scholarly journals The behaviour of electrolytes in mixed solvents. Part I.—The free energies and heat contents of hydrogen chloride in water—Ethyl alcohol solutions

1929 ◽  
Vol 125 (799) ◽  
pp. 694-712 ◽  
Keyword(s):  
Hydrogen Chloride ◽  
Electric Fields ◽  
Mixed Solvents ◽  
Dielectric Constants ◽  
Free Energies ◽  
Dissolved Ions ◽  
Uniform Medium ◽  
The Mean ◽  
Solvent Molecules ◽  
Water Alcohol

Previous studies on the effect of a change of medium on tire properties of dissolved electrolytes have aimed at correlating the behaviour of the electrolyte with the mean physical properties, e. g ., dielectric constants, of the medium. While this approach may be justified in the case of solvents containing molecules of only one kind, it is not sufficient to regard a mixed solvent as a uniform medium affecting the dissolved ions solely through the effect of its dielectric constant on the electric forces between them. For the electric fields of ions exert a differential attraction on molecules possessing different degrees of polarisability and since tire more polarisable molecules must tend to congregate round the ions, the properties of the latter cannot depend solely on tire mean properties of tire medium. Studies on the behaviour of ions in such cases will throw light on the interaction between ions and solvent molecules. The present paper gives tire results of measurements of the free energies and heat contents of hydrogen chloride in water-alcohol solutions, obtained by determining the electromotive forces of cells of the type:— H 2 ( g ) | HCl ( m ), AgCl ( s ) | Ag water-alcohol

scholarly journals The behaviour of electrolytes in mixed solvents. Part V.–The free energy of lithium chloride in water-alcohol mixtures and the salting-out of alcohol

1933 ◽  
Vol 141 (843) ◽  
pp. 86-94 ◽  
Keyword(s):  
Partial Pressure ◽  
Lithium Chloride ◽  
Mixed Solvents ◽  
Salting Out ◽  
Partial Pressures ◽  
All Solutions ◽  
The Mean ◽  
Alcohol Mixtures ◽  
Solvent Molecules ◽  
Water Alcohol

In Part II of this series of papers are recorded measurements of the partial vapour pressures of solutions of lithium chloride in water-ethyl alcohol mixtures, the alcohol contents of which extended from 6•4 to 100 mols. per cent. It has seemed desirable to extend this range so as to include some smaller concentra­tions of alcohol, and accordingly measurements have now been made of solutions containing 2 and 4 mols. per cent, of alcohol and in each case 0.5, 1.0 and 4.0 m. lithium chloride. The experimental method was the same as that previously described, except that in these cases the viscosity method was less suitable for determining the composition of the condensate, which was obtained by comparison with known compositions in the interferometer. The final values of the partial pressures, each being the mean of at least two deter­minations, are given in Table I. α w /α w 0 and α a /α a 0 are the relative activities, i. e ., the ratio of the partial pressure in a given solution to the partial pressure of the corresponding solvent. Two of the solutions containing 6.4 mols. per cent, alcohol were also redetermined and gave values in close agreement with those previously obtained. We are now in a position to discuss in more detail the behaviour of these solutions. It was shown in the previous paper that while the salt increased the partial pressure of alcohol in solutions containing smaller proportions of alcohol, it caused a lowering of the pressure in the more alcoholic solutions, but the relative lowering of the vapour pressure of alcohol was always less than that of water, indicating that in all solutions the alcohol was salted out with respect to the water. In order to assess this effect more precisely it is necessary to consider what will be the behaviour of a solute which interacts equally with the two solvent molecules.

scholarly journals The behaviour of electrolytes in mixed solvents. Part IV.—The free energy of zinc chloride in water-alcohol solutions

1932 ◽  
Vol 138 (835) ◽  
pp. 450-459 ◽  
Keyword(s):  
Free Energy ◽  
Hydrogen Chloride ◽  
Zinc Chloride ◽  
Electromotive Force ◽  
Mixed Solvents ◽  
Heat Content ◽  
Strong Electrolyte ◽  
Free Energies ◽  
Weak Electrolyte ◽  
Water Alcohol

