Diffusion coefficients of aluminium chloride in aqueous solutions at 298.15, 303.15 and 315.15 K

Mutual diffusion coefficients (interdiffusion coefficients) have been determined for aluminium chloride in water at 298.15, 303.15 and 310.15 K at concentrations from 0.002 to 0.010 mol dm⁻³ together with molar conductivity values. The diffusion coefficients were obtained by using a conductimetric open-ended capillary cell. The experimental data were discussed on the basis of the Onsager-Fuoss model. The Nernst diffusion coefficients derived from diffusion 1.208 × 10⁻⁹ and 1.701 × 10⁻⁹ m² s⁻¹ and from conductance 1.238 × 10⁻⁹ and 1.692 × 10⁻⁹ m² s⁻¹, at two temperatures 298.15 and 310.15 K, respectively, agree well each other.     

Interactions of cobalt chloride with saccharose in aqueous solutions at 298.15 K

Mutual diffusion coefficients (interdiffusion coefficients) and molar electrical conductivities have been measured for cobalt chloride aqueous solutions in the absence and the presence of saccharose at different concentrations (from 0.01 to 0.3 mol dm⁻³) and 298.15 K. The diffusion coefficients were measured by using the conductimetric method. For these aqueous solutions, limiting molar conductivity values have been calculated. The value of λ⁰(Co²⁺) = 105.36 × 10⁻⁴ S m² mol⁻¹, obtained at 298.15 K in pure water solution, agrees well with that reported in the literature. The Nernst diffusion coefficient values derived from diffusion (1.301 × 10⁻⁹ m² s⁻¹) and from conductance (1.295 × 10⁻⁹ m² s⁻¹) are also in good agreement.The dependence of diffusion coefficients and electrical conductivity of CoCl₂ on the concentration of saccharose is discussed by considering the effect of the carbohydrate on the electrolyte dehydration, as well as on the ion-pairs and complexes (CoCl₂-saccharose and ions-saccharose) formation.     

Diffusion coefficients in aqueous solutions of hydrochloric acid at 298 K

Diffusion coefficients of HCl solutions at different concentrations, have been measured at 298 K using a conductimetric cell and the results are discussed on the basis of the Onsager-Fuoss theory. The cell uses the open-ended capillary method, and a conductimetric technique is used to follow the diffusion process by measuring the resistance of a solution inside the capillaries at recorded times.     

Diffusion coefficients in aqueous solutions of potassium perchlorate at 298 K

Diffusion coefficients of KClO₄ solutions at different concentrations, have been measured at 298 K using a conductometric cell and the results are discussed on the basis of the Onsager-Fuoss theory. The cell uses an open-ended capillary method, and a conductometric technique is used to follow the diffusion process by measuring the resistance of a solution inside the capillaries at recorded times.     

The activity coefficients of glycine,DL‐Serine and DL‐Valine in aqueous solutions containing nitrates at 298.15 K

An electrochemical method was used to measure the mean activity coefficients of amino acids in water‐electrolyte‐amino acid systems. The amino acids were glycine, DL‐serine and DL‐valine and the electrolytes were KNO₃ and NaNO₃. The activity coefficients of the electrolytes were obtained from the e.m.f measurements in an electrochemical cell with an anion and a cation ion‐selective electrodes, each measured versus a double junction reference electrode at 298.15 K. The activity coefficients of the amino acids in the ternary systems were obtained from those of the electrolyte according to the cross differential relation. A simple semi‐empirical model based on a modification of a more complex form, derived from perturbation theory, was used to correlate the activity coefficients in binary aqueous solutions and in ternary systems.     

Diffusion coefficients in strong aqueous amine solutions

Diffusion coefficients measured with a flowing junction cell and a wavefront shearing interferometer are reported. These coefficients were correlated with respect to solution concentration for three liquid systems: monoethanolamine-water, diethanolamine-water and triethanolamine-water at 25°. Equations from fundamental electrolytic theory were used as a basis for correlation.     

