An approximation of the second dissociation constant for H2S
An approximation of the second dissociation constant for H2S
复制标题
H2S 第二解离常数的近似值
DOI：
10.1016/0016-7037(88)90326-2
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发表时间：
1988
影响因子：
5
通讯作者：
H. Barnes
中科院分区：
文献类型：
--
作者：
M. Schoonen;H. Barnes
S 2−的差分辨率ΔG 0影响水热络合参数、硫化物溶度积的评估和水溶液硫形态的计算。H2S的第二解离常数（logK HS−）如果是已知的，可以用来确定这个自由能。logK HS−在此通过外推多硫化物（H 2 Sn）解离的热力学数据作为链长倒数（1 n）的函数进行了计算。外推法得到了标准弱酸理论的支持。外推进一步基于絮凝实验，该实验确定了胶体硫表面质子化的平衡常数，这是无限硫链质子化的反应模拟物，H 2 S∞。导出的log K HS−值为− 18.51±0.56（20° C），这意味着S2 −从来不是一个占优势的水相物种。这一新的溶度值已被用来推导某些金属硫化物的替代溶度积。
Poor resolution ΔG ƒ 0 forS 2− affects hydrothermal complexing arguments, evaluation of sulfide solubility products, and calculation of aqueous sulfur speciation. The second dissociation constant for H 2 S (logK HS−) if well known could be used to determine this free-energy. The logK HS− has been evaluated here by extrapolating the thermodynamic data for the dissociation of polysulfides (H 2 S n) as a function of the reciprocal chain length (1 n). The extrapolation method is supported by standard weak acid theory. The extrapolation is further based on flocculation experiments which determined the equilibrium constant for the protonation of a colloidal sulfur surface, which is a reaction analog for the protonation of an infinite sulfur chain, H 2 S∞. The derived log K HS− value,− 18.51±0.56 (20° C), implies that S 2− is never a dominant aqueous species. This new value has been used to derive alternative solubility products of some metal sulfides.