In Part I of this series were described measurements of the free energy and heat content of hydrogen chloride in a series of water-alcohol mixtures. It appeared to be very desirable to find if the behaviour shown by hydrogen chloride is typical of that of strong electrolytes in general. For this purpose an attempt was made in the first place to determine the free energies of lithium chloride in these solvents, using amalgam electrodes. Preliminary measurements showed that even Under rigidly air-free conditions reproducible values of the electromotive forces of cells containing lithium amalgams could not be obtained in alcohol solutions. Similar experiences with sodium amalgams have been reported from the Balliol College Laboratory, while Scatchard has also experienced similar difficulties with calcium amalgams. It appeared that zinc chloride might be suitable, for when proper precautions are taken for the with zinc amalgam in aqueous solutions. The conductivities show that zinc chloride is a strong electrolyte in aqueous solution, and although several investigators have found that their product hydrolysed to give turbid solutions in water, we had no difficulty in obtaining a salt which gave perfectly clear solutions at all dilutions. The conductivity measurements of Getman and Gibbons, which show that in alcoholic solution zinc chloride is an extremely weak electrolyte, escaped our notice at the beginning of this work. But although on this account the behaviour of zinc chloride does not extend our knowledge of the properties of completely ionised substances in mixed solvents, it has proved to be an interesting case showing in the range of solvents investigated the transition from a strong to an exceedingly weak electrolyte. The free energies were determined by measuring the electromotive force of cells of the type Zn 1 percent. amalgam | ZnCl 2 , ( m ) Alcohol, N mols. per cent. AgCl( s ) | Ag The free energy change in the cell reaction, viz., Zn (Hg) + 2AgCl( s ) = ZnCl 2 ( m , N) + 2Ag, is given by ∆F = - 2 EF = - 46148E calories, where E is the electromotive force and F the electrochemical equivalent. The electromotive forces were determined in solvents containing 0, 25, 50, 90 and 100 mols. per cent, alcohol, each for a range of salt concentrations from about m = 0⋅01 to m = 1, at 15 ± 0⋅02°. It was originally intended to make a similar series of measurements also at 25°, in order to evaluate the heat content changes, but the reproducibility of the results in solutions containing large proportions of alcohol did not warrant this extension.

Electron microscopy studies of PZT ferroelectric film capacitor structures

1992 ◽  
Vol 50 (2) ◽  
pp. 1364-1365
Author(s):  
V. Kaushik ◽  
P. Maniar ◽  
J. Olowolafe ◽  
R. Jones ◽  
A. Campbell ◽  
...  
Keyword(s):  
Electric Fields ◽  
Sol Gel ◽  
Ferroelectric Material ◽  
Dielectric Constants ◽  
Dielectric Films ◽  
Lead Zirconium Titanate ◽  
Si Substrate ◽  
Film Capacitor ◽  
Pzt Films ◽  
High Dielectric

Lead zirconium titanate films (Pb (Zr,Ti) O3 or PZT) are being considered for potential application as dielectric films in memory technology due to their high dielectric constants. PZT is a ferroelectric material which shows spontaneous polarizability, reversible under applied electric fields. We report herein some results of TEM studies on thin film capacitor structures containing PZT films with platinum-titanium electrodes.The wafers had a stacked structure consisting of PZT/Pt/Ti/SiO2/Si substrate as shown in Figure 1. Platinum acts as electrode material and titanium is used to overcome the problem of platinum adhesion to the oxide layer. The PZT (0/20/80) films were deposited using a sol-gel method and the structure was annealed at 650°C and 800°C for 30 min in an oxygen ambient. XTEM imaging was done at 200KV with the electron beam parallel to <110> zone axis of silicon.Figure 2 shows the PZT and Pt layers only, since the structure had a tendency to peel off at the Ti-Pt interface during TEM sample preparation.

Tuning the Electric Field Response of MOFs by Rotatable Dipolar Linkers

2019 ◽  
Author(s):  
Johannes P. Dürholt ◽  
Babak Farhadi Jahromi ◽  
Rochus Schmid
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Structural Changes ◽  
Dielectric Behavior ◽  
Two Dimensions ◽  
Dielectric Constants ◽  
Electric Response ◽  
Dipole Strength ◽  
Metal Organic ◽  
Dynamics Simulations

Recently the possibility of using electric fields as a further stimulus to trigger structural changes in metal-organic frameworks (MOFs) has been investigated. In general, rotatable groups or other types of mechanical motion can be driven by electric fields. In this study we demonstrate how the electric response of MOFs can be tuned by adding rotatable dipolar linkers, generating a material that exhibits paralectric behavior in two dimensions and dielectric behavior in one dimension. The suitability of four different methods to compute the relative permittivity κ by means of molecular dynamics simulations was validated. The dependency of the permittivity on temperature T and dipole strength μ was determined. It was found that the herein investigated systems exhibit a high degree of tunability and substantially larger dielectric constants as expected for MOFs in general. The temperature dependency of κ obeys the Curie-Weiss law. In addition, the influence of dipolar linkers on the electric field induced breathing behavior was investigated. With increasing dipole moment, lower field strength are required to trigger the contraction. These investigations set the stage for an application of such systems as dielectric sensors, order-disorder ferroelectrics or any scenario where movable dipolar fragments respond to external electric fields.