氨基酸在水溶液中的扩散系数

There are still limited experimental data of liquid diffusion coefficients in literature. Therefore, the experimental investigation and prediction model are of practical and theoretical significance. The diffusion coefficients of L-serine, L-threonine, L-arginine, in aqueous solution at 298. 15 K were measured respectively by holographic interferometer. The affecting factors of molecular structure and polarity were analyzed and discussed. Finally, a modified semi-empirical model for correlating the diffusion coefficients of solid organic compounds in aqueous solutions at 298. 15 K was proposed with an adjustable parameter added. The average deviation between model prediction values and experimental ones is less than 0.2%, which shows a considerably satisfactory accuracy.     

Excess molar volumes for titanium butoxide contained binary and ternary systems at 298.15 K

The reported mixture properties of metal alkoxide are almost none in spite of their increasing usages. In this work, the excess molar volumes (V^E) were determined from measured densities for six binary systems of titanium butoxide (1) + ethanol (2), titanium butoxide (1) + 1-propanol (2), titanium butoxide (1) + 1-butanol (2), ethanol (1) + 1-propanol (2), 1-propanol (1) + 1-butanol (2) and ethanol (1) + 1-butanol (2) at 298.15 K. The experimental V^E were correlated with the Redlich–Kister polynomial. The partial excess molar volumes at infinite dilution were calculated with fitted binary parameters. Additionally the ternary V^E data at 298.15 K were also predicted for three systems of titanium butoxide (1) + ethanol (2) + 1-propanol (3), titanium butoxide (1) + ethanol (2) + 1-butanol (3) and titanium butoxide (1) + 1-propanol (2) + 1-butanol (3) by using the binary contribution model of Radojkovič with the binary Redlich–Kister parameters.     

Viscous behaviour of quaternary fluid solutions at 298.15 K

Assuming a quaternary fluid solution to be made up of six binaries, a statistical approach of Flory has been extended to develop the expression for dynamic viscosity of multicomponent system using the concept of absolute rate and free volume approaches of liquid state. A reasonable agreement has been achieved between theory and the experiment for n‐hexadecane + carbon tetrachloride + benzene + n‐hexane quaternary system at 298.15 over a wide range of composition. An attempt has also been made to explain the nature of the molecular interactions, involved in the light of excess thermodynamic functions whose sign and magnitude depend upon the chain length and size of the component liquids.     

Measurement and modeling of the phase behavior of the (carbon dioxide + water) mixture at temperatures from 298.15 K to 448.15 K

An analytical apparatus has been designed to study the phase behavior of fluid mixtures of relevance to CO₂-enhanced oil recovery and carbon dioxide storage in deep aquifers or depleted oil fields. The fluid phases are circulated by means of a dual-channel magnetically-coupled pump and aliquots may be withdrawn from the re-circulation loops, by means of high-pressure sampling valves, for analysis by gas chromatography. The high-pressure cell is fitted with a special probe that may be rotated in order to draw liquid into the re-circulation loop from different heights within the cell, thereby permitting the study of three-phase vapor–liquid–liquid equilibria. The working temperature range of the apparatus is from (298 to 448) K and the maximum working pressure is 50 MPa.In this work, measurements have been made on the binary system (CO₂ + H₂O) at temperatures from (298.15 to 448.15) K and pressure from (1.5 to 18.0) MPa, and the results are compared with the available literature data. Vapor–liquid–liquid and liquid–liquid equilibrium points were also measured at T = 298.15 K. Standard uncertainties were 0.04 K for temperature, 0.04% of reading for pressure, and typically 3 × 10⁻⁴ and 8 × 10⁻⁴ for the mole fractions in liquid and vapor phases respectively. The results have been correlated by means of an asymmetric approach based on the Peng–Robinson equation of state, for the vapor phase, and an extended form of Henry's law incorporating the NRTL solution model, for the aqueous liquid-phase. The ability of the Krichevsky–Kasarnovsky (KK) approach to correlate the data has also been evaluated.     

