摘要
以Ag+ 滴定Cl-的沉淀滴定计算分析为例 ,研究了电动势测定误差对滴定计算分析法的影响规律。理论推导与实验验证表明 :电动势测定误差对滴定计算分析法的影响小于直接电位法。电动势测定误差对滴定计算分析法测定结果C的影响与滴定分数α有关 ,在α =1处 ,这种影响为 0 ,α离 1越远 ,这种影响越大。这是因为C由D1 与D2 两部分组成 ,其中D1 与电动势无关 ,D2 与电动势有关。在α =1处 ,D2 对C的贡献为 0 ,α离 1越远 ,D2 对C的贡献越大。电动势测定的系统误差与偶然误差对单点滴定法均有影响 ,但在α =1附近 ,这种影响最小。电动势测定的系统误差是影响线性滴定法的主要因素 ,而偶然误差对线性滴定法的影响较小。电动势测定的偶然误差是影响双点滴定法的主要因素 ,而系统误差对双点滴定法没有影响 ;当电动势增量ΔE >- 0 .0 1 8V时 。
This paper deals with the influence of error in electromotive force (EMF) measurement on calculation of titration analysis in which Ag+ as the titrant and Cl- as the titrate. Both corollaries from theory and result of the experiment indicate that the influence of error in EMF measurement on calculation of titration analysis is less than that on direct potential measurement. The resulting concentration (C) in the calculation of titration analysis affected by the error in EMF measurement relates to the titration percentage. At the stoichiometric point (SP) where the titration percentage reaches 100% the influence of this error is zero and further away from SP the bigger the influence becomes because C consists of two parts D-1 and D-2 in which D-1 does not relate to EMF and D-2 does to EMF. The contribution D-2 to C relates to the titration percentage and at SP this contribution to C becomes zero and the further away from SP the bigger contribution D-2 to C is. Both systematic and random errors in EMF measurement influence the single-point titration, but at the SP this influence reaches its smallest. Though in linear titration random error in EMF measurement has less influence than the systematic error does while in double-point titration the opposite results could be seen. When the DeltaE is bigger than - 0.018 V the error in double-point titration is usually greater than that in single-point titration.
出处
《分析化学》
SCIE
EI
CAS
CSCD
北大核心
2004年第4期464-468,共5页
Chinese Journal of Analytical Chemistry
基金
同济大学理科发展基金资助项目 (No .0 2 3 76)
