NaCl在CH~3OH-H~2O混合溶剂中活度系数的测定(298.15K)

用电动势法测定了298.15K时,由Na^+和Cl^-离子选择电极组成的电池在NaCl-CH~3OH-H~2O混合体系中的电动势,用扩展的Debye-huckel方程和Pitzer方程关联不同溶剂组成下电动势的实验值,得到电池的标准电动势能和NaCl 在混合溶剂中的活度系数.将Pitzer-Simonson方程应用于含离子缔合体系.求出NaCl 在混合溶剂中的缔合常数,结果表明NaCl在甲醇含量为60%时,可能已有离子对生成     

甲醇-苯混合溶剂中NaI活度系数的测定与计算

测定了甲醇-苯-NaI体系在恒压条件下的汽液平衡数据,采用双标准检验法对数据进行检验,检验结果全部合格.应用P itzer强电解质在水溶液中的活度系数模型,采用全部合格的汽液平衡数据拟合出方程中的维利系数,从而获得在双液比固定条件下盐在甲醇-苯混合溶剂中的活度系数.计算结果表明,正常泡点温度下在具有固定双液比的甲醇-苯混合溶剂中,NaI的平均活度系数随盐浓度的增加先减小,经过一个极小值后又增加.     

298.15K下果糖水溶液中卤化钠单个离子活度系数

利用离子选择性电极和甘汞电极分别测定了NaX+果糖+水体系中的单个离子活度系数和离子平均活度系数.结果表明:基于Debye-Hückel扩展方程和Pitzer方程求得的单个离子活度系数彼此一致;由单个离子加合求得的与直接测定的平均离子活度系数也很一致;随果糖含量的增大,单个离子活度系数减小;在相同混合溶剂(果糖+水)和相等电解质浓度条件下,对于不同的NaX,Na+的活度系数大小顺序为NaFNaClNaBr.基于离子间的相互作用对结果进行了讨论.     

电动势法对LiCl-MgCl2-H2O体系热力学性质的研究

用自制的锂离子选择电极和经典的Ag-AgCl电极, 以电动势法测定了25 ℃时离子强度为0.05—6.0 mol·kg~(-1)范围的LiCl-MgCl_2-H_2O三元体系中LiCl的平均活度系数. 由实验数据, 求出了Pitzer方程、Harned方程和Scatchard方程的参数和系数. 用上述方程计算了LiCl 在该体系中的活度系数, 并与实验值进行比较, 标准偏差小于0.008. 与等压法测定的渗透系数拟合的Pitzer方程参数计算值比较在实验误差范围内. 同时计算了MgCl_2在该体系中的平均活度系数和混合溶液的渗透系数.     

活度系数法测定A2B型难溶盐的溶度积——以Ag2SO4为例

实验假设水溶液中Ag+和SO42－的浓度非常低时,其活度无论处于同一体系还是在不同体系均相同。依此设计原电池,使该原电池的电池反应为Ag2SO4(s)→2Ag+(aq)+SO42－(aq),采用补偿法测量一定温度下此原电池中AgNO3溶液浓度和K2SO4溶液浓度发生变化时的电池电动势E。依据能斯特方程和Debye-Huckel极限公式,推导出原电池标准电动势E?与电解质的平均活度系数γ±及溶液浓度的关系,用外推法作图得到此电池反应的标准电动势E?。由平衡常数与原电池标准电动势的关系,得到Ag2SO4的溶度积Ksp(Ag2SO4)。     

RbCl在H2O-DMF混合溶剂中活度系数的测定

应用Corning-价阳离子选择电极（M~＋－ISE）和Orion氯离子选择电极组成可逆电池，CI~－－ISE|RbCl（m），H2O（1－x），DMF（x）M~ －ISE．测量该电池标准电动势E_m，运用扩展的Debye－Hckel公式，计算RbCl在283．15至318．15K七个温度下由H2O至H2O－DMF混和溶剂的标准迁移自由能ΔG和在不同组成（H2O－DMF）混合溶剂中平均离子活度系数γ±，并对迁移自由能及活度系数随混合溶剂有机物组份的摩尔分数的变化进行了讨论。     

混合溶剂中混合电解质活度系数的研究——HCl+NaCl+PrOH+H_2O体系,298.15K

电动势法是测定混合电解质活度系数时常用的主要方法,曾用这种方法对混合电解质水溶液活度系数作过火量的研究。可是,在有机溶剂和水的混合溶剂中混合电解质的电动势数据和活度系数数据却很少。Akerlof等人在这方面进行了开创性的研究工作,他们在恒定总     

特丁醇和水混合溶剂多组分电解质热力学HCl—NaCl—tert—C_4H_9OH—H_2O体系(5～45℃)

本文在恒定特丁醇质量分数x=0.10的条件下,应用电动势法测定了无液接界电池(A)和电池(B)的电动势:Pt,H_2(1.013×10~5Pa)HCl(m),tert.-C_(4)H_9OH(x),H_2O(1-x)AgCl-Ag(A)Pt,H_2(1.013×10~5Pa)|HCI(m_A),NaCl(m_B),tert,-C_4H_9OH(x),H_2O(1-x)|AgCl-Ag(B)根据电池(A)电动势确定了混合溶剂中的Ag-AgCl电极的标准电极电势,讨论了HCl的迁移性质;利用电池(B)的电动势计算了HCl在该体系中的活度系数γ_A,结果表明,在恒定总离子强度下,HCl的活度系数服从Harned规则.计算了HCl的一级、二级和总介质效应.     

