The dependences on ionic strength of the hydrolysis constants of Fe³⁺ and of the first dissociation constant of sulfurous acid are briefly reviewed. The data are needed to derive from apparent stability constants reported in the literature the stability constants for the three iron–sulfito complexes defined by the equilibria (c1) FeOH²⁺ + HSO₃⁻ = FeSO₃⁺ + H₂O, (c2) FeSO₃⁺ + HSO₃⁻ = Fe(SO₃)₂⁻ + H⁺, (c3a) Fe(SO₃)₂⁻ + HSO₃⁻ = Fe(SO₃)₃H²⁻, where K_c1 = 1982 ± 518 dm³ mol⁻¹, K_c2 = 0.72 ± 0.08, K_c3a = 189 ± 9 dm³ mol⁻¹ (ionic strength μ = 0.1 mol dm⁻³). The rapid formation of these complexes is followed by a slower decomposition leading to the formation of SO₃⁻ radicals; the associated rate coefficients are k₁ = 0.19 s⁻¹, k_1a ≈ 0.04 s⁻¹, and k_1b ≈ 0.08 s⁻¹, respectively. The subsequent reaction leads to dithionate and sulfate as products. Overall rates and product yields from a variety of studies of the slow reaction are found to be consistent with a mechanism, in which the production of dithionate occurs mainly by the reaction of SO₃⁻ with FeSO₃⁺ and that of sulfate by the reaction of SO₃⁻ with FeOH²⁺ and/or Fe³⁺. The role of copper as a catalyst is also analyzed. Rate coefficients for individual reactions are estimated from the data at low pH (μ = 1.0 mol dm⁻³) under conditions where the 1 : 1-complex is prevalent. They are extrapolated to lower ionic strengths for an analysis of the data obtained at higher pH to explore conditions when reactions of the higher complexes become important. The overall rate and the product yields of the reaction depend critically on the pH, the initial ratio of S(IV) to Fe(III) and the ionic strength of the solution.

中文翻译：

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与铁（iii）反应 氧化硫（iv）：严格的审查和数据分析

简要回顾了Fe ³⁺的水解常数和亚硫酸的第一离解常数对离子强度的依赖性。的数据需要从表观稳定常数推导文献中报道的稳定常数对由均衡（C1）中定义的三种铁sulfito络合物FeOH ²⁺ + HSO ₃ ^- =的FeSO ₃ ⁺ + H ₂ O，（c2）的的FeSO ₃ ⁺ + HSO ₃ ^- =的Fe（SO ₃）₂ ^- + H ⁺，（C3A）的Fe（SO ₃）₂ ^- + HSO ₃ ^-= Fe（SO ₃）₃ H ²⁻，其中K _c1 = 1982±518 dm ³ mol ^-1，K _c2 = 0.72±0.08，K _c3a = 189±9 dm ³ mol ^-1（离子强度μ = 0.1 mol dm ^-3）。这些配合物的快速形成之后是较慢的分解导致SO形成₃ ^-基团; 相关联的速率系数是ķ ₁ = 0.19小号^-1，ķ _1A ≈0.04小号^-1，和ķ _1B ≈0.08小号^-1，分别。随后的反应导致生成二硫代酸盐和硫酸盐。总体速率和从多种慢反应的研究的产物产率被发现是提供一种机制，其中，所述生产连二的主要发生由SO的反应一致₃ ^-用的FeSO ₃ ⁺通过反应和硫酸的SO ₃ ^-与FeOH ²⁺和/或Fe ³⁺。还分析了铜作为催化剂的作用。根据低pH（μ = 1.0 mol dm ^-3时的数据）估算各个反应的速率系数）在1：1络合物盛行的条件下进行。将其推断出较低的离子强度，以分析在较高pH下获得的数据，以探索当高级络合物的反应变得重要时的条件。反应的总速率和产物产率关键地取决于pH，S（IV）与Fe（III）的初始比例以及溶液的离子强度。