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首页> 外文期刊>The journal of physical chemistry, B. Condensed matter, materials, surfaces, interfaces & biophysical >Tests of Equations for the Electrical Conductance of Electrolyte Mixtures: Measurements of Association of NaCl (Aq) and Na_2SO_4 (Aq) at High Temperatures
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Tests of Equations for the Electrical Conductance of Electrolyte Mixtures: Measurements of Association of NaCl (Aq) and Na_2SO_4 (Aq) at High Temperatures

机译：电解质混合物电导率方程的测试：高温下NaCl（Aq）和Na_2SO_4（Aq）缔合的测量

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摘要

A review of requirements for equations to calculate the conductivity of a mixture of ions in low dielectric constant solvents (i.e., water at high temperatures) shows that there are conceptual difficulties with all current equations. To explore whether these difficulties limit our ability to predict mixtures, four models for the activity coefficients, two models for the conductivity of a single strong electrolyte, and an equation for the change in equivalent conductivity on mixing single strong electrolytes were chosen. These equations were then tested on the theoretical equation of Turq et al. (1. Phys. Chem.I995, 99, 822-827) for three ion mixtures. Next the equations were tested on a single 1~(-1) electrolyte, NaCl (aq) at 652.6 K and 22.75 MPa measured by Gruskiewicz and Wood {1. Phys. Chem. B 1997, 101,61549--6559) and new measurements at 623.9 K and 19.79 MPa. Then it was tested with new measurements on Na2S04 (aq) from 300 to 574 K because, in water at. high temperatures, this salt produces a solution containing six different ions (Na~+ , SO_4~(2-), SO_4~-, HSO_4~-, H+;OH-). The equations were able to reproduce the experimental data. Values of equilibrium constants, K, for the dissociation of NaCl and NaSO_4~- and equivalent conductances Ao derived by a least-squares fit agreed with reported data determined by other methods, showing that conductivity measurements can yield accurate equilibrium co~stants in complex mixtures of ions. The values of K and Au were not very sensitive to changes in (1) the single electrolyte conductance equation, (2) assumed values of Au for minor species, or (3) equilibrium fronstants for minor reactions. Uncertainty in the activity coefficient model was the largest contributor to dncertainty in K and Au. This method should allow rapid and acCurate measurements of the equilibrium constant for any reaction, which changes the number of ions in solutioaTheequilibrium constants for many reactions of this type are unknown in water at high temperatures.
机译：对计算低介电常数溶剂（即高温下的水）中离子混合物电导率的方程式要求的审查表明，所有当前方程式在概念上都有困难。为了探索这些困难是否会限制我们预测混合物的能力，选择了四个活度系数模型，两个用于单一强电解质电导率的模型以及用于混合单一强电解质时等效电导率变化的方程。然后在Turq等人的理论方程式上测试这些方程式。 （1. Phys。Chem.I995，99，822-827）中的三种离子混合物。接下来，方程由Gruskiewicz和Wood {1.在12.6（-1）的单一电解质NaCl（aq）在652.6 K和22.75 MPa下测试。物理化学B 1997，101,61549--6559）和在623.9 K和19.79 MPa下的新测量值。然后在300至574 K的Na2SO4（水溶液）上进行了新的测试，因为在水中。在高温下，这种盐产生的溶液包含六个不同的离子（Na〜+，SO_4〜（2-），SO_4〜-，HSO_4〜-，H +; OH-）。这些方程能够重现实验数据。 NaCl和NaSO_4〜-的解离的平衡常数K的值，以及通过最小二乘拟合得出的等效电导Ao与其他方法确定的报道数据相一致，表明电导率测量可以在复杂混合物中产生准确的平衡常数离子。 K和Au的值对（1）单一电解质电导方程，（2）假设的Au少数物种的值或（3）平衡氟烷烃的较小反应的变化不是很敏感。活度系数模型的不确定性是导致K和Au不确定性的最大因素。此方法应允许快速准确地测量任何反应的平衡常数，这会改变溶液中的离子数。高温下在水中这种类型反应的平衡常数是未知的。

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