Electrochemical study of potassium and iodide ions resolvation in aqueous methanol mixtures

The results from the compensating voltage measurements of Volta circuits by the Kenrik method at 298.15 K were used to calculate the real primary media effect of potassium and iodide ions and real Gibbs energy of K⁺ and I⁻ transfer from water to aqueous methanol (MeOH) mixed solvent. The surface potential $\Delta \chi _{H_2 O}^{MeOH} $\Delta \chi _{H_2 O}^{MeOH} at non-aqueous solvent/gas interface was found. This value was used to calculate the chemical thermodynamic characteristics of the studied ions. The solvation features of the studied ions were revealed in the aqueous methanol mixed solvent.     

Comparison study of adsorption of Cl<Superscript>−</Superscript>, Br<Superscript>−</Superscript>, and I<Superscript>−</Superscript> ions from dimethyl formamide on In-Ga and Tl-Ga electrodes

The adsorption of Cl⁻, Br⁻, and I⁻ ions on the renewable liquid In-Ga and Tl-Ga electrodes from 0.1 M solutions in dimethyl formamide (DMF) is investigated by using the method of differential capacitance measurements. The results are compared with similar data obtained on Hg and Ga electrodes in DMF and with the corresponding data obtained in acetonitrile (AN). It is shown that, in DMF, the adsorption parameters and the series of surface activity of halide ions (Hal⁻) significantly depend on the metal nature. In contrast to Hg electrode, on which the surface activity of halide ions increases in the series: Cl⁻ < Br⁻ < I⁻, on In-Ga, as well as on the Ga electrode, it varies in the reverse order: I⁻ < Br⁻ < Cl⁻, whereas on the Tl-Ga electrode, partially reversed series of surface activity is observed: Br⁻ < I⁻ < Cl⁻. The results are explained within the framework of Andersen-Bockris model. An analysis of experimental results leads to the following qualitative conclusions: (1) on the In-Ga and Tl-Ga electrodes, as well as on Ga electrode, free energy of metal-Hal⁻ interaction ( $ \Delta G_{_{M - Hal^ - } } $ \Delta G_{_{M - Hal^ - } } ) increases in series I⁻ < Br⁻ < Cl⁻; (2) for Cl⁻, Br⁻, and I⁻, $ \Delta G_{_{M - Hal^ - } } $ \Delta G_{_{M - Hal^ - } } ) grows in series Tl-Ga < In-Ga < Ga; (3) an absolute magnitude of $ \Delta G_{_{M - Hal_1^ - } } - \Delta G_{_{M - Hal_2^ - } } $ \Delta G_{_{M - Hal_1^ - } } - \Delta G_{_{M - Hal_2^ - } } (Hal₁⁻, and Hal₂⁻ are any ions of Cl⁻, Br⁻, and I⁻) increases in series Hg < Tl-Ga < In-Ga < Ga; (4) the metal-DMF chemisorption interaction is much stronger than the metal-AN interaction and increases in series Tl-Ga < In-Ga < Ga.     

Electrochemical determination of the standard thermodynamic characteristics of copper(II) ion resolvation in water-methanol mixtures

The real and chemical thermodynamic characteristics of the resolvation of Cu²⁺ ions in water-methanol mixtures were determined by the Kenrick method at 298.15 K from the experimental compensating voltages of the Volta circuits and the surface potential at the interface between the nonaqueous solvent and the gas phase Dc_{H2 O}^MeOH\Delta \chi _{H_2 O}^{MeOH}. The assumption about the constancy of Dc_{H2 O}^MeOH\Delta \chi _{H_2 O}^{MeOH} starting from X = 0.1 of methanol in the mixture was confirmed by the Harkins method.     

