Activity coefficients of NaCl in PEG 4000 + water mixtures at 288.15, 298.15 and 308.15 K

The electromotive force of the cell containing two ion-selective electrodes (ISE),

Na-ISE|NaCl (m), PEG ??4000 (Y), H₂O (100−Y)|Cl-ISE$\text{Na-ISE}|\text{NaCl}(m),\text{PEG}\text{\hspace{0.17em}??}4000(Y),{\text{H}}_2\text{O}(100-Y)|\text{Cl-ISE}$

Activity coefficients and conductivities of calcium nitrate in glucose/galactose–water mixtures at 298.15 K

Activity coefficients, Gibbs energy interaction parameters (g_ES), salting constants (k_S), limiting molar conductivities (Λ₀), and Walden products (Λ₀η) for the calcium nitrate−monosaccharide (d-glucose and d-galactose)–water systems were determined from electrical potential and conductance measurements. Results show that both the g_ES and Λ₀η values for saccharide−calcium nitrate–water systems are in the order: d-glucose > d-galactose. This can be ascribed to the fact that the interactions of Ca²⁺ with d-galactose are stronger than those of the ions with d-glucose. d-Glucose is salted-out whereas d-galactose is salted-in by calcium nitrate in water, which results from the difference in stereo-structures of the saccharide molecules (axial hydroxyl, a-OH-4 and equatorial hydroxyl, e-OH-4).     

Measurement and modeling of mean activity coefficients of NaBr and amino acid in (sodium bromide + potassium phosphate + glycine + water) system at T (298.15 and 308.15) K

Electrochemical measurements are done on (water + NaBr + K₃PO₄ + glycine) mixtures at T (298.15 and 308.15) K by using (Na⁺ glass) and (Br⁻ solid-state) ion selective electrodes. The mean ionic activity coefficients of NaBr are determined at five NaBr molalities (0.1, 0.3, 0.5, 0.7, and 1) in the above mixtures. The activity coefficients of glycine are evaluated from mean ionic activity coefficients of sodium bromide. The ratio of mean ionic activity coefficient of NaBr in the (water + NaBr + K₃PO₄ + glycine) mixtures to the mean ionic activity coefficients of NaBr at the same molalities in the (H₂O + NaBr) mixtures are correlated by using a new expression.     

Activity coefficients of NaCl in polyelectrolyte solutions from EMF measurements

Electromotive force (EMF) data were measured at 298.15 K for the cell, Na–ISE |polyelectrolyte(m_p), NaCl(m_s)| AgCl, Ag, where a salt NaCl with different concentrations is added in aqueous poly(diallyl dimethyl ammonium chloride), poly(anethole sulfonic acid, sodium salt) and sodium polyacrylate solutions, respectively. ISE means ion-selective electrode. Mean activity coefficients of the salt NaCl in these aqueous polyelectrolyte solutions were calculated correspondingly. The standard cell potential needed for calculations were obtained from EMF measurements of an another cell, Na–ISE |NaCl(m)| AgCl, Ag, where the solution contains only a single electrolyte. Activity coefficients of the electrolyte NaCl in this cell were estimated by Pitzer model. For poly(diallyl dimethyl ammonium chloride) solutions with different concentrations, mean activity coefficients of the salt NaCl decrease monotonically as the concentration of NaCl increases. However, for poly(anethole sulfonic acid, sodium salt) solutions and sodium polyacrylate solutions, the salt-concentration dependence of the mean activity coefficients of NaCl exhibit a maximum.     

Quinary liquid–liquid equilibria for mixtures of nonane + undecane + two pairs of aromatics (benzene/toluene/m-xylene) + sulfolane at 298.15 and 313.15 K

In this work, liquid–liquid equilibrium data were measured for three quinary mixtures (nonane + undecane + benzene + toluene + sulfolane), (nonane + undecane + benzene + m-xylene + sulfolane) and (nonane + undecane + toluene + m-xylene + sulfolane) at 298.15 and 313.15 K and ambient pressure. The experimental LLE data were determined by using a jacketed glass cell with temperature controlled. The quantitative analysis was performed by using a Varian gas chromatograph equipped with a flame ionization detector and a SPB™-1 column. The experimental quinary liquid–liquid equilibrium data have been satisfactorily correlated by using NRTL and UNIFAC-LLE models. The calculated values based on the NRTL model were found to be in a better agreement with the experiment than those based on the UNIFAC-LLE model.     

