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用桥式电路测定了H_2O-C_2H_5OH-NaCl体系的摩尔电导,并用Lee-Wheaton模型回归出H_2O-C_2H_5OH-NaCl(KCl、CsCl、KBr)体系的离子缔合常数、极限摩尔电导和距离参数,并求出缔合反应标准自由焓。结果表明离子缔合能力的顺序为Cs~+>K~+>Na~+,Cl~->Br~-,此四种盐在乙醇中都形成溶剂分开型离子对。并用液上空间气相色谱法测定了水-乙醇-(NaCl、KCl、KBr)体系中溶剂的活度,用改进的Pitzer-Li公式计算了此体系的活度系数,计算时考虑了盐在低介电常数溶剂中的离子缔合,结果表明这种处理是合适的。还表明离子缔合程度随着乙醇浓度上升而加大,以及盐的存在对水呈盐溶效应而对乙醇呈盐析效应。
The molar conductance of H_2O-C_2H_5OH-NaCl system was determined by bridge circuit. The ionic association constant, the limit molar conductance and distance parameters of H_2O-C_2H_5OH-NaCl (KCl, CsCl, KBr) Find the standard free enthalpy of association reaction. The results showed that the order of ionic association was Cs ~ +> K ~ +> Na ~ + and Cl ~ -> Br ~ -. These four salts all formed solute separate ion pairs in ethanol. The activity of solvent in water-ethanol- (NaCl, KCl, KBr) system was determined by headspace gas chromatography. The activity coefficient of this system was calculated by the improved Pitzer-Li formula. The dielectric constant of the ionic association in the solvent shows that this treatment is suitable. It also showed that the degree of ionic association increased with the increase of ethanol concentration, and the presence of salt showed salinization effect on water and salt precipitation effect on ethanol.