示波指示技术在动力学分析法中的应用 Ⅰ.利用KBrO_3-KBr-HCI体系测定还原性物质

OSCILLOGRAPHIC INDICATION TECHNIQUE IN KINETICALLY CONTROLLED ANALYSIS Ⅰ.DETERMINATIONS OF REDUCING SUBSTANCES WITH KBrO_3-KBr-HCI SYSTEM

示波滴定至今主要用于常量或半微量分析。示波滴定终点指示技术能否在微量和痕量分析中发挥作用是一个需要探索的新课题。本文报道用零电流示波双电位指示技术与动力学分析相法相结合的方法测定微量还原性物质。 在反应BrO_3~_+5Br^-+6H^+=3Br_2+3H_2O中,Br_2的生成速率受动力学控制,在一定条件下d[Br_2]/dt=k。若生成的Br_2达某一特定浓度(终点可用某一方法指示)的时间为t_0。

This paper reports the use of the oscillographic indication technique in the kineticmethod of analysis.The product resulted from the kinetic reaction in KBrO_3-KBr-HClsystem is used as a titrant and the zero current oscillographic bipotentiometric titrationtechnique is used to indicate the end point. The results obtained with KBrO_3-KBr-HClsystem show that this method can be used to determine reducing substances such as As(Ⅲ),ascorbic acid,ete.and has a sensitivity about 10^(-6)--10^(-7)mol/dm^3 .This method is dire-ctly visible and rapid and needs only simple equipment.