Activity coefficients of NaCl in the NaCl + NaBF4 + H2O ternary system at 298.15 K

The activity coefficients of sodium chloride in the NaCl + NaBF₄ + H₂O ternary system were experimentally determined at 298.15 K, at ionic strengths of 0.3. 0.5, 1, 2 and 3 mol kg⁻¹ from emf from the bi-ISE cell without liquid junction:

ISE-Na|NaCl(m_A), NaBF₄(m_B)|ISE-Cl

Osmotic and activity coefficients of two macrocyclic aminals in aqueous solution at 288.15, 293.15, 298.15 and 303.15 K

The osmotic coefficients of 1,3,5,7-tetrazatricyclo (3.3.1.13,7) decane (HMT) and 1,3,6,8-tetrazatricyclo (4.4.1.13,8) dodecane (TATD) in aqueous solutions were measured at 288.15, 293.15, 298.15 and 303.15 K. The technique used was the isopiestic. The data were used to calculate the activity coefficients of the two solutes at the four temperatures. The few data points found for HMT in literature at 298.15 K agree well with the new data. The reinforcement of water structure by the two aminals is discussed.     

Excess Gibbs energies and volumes of the ternary system chloroform + tetrahydrofuran + cyclohexane at 298.15 K

Vapour–liquid equilibria and densities for the ternary system chloroform + tetrahydrofuran + cyclohexane and for the binary mixtures containing chloroform have been determined at 298.15 K. Vapour–liquid equilibrium data have been collected by head-space gas-chromatographic analysis of the vapour phase directly withdrawn from an equilibration apparatus. Density measurements have been carried out by means of a vibrating tube densimeter. Molar excess Gibbs energies G^E and volumes V^E, as well as activity coefficients and apparent molar volumes of the components, have been obtained from the measured quantities and discussed. The binary chloroform + tetrahydrofuran displays negative deviations from ideality, while chloroform + cyclohexane positive deviations, for both volume and Gibbs energy. The G^E's and V^E's for the ternary system are positive in the region rich in cyclohexane while negative in the region rich in chloroform + tetrahydrofuran. This indicates that hydrogen bonding between chloroform and tetrahydrofuran molecules produces negative values of G^E and V^E and strongly influences the behaviour of the ternary system.     

Activity Coefficients of NaCl in Ethylene Glycol‐Water Mixtures Using Potentiometric Measurements at 288.15, 298.15 and 308.15 K

The mean activity coefficients of NaCl in ethylene glycol‐water mixtures were determined in the range of w=0.10 to 0.40 ethylene glycol at 288.15, 298.15 and 308.15 K using potentiometric measurements. The Pitzer and extended Debye‐Hückel equations were used to describe the nonideal behavior of the electrolyte. Osmotic coefficients and the standard Gibbs energy of NaCl‐ethylene glycol‐water were calculated.     

Partial molar volume of paracetamol in water, 0.1 M HCl and 0.154 M NaCl at T = (298.15, 303.15, 308.15 and 310.65) K and at 101.325 kPa

The apparent molar volume of paracetamol (4-acetamidophenol) in water, 0.1 M HCl and 0.154 M NaCl as solvents at (298.15, 303.15, 308.15 and 310.65) K temperatures and at a pressure of 101.325 kPa were determined from the density data obtained with the help of a vibrating-tube Anton Paar DMA-48 densimeter. The partial molar volume, V_m, of paracetamol in these solvents at different temperatures was evaluated by extrapolating the apparent molar volume versus molality plots to m = 0. In addition, the partial molar expansivity, E^°, the isobaric coefficient of thermal expansion, α_p, and the interaction coefficient, S_v, have also been computed. The expansivity data show dependence of E^° values on the structure of the solute molecules.     

The limiting partial molar volume and apparent molar volume of glycylglycine in aqueous KCl solution at 298.15 and 308.15 K

Apparent molar volumes V_Φ of glycylglycine in aqueous KCl solutions have been obtained from densities at 298.15 and 308.15 K measured with a vibrating-tube densimeter. These data have been used to deduce partial molar volumes of transfer from water to different KCl–water mixtures. values are positive. This result arises from the interaction of KCl with the charged centers of glycylglycine. The results show that depends less on temperature. Hydration numbers are calculated from data and are interpreted in terms of various interactions.     

