钨酸钠水溶液的活度系数和渗透系数

The activity coefficients and osmotic coefficients of Na_2WO_4 aqueous solution in the concentration range of 0.3--2.5 mol·kg~(-1) have been determined by the isopiestic method. The excess Gibbs free energies are evaluated with the correspording activity coefficientc and osmotic coefficients.     

Thermodynamics of mixed electrolyte solutions. IX. Calculation of the osmotic and activity coefficients in a pseudoternary system (NaCl−nKCl)−MgCl2-H2O at 298.15°K

The equation of Reilly, Wood, and Robinson was used to predict the osmotic coefficient of a pseudoternary system (NaCl–nKCl)–MgCl₂–H₂O over a molal ionic strength range of 1.0 to 5.0 moles-kg^–1. The results are in close agreement with experimental data at most ionic strengths. The standard deviation in the osmotic coefficients over the entire concentration range lies within 0.0035. The predicted values of the mean activity coefficients are in good agreement with those obtained by the treatments of both Scatchard and Friedman. Mean activity coefficients for the other components were also predicted.     

等压法测定Li2SO4-MgSO4-H2O体系的渗透和活度系数

在25 ℃下, 离子强度范围分别为0.2—8.7、0.6—12.7和1.4—13.5 mol·kg~(-1)时, 测定了纯Li_2SO_4、MgSO_4及Li_2SO_4-MgSO_4混盐水溶液的渗透系数. 计算了Pitzer方程和Scatchard方程的离子作用参数. 用上述两种方程及由热力学关系式直接推导出的Mckay-Perring方程计算并比较了Li_2SO_4和MgSO_4在混合溶液中的平均活度系数, 三者在实验误差范围内一致. 利用获得的Pitzer参数计算该体系的溶解度与文献值基本一致.     

Thermodynamic properties of alkali halides. V. Temperature and pressure dependence of excess free energies in water

A simple equation has been derived relating the temperature dependence of activity functions with excess enthalpies and excess heat capacities. Using experimentally determined parameters at 298.15°K, it is possible to predict osmotic coefficients and mean activity coefficients of alkali halides in water up to 1 m from 273°K to about 350°K. In general, the predicted functions agree with the measured values within the uncertainty of the activity data. An equation is also given for the pressure dependence of the excess free energies, but it was not possible to check the limitation of this equation due to lack of activity data at various pressures.To whom correspondence should be addressed.     

多羟基化合物水溶液渗透系数的测定

The determination of the osmotic coefficients of the aqueous solution of polyhydroxylated compounds such as glycol, glycerol, sucrose and glucose by Vapour Pressure Osmometry at 313, 323 and 333K was carried out over the concentration range of 0.0-2.1mol﹒kg-1 and 0.0-2.0 mol﹒kg-1 respectively. By using a linear least-square fitting routine, the osmotic coefficients were fitted by a simple polynomial equation, It was found that the relation between the experimental results of molal osmotic coefficients Φ and the mass molal concentration of the solution m are in agreement with that from the polynomial fitting at different temperature. Factors which influence the osmotic coefficient such as the number of hydroxyl of polyhydroxylated compounds or the molecule weight of the solute molecules should be further studied, this work will also contribute to the studies of other thermodynamical properties of the aqueous solution of polyhydroxylated compound.     

等压法装置和焦磷酸钾活度的测定

测量活度的方法很多,等蒸气压法是其中的主要方法之一,我们根据等压法原理设计和安装了一套较简单的实验装置,测量了焦磷酸钾在不同浓度水溶液中的平均活度系数和渗透系数,结果与文献[1]相符,证明实验装置合乎要求。     

Isopiestic Determination of Osmotic and Activity Coefficients for Solutions of LiCl, LiBr, and LiNO3 in 2-Propanol at 25°C

The osmotic coefficients of lithium chloride, lithium bromide, and lithium nitrate in 2-propanol have been measured by the isopiestic method at 25^°C. Sodium iodide was used as the isopiestic standard. The molality ranges covered were from 0.2 to 1.5 for LiCl and LiBr, and to 1.9 mol-kg^-1 for LiNO₃. The system of equations developed by Clegg–Pitzer and Pitzer were used to fit each set of osmotic coefficients. The experimental osmotic coefficient data are successfully correlated with these models. The parameters from the fit were used to calculate the mean molal activity coefficients.     

Thermodynamics of electrolyte solutions: Activity and osmotic coefficients of aqueous NaCl in the NaCl-MgCl2-H2O system at different temperatures by the EMF method

The activity and osmotic coefficients of aqueous NaCI in the NaCl-MgCl₂-H₂O system at 25, 35 and 45°C and total ionic strengths of 0.5, 1, 2 and 3 were obtained by an EMF method using a sodium ion-selective electrode and an Ag/AgCl electrode. The Harned coefficients and Pitzer binary and ternary interaction coefficients were also determined.     

