碘钟反应测定反应级数中的试剂因素分析  

Influence of Key Reagents in Reaction Order Determination through Iodine Clock Reaction

作　　者：沈家国[1] 杨涛[2] 吴思展[1] 

机构地区：[1]铜仁学院材料与化学工程学院,贵州铜仁554300 [2]铜仁学院生物与农林工程学院,贵州铜仁554300

出　　处：《化学教育》2015年第12期70-76,共7页Chinese Journal of Chemical Education

摘　　要：分析了（NH4）2S2O8和KI反应级数测定的实验,认为（NH4）2S2O8和KI的变质会引起反应速率与反应物浓度的非线性关系,变化过大时无法正确测得反应级数。（1）（NH4）2S2O8或KI部分变质,非线性变化突出,数学处理可采用有效浓度法扣除变质部分。一般主要是（NH4）2S2O8的变质,用Na2SO3或Na2S2O3预先处理（NH4）2S2O8产生的中间氧化性物质,可测得正确的反应级数,也可简化数学处理。（2）测速剂Na2S2O3的用量过大或过小,均会导致反应速率与（NH4）2S2O8浓度的非线性关系。Na2S2O3的用量较大时,应使用反应进程系数将平均速率校正为初始速率;而Na2S2O3的用量过小时,则操作的随机性误差将增大;只有Na2S2O3的用量适中时,平均速率与初始速率的差别较小,无需校正。该分析有助于理解反应级数的测定原理,其校正措施可得到较理想的实验结果。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）2S2 O8 or KI could cause nonlinear variation. The effective concentration method could be used to eliminate mathe- matically the interference of deterioration. In addition, correct reaction order could be obtained simply by removing the oxidative derivate from （NH4）2S2O8 via Na2 SO3 or Na2 S2O3 in the experi- ment because the main deterioration is from （NH4）2S2O8. Secondly, excessive abuse or insuffi- ciency 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.

关 键 词：反应级数 线性校正 实验理论教学 

分 类 号：O643.1-4[理学—物理化学] G642[理学—化学]