Experimental measurement and thermodynamic modeling of liquid-liquid equilibrium for 1-pentanol + water + NaNO3 at 298.15 and 308.15 K

Experimental measurements have been performed for liquid-liquid equilibria in aqueous systems containing 1-pentanol and sodium nitrate at temperatures of 298.15 and 308.15 K and at atmospheric pressure. The results have been modeled using the extended UNIQUAC model and also a modified version of this model. Relevant model parameters have been adjusted using the experimental data. Both models are capable of correlating the experimental data with an average deviation of less than 0.8 weight percent, with the modified model producing slightly better results. The predictive nature of the models has also been verified.     

Activity coefficients of CaCl2 in (maltose + water) and (lactose + water) mixtures at 298.15 K

Activity coefficients of CaCl₂ in disaccharide {(maltose, lactose) + water} mixtures at 298.15 K were determined by cell potentials. The molalities of CaCl₂ ranged from about 0.01 mol · kg^?1 to 0.20 mol · kg^?1, the mass fractions of maltose from 0.05 to 0.25, and those of lactose from 0.025 to 0.125. The cell potentials were analyzed by using the Debye–Hückel extended equation and the Pitzer equation. The activity coefficients obtained from the two theoretical models are in good agreement with each other. Gibbs free energy interaction parameters (g_ES) and salting constants (k_S) were also obtained. These were discussed in terms of the stereo-chemistry of saccharide molecules and the structural interaction model.     

Vapour pressure and excess Gibbs energy of binary 1,2-dichloroethane + cyclohexanone,chloroform + cyclopentanone and chloroform + cyclohexanone mixtures at temperatures from 298.15 to 318.15 K

The vapour pressures of the binary systems 1,2-dichloroethane + cyclohexanone, chloroform + cyclopentanone and chloroform + cyclohexanone mixtures were measured at temperatures between 298.15 and 318.15 K. The vapour pressures vs. liquid phase composition data for three isotherms have been used to calculate the activity coefficients of the two components and the excess molar Gibbs energies, G^E, for these mixtures, using Barker's method. Redlich–Kister, Wilson, NRTL and UNIQUAC equations, taking into account the vapour phase imperfection in terms of the 2-nd virial coefficient, have represented the G^E values. No significant difference between G^E values obtained with these equations has been observed. Our data on vapour–liquid equilibria (VLE) and excess properties of the studied systems are examined in terms of the DISQUAC and modified UNIFAC (Dortmund) predictive group contributions models.     

Liquid–liquid equilibria for quaternary mixtures of nonane + undecane + (benzene or toluene or m-xylene) + sulfolane at 298.15 and 313.15 K

Liquid–liquid equilibrium (LLE) data were measured for three quaternary systems containing sulfolane, nonane + undecane + benzene + sulfolane, nonane + undecane + toluene + sulfolane and nonane + undecane + m-xylene + sulfolane, at T = 298.15 and 313.15 K and ambient pressure. The experimental quaternary liquid–liquid equilibrium data have been satisfactorily represented by using NRTL and UNIFAC-LLE models for the activity coefficient. The calculated compositions based on the NRTL model were found to in a better agreement with the experiment than those based on the UNIFAC-LLE model.     

Physical properties and their corresponding changes of mixing for the ternary mixture acetone + n-hexane + water at 298.15 K

Experimental density and the refractive index of the ternary mixture acetone + n-hexane + water, and their binary systems were experimentally measured and correlated at 298.15 K and atmospheric pressure. A maximum in refractive indices has been observed for the acetone + water system while the excess molar volume and the molar refraction change are all negative. For the mixture acetone + n-hexane, the excess molar volume is always positive and the molar refraction change of mixing showed a S-shaped dependence on acetone composition. The excess molar volumes and molar refraction changes of mixing were correlated using the Redlich-Kister expression and Cibulka equation. The coefficients and standard deviation between the experimental and fitted values were estimated. Good agreement between both results was obtained.     

Molecular interactions in (2,4,6-trimethyl-1,3,5-trioxane + n-alkyl acetates) at T = (298.15, 303.15, and 308.15) K

Densities and viscosities of the binary mixtures of 2,4,6-trimethyl-1,3,5-trioxane with methyl acetate, ethyl acetate, and 1-butyl acetate were measured over the entire mole fractions at (298.15, 303.15, and 308.15) K. Using the experimental values of densities ρ and viscosities η, excess molar volumes V^E, viscosity deviations δη were calculated. The values of excess molar volumes V^E and viscosity deviations δη were fitted to the Redlich-Kister polynomial.