TERNARY NaCl+LiCl+H2O MIXED ELECTROLYTE SYSTEM: DETERMINATION OF ACTIVITY COEFFICIENTS BASED ON POTENTIOMETRIC METHOD

The mean activity coefficients for NaCl in a ternary electrolyte system were determined by the potentiometric method, at 25°C, using a solvent polymeric (PVC) sodium-selective membrane electrode (Na⁺ ISE), containing N,N′-dibenzyl-N,N′-diphenyl-1,2-phenylenedioxydiacetamide as ionophore, and combined with an Ag/AgCl electrode. The potentiometric measurements were performed at the same ionic strengths in different series of mixed salt solutions, each characterized by a fixed salt molal ratio r (where r = m₁/m₂ = 1, 10, 50, 100). The nonideal behavior of the ternary NaCl(m₁) + LiCl(m₂) + H₂O electrolyte system was described based on the Pitzer ion-interaction model for mixed salts over the ionic strength ranging from 0.01 up to about 4 mol/kg. Two- and three-particle Pitzer interaction parameters for a mixed electrolyte system were determined based on potentiometric data, and the critical role of potentiometric selectivity coefficient (K ₁₂) of ISE as limiting factor in the potentiometric measurements was analyzed.     

连续滴加法快速测定混合溶剂中电解质的活度系数

改变通常的逐点称重配制溶液方法,用连续滴加的方法借助离子选择电极建立了混合溶剂中电解质较高浓度下活度系数的快速测定方法和装置。用以下电池: H~+玻璃电极|HCl(m),H_2O(1-x),MeOH(x)|AgCl-Ag电极测定了298.15K、溶剂比x=0,10,20,30,50,70,90％MeOH(wt)时的电动势,并用Pitzer方程关联出HCl的活度系数,同298.15K下的活度系数不同来源的文献值比较,表明本文测定方法和装置是可靠的,都能得到与之相一致的结果。     

用ISE法快速测定混合电解质溶液的活度系数

对ＮａＣｌ－ＫＣｌ－Ｈ２Ｏ溶液利用离子选择性电极（ＩＳＥ）的连续滴加法，快速测定出响应ＮａＣｌ的电动势，获得与用文献报道的活度系数计算出的电动势相一致的结果。由此电动势出发可以关联得到混合电解质溶液活度系数的Ｐｉｔｚｅｒ方程的参数，计算ＫＣｌ的活度系数同陆小华－Ｍａｕｒｅｒ提出的电解质溶液模型的预测结果也完全一致，表明本文方法可用于混合电解质溶液活度系数的快速测定。     

Solubility measurement and prediction of phase equilibria in the quaternary system LiCl + NaCl + KCl + H_2O and ternary subsystem LiCl+ NaCl + H_2O at 288.15 K

Using isothermal dissolution method, the phase equilibrium relationship in quaternary system LiCl + NaCl + KCl+ H_2O and the ternary subsystem LiCl + NaCl + H_2O at 288.15 K were investigated. Each phase diagram of two systems was drawn. The phase diagram of LiCl + NaCl + H_2O system contains two solid phase regions of crystallization LiCl·2H_2O and NaCl. In the phase diagram of LiCl + NaCl + KCl + H_2O system, there are three crystallization regions: LiCl·2H_2O, NaCl and KCl respectively. In this paper, the solubilities of phase equilibria in two systems were calculated by Pitzer's model at 288.15 K. The predicted phase diagrams generally agree with the experimental phase diagrams.     

混合电解质NaBr+NaAc十H_2O体系的活度系数的测定

用电势法测定了298.15K以及I为0.1、0.5、1.0、1.5、2.0、2.5和3.0 mol/kg时,NaBr在混合电解质溶液NaBr+NaAc+H_2O中的活度系数.实验结果用Harned、SRJ和Pitzer方程拟合,得到各种方程的相互作用参数,由拟合的标准偏差得知,Pitzer方程的拟合精度略好于前2个方程.用Pitzer混合参数θ_(Br-Ac)和ψ_(Br-Na-Ac)计算了NaAc在该混合体系中的活度系数和体系的过量Gibbs自由能.     

混合电解质NaBr+NaAc十H_2O体系的活度系数的测定

用电势法测定了298.15K以及I为0.1、0.5、1.0、1.5、2.0、2.5和3.0 mol/kg时,NaBr在混合电解质溶液NaBr+NaAc+H_2O中的活度系数.实验结果用Harned、SRJ和Pitzer方程拟合,得到各种方程的相互作用参数,由拟合的标准偏差得知,Pitzer方程的拟合精度略好于前2个方程.用Pitzer混合参数θ_(Br-Ac)和ψ_(Br-Na-Ac)计算了NaAc在该混合体系中的活度系数和体系的过量Gibbs自由能.     

NaCl在聚电解质溶液中活度系数的实验测定

引　言聚电解质是指在极性溶剂中能够电离形成聚离子和反离子的高分子[1] ,在生物体中广泛存在 ,如蛋白质、ＤＮＡ和ＲＮＡ等都是聚电解质 ,聚丙烯酸盐和聚苯乙烯磺酸盐则是典型的人工合成聚电解质 .在聚电解质的水溶液中 ,由于聚离子带有大量的电荷 ,对反离子具有很强的静电吸引作用 ,即使在极低的浓度下溶液仍具有很大的非理想性 ,这与普通电解质溶液显著不同[2 ,3 ] .建立聚电解质溶液热力学性质的计算方法一直是溶液理论研究的热点 ,现已取得长足进展 ,如Ｍａｎｎｉｎｇ的反离子凝聚理论[2 ,3 ] 、柱状胞腔模型基础上的ＰＢ方程理论[4 ,…     

NaCl在混合溶剂(DMF-H2O)中热力学性质的研究

应用钠离子选择性电极和Ag-AgCl电极组成可逆电池,通过测定电池的电动势,应用Debye-Hückel极限公式,求得不同温度下NaCl在混合溶剂(DMF-H2O)中的活度系数(γ±),计算了NaCl在混合溶剂(DMF-H2O)中的相对偏摩尔自由能,并据电解质溶液的溶剂化理论对NaCl溶液的活度系数及相对偏摩尔自由能的变化规律进行了初步的讨论。