Effect of temperature on the behavior of osmotic and activity coefficients of amides in aqueous solutions

The osmotic coefficients of acetamide, propionamide and butyramide in water were measured at 293.15, 298.15 and 308.15 K using the isopiestic method. The activity coefficients were calculated for the aliphatic amides and the pairwise free energy coefficients for solute-solute interactions were determined according to the McMillan-Mayer theory. The osmotic and activity coefficients of amides are discussed in terms of solute-solute interactions.     

Osmotic and Activity Coefficients of Nonaqueous Electrolyte Solutions. 1. Lithium Perchlorate in the Protic Solvents Methanol, Ethanol, and 2-Propanol

Vapor pressure lowering by the addition of LiClO₄ to the protic solvents methanol (0.04–5.1 m), ethanol (0.03–1.5 m), and 2-propanol (0.05–1.5 m) was measured at 25°C with high precision. The experimental data of the corresponding osmotic coefficients are compared to those obtained by the use of Pitzer equations and chemical model calculations. Mean activity coefficients are derived from the osmotic coefficients.     

Calculation of the osmotic and activity coefficients of seawater at 25°C

The equation of Reilly, Wood, and Robinson was used to predict the osmotic coefficient of seawater and of its concentrates at molal ionic strengths of 0.5 to 6.0 at 25°C. The results agree closely with experimental data at ionic strengths below 5. The average difference in osmotic coefficients over the entire concentration range is 0.0014. The only serious discrepancy is at an ionic strength of 6, where a difference of 0.0068 is found. The accuracy of the predictions of osmotic coefficients prompted the calculation of the activity coefficients of NaCl, Na₂SO₄, MgCl₂, MgSO₄, KCl, and K₂SO₄ in the mixture. The calculated activity coefficients of NaCl and Na₂SO₄ agree within experimental error with previous measurements. This agreement demonstrates the prediction of activity and osmotic coefficients for complex mixtures.     

等压法测定298.15K下LiCl-CaCl2-H2O体系的活度系数

电解质水溶液热力学性质的研究一直是一个很活跃的研究领域.对含锂水盐体系热力学性质的研究不仅对电解质水溶液理论,而且对盐湖锂资源的开放利用都有非常重要的意义.姚燕等对ＬｉＣｌＫＣｌＨ2Ｏ[1],ＬｉＣｌＭｇＣｌ2Ｈ2Ｏ[2],ＬｉＣｌＭｇＳＯ4Ｈ2Ｏ[3,4],ＬｉＣｌＬｉ2ＳＯ4Ｈ2Ｏ[5]体系多温下热力学性质进行了研究,应用Ｐｉｔｚｅｒ电解质水溶液理论模型进行处理,计算出ＬｉＣｌ在不同体系中,很大的浓度范围内的活度系数.但在盐湖卤水中,ＣａＣｌ2的存在很普遍.对ＬｉＣｌＣａＣｌ2混合物在水溶液中的热力学性质研究对理解ＬｉＣｌ在盐…     

Statistical associating fluid theory coupled with restrictive primitive model extended to bivalent ions. SAFT2: 1. Single salt + water solutions

Statistical associating fluid theory coupled with the restricted primitive model is extended to multivalent ions by relaxing the range of the square-well width parameter, which leads to a new dispersion term approximation and calls for a new set of salt and ion parameters. This new approximation, referred to as SAFT2, requires a single set of parameters derived from the salt (mean ionic) activity coefficients and liquid densities of single-salt solutions for five cations (Li(+), Na(+), K(+), Ca(2+), Mg(2+)), six anions (Cl(-), Br(-), I(-), NO(3)(-), SO(4)(-2), HCO(3)(-)), and 24 salts. These parameters, in turn, are shown to predict the osmotic coefficients for single salt + water solutions.     

Estimation of activity and osmotic coefficients of strong electrolytes in water at elevated temperatures

It was found over a wide concentration and temperature range that differences between osmotic coefficients of a given electrolyte and a standard electrolyte, - ^st , can be approximated by a linear relation. Sodium chloride, calcium chloride and sodium sulfate were chosen as standard electrolytes for 1:1, 2:1 and 1:2 electrolytes, respectively. Special numerical procedures were developed for the prediction and estimation of activity and osmotic coefficients at elevated temperatures based on data at two temperatures or on data at room temperature only. Reasonable agreement was found between activity coefficients estimated by the present procedure and those correlated by Pitzer's and Meissner's equations.     

