Influence of Key Reagents in Reaction Order Determination through Iodine Clock Reaction
SHEN Jia-Guo1, YANG Tao2, WU Si-Zhan1
1. College of Material and Chemical Engineering, Tongren University, Tongren 554300, China; 2. College of Biological and Agriculture and Forestry Engineering, Tongren University, Tongren 554300, China
Abstract This article analyzed the experiment of reaction order determination of (NH4)2S2O8 and KI, and concluded that deterioration of (NH4)2S2O8 or KI could cause nonlinear relationship between reaction rate and concentration of reactants. Correct reaction order could not be got while deterioration was distinct. Firstly, partial deterioration of (NH4)2S2O8 or KI could cause nonlinear variation. The effective concentration method could be used to eliminate mathematically the interference of deterioration. In addition, correct reaction order could be obtained simply by removing the oxidative derivate from (NH4)2S2O8 via Na2SO3 or Na2S2O3 in the experiment because the main deterioration is from (NH4)2S2O8. Secondly, excessive abuse or insufficiency of Na2S2O3 could cause nonlinear variation also. Initial rate could be obtained from average rate adjusted by reaction process coefficient while Na2S2O3 was excessive. Random error of the operation would be increased while Na2S2O3 was insufficient. Only when the amount of Na2S2O3 was moderate, a good linear relationship between reaction rate and concentration would be shown without any correction, for the average rate nearly equal to the initial rate. Above analysis is helpful for thoroughly understanding the primary principle of reaction order determination, and the mentioned correction methods are expected to provide more ideal experiment results.