HCl-NaCl-C3H8O3-H2O体系溶液热力学性质

在恒定丙三醇质量分数x=0．1的条件下，测定了无液接电池（A）和电池（B）的电动势根据电池（A）电动势确定了丙三醇和水混合溶剂中的Ag－AgCl电极的标准电极电势，讨论了HCl的迁移性质；由电池（B）测得的电动势计算了HCl在该体系中的活度系数γA，计算的结果表明，对于所讨论的体系，在溶液中总离子强度保持恒定，HCl的活度系数服从Harned规则．在溶液组成恒定时，IgγA是温度倒数1／T的线性函数，讨论了混合物中HCl的相对偏摩尔焓及介质效应．     

混合溶剂中多组分电解质溶液热力学性质的研究III: HCl-NaCl-i-PrOH-H2O体系(5-45℃)

在恒定溶液总离子强度I=1.00mol.kg^-^1, 改变异丙醇在混合溶剂中的摩尔分数x=0.025、0.075和0.100条件下, 测定了无液接界电池(A)和电池(B)的电动势.Pt, H2(1.013x10^5Pa)|HCl(m), i-PrOH(x), H2O(1-x)|AgCl-AgPt, H2(1.013X10^5Pa)|HCl(mA), NaCl(mB), i-PrOH(x), H2O(1-x)AgCl-Ag (B)根据电池(A)的电动势, 确定混合溶剂中Ag-AgCl电极的标准电极电势, 讨论了HCl的迁移性质. 利用电池(B)的电动势, 确定HCl活度系数γA. 结果表明, 在恒定I为1.00mol.kg^-^1时, HCl的活度系数仍然服从Harned规则. 在恒定溶液组成时, lgγA对热力学温度的倒数1/T作图, 具有良好直线关系. 进一步讨论了混合物中HCl的相对偏摩尔焓和HCl的溶剂化数及介质效应.     

用氯离子选择电极测定浓盐酸的活度系数及氯离子吸附效应的探讨

在25 ℃下, 用氯离子选择电极与玻璃电极组成电池测定了0.00498～15.02 molkg~(-1)浓度范围盐酸体系的电势, 发现用Nernst方程计算出的活度系数与文献值偏差极大。用氯离子吸附原理和形成吸附对的平衡原理导出的电势方程, 由此计算出的盐酸活度系数与文献值十分一致, 这表明氯离子在电极表面发生了特性吸附作用。     

New Physico-Chemical Properties of Extremely Diluted Solutions. Electromotive Force Measurements of Galvanic Cells Sensible to the Activity of NaCl at 25 °C

The mean ionic activity coefficients for sodium chloride in the NaCl+H₂O binary system have been experimentally determined at 298.15 K, from electromotive force measurements of the cell:

Activity coefficients of NaF in aqueous mixtures with ɛ-increasing co-solvent: formamide–water mixtures at 298.15 K

The electromotive force E, of the cell containing the ion-selective electrodes Na-ISE | NaF(m), formamide (Y), H₂O(100 − Y) | F-ISE has been measured at 298.15 K as a percentage of the weight of the amide in the mixed solvent. The percentage (Y) was varied from 0 to 90% in 10-unit steps, and the molality of the electrolyte (m) from approximately 0.005 to saturation. The corresponding standard electromotive forces, E⁰ (molal scale), were determined using traditional methods of extrapolation (Debye–Hückel and Pitzer equations). The results obtained by application of both equations show experimental errors of the same sort as those for this type of measurements. Once the E⁰ was obtained, we determined the mean ionic activity coefficients for NaF, the transfer free energy from water to the water–formamide mixture, and the NaF primary hydration number. The variation of these parameters, with the composition of this ɛ-increasing solvent, is discussed in comparison with that previously obtained for the ɛ-decreasing methanol–water and ethanol–water systems, in terms of both ion–solvent and ion–ion interactions and of the effect of the medium dielectric constant change.     

Activity coefficients of DL-valine in aqueous solutions of KCl at 25°C. Measurement with ion selective electrodes and modelling

Electrochemical cells with two ion selective electrodes, a cation and an anion ion selective electrode, versus a double junction reference electrode were used to measure the activity coefficients of DL-valine at 298.15 K, up to 0.5 molality, in aqueous solutions of KCl up to 1.0 molality. The results obtained in this work are compared with those reported before for the activity coefficients of DL-valine in aqueous solutions of NaCl. The experimental data were correlated using the model proposed previously by Khoshkbarchi and Vera for the activity coefficients of amino acids in aqueous electrolytes solutions.     