Thermodynamics of Re-Solvation of Cadmium Ions in Water-Acetone Solvents

On the basis of a method of differences of Volta-potentials at 298.15 K the real primary effect of an environment of cadmium ions and the real Gibbs energy for the transport of Cd²⁺ out of water into a water-acetone solvent (Me₂CO) are determined. The surface potential at the nonaqueous solvent/gas phase interface \(\Delta \chi _{H_2 O}^S\) is obtained. This quantity is taken into account when calculating chemical thermodynamic characteristics for cadmium ions and the surface potential at the gas phase/acetone interface \(\Delta \chi ^{\operatorname{Me} _2 \operatorname{O} } = - 0.337\operatorname{V}\). Thermodynamic characteristics of the over-solvation of a II-I electrolyte with those for a I-I electrolyte are compared.     

Thermochemistry of 2-Aminopyridine (C<Subscript>5</Subscript>H<Subscript>6</Subscript>N<Subscript>2</Subscript>)(s)

The molar enthalpies of solution of 2-aminopyridine at various molalities were measured at T=298.15 K in double-distilled water by means of an isoperibol solution-reaction calorimeter. According to Pitzer’s theory, the molar enthalpy of solution of the title compound at infinite dilution was calculated to be D_solH_m^￥ = 14.34 kJ·mol^-1\Delta_{\mathrm{sol}}H_{\mathrm{m}}^{\infty} = 14.34~\mbox{kJ}\cdot\mbox{mol}^{-1}, and Pitzer’s ion interaction parameters b_MX^(0)L, b_MX^(1)L\beta_{\mathrm{MX}}^{(0)L}, \beta_{\mathrm{MX}}^{(1)L}, and C_MX^fLC_{\mathrm{MX}}^{\phi L} were obtained. Values of the relative apparent molar enthalpies ( ^φ L) and relative partial molar enthalpies of the compound ([`(L)]₂)\bar{L}_{2}) were derived from the experimental enthalpies of solution of the compound. The standard molar enthalpy of formation of the cation C₅H₇N₂ ⁺\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{ +} in aqueous solution was calculated to be D_fH_m^o(C₅H₇N₂⁺,aq)=-(2.096±0.801) kJ·mol^-1\Delta_{\mathrm{f}}H_{\mathrm{m}}^{\mathrm{o}}(\mathrm{C}_{5}\mathrm{H}_{7}\mathrm{N}_{2}^{+},\mbox{aq})=-(2.096\pm 0.801)~\mbox{kJ}\cdot\mbox{mol}^{-1}.     

Theoretical investigation of some O-nitrosyl carboxylate biologic molecules �� A natural bond orbital study

Theoretical study of several O-nitrosyl carboxylate compounds have been performed using quantum computational ab initio RHF and density functional B3LYP and B3PW91 methods with 6-31G** basis set. Geometries obtained from DFT calculations were used to perform the natural bond orbital (NBO) analysis. It is noted that weakness in the O₃-N₂ bond is due to $ n_{O_1 } \to \sigma _{O_3 - N_2 }^* $ n_{O_1 } \to \sigma _{O_3 - N_2 }^* delocalization and is responsible for the longer O₃-N₂ bond lengths in O-nitrosyl carboxylate compounds. It is also noted that decreased occupancy of the localized $ \sigma _{O_3 - N_2 } $ \sigma _{O_3 - N_2 } orbital in the idealized Lewis structure, or increased occupancy of $ \sigma _{O_3 - N_2 }^* $ \sigma _{O_3 - N_2 }^* of the non-Lewis orbital, and their subsequent impact on molecular stability and geometry (bond lengths) are related with the resulting p character of the corresponding sulfur natural hybrid orbital (NHO) of $ \sigma _{O_3 - N_2 } $ \sigma _{O_3 - N_2 } bond orbital. In addition, the charge transfer energy decreases with the increase of the Hammett constants of subsitutent groups.     

