Dielectric spectroscopy on aqueous solutions of zinc(II) chloride. Evidence of ion complexes
Dielectric spectroscopy on aqueous solutions of zinc(II) chloride. Evidence of ion complexes
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氯化锌(II) 水溶液的介电谱。
DOI：
10.1021/j100292a046
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发表时间：
1987
期刊：
影响因子：
--
通讯作者：
R. Pottel
中科院分区：
文献类型：
--
作者：
U. Kaatze;V. Lönnecke;R. Pottel
氯化锌在水中的溶解行为长期以来引起物理化学家的兴趣。该体系的热力学、结构和输运性质与碱土金属卤化物和过渡金属卤化物水溶液有本质的不同。到目前为止，还没有找到令人满意的解释。有证据表明，在稀水溶液中，ZnCl 2完全离解，但在更浓的溶液中，存在离子络合物结构。然而，系统改变其行为的浓度取决于所考虑的性质。例如，阳离子迁移数作为溶质浓度的函数的图显示在0.5 mol/L氯化锌处斜率的突然变化。1对ZnCl_2和ZnBr_2溶液的活度系数的分析表明，在浓度高于约0.3M时形成新的络合物结构。[2]根据电导率和粘度数据，Weingártner等人[3]得出结论，ZnCl 2在低于0.1 mol/L时应完全解离，但在高于该浓度时络合物的形成会突然发生。这些作者指出，ZnCl 2水溶液中的离子扩散系数表明，即使低于0.1 mol/L，也存在氯化锌络合物。
The solution behavior of zinc chloride in water has intrigued physical chemists for a long time. The thermodynamic, structural, and transport properties of that system are essentially different from those of alkaline-earth halideand transition-metal halide aqueous solutions. 1™ 3 No satisfactory explanation has so far been found. Evidence suggests that in dilute aqueous solution ZnCl2 is completely dissociated but that in more concentrated solutions ion complex structures exist. The concentration at which the system changes its behavior, however, depends on the property considered. For example, plots of the cationic transference number as a function of solute concentration show an abrupt change in slope at 0.5 mol/L zinc chloride. 1 Analysis of the activity coefficients of ZnCl2 and ZnBr2 solutions suggests that new complex structures are formed at concentrations above about 0.3 m. 2 From conductance and viscosity data Weingártner et al. 3 concluded that ZnCl2should be completely dissociated below 0.1 mol/L but that complex formation occurs rather suddenly above that concentration. These authors stated that ionic diffusion coefficients in aqueous ZnCl2 solutions point to the existence of zinc chloride complexes even below 0.1 mol/L.