邻苯二甲酸在异丙醇-水混合溶剂中电离热力学性质的研究

有机酸在混合溶剂中电离热力学性质的研究,无论在化学还是在生物领域中都有十分重要的意义。长期以来,人们对其进行了大量的研究,但对芳香族酸在混合溶液中的电离热力学性质的研究还只限于单取代苯甲酸在乙醇-水等少数几种混合溶剂中的热力学性质。为此,我们在278.15—318.15K范围内测定了无液接电池:     

邻苯二甲酸在异丙醇-水混合溶剂中电离热力学性质的研究

The first thermodynamic dissociation constants of o-phthalic acid were determined at five temperatures from 278.15 to 318.15 K in 10, 14.93 and 20 wt% isopropanol-water solvent mixtures, by precise e. m. f. measurements of hydrogen-silver chlorld electrodes in cells without liquid junction. On the basis of Pitzer's theory, the method of polynomial approximation was used to determine the dissociation constants of H_2P and the results obtained were compared with traditional extrapolation according to the extended Debye-Huckel equation Results obtained from both methods agree within experimental error. The dependence of the first thermodynamic dissociation constant on temperature was given as a function of the thermodynamic temperature T by the empirical equation: pK_1=A_0+A_1/T+A_2/T. The thermodynamic quantities of dissociation in the mixed solvents have been calculated, and the results have been discussed.     

尿素-水混合溶剂中硫酸热力学性质的研究

本文应用电动势法测定下面无液接电池在278．15-318．15K温度范围内的电动势。     

水-乙醇混合溶剂中弱酸电离的溶剂效应

本文用LKB2277Bioactivity monitor微量流动热量计测定卤代乙酸. 脂肪酸在水-乙醇混合溶剂中的标准电离焓,计算了热力学函数.结合文献数据,计算各酸根离子从水迁移到混合溶剂的迁移自由能,并讨论溶剂效应对弱酸电离的影响1.     

异丙醇-水体系中分子间相互作用对萘迁移热力学性质的影响

研究了萘从水到H2O-异丙醇(IPA)混合溶剂中的迁移变化,表明萘的迁移随异丙醇摩尔分数x(IPA)的增加呈复杂的下降趋势．标准迁移熵和标准迁移焓的研究表明,随异丙醇摩尔分数x(IPA)的增加,二者呈现双峰变化．迁移熵和迁移焓的双峰变化,表明系列H2O-IPA混合溶剂的微观结构经历了从相对的有序到元序到再有序、再元序、再有序的变化过程,H2O-IPA混合溶剂中除了在富水区存在着笼合物的特殊结构外,在x(IPA)约为0．08处还存在着一相对有序的结构．研究表明,H2O-异丙醇(IPA)混合溶剂组成、结构变化均对萘的迁移产生着明显的影响．     

混合溶剂中氨基酸热力学性质的研究 IV: 278.15-318.15K下甘氨酸-乙醇-水体系

在混合溶剂中恒定乙醇的质量百分数χ=10%, 应用电动势法测定了无液接电池(A)和电池(B)的电动势。根据电池(A)和电池(B)的电动势, 用传统的Debye-Huckel外推法和我们在前文提出的多项式逼近程序, 确定了甘氨酸有278.15-318.15k范围内5个温度下的第一、第二热力学解离常数, 两种方法所得的结果在实验误差范围内一致。并相应计算了该体系的热力学量。     

混合溶剂中氨基酸热力学性质的研究 IV: 278.15-318.15K下甘氨酸-乙醇-水体系

在混合溶剂中恒定乙醇的质量百分数χ=10%, 应用电动势法测定了无液接电池(A)和电池(B)的电动势。根据电池(A)和电池(B)的电动势, 用传统的Debye-Huckel外推法和我们在前文提出的多项式逼近程序, 确定了甘氨酸有278.15-318.15k范围内5个温度下的第一、第二热力学解离常数, 两种方法所得的结果在实验误差范围内一致。并相应计算了该体系的热力学量。     

盐酸在氨基酸水溶液中热力学性质的研究——Ⅰ.甘氨酸+盐酸+水体系

生物体液可看作是由多种离子与氨基酸、蛋白质组成的混合电解质溶液,研究电解质或离子与这些氨基酸、蛋白质间的相互作用对了解生物体液内复杂的作用机理,揭示许多生命现象具有重要意义。1978年以来,Kelley采用有液体接界的电池研究了几种氨基酸或肽与一些碱金属氯化物的相互作用自由能,为研究电解质与氨基酸、蛋白质间的相互作用奠定了基础。研究溶质的迁移热力学性质是了解溶质-溶剂间相互作用以及溶液微观结构的常用手段。以氨基酸水溶液作为含水离子溶剂,用电动势法研究电解质从水到该溶液中的迁移热力学性质,进而研究电解质与氨基酸间的相互作用是可行的,目前这方面的研究工作很少见文献报导。本文通过测定电池:     

盐酸在氨基酸水溶液中热力学性质的研究 I. 甘氨酸+盐酸+水体系

Standard potentials (E°_m) of the Ag-AgCl electrode in Glycine+H_2O mixture at 25 ℃, 30 ℃, 35 ℃, 40 ℃, and 45 ℃ have been determined from the EMF measurements of cells of the type: Pt, H (g, 101.325 kPa)|HCl(m)+Glycine+H_2O|AgCl-AgThese values have been utilized to evaluate the transfer energetics (ΔG°_t, ΔH°_t, ΔS°_t) accompanying the transfer of 1 mol HCl from the standard state in water to the standard state in Glycine+H_2O mixtures. Attempts have been made to explain the transfer energetics varying with different compositions of Glycine+H_2O mixtures in the light of ion-solvent interactions and the structureal effects of the solvents.     

葡萄糖和水混合溶液多组分电解质热力学II. HCl-NaCl-d-Glucose-H2O体系(5-45 ℃)

The thermodynamic properties of HCl-NaCl-d-Glueose-H_2O system was studied by emf measurement without liquid junction. Pt, H_2(1.013×10~5 Pa)|Hel(m), d-Glucose(x), H_2O(1-x)| Agel-Ag (A) Pt, H_2(1.013×10~5Pa)|HCl(m_A), NaCl(m_B), d-Glucose(x), H_2O(1-x)|AgCl-Ag (B) at the mass percentage of d-Glucose x=5%, 15% and 20% in the mixed solution, from 5 to 45 ℃, for cell (B) at constant total ionic strength I=1.00 mol·kg~(-1). The standard electrode potential of Ag-AgCI in the mixed solution have been determined from cell (A). The activity coefficients of HCl, γ_A, in the mixed solution system have been determined from cell (B). The results show that the activity coefficients of HCl in HCl-NaCl solutions still obeye Harned Rule. The standard transfer Gibbs free energies of HCl have calculated. The primary, secondary and total medium effect of HCl have been calculated.