化学学报 ›› 1994, Vol. 52 ›› Issue (10): 937-946.    下一篇

研究论文

NaCl在CH~3OH-H~2O混合溶剂中活度系数的测定(298.15K)

阎卫东;徐奕瑾;韩世钧   

  1. 浙江大学化学系
  • 发布日期:1994-10-15

Activity coefficients of sodium chloride in methanol-water mixed solvents at 298.15K

YAN WEIDONG;XU YIJIN;HAN SHIJUN   

  • Published:1994-10-15

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

关键词: 水, 甲醇, 氯化钠, 活度系数, 缔合常数, DEBYE-HUCKEL方程, PITZER方程

Emf. measurements of the cell, Na-ISE | NaCl(m), CH3OH(Y), H2O (100-Y) | Cl-ISE (solid state), were carried out at the different molalities of NaCl in the mixtures of CH3OH-H2O containing 0, 20, 40, 60, 80, 90 and 100 of wt.(%) of CH3OH, resp. at 298.15K. Calcns. of standard cell potential of each condition were made by using the extended Debye-Hueckel equation and the Pitzer equation. The calculating results of standard potential of two equations were in good agreements with each other. The mean activity coefficients of NaCl were obtained from the standard potentials by means of the Pitzer equation. The Pitzer-Simonson equation was applied to the system containing ionic pairs. According to this equation the association constants of NaCl in mixtures of CH3OH-H2O are estimated from the experimental emf. data. It showed that NaCl may be associated in 60% of CH3OH. Finally the standard molar Gibbs free energies of transfer, DG癵, of the NaCl from water to methanol-water mixed solvents were calculated using the E?of the cell (I).

Key words: WATER, METHANOL, SODIUM CHLORIDE, ACTIVITY COEFFICIENT, ASSOCIATION CONSTANT

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