Thermodynamic Study on the Protonation and Na<Superscript>+</Superscript>, Ca<Superscript>2+</Superscript>, Mg<Superscript>2+</Superscript>-Complexation of a Biodegradable Chelant (HEIDA) at Different Ionic Strengths and Temperatures

A potentiometric method has been used for the determination of the protonation constants of N-(2-hydroxyethyl)iminodiacetic acid (HEIDA or L) at various temperatures 283.15?≤?T/K?≤?383.15 and different ionic strengths of NaCl_(aq), 0.12?≤?I/mol·kg^?1?≤?4.84. Ionic strength dependence parameters were calculated using a Debye–Hückel type equation, Specific Ion Interaction Theory and Pitzer equations. Protonation constants at infinite dilution calculated by the SIT model are \( \log_{10} \left( {{}^{T}K_{1}^{\text{H}} } \right) = 8.998 \pm 0.008 \) (amino group), \( \log_{10} \left( {{}^{T}K_{2}^{\text{H}} } \right) = 2.515 \pm 0.009 \) and \( \log_{10} \left( {{}^{T}K_{3}^{\text{H}} } \right) = 1.06 \pm 0.002 \) (carboxylic groups). The formation constants of HEIDA complexes with sodium, calcium and magnesium were determined. In the first case, the formation of a weak complex species, NaL, was found and the stability constant value at infinite dilution is log₁₀K_NaL?=?0.78?±?0.23. For Ca²⁺ and Mg²⁺, the CaL, CaHL, CaL₂ and MgL species were found, respectively. The calculated stability constants for the calcium complexes at T?=?298.15 K and I?=?0.150 mol·dm^?3 are: log₁₀β_CaL?=?4.92?±?0.01, log₁₀β_CaHL?=?11.11?±?0.02 and \( \log_{10} \beta_{\text{Ca{L}}_{2}} \)?=?7.84?±?0.03, while for the magnesium complex (at I?=?0.176 mol·dm^?3): log₁₀β_MgL?=?2.928?±?0.006. Protonation thermodynamic functions have also been calculated and interpreted.     

Heat capacity and density of methylpyrrolidone solutions of sodium and potassium perchlorates at different concentrations and 298.15 K

The heat capacity and density of solutions of sodium and potassium perchlorates in N-methylpyrrolidone (MP) at 298.15 K were studied by calorimetry and densimetry. The standard partial molar heat capacities $ \bar C_{p2}^ \circ $ \bar C_{p2}^ \circ and volumes $ \bar V_2^ \circ $ \bar V_2^ \circ of NaClO₄ and KClO₄ in MP were calculated. The standard heat capacities $ \bar C_{pi}^ \circ $ \bar C_{pi}^ \circ and volumes $ \bar V_i^ \circ $ \bar V_i^ \circ of the perchlorate ion in an MP solution at 298.15 K were determined. The results are discussed with allowance for the specifics of solvation in the solutions of the salts under study. The coordination number of the ClO₄⁻ ion in an MP solution at 298.15 K was calculated.     

PuPO<Subscript>4</Subscript>(cr,hyd.) Solubility Product and Pu<Superscript>3+</Superscript> Complexes with Phosphate and Ethylenediaminetetraacetic Acid

