KCl+KHCO_3水溶液中氯化钾的平均活度系数和KHCO_3~0的缔合常数  

DETERMINATION OF THE ACTIVITY COEFFICIENTS OF KC1 IN KCl-KHCO_3 AQUEOUS SOLUTIONS AND THE ASSOCIATION CONSTANT OF KHCO_3~0

作　　者：陈国华[1] 季荣[1] 薛小平[1] 陈颖[1] 

机构地区：[1]青岛海洋大学海洋化学系

出　　处：《青岛海洋大学学报（自然科学版）》1993年第3期36-44,共9页Journal of Ocean University of Qingdao

摘　　要：用钾离子选择电极和银—氯化银电极构成的无液界电池测量了KCl+KHCO_3混合水溶液中KCl的平均活度系数,发现其活度系数的对数与混合溶液中KHCO_3的浓度m_2服从哈奈特关系式。用最小二乘法计算机处理求得了各离子强度条件下相应的哈奈特系数。还用适用于混合电解质溶液的皮茨公式计算了该体系电解质的平均活度系数和溶液的超额自由能,计算出活度系数与实验值之间的平均标准偏差为±0.006。溶液的超额自由能随溶液组成变化表明,对于有相同阳离子(K^+)的该混合溶液中离子间短程作用力主要受Cl^-作用的影响。用累代逼近法用微机计算,求得了KHCO_3~0的化学计量缔合常数经验公式及其热力学缔合常数。The cells without liquid junction: Ag -AgCl, KCl(m1)+ KHCO3 (m2), K + ion sensitive membrane electrode, have been used to determine the activity coefficient of KCl, in KC1+KHCO3 aqueous solutions at constant ion strengths (I = 0. 1, 0. 3, and 0. 7) at 298. 15K, which covers concentration ranges of KCl and KHCO3 from 0. 02 to 0. 676m and from 0. 01 to 0. 12m, respectively. We have found that the relationship between the logarithm of the mean activity coefficient of KCl and the concentration of KHCO3 in the above mixtures can be described by the follwing equation : 1g γ1±=1g γ10± -a12m2 - β2m22. The Harned Rule coefficients a12and β12 at each ion strength have been computed by the least square method. The mean activity coefficients of KCl and KHCO3 of the mixed salts solutions were evaluated by the Pitzer equations. The stoi-chiometric association constants KHCO30 were calculated by a simple iterative process. The results were fitted into an empirical equation of the form In K =a+bm/I. The value of K obtained from the above equation is 1. 03 at the ionic strength of sea water (I = 0. 7) and m2 = 0. 002mol/kg. The thermodynamic association constant of KHCO30 was obtained by extrapolating the stoichiometric association constant to infinite dilution is 1.80 at 298. 15K

关 键 词：KCL KHCO3 活度系数 电解质溶液 

分 类 号：O645.646.1[理学—物理化学]