果糖-水混合溶液中多组分电解质热力学

恒定混合溶液总离子强度I=1.0000 mol•kg－1,改变果糖-水混合溶液中果糖的质量分数w=2.5％、5.0％和7.5％的条件下,应用电动势方法测定下列无液体接界电池(A)和(B)在278.15、283.15、288.15、293.15、298.15、303.15、308.15、313.15、318.15 K等9个温度下的电动势: Pt, H2 (105 Pa)│HCl(m), C6H12O6(w), H2O(1－w)│AgCl-Ag (A) Pt, H2 (105 Pa)│HCl(mA), NaCl(mB), C6H12O6(w), H2O(1－w)│AgCl-Ag (B)根据测得电池的电动势,计算出混合溶剂中AgCl-Ag电极的标准电极电势和HCl的标准迁移吉布斯自由能、迁移熵和迁移焓; 求出四元混合溶液中HCl的活度系数γA.结果表明在溶液中总离子强度I保持恒定,HCl的活度系数服从Harned规则,进一步讨论了混合物中HCl的介质效应.

Thermodynamics of Mixed Electrolytes in Mixed Solvents of Fructose and Water

Sugars are not only biologically important compounds but also typical nonelectrolyte with hydrophilic hydroxyl group, which are capable of hydrogen bonding. D-fructose is an important class of single sugar, and exists in human body with a certain concentration. D-fructose can be absorbed by cells directly. Chemists and biologists pay great attention to it, because of its importance in the research work of biochemistry. In this paper the thermodynamic properties of HCl-NaCl- C6H12O6-H2O system has been studied by EMF measurement in cells without liquid junction from 278.15 to 318.15 K Pt, H2(105 Pa)|HCl(m), C6H12O6 (w), H2O(1－w)|AgCl-Ag (A) Pt, H2(105 Pa)|HCl(mA), NaCl(mB), C6H12O6 (w), H2O(1－w)|AgCl-Ag (B)with the mass fraction of fructose w(C6H12O6)=2.5％、5％ or 7.5％ at a total ionic strength I=1.0000 mol•kg－1. The standard electrode potential of AgCl-Ag in the mixed solvent was determined for cell (A). The standard transfer Gibbs free energies, entropy and enthalpy of HCl from water to mixed solvent were calculated. The activity coefficients of HCl(γA) in the mixed solvent was determined from cell (B). The results show that the activity coefficients of HCl in HCl-NaCl solutions still obeys Harned′s Rule. The primary,secondary and total medium effect of HCl were calculated and discussed.