To determine the solubility product of PuPO₄(cr, hyd.) and the complexation constants of Pu(III) with phosphate and EDTA, the solubility of PuPO₄(cr, hyd.) was investigated as a function of: (1) time and pH (varied from 1.0 to 12.0), and at a fixed 0.00032 mol⋅L⁻¹ phosphate concentration; (2) NaH₂PO₄ concentrations varying from 0.0001 mol⋅L⁻¹ to 1.0 mol⋅L⁻¹ and at a fixed pH of 2.5; (3) time and pH (varied from 1.3 to 13.0) at fixed concentrations of 0.00032 mol⋅L⁻¹ phosphate and 0.0004 mol⋅L⁻¹ or 0.002 mol⋅L⁻¹ Na₂H₂EDTA; and (4) Na₂H₂EDTA concentrations varying from 0.00005 mol⋅L⁻¹ to 0.0256 mol⋅L⁻¹ at a fixed 0.00032 mol⋅L⁻¹ phosphate concentration and at pH values of approximately 3.5, 10.6, and 12.6. A combination of solvent extraction and spectrophotometric techniques confirmed that the use of hydroquinone and Na₂S₂O₄ helped maintain the Pu as Pu(III). The solubility data were interpreted using the Pitzer and SIT models, and both provided similar values for the solubility product of PuPO₄(cr, hyd.) and for the formation constant of PuEDTA⁻. The log ₁₀ of the solubility product of PuPO₄(cr, hyd.) [PuPO₄(cr, hyd.) \rightleftarrows\rightleftarrows Pu³⁺+PO₄^3-\mathrm{Pu}^{3+}+\mathrm{PO}_{4}^{3-}] was determined to be −(24.42±0.38). Pitzer modeling showed that phosphate interactions with Pu³⁺ were extremely weak and did not require any phosphate complexes [e.g., PuPO₄(aq), PuH₂PO₄²⁺\mathrm{PuH}_{2}\mathrm{PO}_{4}^{2+}, Pu(H₂PO₄)₂⁺\mathrm{Pu(H}_{2}\mathrm{PO}_{4})_{2}^{+}, Pu(H₂PO₄)₃(aq), and Pu(H₂PO₄)₄^-\mathrm{Pu(H}_{2}\mathrm{PO}_{4})_{4}^{-}] as proposed in existing literature, to explain the experimental solubility data. SIT modeling, however, required the inclusion of PuH₂PO₄²⁺\mathrm{PuH}_{2}\mathrm{PO}_{4}^{2+} to explain the data in high NaH₂PO₄ concentrations; this illustrates the differences one can expect when using these two different chemical models to interpret the data. Of the Pu(III)-EDTA species, only PuEDTA⁻ was needed to interpret the experimental data over a large range of pH values (1.3–12.9) and EDTA concentrations (0.00005–0.256 mol⋅L⁻¹). Calculations based on density functional theory support the existence of PuEDTA⁻ (with prospective stoichiometry as Pu(OH₂)₃EDTA⁻) as the chemically and structurally stable species. The log ₁₀ value of the complexation constant for the formation of PuEDTA⁻ [ Pu³⁺+EDTA^4-\rightleftarrows PuEDTA^-\mathrm{Pu}^{3+}+\mathrm{EDTA}^{4-}\rightleftarrows \mathrm{PuEDTA}^{-}] determined in this study is −20.15±0.59. The data also showed that PuHEDTA(aq), Pu(EDTA)₄^5-\mathrm{Pu(EDTA)}_{4}^{5-}, Pu(EDTA)(HEDTA)⁴⁻, Pu(EDTA)(H₂EDTA)³⁻, and Pu(EDTA)(H₃EDTA)²⁻, although reported in the literature, have no region of dominance in the experimental range of variables investigated in this study.     

Mass and charge transfer in systems containing nanocluster molybdenum polyoxometallates with a fullerene structure

The sorption capacity of polyoxometallates with a buckyball structure (fullerene)

Electrochemical Studies on <Emphasis Type="Italic">cis</Emphasis>-[Cr<Superscript>III</Superscript>(bipy)<Subscript>2</Subscript>(SCN)<Subscript>2</Subscript>]I<Subscript>3</Subscript> (Where bipy Denotes 2,2′-Bipyridine) in Acetonitrile

