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高碘酸盐氧化硫脲的非线性动力学行为和机理
引用本文:林娟娟,王舜,高庆宇,王新红,徐良芹.高碘酸盐氧化硫脲的非线性动力学行为和机理[J].化学学报,2003,61(9):1346-1351.
作者姓名:林娟娟  王舜  高庆宇  王新红  徐良芹
作者单位:1. 温州师范学院化学与材料科学系,温州,325027
2. 温州师范学院化学与材料科学系,温州,325027;中国矿业大学化工学院,徐州,221008
3. 中国矿业大学化工学院,徐州,221008
基金项目:国家自然科学基金 (No.2 0 1 0 30 1 0 ),教育部优秀青年教师资助计划项目
摘    要:在酸性介质中,高碘酸盐氧化硫脲的非线性反应呈现多种不同的化学计量方程 式。当KIO_4]_0/SC(NH_2)_2]_0 > 4时,计量方程为4IO_4~- + SC(NH_2)_2 + 3H_2O = 4IO_3~- + SO_4~(2-) + CO_3~(2-) + 2H~+ + 2NH_4~+;当KIO_4]_0/ SC(NH_2)_2]_0 = 8:7时,计量方程为8IO_4~- + 7SC(NH_2)_2 + 17H_2O = 4I_2 + 7SO_4~(2-) + 7CO_3~(2-) + 6H~+ + 14NH_4~+;而当KIO_4]_0/SC(NH_2)_2] _0 < 1时,反应的主要计量方程为IO_4~- + 4SC(NH_2)_2 + 8H_2O = I~- + 4S + 4CO_3~(2-) + 8NH_4~+。同时反应体系在氧化剂过量的条件下碘钟产生的诱导期 与1/H~+]~2成正比;而当还原剂过量时,体系I_2逐渐累积至极值的诱导期与体系 初始pH呈线性关系。运用包含质子平衡反应、碘化合物自身反应、碘化合物-硫化 合物反应以及硫-硫反应的15步反应机理较好地模拟出封闭体系中pH,I~-]以及 I_2]的准振荡行为。

关 键 词:振荡化学反应  高碘酸盐  硫脲  氧化  反应动力学  反应机理
修稿时间:2003年3月20日

Nonlinear Kinetic Behavior and Mechanism of the Oxidation of Thiourea by Periodate
Institution:Department of Chemistry and Material Science, Wenzhou Teachers' College;College of Chemical Engineering, China University of Mining and Technology
Abstract:The reaction between periodate and thiourea in acidic medium has been investigated in a batch. The stoichiometries of the reaction are: 4IO_4~- + SC(NH_2)_2 + 3H_2O = 4IO_3~- + SO_4~(2-) + CO_3~(2-) + 2H~+ + 2NH_4~+ (IO_4~-]/SC(NH_2)_2]_0 > 4) (1) 8IO_4~- + 7SC(NH_2)_2 + 17H_2O = 4I_2 + 7SO_4~(2-) + 7CO_3~(2-) + 6H~+ + 14NH_4~+ (IO_4~-]/ SC(NH_2)_2] ≈ 8:7) and mixed reaction of (l) and (2) (8/7 < IO_4~-]/ SC(NH_2)_2]< 4 ), respectively. In closed systems the reaction is autocatalytic in H+ and I" , and can be characterized by two different induction periods. In excessive periodate, the induction period defined as the time between the beginning of reaction and the appearance of a red-brown colour, indicating the product of iodine, has a linear relation with 1/H~+ ]~2. In excessive thiourea, the induction period from the start of reaction to maximal l2] is directly proportional to the initial pH. A fifteen-step mechanism, including iodine-iodine reactions, iodine-sulfur reactions and sulfur- sulfur reactions, simulated the observed kinetics.
Keywords:oligooscillations  nonlinear reaction mechanism  dynamic simulation
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