用玻璃电极测定直到15 m的浓盐酸体系的活度系数

本文在25 ℃下, 对0.01844—15.02 mol kg~(-1)浓度范围内的盐酸体系, 用自制Ag|AgGl电极和氢电极, 测定了Harned电池的电动势。在此基础上, 以玻璃电极代替氢电极, 测量上述盐酸体系的电动势, 计算了HCl的平均活度系数和H_2O的活度。实验结果表明, 玻璃电极在浓盐酸体系的“标准电势”是稳定的, 且遵从Nernst响应, 重现性良好, 响应速度快; 在高浓度和稀溶液中交替测量时, 电势无明显偏差。这说明电极有较好的可复性。求得的HCl的活度系数与文献值偏差小于1.2％。玻璃电极的“标准电势”的标准偏差为0.016％。     

Determination of activity coefficients using a flow EMF method. 1. HCl in methanol-water mixtures at 25, 35 and 45°C

A method to determine activity coefficients of electrolytes in mixed solvent is described which makes use of ion-selective electrode(s) (ISE) and in which a concentrated electrolyte solution is continuously added. Activity coefficients for HCl in methanol-water mixtures containing 0, 10, 20, 30, 50, 70, and 90 weight percent methanol at 25, 35 and 45°C were calculated using the Pitzer equation, and the electromotive force (emf) data of the cell: The experimental results agree well with literature values indicating that the proposed method is procise and reliable.     

三元体系NaCl-KCl-H2O35℃活度系数的研究

研究了35℃ NaCl-KCl-H2O三元体系的活度系数.用Na+、 K+和Cl-的离子选择性电极分别测得了(0.1～ 1.5 mmol/L)不同离子强度下该体系中NaCl和KCl的平均活度系数.回归了该体系Pitzer方程的相互作用参数.实验值与计算值最大相对误差为5.6%,而平均相对误差为2.3%.     

Thermodynamic behaviour of binary mixture of 1,3-dimethoxyimidazolium bis(trifluoromethyl-sulfonyl)imide and water

The osmotic coefficient value of binary aqueous solution containing ionic liquid was obtained by using vapour-pressure osmometry technique. The change in activity and vapour pressure depression of solvent on addition of 1,3-dimethoxyimidazolium bis(trifluoromethylsulfonyl) imide ((OMe)₂Im:NTf₂) to water have been estimated at two different temperatures (T =313 K and 323 K). The experimental osmotic coefficient values of (OMe)₂Im:NTf₂ at different molality were correlated by extended Pitzer model of Archer and the ion interaction parameters were evaluated. The correlation coefficients obtained from this model were used to estimate the mean molal activity coefficient, and excess Gibbs free energy of this mixture. The osmotic coefficient values were decreased with increase in molality of the ionic liquid within the solution. The osmotic coefficient values were found to be increased with increase in temperature of the system.     

Activity coefficients of KCl 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), K-ISE|KCl(m), PEG 4000(Y), H₂O(100 − Y)|Cl-ISE has been measured at temperatures of 288.15, 298.15, and 308.15 K as a function of the weight percentage Y of PEG 4000 in a mixed solvent. Y was varied between 0 and 25 wt.% in five-unit steps and the molality of the electrolyte (m) was between ca. 0.05 mol kg⁻¹ and almost saturation. The values of the standard electromotive force were calculated using routine methods of extrapolation together with extended Debye-Hückel and Pitzer equations. The results obtained produced good internal consistency for all the temperatures studied. Once the standard electromotive force was determined, mean ionic activity coefficients for KCl, Gibbs energy of transfer from the water to PEG 4000 + water mixtures, interaction parameters (g_EN, h_EN, s_EN, c_p,EN), salting constants, and the KCl primary hydration number were estimated and comparatively discussed in terms of a model of structural and electrostatic interactions with those of the LiCl and NaCl previously obtained in similar mixtures.     

Osmotic and activity coefficients in the binary solutions of 1-butyl-3-methylimidazolium chloride and bromide in methanol or ethanol at T = 298.15 K from isopiestic measurements

Osmotic coefficients of the binary solutions of two room-temperature ionic liquids (1-butyl-3-methylimidazolium chloride and bromide) in methanol and ethanol have been measured at T = 298.15 K by the isopiestic method. The experimental osmotic coefficient data have been correlated using a forth-order polynomial in terms of (molality)^0.5, with both, ion interaction model of Pitzer and electrolyte non-random two liquid (e-NRTL) model of Chen. The values of vapor pressures of above-mentioned solutions have been calculated from the osmotic coefficients. The model parameters fitted to the experimental osmotic coefficients have been used for prediction of the mean ionic activity coefficients of those ionic liquids in methanol and ethanol.