The molar conductivities (Λ) of solutions of bis(2,2′-bipyridine)bis(thiocyanate)chromium(III) triiodide [Cr^III(bipy)₂(SCN)₂]I₃ (where bipy denotes 2,2′-bipyridine, C₁₀H₈N₂), [ _3^-\mathrm{A}^{+}\mathrm{I}_{3}^{-} ], were measured in acetonitrile (ACN) at the temperatures 294.15, 299.15, and 305.15 K. In addition, cyclic voltammograms (CVs) of [ A⁺I₃^-\mathrm{A}^{+}\mathrm{I}_{3}^{-} ] were recorded on platinum, gold, and glassy carbon working electrodes in ACN, using n-tetrabutylammonium hexafluorophosphate (NBu₄PF₆) as the supporting electrolyte, at scan rates (v) ranging from 0.05 to 0.12 V⋅s⁻¹. Furthermore, electrochemical impedance spectroscopic (EIS) measurements were carried out in the frequency range 50 Hz<f<50 kHz using these three working electrodes. The measured molar conductivities (Λ) demonstrate that [ A⁺I₃^-\mathrm{A}^{+}\mathrm{I}_{3}^{-} ] behaves as uni-univalent electrolyte in ACN over the investigated temperature range. The Λ values were analyzed by means of the Lee-Wheaton conductivity equation in order to estimate the limiting molar conductivities (Λ _o), as well as the thermodynamic association constants (K _A), at each experimental temperature for formation of [A⁺ I₃^-\mathrm{I}_{3}^{-} ] ion-pairs. The limiting ionic conductivities ( l_±^o\lambda_{\pm}^{\mathrm{o}} ), the diffusion coefficients at infinite dilution (D _±), as well as the Stokes’ radii (r _St) were determined for both A⁺ and I₃^-\mathrm{I}_{3}^{-} ions. The thermodynamic parameters for the ionic association process, i.e. the Gibbs energy ( DG_A^o\Delta G_{\mathrm{A}}^{\mathrm{o}} ), enthalpy ( DH_A^o\Delta H_{\mathrm{A}}^{\mathrm{o}} ), and entropy ( DS_A^o\Delta S_{\mathrm{A}}^{\mathrm{o}} ), were also determined. The mobility and diffusivity of the A⁺ ion increase linearly with increasing temperature because the solvent medium becomes less viscous as the temperature increases. The K _A values indicate that significant ion association occurs that is not influenced by temperature changes. The ion-pair formation process is exothermic ( DH_A^o < 0\Delta H_{\mathrm{A}}^{\mathrm{o}}<0 ), leading to the generation of additional entropy ( $\Delta S_{\mathrm{A}}^{\mathrm{o}}>0$\Delta S_{\mathrm{A}}^{\mathrm{o}}>0 ). As a result, the Gibbs energy DG_A^o\Delta G_{\mathrm{A}}^{\mathrm{o}} is negative ( DG_A^o < 0\Delta G_{\mathrm{A}}^{\mathrm{o}}<0 ) and the formation of [A⁺I₃^-][\mathrm{A}^{+}\mathrm{I}_{3}^{-}] becomes favorable. CV studies on [A⁺I₃^-][\mathrm{A}^{+}\mathrm{I}_{3}^{-}] solutions indicated that the redox pair Cr^3+/2+ appears to be quasi-reversible on a glassy carbon electrode but is completely irreversible on platinum and gold electrodes. EIS experiments confirm that, among these three electrodes, the glassy carbon working electrode has the smallest resistance to electron transfer.     

Studies on electron transfer reactions: reduction of heteropoly 10-tungstodivanadophosphate by <Emphasis Type="SmallCaps">l</Emphasis>-cysteine in aqueous acid medium

l-cysteine undergoes facile electron transfer with heteropoly 10-tungstodivanadophosphate, [ \textPV^\textV \textV^\textV \textW _{1 0} \textO _{4 0} ]^{5 -} , \left[ {{\text{PV}}^{\text{V}} {\text{V}}^{\text{V}} {\text{W}}_{ 1 0} {\text{O}}_{ 4 0} } \right]^{5 - } , at ambient temperature in aqueous acid medium. The stoichiometric ratio of [cysteine]/[oxidant] is 2.0. The products of the reaction are cystine and two electron-reduced heteropoly blue, [PV^IVV^IVW₁₀O₄₀]⁷⁻. The rates of the electron transfer reaction were measured spectrophotometrically in acetate–acetic acid buffers at 25 °C. The orders of the reaction with respect to both [cysteine] and [oxidant] are unity, and the reaction exhibits simple second-order kinetics at constant pH. The pH-rate profile indicates the participation of deprotonated cysteine in the reaction. The reaction proceeds through an outer-sphere mechanism. For the dianion ⁻SCH₂CH(NH₃ ⁺)COO⁻, the rate constant for the cross electron transfer reaction is 96 M⁻¹s⁻¹ at 25 °C. The self-exchange rate constant for the ^- \textSCH₂ \textCH( \textNH₃ ⁺ )\textCOO ^- \mathord

