Diffusion with hydrolysis and ion association in aqueous solutions of beryllium sulfate
Diffusion with hydrolysis and ion association in aqueous solutions of beryllium sulfate
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DOI：
10.1007/bf00972522
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发表时间：
1996-03-01
影响因子：
1.2
通讯作者：
Leaist, DG
中科院分区：
文献类型：
--
作者：
Hao, L;Lu, RH;Leaist, DG
在25℃下，用泰勒扩散法测量了浓度为0.005-L摩尔L(-1)的硫酸铍水溶液的互扩散系数。最小二乘分析表明，部分水解盐的扩散产生了少量的额外硫酸流量，每摩尔硫酸铍约0.04摩尔。BeSO_4-H_2SO_4水溶液体系的三元扩散系数与Nernst-Planck预测的结果定性一致，该预测基于硫酸铍离子对和硫酸氢根离子的形成，以及2Be(2+)+H2O=Be2OH3+H+，3Be(2+)+2H(2)O=Be-3(OH)(2)(4+)+2H(+)。除了非常稀薄的溶液外，预测的硫酸流量与硫酸铍的流量相比很小，因为大多数铍离子通过形成BeSO4离子对而被保护不被水解，而且大多数由水解产生的氢离子被转化为流动性较小的硫酸氢离子。
Taylor dispersion is used to measure mutual diffusion coefficients for aqueous solutions of beryllium sulfate at concentrations from 0.005 to l mol-L(-1) at 25 degrees C. Least-squares analysis of the dispersion profiles shows that diffusion of the partially hydrolyzed salt produces a small additional flow of sulfuric acid about 0.04 mol sulfuric acid per mole of total beryllium sulfate. Ternary diffusion coefficients measured for the aqueous BeSO4-H2SO4 system are qualitatively consistent with Nernst-Planck predictions based on the formation of beryllium sulfate ion pairs, bisulfate ions, and the hydrolysis equilibria 2Be(2+) + H2O = Be2OH3+ + H+, 3Be(2+) + 2H(2)O = Be-3(OH)(2)(4+) + 2H(+). Except for very dilute solutions, the predicted flow of sulfuric acid is small compared to the flow of beryllium sulfate because most of the beryllium ions are protected from hydrolysis by the formation of BeSO4 ion pairs, and most of the hydrogen ions produced by hydrolysis are converted to less-mobile bisulfate ions.