Diffusion coefficients of aqueous cesium fluoride at 40°C

Diaphragm cell technique has been employed to determine diffusion coefficient for cesium fluoride at 40°C in the concentration range varying from 0.01 to 0.1 M. The data were analysed in the light of the theory of Onsager and Fuoss (O-F), J. chem. Phys.2, 599 (1932)[20]. The results indicate that the O-F theory is inadequate to explain the behaviour of this salt at 45°C. The results are also discussed with other 1:1 type salts of cesium.     

Effect of density on the electrical conductance of aqueous sodium chloride solutions

Concentrated sodium chloride solutions are commonly used in electrochemical machining and a knowledge of their conductance is important. A study was made of the conductivity of a range of concentrations from 0.01 M to 5 M to temperatures >500°C and to pressures of 2000bar. The conductances were found to go through maxima at 250–300°C after increasing in magnitude by a factor of >4.     

Physicochemical properties of aqueous solutions of sodium glycinate in the non-precipitation regime from 298.15 to 343.15 K

The physicochemical properties, including the density, viscosity, and refractive index of aqueous solutions of sodium glycinate as a solvent for CO2 absorption in the non-precipitation regime were measured under the wide temperature range of 298.15 to 343.15 K. The concentration of the sodium glycinate in an aqueous form in the non-precipitation regime was identified up to 2.0 mol·L?1. The coefficients of thermal expansion values were estimated from measured density data. It was found that, the densities, viscosities and refractive indices of the aqueous sodium glycinate decrease with an increase in temperature, whereas with increasing sodium glycinate concentration in the solution, all three properties increase. Thermal expansion coefficients slightly increase with rising temperature and concentration. The measured values of density, viscosity and refractive index were correlated as a function of temperature by using the least squares method. The predicted data obtained from correlation equations for all measured properties were in fairly good agreement with the experimental data.     

Excess molar volumes and deviations of refractive indices at 298.15 K for binary and ternary mixtures with pyridine or aniline or quinoline

Excess molar volume (V^E) at 298.15 K are reported for the binary systems of heterocyclic nitric compounds: {ethanol + pyridine}, {ethanol + aniline}, {ethanol + quinoline}, {pyridine + aniline}, {pyridine + quinoline}, {aniline + quinoline}, {N-methylformamide (NMF) + pyridine}, {NMF + aniline}, {NMF + quinoline}, {N,N-dimethylformamide (DMF) + pyridine}, {DMF + aniline} and {DMF + quinoline}. The deviations in molar refractivity (ΔR) at 298.15 K are also reported for binary systems: {ethanol + pyridine}, {ethanol + aniline}, {NMF + pyridine}, {NMF + aniline}, {DMF + pyridine}, {DMF + aniline} and {pyridine + aniline}. The determined V^E and ΔR were correlated with the Redlich–Kister equation. In addition, the ternary V^E data at 298.15 K were predicted with correlated binary parameters for the systems: {ethanol + pyridine + aniline}, {ethanol + pyridine + quinoline}, {ethanol + aniline + quinoline}, {NMF + pyridine + aniline}, {NMF + pyridine + quinoline}, {NMF + aniline + quinoline}, {DMF + pyridine + aniline}, {DMF + pyridine + quinoline} and {DMF + aniline + quinoline}. The ternary ΔR data at 298.15 K are also predicted for the systems: {ethanol + pyridine + aniline}, {NMF+ pyridine + aniline} and {DMF + pyridine + aniline}.     

Electrical conductivities for four ternary electrolyte aqueous solutions with one or two ionic liquid components at ambient temperatures and pressure

Thiswork provides amethod to explore the transport property of the electrolyte aqueous solutionswith one or two ionic liquids, especially focus on their electrical conductivity. The conductivities were measured for the ternary systems NaCl–[C₆mim][Cl] (1-hexyl-3-methylimidazolium chloride)–H₂O, [C₆mim][BF₄]–[C₆mim][Cl]–H₂O, NaNO₃–[C₆mim][BF₄](1-hexyl-3-methylimidazolium tetrafluoroborate)–H₂O, and [C₄mim][BF₄] (1-butyl-3- methylimidazolium tetrafluoroborate)–[C₆mim][BF₄]–H₂O, and their binary subsystems NaNO₃–H₂O, NaCl–H₂O, [C₆mim][BF₄]–H₂O, [C₆mim][Cl]–H₂O, and [C₄mim][BF₄]–H₂O, respectively. The conductivities of the ternary systems were also determined using generalized Young's rule and semi-ideal solution theory in terms of the data of their binary solutions. The comparison showed that the two simple equations provide good predictions for conductivity of mixed electrolyte solutions and the mixed ionic liquid solutions based on the conductivity of their binary subsystems.     