Electrochemical and thermodynamic properties of thulium trichloride in a molten NaCl-KCl-CsCl eutectic

Potentiometric method was used to measure the redox potentials of Tm³⁺/Tm²⁺ in a eutectic melt of sodium, potassium, and cesium chlorides relative to a chlorine reference electrode in the temperature range 823–973 K. The main thermodynamic characteristics of the redox reaction TmCl_2(solution) + 1/2Cl_2(g) ⇆ TmCl_3(solution) were calculate from the conditional standard potentials $ E_{{{Tm^{3 + } } \mathord{\left/ {\vphantom {{Tm^{3 + } } {Tm^{2 + } }}} \right. \kern-\nulldelimiterspace} {Tm^{2 + } }}}^* $ E_{{{Tm^{3 + } } \mathord{\left/ {\vphantom {{Tm^{3 + } } {Tm^{2 + } }}} \right. \kern-\nulldelimiterspace} {Tm^{2 + } }}}^* .     

New approximation for the general temperature integral

A new approximation has been proposed for calculation of the general temperature integral $ \int\limits_0^T {T^m } e^{ - E/RT} dT $ \int\limits_0^T {T^m } e^{ - E/RT} dT , which frequently occurs in the nonisothermal kinetic analysis with the dependence of the frequency factor on the temperature (A=A ₀ T ^m). It is in the following form:

Rate constant of the recombination of CF<Stack><Subscript>3</Subscript><Superscript>•</Superscript></Stack> radicals in a gas (He,Ar, N<Subscript>2</Subscript>, or CF<Subscript>3</Subscript>I)

From recent rate constant data for the recombination reaction 2CF₃^• → C₂F₆ ($ k_{(CF_3 )_2 }^M $ k_{(CF_3 )_2 }^M ) in the high-pressure limit and from experimental data obtained at intermediate pressures of buffer gases M (M = He, Ar, N₂, CF₃I), analytical expressions for $ k_{(CF_3 )_2 }^M $ k_{(CF_3 )_2 }^M (in Lindemann’s formulation) are derived for the temperature range of 300–1300 K and intermediate pressures of the buffer gases.     

Synergistic extraction of some univalent cations into nitrobenzene by using sodium dicarbollylcobaltate and hexaethyl <Emphasis Type="Italic">p</Emphasis>-<Emphasis Type="Italic">tert</Emphasis>-butylcalix[6]arene hexaacetate

From extraction experiments and γ-activity measurements, the exchange extraction constants corresponding to the general equilibrium M⁺ (aq) + NaL⁺ (nb) ⇔ ML⁺ (nb) + Na⁺ (aq) taking place in the two-phase water–nitrobenzene system (M⁺ = H₃O⁺, \textNH₄⁺ {\text{NH}}_{4}{}^{+} , Ag⁺, Tl⁺; L = hexaethyl p-tert-butylcalix[6]arene hexaacetate; aq = aqueous phase, nb = nitrobenzene phase) were evaluated. Furthermore, the stability constants of the ML⁺ complexes in nitrobenzene saturated with water were calculated; they were found to increase in the following order: \textAg ⁺   <  NH₄ ⁺   <  \textH ₃ \textO ⁺   <  \textNa ⁺   <  \textTl ⁺ . {\text{Ag}}^{ + } \, < \,\hbox{NH}_{4}{}^{ + } \, < \,{\text{H}}_{ 3} {\text{O}}^{ + } \, < \,{\text{Na}}^{ + } \, < \,{\text{Tl}}^{ + }.     

