摘要
根据络合返滴定中的络合平衡,推导了离子选择电极指示单点络合返滴定的计算公式和滴定曲线表达式,讨论了单点络合返滴定中测定结果的相对误差与电位测定误差之间的关系。用镉离子选择电极示指示电极,以 EDTA 为络合剂,Cd(NO_3)_2为返滴定剂,对 Zn^(2+),Cu^(2+),Al^(3+)Ti^(4+)分别进行了测定。结果表明,本法的测定误差与一般容最分析相近。还用本法测定了矾土试样中 Al_2O_3和 TiO_2的含量。
Based on complexomeric equilibria,expresion for titration curve in complex- ometric back-titrationand the calculating formula for single point complexometrie back-titration are derived as follows respectively: where C_N,C_M and C_L are concentrations of ion to be determined,backtitrantand complexing agent respectively; [M]represents the concentration of free metal ion M in the titration system,which can be detected by ion selective electrode; V_N,V_M and V_L are volumes of sample solution,back titrant and eomplexing agent respectively; V_(tot) is the total volume of the titration system;K_(ML) and K_(NL) are the stability constants of ML and NL respectively.Relationship between the relative error in single point complexometric back-titration and that in potentiometric determination is discussed.Concentrations of Zn^(2+),Cu^(2+),Al^(3+) and Ti^(4+) are determined by means of Cd^(2+) ion selective electrode as indicator electrode,EDTA as complexing agent,and Cd(NO_3)_2 standard solution as backtitrant.The results obtained indicate that the relative errors of this method in suitable conditions are as those in traditional volumetry.As the application of this method,contents of Al_2O_3 and TiO_2 in alumina are determined.
出处
《大连理工大学学报》
EI
CAS
CSCD
北大核心
1989年第1期33-39,共7页
Journal of Dalian University of Technology
关键词
络合滴定
离子选择电极
单点滴定
complexometry
ion selective electrode/single point titration
titration curve