Conductivities of calcium chloride and calcium chloride-sodium chloride solutions saturated in calcium carbide and unsaturated in calcium oxide

The specific conductivity variation of the named solutions vs temperature in the range 750–950°C and vs the sodium chloride molar fractions have been measured. The specific conductivity increases sharply with increasing sodium chloride M fraction and reaches a maximum when the M fraction ratio of sodium chloride to calcium carbide is nearly two. This experimental result has been interpreted by assuming interactions between calcium carbide and sodium chloride, and constitutes a verification of a previous thermodynamic result obtained by the same authors.     

The pH of CO2-saturated water at temperatures between 308 K and 423 K at pressures up to 15 MPa

We report pH measurements for CO₂-saturated water in the pressure range from (0.28 to 15.3) MPa and temperatures from (308.3 to 423.2) K. Commercially available pH and Ag/AgCl electrodes were used together with a high pressure equilibrium vessel operating under conditions of precisely controlled temperature and pressure. The results of the study indicate that pH decreases along an isotherm in proportion to −log₁₀(x), where x is the mole fraction of dissolved CO₂ in H₂O. The expanded uncertainty of the pH measurements is 0.06 pH units with a coverage factor of 2. The reported results are in good agreement with the literature in pressure ranges up to 16 MPa at temperatures below 343 K. An empirical equation has been developed to represent the present results with an expanded uncertainty of 0.05 pH units. We also compare our results with a chemical equilibrium model and find agreement to within 0.1 pH unit.     

Deterioration in mechanical properties of glass fiber‐reinforced nylon 6,6 composites by aqueous calcium chloride mixture solutions

In this article, nylon 6,6 (NY66) and glass fiber‐(30 wt%) reinforced NY66 (GFNY66) specimens were immersed in various aqueous calcium chloride (aq. CaCl₂) mixture solutions at different thermal conditions for varying intervals of time, and analyzed using attenuated total reflection‐infrared (ATR‐IR) spectroscopy, inductively coupled plasma (ICP), energy dispersive X‐ray (EDX), gel permeation chromatography (GPC), and mechanical studies. ICP data revealed increasing concentration of absorbed Ca²⁺ ions with increasing immersion time resulting in disruption of intra‐ and intermolecular H‐bonding as confirmed using ATR‐IR results. From EDX data, the ratio of Ca²⁺ and Cl⁻ ions absorbed by NY66 was calculated and found to follow its stoichiometric equivalence. GPC data exhibited less reduction in M_n and M_w for aq. CaCl₂‐treated NY66 specimens suggesting the absence of any significant chemical degradation, but the occurrence of only physical changes involving H‐bond breakage and the formation of new CO···Ca²⁺ dative bond in NY66 matrix. The mechanical properties of GFNY66 samples treated with various types of aq. CaCl₂ solutions exhibited pronounced deterioration, possibly due to the interfacial failure between glass fiber and NY66 matrix. The results obtained from this study were quite useful toward understanding the degradation mechanism in NY66 and GFNY66 caused by various aq. CaCl₂ mixture solutions, and will be helpful in improving the mechanical properties of recycled NY66. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers     

Stoichiometric activity coefficients of aqueous H2SO4 solutions at 298·15°K

Earlier emf data on cells using the PbSO₄/Pb(Hg) electrode have been used, in conjunction with a recent determination of the standard potential of this electrode, to calculate stoichiometric activity coefficients of H₂SO₄ in water at 298·15°K.