Temperature dependence of europium carbonate complexation

The temperature dependencies of europium carbonate stability constants were examined at 15, 25, and 35°C in 0.68 molal Na⁺(ClO ₄ ^? , HCO ₃ ^? ) using a tributyl phosphate solvent extration technique. Our distribution data can be explained by the equilibria $$\begin{gathered} Eu^{3 + } + H_2 O + CO_2 (g)_ \leftarrow ^ \to EuCO_3^ + + 2H^ + \hfill \\ - log\beta _{12} = 9.607 + 496(t + 273.16)^{ - 1} \hfill \\ Eu^{3 + } + 2H_2 O + 2CO_2 (g)_ \leftarrow ^ \to Eu(CO_3 )_2^ - + 4H^ + \hfill \\ - log\beta _{24} = 21.951 + 670(t + 273.16)^{ - 1} \hfill \\ Eu^{3 + } + H_2 O + CO_2 (g)_ \leftarrow ^ \to EuHCO_3^{2 + } + H^ + \hfill \\ - log\beta _{11} = 1.688 + 1397(t + 273.16)^{ - 1} \hfill \\ \end{gathered}$$      

Microcalorimetric Studies on the CMC and Thermodynamic Functions of a Nonionic Surfactant (Tween80) in DMF/Long-Chain Alcohol Systems from <Emphasis Type="Italic">T</Emphasis>=298.15 to <Emphasis Type="Italic">T</Emphasis>=313.15 K

The power-time curves of the micelle formation process were determined for the nonionic surfactant Tween80/nonaqueous solvent (DMF)/long-chain alcohol (n-heptanol, n-octanol, n-nonanol, and n-decanol) systems by titration microcalorimetry at temperatures of (298.15, 303.15, 308.15, and 313.15) K. From the power-time curves, the CMC and DH_m^\uptheta\Delta H_{\mathrm{m}}^{\uptheta} values were obtained. The corresponding values of DG_m^\uptheta\Delta G_{\mathrm{m}}^{\uptheta} and DS_m^\uptheta\Delta S_{\mathrm{m}}^{\uptheta} were also calculated. The relationships of the CMC with the carbon number of the alcohol, the concentration of alcohol, and the temperature, along with the thermodynamic functions, are discussed.     

Constant current anodic stripping chronopotentiometric determination of uranium in uranium mineral ores via accumulation of K<Subscript>2</Subscript>UO<Subscript>2</Subscript>[Fe(CN)<Subscript>6</Subscript>] on the palladium plated aluminum electrode

In the present work the uranyl hexacyanoferrate (K₂UO₂[Fe(CN)₆]) is deposited on the palladized aluminum (Pd-Al) electrode from a \textUO₂^{2 +} + \textFe( \textCN )₆ ^{- 3} {\text{UO}}_{2}^{2 + } + {\text{Fe}}\left( {\text{CN}} \right)_{6}^{ - 3} solution. Then the anodic stripping chronopotentiometry (ASCP) was used to strip the K₂UO₂[Fe(CN)₆] from the Pd-Al surface. The operational conditions including: pH, K₃Fe(CN)₆ concentration, deposition potential, deposition time and stripping current were optimized. The ASCP calibration graph was linear in concentration range 10–460 μM. of \textUO₂^{2 +} {\text{UO}}_{2}^{2 + } and the detection limit was 8.5 μM. The interference of some concomitant ions during the deposition process of K₂UO₂[Fe(CN)₆] was studied. The proposed method was successfully applied for analysis of some uranium mineral ores.     

Kinetics and mechanism of oxidation of aquaethylenediaminetetraacetatocobaltate(II) by <Emphasis Type="Italic">N</Emphasis>-bromosuccinimide in aqueous acidic solution

The oxidation of aquaethylenediaminetetraacetatocobaltate(II) [Co(EDTA)(H₂O)]⁻² by N-bromosuccinimide (NBS) in aqueous solution has been studied spectrophotometrically over the pH 6.10–7.02 range at 25 °C. The reaction is first-order with respect to complex and the oxidant, and it obeys the following rate law: