离子从水向20wt％和40wt％乙醇-水混合溶剂中迁移的标准自由能的测定

Determination of Standard Free Energies of Transfer of Individual Ions from Water to 20wt% and 40wt% Ethanol-Water Mixtures

本文论证了由于Cl^-是硬碱而I^-是软碱根据电解质标准迁移自由能ΔG_t^0(MCl)、△G_t^0(MBr)和△G_t^0(MI)作图外推计算单独离子标准迁移自由能ΔG_t^0(i)的方法是不正确的,提出了根据ΔG_t^0(MF)和ΔG_t^0(MCl)的作图外推法,对于20wt％和40wt％乙醇一水混合溶剂,所计算的ΔG_t^0(i)与碱金属氯化物的ΔG_t^0(MCl)作图外推法所计算的值比较一致,用离子选择电极电位法系统地测定了ΔG_t^0(NaX)(X=F^-、Cl^-、Br^-、I^-)、ΔG_t^0(LiCl)和ΔG_t^0(HCl)。

The paper demonstrated that the extrapolation procedure based on the standard free energies of transfer of electrolytes, ΔG_t^0(MCl), ΔG_t^0(MBr) and ΔG_t^0(MI), for calculating standard free energies of transfer of individual ions, ΔG_t^0(i),is not correct because chloride ion is a hard base and iodide ion is a soft one.Anextrapolation procedure based on ΔG_t^0(NaF) and ΔG_t^0(NaCl) is given, the ΔG_t^0(i) calculated agrees with that calculated using the extrapolation procedure based on the ΔG_t^0(MCl) of alkali-metal chloride for 20wt% and 40wt% ethanol-water mixtures.The ΔG_t^0(NaX) (X=F, Cl, Br, I), ΔG_t^0(LiCl) and ΔG_t^0(HCl) were determined by use of ion-selective electrode potentiometries.