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Showing 1 to 20 of 33 for “"Activity coefficients"”.
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Limiting Activity Coefficients for Aqueous Solutions
Measurement techniques for limiting activity coefficients ($\gamma\sp\infty$) are reviewed with respect to aqueous solutions. Literature values for $\gamma\sp\infty$ of solutes in water at 25$\sp\circ$C were compiled and critically evaluated to form a database of high confidence for 120 compounds. …
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Measurement and Prediction of Limiting Activity Coefficients
Activity coefficients at infinite dilution ((gamma)('(INFIN))'s) were determined for several classes of solutes in the polar solvents 1-octanol, acetophenone, and furfural at 20, 40, and 60(DEGREES)C by a gas chromatographic technique. An improved form of the Modified Separation of Cohesive Energy …
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Slab-Geometry Molecular Dynamics Simulations: Development and Application to Calculation of Activity Coefficients, Interfacial Electrochemistry, and Ion Channel Transport
… compared, and applied to the prediction of activity coefficients, interfacial electrochemistry characterization, and ion transport through a model biological channel-membrane structure. The charged-sheets, 2-D Ewald, corrected 3-D Ewald, and corrected particle-particle-particle-mesh (P3M) …
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Prediction of electrolyte solution properties using a combined Debye-Huckel, association and solvation model
… model that estimates individual and mean ionic activity coefficients in the NaCl-NaOH-HCl-H₂O system at 25°C. This extra thermodynamic model incorporates long-range electrostatic ion-ion interaction (Debye- Hückel effects), short-range ion-ion interactions (ion association), and short-range …
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The alkaline hydrolysis of esters in aqueous-organic solvent mixtures. The effects of solvents and of the activity coefficients of reactants on the kinetics of the alkaline hydrolysis of methyl acetate in aqueous dioxan, aqueous dimethyl sulphoxide and aqueous diglyme (bis (2-methoxyethyl ) ether) mixtures as solvents.
… adapted is to experimentally determine the activity coefficient of the ester (YE ) and the activity of the water (aH20', mechanistically, at least one molecule of water is involved in the rate-determining step) and then to use the Bronsted-Bjerrum equation to determine the residual activity …
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ΜΕΘΟΔΟΣ ΣΥΝΘΕΣΗΣ Η/ΚΑΙ ΕΠΙΛΟΓΗΣ ΑΡΙΣΤΩΝ ΔΙΑΛΥΤΩΝ ΠΡΟΣ ΕΠΙΤΑΧΥΝΣΗ ΑΝΤΙΔΡΑΣΕΩΝ DIELS-ALDER
BASED ON A RELATION BETWEEN REACTIONS RATE AND ACTIVITY COEFFICIENTS (Γ) AND, ON A COMPUTING METHOD OF ACTIVITY COEFFICIENTS (NAMED UNIFAC), SOLVENTS EFFECTS WERE STUDIED ON 2 DIELS-ALDER REACTIONS RATE AND GENERAL CONCLUSIONS CAME OUT. THESE CONCLUSIONS WERE PROVED AND EXTENDED TO 9 DIELS-ALDER …
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Physical and Chemical Interactions in Liquid Metal Mixtures
Activity coefficients for the more volatile component have been determined for liquid solutions of the copper-lead, titanium-tin and titanium-copper systems. Activities were derived using a weight loss technique based on the Knudsen effusion method. Positive deviations from ideality occur for the …
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The Formal Redox Potential of the Permanganatemanganous System in Sulfuric Acid
… degree of completeness of respective reactions, activity coefficients of solutes, choice of reducing or oxidising agents to be used—those and many other problems in analytical chemistry can be calculated or predicted satisfactorily through a knowledge of the formal potential of many conjugate …
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Measurement, prediction, and application of the limiting activity coefficient and its temperature derivative
Infinite dilution activity coefficients ($\gamma\sp\infty$) were measured for 54 systems using an improved differential boiling point apparatus which exhibited better temperature stability allowing more precise and accurate data to be measured. Values of $\gamma\sp\infty$ for most systems were …
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Transfer Learning for Accelerated Process Development
… I introduce *DeepGamma* for predicting activity coefficients and ML-SAFT for predicting PCP-SAFT parameters, showing steps towards improving thermodynamic predictions using transfer learning. Together, all of these studies demonstrate the potential of transfer learning to accelerate …
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A systems approach to evaluate water quality oriented land management plans
… annual sediment yields which were used as activity coefficients in a linear programming (LP) optimization model. The LP model selected the set of cropland management practices that minimized total sediment yield while meeting economic and agricultural production constraints. A …
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Chemistry of the drainage from a waste dump at BHP-Utah Mines Ltd, Island Copper mine
… has a total ionic strength of 0.0426and that the activity coefficients of the dissolved species in consideration depart markedly from unity. Most dissolved species are found to be under-saturated with respect to their most insoluble compounds, although over-saturation also exists. Levels of …
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Free energy relationships in sodium halide-alcohol-water mixtures
<p>The variation of the logarithm of the activity coefficient of the four alcohols, ethylene glycol, methanol, ethanol, and l-propanol, on the addition of three salts, sodium chloride, sodium bromide, and sodium iodide, has been measured. The data were fit to an empirical equation of the form: (∂ …
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Effect of temperature on the association constants of some divalent metal ions with chloride in sea water-like solutions
… on the formation of the complex ions. The activity coefficients were assumed constant at a given temperature.</p><p>The values for the base ten logarithm of the overall formation constants at 25.0° are 1.11, 1.48 and 1.83 for PbCl<sup>+</sup>, PbCl°<sub>2</p> and …
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The effects of a walking program on aerobic fitness, riboflavin and thiamin status, and birth outcome in pregnant women taking vitamin-mineral supplements
… by erythrocyte glutathione and transketolase activity coefficients, was adequate for 86% of the subjects with respect to riboflavin and 96% for thiamin. There was a significant correlation (r = 0.58) between aerobic activity scores and ETKAC values (W group). Participation in a walking program …
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Infinite dilution activity coefficient measurements of organic solutes in selected deep eutectic solvents by gas-liquid chromatography
Submitted in fulfillment of the academic requirements for the degree of Master of Engineering: Chemical Engineering, Durban University of Technology, Durban, South Africa, 2018.
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Binary gas adsorption on molecular sieves. Experimental data for the adsorption of oxygen, nitrogen and oxygen-nitrogen mixtures on five molecular sieve adsorbents at various temperatures and pressures and a comparison with theoretical models.
… representation of the experimental data. The activity coefficients of the adsorbed phase for the binary experimental data have been calculated and the results showed no appreciable deviation of the adsorbed phase from ideality.
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Thermodynamic Measurements by Gas-Liquid Chromatography
… was modified to enable the partition coefficients of various solutes in polymer stationary phases to be measured at finite concentrations of the solute. The technique chosen was “Elution on a Plateau” in which the chromatographic column is first equilibriated by a carrier gas …
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Ab initio modeling of complex aqueous and gaseous systems containing nitrogen
… is paid to fully understanding the role of activity coefficients, standard states, and reference states and how these affect the subsequent expressions. A procedure is outlined for estimating the thermochemical properties of small molecules in aqueous solution based on computational …
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