Freezing points and related properties of electrolyte solutions. II. Mixtures of lithium chloride and sodium chloride in water

The freezing points of aqueous lithium chloride and its mixtures with sodium chloride have been measured from 0.1 to 1.5m. From these measurements, calorimetric enthalpies of mixing, and osmotic coefficients of the pure salts at 298°K, osmotic and activity coefficients of the mixtures have been calculated up to 6.0m at 298°K. Excellent agreement with the literature values is found over the entire range of composition. This method of computation is considered to be superior to the analysis of only isopiestic results in the calculation of activity coefficients in mixed electrolytes.     

Thermodynamics of electrolytes. IX. Rare earth chlorides,nitrates, and perchlorates

The extensive data for the osmotic coefficients, heats of dilution, and densities of aqueous solutions of rare earth chlorides, nitrates, and perchlorates are fitted to a single type of equation found satisfactory for many other solutes Good agreement is obtained. The various parameters do not show simple trends with cation radius. While there are some plausible explanations of these complexities, the total picture is far from clear.     

273.15K时LiCl-Li2SO4-H2O体系热力学性质的等压研究

0℃下用改进的等压设备和改进的实验方法测定了纯水溶液(LiCl 0.5～9.2mol·kg-1,Li2SO40.3～2.5mol·kg-1)以及混合水溶液(离子强度0.5～9.5mol·kg-1)的水活度和渗透系数.该体系的等水活度线与Zdanovskii规则非理想混合溶液表达式的标准偏差为0.0088,当Li2SO4溶液达到饱和后,用Zdanovskii规则扩展式计算,标准偏差为0.0027.根据Pitzer离子相互作用模型对实验数据进行了理论分析,用本文和不同来源的文献数据拟合求取了0℃下该体系的Pitzer纯盐参数和混合参数,计算值与实验值相吻合.     

Thermodynamic studies of molecular interactions in aqueous alpha-cyclodextrin solutions: application of McMillan-Mayer and Kirkwood-Buff theories

Osmotic vapor pressure and density measurements were made for aqueous alpha-cyclodextrin (alpha-CD) solutions in the temperature range between 293.15 and 313.15 K. The experimental osmotic coefficient data were used to determine the corresponding activity coefficients and the excess Gibbs free energy of solutions. Further, the activity data obtained at different temperatures along with the enthalpies of dissolution (reported in the literature) were processed to obtain the excess enthalpy and excess entropy values for the solution process. The partial molar entropies of water and of alpha-cyclodextrin were calculated at different temperatures and also at different concentrations of alpha-CD. Using the partial molar volume data at infinite dilution, the solute-solvent cluster integrals were evaluated which yielded information about solute-solvent interactions. The application of McMillan-Mayer theory of solutions was made to obtain osmotic second and third virial coefficients which were decomposed into attractive and repulsive contributions to solute-solute interactions. The second and third osmotic virial coefficients are positive and show minimum at 303.15 K. The Kirkwood-Buff (KB) integrals G(ij), defined by the equation G(ij) = f(infinity)0 (g(ij)- 1)4pir(2) dr, have been evaluated using the experimental osmotic coefficient (and hence activity coefficient) and partial molar volume data. The limiting values of KB integrals, G(ij)(0) are compared with molecular interaction parameters (solute-solute i.e., osmotic second virial coefficient) obtained using McMillan-Mayer theory of solutions. We found an excellent agreement between the two approaches.     

Statistical associating fluid theory coupled with restrictive primitive model extended to bivalent ions. SAFT2: 2. Brine/seawater properties predicted

Statistical associating fluid theory coupled with restricted primitive model (SAFT2) represents the properties of aqueous multiple-salt solutions, such as brine/seawater. The osmotic coefficients, densities, and vapor pressures are predicted without any additional parameters using the salt hydrated diameters obtained for single-salt solutions. For a given ion composition of brine, the predicted vapor pressure, osmotic coefficient, activity of water, and density are found to agree with the experimental data.     

Osmotic Coefficients and Activity Coefficients of Nonaqueous Electrolyte Solutions. Part 2. Lithium Perchlorate in the Aprotic Solvents Acetone, Acetonitrile, Dimethoxyethane, and Dimethylcarbonate

Vapor pressure lowering by the addition of lithium perchlorate to the aprotic solvents acetone (0.02–0.6 m), acetonitrile (0.05–1.2 m), dimethoxyethane (0.02–0.4 m), and dimethylcarbonate (0.03–1.8 m) was measured at 25°C with high precision. The experimental data for the corresponding osmotic coefficients are compared to those obtained from the Pitzer equations and chemical model calculations. Mean activity coefficients are derived from the osmotic coefficients.