Electrochemical Studies on the Interaction of Cadmium Ion with Kryptofix 22 in MeOH-DMF Solutions at different Temperatures (original) (raw)
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Journal of Solution Chemistry, 2016
Systematic and precise measurements of electrical conductivities of dilute aqueous solutions of cadmium bromide and cadmium iodide were performed from 15 to 35°C. The conductances were interpreted in terms of a molecular model that includes a mixture of two 1:1 and 2:1 electrolytes. The molar limiting conductances of k 0 (CdX ? , T) ions, the equilibrium constants of formation of CdX ? complexes K(T) and the corresponding standard thermodynamic functions were evaluated using the Quint-Viallard conductance equations, the Debye-Hückel equations for activity coefficients and the mass action equations. Mathematical representations are also presented to an extension of molecular models, to the simultaneous formation of MeX ? and MeX 2 species and to the possibility of hydrolysis reactions with formation of Me(OH) ? ions.
The Journal of Physical Chemistry, 2013
Systematic and precise measurements of electrical conductivities of aqueous solutions of cadmium chloride were performed in the 2 × 10 −5-1 × 10 −2 mol•dm −3 concentration range, from 278.15 to 313.15 K. Determined conductances were interpreted in terms of molecular model which includes a mixture of two 1:1 and 2:1 electrolytes. The molar limiting conductances of λ 0 (CdCl + , T) and λ 0 (1/2Cd 2+ , T), the equilibrium constants of CdCl + formation K(T) and the corresponding standard thermodynamic functions were evaluated using the Quint-Viallard conductivity equations, the Debye−Huckel equations for activity coefficients and the mass-action equation. An excellent agreement between calculated and experimental conductivities was reached.
The Journal of Physical Chemistry B, 2013
Systematic and precise measurements of electrical conductivities of aqueous solutions of cadmium chloride were performed in the 2 × 10(-5)-1 × 10(-2) mol·dm(-3) concentration range, from 278.15 to 313.15 K. Determined conductances were interpreted in terms of molecular model which includes a mixture of two 1:1 and 2:1 electrolytes. The molar limiting conductances of λ(0)(CdCl(+), T) and λ(0)(1/2Cd(2+), T), the equilibrium constants of CdCl(+) formation K(T) and the corresponding standard thermodynamic functions were evaluated using the Quint-Viallard conductivity equations, the Debye-Hückel equations for activity coefficients and the mass-action equation. An excellent agreement between calculated and experimental conductivities was reached.
2009
Studies of Cd(II) complexes with Itaconic acid have been carried out by polarographic method in non-aqueous media (20%, 40%, 60% DMSO) under varying temperatures, at 298K and 308K in presence of KCl as a supporting electrolyte. The reduction of Cd(II) was found to be reversible in non-aqueous medium for Itaconic acid ligand and have shown the formation of 1:1, 1:2 and 1:3 complexes. DeFord and Hume's method as modified by Irving has been applied for the determination of composition and stability constant of the complexes species. The changes in thermodynamic parameters ∆H°, ∆G° and ∆S° accompanying complexation have been evaluated. The mathematical Mihailov's method has also been applied for the comparison of stability constants values.
