water to the standard states in the respective solvent media. The chemical effects of solvents on the transfer process have been obtained by subtracting the electrostatic contributions from the total transfer quantities. The results have been discussed in the light of ion—solvent interactions as well as the structural changes of the solvents.     

Thermodynamics of hydrochloric acid in (1-propanol+water) from electromotive-force measurements

The standard electromotive force of the cell: PtH₂(g)|HCl(m) in solvent |AgCl|Ag has been determined at 9 different temperatures ranging from 288.15 to 328.15 K in 20 (propan-1-ol+water) mixtures covering the whole range of solvent composition, by an extrapolation method making use of the extended terms of the Debye-Hückel theory. In solvents of high alcohol content, where the dielectric constant is small, it was necessary to correct for ion-pair formation. The temperature variation of the standard e.m.f. was used to calculate the standard thermodynamic functions for the cell reaction, the primary medium effects of various solvents upon HCl, and the standard quantities for the transfer of HCl from the standard state in water to the standard states in each other solvent. The significance of the transfer functions is discussed in relation to the acid-base strength, as well as the structural features of the solvents.     

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.     

Standard thermodynamics of transfer: V. The silver and silver salt electrodes in t-butyl alcohol-water mixtures at various temperatures

From the electromotive force measurements of cells with liquid-junction potentials, the standard potentials of the silver, silver-silver halide, silver-silver pseudohalide and silver-silver oxyhalide electrodes have been determined in 10 and 20 wt.% t-butyl alcohol-water mixtures at 5, 15. 25 and 35 °C. The values of the standard potentials have been used to evaluate the primary medium effects and the standard thermodynamic functions for the transfer of the ion from water to the respective solvent media. The results have been discussed in relation to the breakdown of the structure of water on the addition of t-butyl alcohol.     

The ion transfer of the basic dye rhodamine B across the liquid-liquid interface of two immiscible solvents

The ion transfer of the basic dye rhodamine B at the interface between water and nitrobenzene, water and 1, 2-dichloroethane, as well as water and nitrobenzene - chlorobenzene mixtures has been studied by cyclic voltammetry and chronopotentiometry with linear current scanning. A transfer mechanism of rhodamine B is proposed in terms of its electrochemical behavior, dissociation and distribution equilibria, and is ascribed as diffusion-controlled reversible process of rhodamine B. The experimental data obtained for the relationship between interracial half-wave potential Δ^W_oφ° and pH are in agreement with the theoretical equation based on the mechanism, and the standard interfacial potential differences Δ^W_oφ° and standard Gibbs energies Δ^W_oG° are calculated by extrapolation. The effect of the nature of solvent on the transfer behavior and the stability of the interface have been discussed.     

Water-methanol-benzene ternary system. Thermochemical experiment and computer simulation

Solution heats have been measured for benzene dissolved in mixtures of water with methanol at 25°C. The resulting values are compared with data for water-methanol-aniline, water-acetonitrile-benzene, and water-acetonitrile-aniline systems. Computer simulations have been performed for binary mixtures of water with methanol and dilute solutions of benzene in these mixtures. Thermodynamic and structural characteristics of solutions were obtained by calculations. The enthalpy of benzene transfer from water into a mixed solvent correlates with the relative deviation of the local composition from the mean composition of the mixture.     

Standard potentials of silver-silver bromide electrode and related thermodynamic quantities in (5, 10 and 15 wt-%) 2-butanol-water mixtures

The standard potentials of silver-silver bromide electrode in 5, 10 and 15 wt.-% 2-butanol have been determined from e.m.f. measurements of a cell of the type: Pt(or Pd), H₂(g)|HBr(m), 2-butanol-water mixtures| AgBr, Ag at temperatures 15°, 25° and 35°C and in the molality range of HBr from 0.003 to 0.1 mol kg^?1. Standard potentials were utilized to calculate: (1) the standard thermodynamic quantities for the cell reaction and for the reaction of HBr formation, (2) the mean activity coefficients of HBr, and (3) the standard thermodynamic quantities for transfer of HBr from water to 2-butanol-water mixtures. The thermodynamic functions for the transfer process have been interpreted in regard to the acid-base properties and structure of the solvents.     

The standard electrode potential of the silver-silver chloride electrode in 5 wt. % tetramethylurea-water mixture at 30°C

Electromotive force measurements were made at 30°C with the cell $$H_2 (g)|Pt(s)|HCl(m){\text{ }}TMU(x){\text{ }}H_2 O(100 - x)|AgCl(s)|Ag(s)$$ wherex=5 wt. % tetramethylurea (TMU). The standard electrode potential of the silver-silver chloride electrode, the mean molal activity coefficient of hydrogen chloride, the primary medium effect, and the free energy of transfer of hydrogen chloride from the aqueous standard state to the standard state in the mixed solvent were derived from the measurements. The acquisition of data was limited to this single composition and temperature because of the difficulty of preparing hydrogen electrodes for this solvent medium. The results obtained for hydrogen chloride in 5 wt. % tetramethylurea-water mixture are discussed, relative to other organic-aqueous mixtures of the same composition, in terms of structural effects and hydrogen bonding.     

Absolute electrode potential and thermodynamics of single ions

A new method, relating the electrode potential to the radius of the solvated ion on whose activity the potential depends, has been developed for the determination of absolute electrode potentials and the thermodynamics of single ions in solution. It is successfully applied to the cells: Pt|H₂(g, 1 atm)|HX, solvent |AgX|Ag, and M|MX, solvent|AgX|Ag, in aqueous, partially aqueous, and non-aqueous solvents. The absolute electrode potentials have been computed in aqueous and methanol+water solvents. The single ion activities, activity coefficients, the radii of solvated cations, and their solvation extent have been calculated. The temperature variation of the standard absolute potential has been utilized to evaluate the standard thermodynamic functions for the electrode reactions, and the standard transfer thermodynamic quantities of single ions from water to methanolic solvents. The results are interpreted in terms of ion—solvent interactions as well as the structural features and the acid—base properties of these solvents.     

Solvent Effect on the Kinetics of Oxidation of [Co(en)2SCH2CH2 NH2]2+ by S2O8 2−

The effect of the solvent on rate of the oxidation of [Co(en)₂SCH₂CH₂NH₂]²⁺ by S₂O₈ ²⁻ in aqueous mixtures of methanol (MeOH), tert-butyl alcohol (Bu ^t OH), acetonitrile (AN), ethylene glycol (EG) and ethylene carbonate (EC) has been analysed as regards initial and transition state contributions. From kinetic measurements and solubilities of the reactants, the Gibbs transfer functions, ΔG _t°, corresponding to transfer of reactants and activated complex from water to water-organic mixtures were evaluated. The trends of the transfer functions are discussed in terms of ion-solvent interactions and the structural effects in the solvent mixtures. This revised version was published online in June 2006 with corrections to the Cover Date.     

Normalisation of standard electrode potential series,and evaluation of liquid junction potentials,between different solvents

An experimental procedure for the interrelation of standard electrode potential series in different solvents is described. The standard molar potentials at 25°C of the cesium amalgam electrode in water, ethylene glycol, and methanol are ?1.950, ?1.881, and ?1.800 V, respectively, with ultimate reference to NHE in water. The net contribution of the solvent to the liquid junction potential at the junctions water-ethylene glycol, water-methanol, and methanol-ethylene glycol is 0.028, 0.007, and 0.021 V, respectively (the positive side of the “solvent” junction potential being indicated by the first solvent mentioned for each pair).     

Solvation behaviour of silver(I) iodate in methanol—acetonitrile and ethanol—acetonitrile mixtures

The solvation behaviour of silver(I) iodate in methanol—acetonitrile (AN) and ethanol—acetonitrile mixtures has been studied at 30°C by solubility and emf measurements. The solubility of the salt increases with the addition of AN and passes through a maximum at X_AN = 0.3 and 0.6 in the case of MeOH-AN and EtOH-AN mixtures, respectively, and then decreases with further addition of AN. The transfer free energy of silver ion decreases while that of iodate ion increases with the addition of AN in both the solvent mixtures. The solvent transport number, Δ of AN is positive with a maximum at X_AN = 0.45 (Δ = 0.45 (Δ = 5.4) and at X_AN = 0.55 (Δ = 2.4) in the case of MeOH-AN and EtOH-AN mixtures, respectively. These results have been interpreted in terms of the heteroselective solvation of the salt, the silver ion being preferentially solvated by AN and the iodate ion by the amphiprotic solvent component in these mixtures.     

