On the agreement with experiment of the dilution formula deduced from the Debye-Hückel theory

Ferguson, A. L.; Vogel, Israel

doi:10.1039/tf9272300404

Cited by 5 publications

(3 citation statements)

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“…al 43 50 . The molar conductivity and diffusion coefficients decrease towards higher electrolyte concentrations, which is a direct result of the ion-ion interaction that is described by the Debye-Hückel theory 51,52 . Most of the literature reported values at the standard temperature of 25°C, whereas the measurements in this study were performed at 20°C.…”

Section: Modelmentioning

confidence: 99%

Ion Transport and Limited Currents in Supporting Electrolytes and Ionic Liquids

Schalenbach

Durmus

Tempel

et al. 2022

Preprint

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Supporting electrolytes contain inert dissolved salts to increase the conductivity, change microenvironments near the electrodes and assist in electrochemical reactions. Herein, a combined experimental and computational study examines the impact of supporting salts on the ion transport and limited currents of electrochemical reactions. A physical model that describes multi-ion transport in liquid electrolytes and the related concentration gradients is discussed. This model and its parameterization are evaluated by the measured limited current of the copper deposition in a CuSO4 electrolyte under a gradually increasing amount of Na2SO4 that acts as a supporting salt. A computational sensibility analysis of the transport model reveals that the shared conductance between the ions lowers the limited currents with larger supporting salt concentrations. When the supporting salt supplies most of the conductance, the electric-field-driven transport of the electrochemically active ions becomes negligible so that the limited current drops to the diffusion-limited current that is described by Fick’s first law. The transition from diluted supporting electrolyte to the case of ionic liquids is elucidated with the transport model, highlighting the different physical transport mechanisms in a non-conducting (polar) and a conducting (ionic) solvent.

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Section: Modelmentioning

confidence: 99%

Ion Transport and Limited Currents in Supporting Electrolytes and Ionic Liquids

Schalenbach

Durmus

Tempel

et al. 2022

Preprint

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“…Highly diluted solutions, such as those in which we typically measure soil pH, resemble the highly dilute solutions to which aqueous models apply well, but we must recognize that soils at typical soil moisture levels are considered highly concentrated solutions, and thus intractably violate the "dilute solution assumption" required for most models of aqueous chemistry. Without meeting this key assumption, we cannot accurately apply−without extreme caution−most aqueous chemical models, such as the Debye-Hückel theory (Debye and Hückel, 1923;Ferguson and Vogel, 1927), Sørensen's acidity function named "pH" (MacInnes, 1948;Sørensen, 1909), and mean ionic activity itself (Lewis and Randall, 1921). Drained mineral soils and the sediments of brackish regions, such as the coasts of all oceans and saline seas, therefore have an effective ionic strength surpassing that which permit standard applications of pH measurements altogether.…”

Section: Relation Of Non-standard Soil Ph Values To Standard Soil Phmentioning

confidence: 99%

Standard and Non-Standard Measurements of Acidity and the Bacterial Ecology of Northern Temperate Mineral Soils

Braus

Whitman

2020

Preprint

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Databases of soil pH values today guide the decisions of land managers and the experimental designs of microbiologists and biogeochemists. Soil acidity underpins fundamental properties and functions in the soil, such as the solubilities of exchangeable ions and nutrients, or bacterial use of gradients of internal and external acidity to generate ATP and turn flagellar motors. Therefore, it is perhaps unsurprising that soil pH has emerged as the strongest predictor of soil bacterial community composition. However, the measurement of these particular values today does not address whether soil pH accurately represents the in situ acidity of soil microhabitats where microorganisms survive and reproduce. This study analyzes and compares soils of a large-scale natural soil pH gradient and a long-term experimental soil pH gradient for the purposes of testing new methods of measuring and interpreting soil acidity when applied to soil ecology. We extracted and prepared soil solutions using laboratory simulation of levels of carbon dioxide and soil moisture more typical of soil conditions while also miniaturizing extraction methods using a centrifuge for extractions. The simulation of in situ soil conditions resulted in significantly different estimates of soil pH. Furthermore, for soils from the long-term experimental soil pH gradient trial, the simulated soil pH values substantially improved predictions of bacterial community composition (from R2 = 0.09 to R2 = 0.16). We offer suggestions and cautions for researchers considering how to better represent soil pH as it exists in situ.

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“…[13][14][15] Further models to calculate the evolution of current-driven concentration gradients [16][17][18] followed, which typically use a constant and concentration-independent parameterization of the molar conductivity, diffusion coefficients, and transfer numbers. However, the interactions between the ions (described by the Debye-Hückel theory [19,20] ) lead to concentration dependence of these electrolyte parameters, which were thus far not included in the reported models.…”

Section: Introductionmentioning

confidence: 99%

Ionic transport modeling for liquid electrolytes ‐ Experimental evaluation by concentration gradients and limited currents

Schalenbach

Hecker

Schmid

et al. 2022

Electrochemical Science Adv

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A direct current in an electrochemical cell with a diluted liquid electrolyte leads to the displacement of ions within the solvent, while diffusion works against the resulting concentration differences. This study aims to experimentally evaluate a physicochemical ion transport model (source code provided) that describes current-driven concentration gradients in diluted electrolytes. Hereto, an aqueous 0.1 M CuSO 4 electrolyte between metallic copper electrodes serves as an experimental test system. Spatially resolved optical measurements are used to monitor the evolution of the ion concentration gradient in the electrolyte. Moreover, measured limited currents are related to computationally modeled concentration gradients. A constant parameterization of the diffusion coefficient, molar conductivity and ion transport number lead to a slight overestimation of the cathodic ion depletion and cell resistance, whereas a literature data based concentration dependent parameterization matches better to the measured data. The limited current is considered under a computational parameter variation and thereby related to the physicochemical impact of different electrolyte properties on the ion transport. This approach highlights the differences between purely diffusion limited currents and the limited current resulting from the combined electric field and diffusion driven ion motion. A qualitative schematic sketch of the physical mechanisms of the ion movement is presented to illustrate the current driven ion displacement in liquid electrolytes.

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On the agreement with experiment of the dilution formula deduced from the Debye-Hückel theory

Cited by 5 publications

References 0 publications

Ion Transport and Limited Currents in Supporting Electrolytes and Ionic Liquids

Ion Transport and Limited Currents in Supporting Electrolytes and Ionic Liquids

Standard and Non-Standard Measurements of Acidity and the Bacterial Ecology of Northern Temperate Mineral Soils

Ionic transport modeling for liquid electrolytes ‐ Experimental evaluation by concentration gradients and limited currents

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