Miguel A. Esteso

Activity coefficients for NaCl in ethanol-water mixtures at 25°C

AbstractActivity coefficient values for NaCl in ethanol-water mixtures containing 20, 40, 60, 70, 80 and 90 weight % ethanol are calculated from the emf for the galvanic cell

Activity coefficients for NaF in methanol-water and ethanol-water mixtures at 25°C

Na - glass|NaCl(m), H_2 O (100 - Y), EtOH(Y), AgCl|Ag

Thermodynamic Study of the NaCl + Na2SO4 + H2O System by Emf Measurements at Four Temperatures

in which the weight % of the corresponding solvent is indicated in parenthesis. The results obtained are analyzed by using different theoretical models. Chemical models which take into account the presence of ion pairs in solutions of high ethanol content are also used. There is good agreement between the results obtained from all the models.

Interactions of Copper (II) Chloride with β‐Cyclodextrin in Aqueous Solutions

The ionic mean activity coefficients of NaCl in trehalose-water and maltose-water mixtures have been experimentally determined at 298.15 K from emf measurements by electrochemical cell containing ion selective electrodes (ISE): Na-ISE/NaCl (m), sugar (Y%), H(2)O (100-Y%)/Cl-ISE. The electrolyte molality (m) ranged between 0.01 and 3 mol kg(-1), approximately, and the weight percent (Y%) of sugar in the mixture of solvents between 0, 10, 20, 30 and 40%. The system is considered as an electrolyte in a mixture of solvents and the data have been analysed by using the Debye-Hückel and Pitzer equations. The results obtained with both equations are in quite agreement with each other. The variation of the fit parameter from both equations were studied relative to the change in the dielectric properties of the mixture of solvents. Standard free energy of transference were comparatively discussed in terms of ion-solvent, ion-ion interactions and the hydration of both the electrolyte and the sugar.

Evaluation of the absorption on mild steel of hydrogen evolved in glucose fermentation by pure cultures of Clostridium acetobutylicum and Enterobacter

Abstract The electromotive force, E, of the cell: Na-ISE | NaF (m), H 2 O (100−Y), alcohol (Y) | F−ISE where (ISE) stands for ion-selective electrode and Y for the weight percent of alcohol (either methanol or ethanol), was measured at 298.15 K. Y was ranged between 0 and 100% for methanol-water system and between 0 and 80% for the ethanol-water one, in both cases by steps of 10 units. The electrolyte molatity (m) was ranged from 0.01 to near saturation. The values for the standard electromotive force, E0 (molal scale), were determined from both the Debye-Huckel extended equation and the Pitzer equation by using extrapolation iterative methods. Electromotive force data were also analysed by using a chemical model to take into account possible ion pair formation (Na+F−)0 and E 0∗ and KA (equilibrium constant of the ion pairs) were obtained. In all cases, the values found for E0 agree with each other within the estimated experimental error for this type of measurements and, consequently, average values were obtained and afterwards used to calculate the stoichiometric mean ionic activity coefficients at each alcohol-water mixture. In water, these last values thus encountered differ from those reported in the literature by less than ±0.005 units. Values for the standard free energy of transference, ΔGt0 and solubility product of NaF, Ksp,s0, were calculated, comparatively discussed in terms of both ion-solvent and ion-ion interactions and the effect of the change in certain physical properties of the solvent and also compared with the sodium halide series. Finally, hydration number of NaF, nhydr, was estimated for the different alcohol-water mixtures studied and compared with other literature data reported for other sodium halides.

Modification of the Pitzer equations for application to electrolyte + polar non-electrolyte mixtures

AbstractActivity coefficients for NaBr in ethanol-water mixtures with 0, 20, 40, 60, 70, 80, 90 and 99.9 weight% of ethanol have been determined at 25°C from the emf measurements of the galvanic cells

Electrochemical measurement of trace concentrations of biological hydrogen produced by Enterobacteriaceae

Na - glass/NaBr(m),H_2 O(100 - Y),EtOH(Y),AgBr_{(S)} /Ag