Potentiometric determination of cadmium–acetate complexation in aqueous solutions to 250°C
Chemical Geology, 2000
The molal formation quotients of cadmium-acetate complexes were measured potentiometrically hydrogen-electrode . concentration cell from 50 to 2508C at ionic strengths of 0.1, 0.3, and 1.0 molal in aqueous sodium trifluoromethanesul-Ž . Ž . q Ž . fonate NaTr media. Two cadmium-acetate species, namely Cd Ac and Cd Ac 8, were identified by regressional analysis 2 of the data. Their formation quotients were modeled by empirical equations to describe their temperature and ionic strength dependencies. The thermodynamic quantities, obtained by differentiating these equations with respect to temperature at 258C Ž . q y 1 y1 and at infinite dilution are for Cd Ac : log K s 1.96 " 0.24, D H8 sy17 " 17 kJ P mol , D S8 sy21 " 53 J P K P 1 y1 y1 y1
2013
The electrochemical impedance spectroscopy was applied in order to characterize and compare the dependence of differential capacitance on temperature at the Cd(0001) | 1-ethyl-3-methylimidazolium tetrafluoroborate and Cd(0001) | 0.1x M KI + 0.033(1−x) M K2SO4 interfaces. For both systems, the impedance spectra were fitted using the modified Frumkin–Melik-Gaikazyan model, including the high-frequency “true” double layer capacitance, equilibrium adsorption capacitance, Warburg-like diffusion impedance and parallel charge transfer resistance. The modified Frumkin–Melik-Gaikazyan model gives better fitting of calculated results to experimental data compared to alternative equivalent circuits. This indicates that the adsorption from aqueous solution and room temperature ionic liquid follows similar general kinetic steps. However, in contrast to the aqueous electrolyte solutions, the high-frequency capacitance for Cd(0001) in room temperature ionic liquid increases with increasing temperature. The presented theoretical explanations lead to the conclusion that the experimental series differential capacitance is determined by the multilayered structure of the electrical double layer, which gradually “dissolves” with increasing temperature.
international journal of chemical sciences, 2009
Studies of Cd (II) complexes with itaconic acid have been carried out by polarographic method in non-aqueous media (20%, 40%, 60% DMF) under varying temperatures, at 298 K and 308 K in presence of KCl as a supporting electrolyte. The reduction of Cd (II) was found to be reversible in nonaqueous medium for itaconic acid ligand and have shown the formation of 1:1, 1:2 and 1:3 complexes. DeFord and Hume's method as modified by Irving has been applied for the determination of composition and stability constant of the complexes species. The changes in thermodynamic parameters H°, G° and S° accompanying complexation have been evaluated. The mathematical Mihailov's method has also been applied for the comparison of stability constant values.
Electrochemical Study of Cadmium (II) Complexation with Cysteine
American Journal of Analytical Chemistry, 2013
The complexation of Cd with cysteine has been investigated at pH ~9, and in constant ionic medium 0.59 M NaNO 3 and borate buffer. Reduction signals of the hydrated Cd 2+ and Cd-cysteinate complex were resolved on the potential scale during amperometric titration of 2 × 10 −6 M Cd 2+ with cysteine and cysteine with Cd 2+ , in a differential pulse (DP) mode on HMDE. The 1:1 molar ratio of Cd 2+ to cysteine, and cysteine to Cd 2+ , was defined for Cd-cysteinate complex formed under the defined conditions. The appearance of the prepeak on the Cd-cysteinate reduction signal is showed, as the result of cysteine adsorption in reduced form. From the mass balance equations, the stoichiometric stability constants of Cd-cysteinate complex were calculated. Under various experimental conditions, comparable log K values were obtained. The grand average log K = 7.83 M −1 refers to 0.59 M ionic strength and 23˚C.
American Journal of Condensed Matter Physics, 2012
On using conductometric technique, new equation is applied for calculation of apparent association constant (K A). The association constant (K A) were studied and calculated for Cu(NO 3) 2 in absence and presence of Kryptofix-22 [1,7,10,16 tetra oxa 4,13 diaze cyclo octa decane] in mixed [MeOH-DMF] solvents at different temperatures. From the experimental results, the molar conductivities (Λ) is evaluated. The limiting molar conduclivities (Λ o) were also calculated by using Shedlovsky and Fouss-Kraus extrapolation method. The Gibbs free energies of association (∆ G A) were estimated in absence and presence of Kryptofix-22, and from these date, we calculated ∆ G (Complexing). We also calculated the value of enthalpy (∆ H A) and entropy (∆ S A) For Cu(NO 3) 2 in absence and presence of Kryptofix-22. In addition to (K A), (∆ G A), (∆ H A), and all the previous results, the molar volume (V), solvated radius (r s), Van der Waals (V w), electrostriction Volume (V e) and apparent molar volume (V φ)were also calculated. All the results were discussed.