Acid-base equilibria in ternary water/methanol/dioxane solvent systems : Determination of pKa values of some aliphatic monocarboxylic acids

The thermodynamic acidity constants of n-butanoic, n-pentanoic, n-hexanoic, and n-heptanoic acids were determined at 25°C in ternary water/dioxane/methanol mixtures. The results obtained show that the composite medium effect, expressed by a parameter b = dpK′/du (u being a variable expressing the solvent composition), depends on the ratio of the organic co-solvent concentrations. In the ternary mixtures, superposition of the various effects detected in the corresponding binary solvents (water/dioxane and water/methanol) enables simple interpolation formulae to be used to estimate the pK_a values in solution with any ratio of the three solvents.     

四苯硼钾由单-到不同混合溶剂的迁移自由能

KBPh4作为一种典型的大阴离子电解质 ,在研究与计算大分子电解质的迁移热力学性质中起着重要的作用 .讨论大分子电解质与不同溶剂间的作用 ,还可以为萃取、色谱及表面活性剂的研究提供理论依据 .一些文献及我们前文曾对四苯硼盐由水到一些纯溶剂 [1,2]及从水到某些水-有机混合溶剂中的标准迁移自由能进行了研究 [3],但对四苯硼盐在有机-有机混合溶剂中的研究报导极少 .本文对 KBPh4由水到水-异丙醇和由甲醇到甲醇-异丙醇混合溶剂的标准迁移自由能进行了研究和探讨 .1实验部分 1.1实验仪器及方法 　　用 CS501型超级恒温槽恒温 ;用 WF…     

A Solution State Study of the Complexation and Thermodynamic Parameters of Binary Complexes of the Inner Transition Metals with Piracetam in Aqueous and Mixed Solvents

An equilibrium study on complexation behavior of the inner transition metals, where M = {Y(III), La(III, Ce(III, Pr(III), Nd(III), Sm(III), Gd(III), Dy(III), Th(IV)} and L = piracetam, has been carried out using the Irving–Rossotti titration technique in aqueous media at different temperatures and ionic strengths. The protonation constant and stability constants (log₁₀ β _n ) of the resulting inner metal–ligand complexes have been calculated with the Fortran IV program BEST using the method of least squares and considering the BESTFIT model. Thermodynamic parameters were also evaluated, yielding negative ΔG°, ΔH° and positive ΔS° values that indicate complex formation is favorable at ordinary temperatures. Species distribution curves of complexes have been plotted as function of pH using the SPEPLOT FORTRAN IV program to visualize the presence of various species in equilibrium in the pH range 2–6. To understand more about these equilibria, the stability of these complexes was studied at different percentages of solvent (10–30 % v/v) in different aqua-organic solvent mixtures with methanol, ethanol, 1-butanol and dimethylformamide.     

Heat properties of Bu<Subscript>4</Subscript>NBr solutions in binary mixtures based on formamide

Heat effects of tetrabutylammonium bromide dissolution in mixtures of formamide with methanol and ethylene glycol at 25°C were determined. Partial molar enthalpies of the components of formamide-ethylene glycol mixtures at 25°C were measured by the calorimetric method, and the mixing enthalpies of this system were determined. Within the limits of the second approximation of the Debye-Hueckel theory the standard enthalpies of dissolution Δ_dis H ⁰ were calculated, and the enthalpies of Bu₄NBr transfer from formamide in its mixtures with water methanol and ethylene glycol were found on this basis. The enthalpy parameters of Bu₄NBr pair interactions with the components of the formamide-water, formamide-methanol, and formamide-ethylene glycol mixtures were calculated. The results obtained were compared with the data for the systems containing N-methylformamide and N,N-dimethylformamide.