Department of Inorganic Chemistry, University of Pécs, Ifjúság útja 6., H-7624 Pécs, Hungary.
J Phys Chem A. 2010 Jun 17;114(23):6521-6. doi: 10.1021/jp102661k.
The trithionate-iodine reaction has been studied spectrophotometrically in a slightly acidic medium at 25.0 +/- 0.1 degrees C in acetate/acetic acid buffer monitoring the absorbance at 468 nm at the isosbestic point of the iodine-triiodide ion system in the absence and presence of initially added iodide ion at I = 0.5 M ionic strength adjusted by sodium perchlorate. The stoichiometry of the reaction was found to be S(3)O(6)(2-) + 4I(2) + 6H(2)O --> 3SO(4)(2-) + 8I(-) + 12H(+). It is also shown that the consumption of iodine is inhibited by iodide ion, but it cannot be simply explained via the fast equilibrium formation of triiodide ion. A five-step kinetic model with four fitted and fixed kinetic parameters is proposed and discussed in detail, on the basis of which all the most important characteristics of the measured kinetic curves are adequately explained.
在 25.0 ± 0.1°C 的微酸性介质中，在醋酸盐/乙酸缓冲液中，通过监测碘-三碘离子体系的等色点处的 468nm 处的吸光度，研究了硫代过碘酸盐-碘反应。在不存在和存在初始加入的碘化物离子的情况下，在 I = 0.5 M 的离子强度下，通过高氯酸钠进行调整。反应的化学计量比为 S(3)O(6)(2-) + 4I(2) + 6H(2)O --> 3SO(4)(2-) + 8I(-) + 12H(+)。还表明，碘化物离子抑制了碘的消耗，但不能简单地通过三碘化物离子的快速平衡形成来解释。提出并详细讨论了一个具有四个拟合和固定动力学参数的五步骤动力学模型，在此基础上，充分解释了测量动力学曲线的所有重要特征。