scholarly journals Use of scaled-particle theory in the assessment of the Ph4As+/Ph4B− assumption for single ions

1979 ◽  
Vol 57 (1) ◽  
pp. 71-76 ◽  
Author(s):  
Michael H. Abraham ◽  
Asadollah Nasehzadeh
Keyword(s):  
Free Energy ◽  
Recent Work ◽  
Scaled Particle Theory ◽  
Cavity Formation ◽  
Energy Term ◽  
Free Energies ◽  
Particle Theory ◽  
Novel Method ◽  
Energy Of Interaction ◽  
Solvent Molecules

A novel method for the assessment of the Ph4As+/Ph4B− assumption for free energies of transfer of single ions has recently been suggested by Treiner, and used by him to deduce that the assumption is not valid for transfers between water, propylene carbonate, sulpholane, dimethylsulphoxide, N-methyl-2-pyrrolidone, and perhaps also dimethylformamide. The basis of the method is the estimation of the free energy of cavity formation by scaled-particle theory, together with the hypothesis that the free energy of interaction of Ph4As+ (or Ph4B−) with solvent molecules is the same in all solvents, ΔGt0(int) = 0. It is shown in the present paper that (a) whether or not the Ph4As+/Ph4B− assumption applies to transfer to a given solvent depends on which other solvent is taken as the reference solvent in Treiner's method, (b) the calculation of the cavity free energy term by scaled-particle theory and by the theory of Sinanoglu – Reisse – Moura Ramos (SRMR) yields values so different that the method cannot be considered reliable, (c) the calculation of cavity enthalpies and entropies for Ph4As+ or Ph4B− by scaled-particle theory yields results that are chemically not reasonable, (d) the hypothesis that ΔGt0(int) = 0 conflicts with SRMR theory, and (e) the conclusions reached by Treiner are not in accord with recent work that in general supports the Ph4As+/Ph4B− assumption for solvents that are rejected by Treiner.

LIMITING CONDUCTANCE OF LYONIUM AND LYATE IONS

1959 ◽  
Vol 37 (1) ◽  
pp. 173-177 ◽  
Author(s):  
Martin Kilpatrick
Keyword(s):  
Mixed Solvents ◽  
Direct Determination ◽  
Solvent Mixture ◽  
Dielectric Constants ◽  
Proton Mobility ◽  
Anhydrous Hydrogen Fluoride ◽  
Ice Leads ◽  
Hydrogen Bonded Systems ◽  
High Dielectric ◽  
Strong Acids

The problem of proton mobility has been considered in H2O–CH3OH, H2O–D2O, and H2O–H2O2 solvents from the current viewpoint of the mechanism of proton mobility for aqueous solutions. Mixed solvents are more complicated in that one must consider the relative basicity and acidity of the species competing for the protons. It is concluded that for dilute solutions of HClO4, where water is replaced by hydrogen peroxide, the decrease in equivalent conductance relative to that of KCl in the same solvent mixture is due to the partial elimination of the proton transfer process.For highly acidic non-aqueous solvents of high dielectric constants such as HF, HCN, and HCOOH, the problem of the weakness of the usual "strong" acids of aqueous solution makes a direct determination of the limiting equivalent conductances difficult. In the case of anhydrous hydrogen fluoride the available experimental evidence indicates that the limiting conductance of the lyonium ion is approximately the same as that of the potassium ion but the lyate ion has a higher limiting conductance than other stable anions.The higher proton mobility in ice leads one to expect that hydrogen-bonded systems may be found where the conductivity may approach that of electronic semiconductors.

Thermodynamic properties of multicomponent electrolyte solutions in mixed solvents. 5• HCl + NaCl + urea + water at 278.5–318.15 K

1988 ◽  
Vol 66 (4) ◽  
pp. 637-644 ◽  
Author(s):  
Dian-Yuan Men ◽  
Jia-Zhen Yang ◽  
Chun-Yu Liang ◽  
Li-Tian Zhang ◽  
Huan Gao ◽  
...  
Keyword(s):  
Mixed Solvents ◽  
Electrolyte Solutions ◽  
Absolute Temperature ◽  
Molar Enthalpy ◽  
Free Energies ◽  
Force Measurements ◽  
Solution Theory ◽  
Electrolytic Solution ◽  
Harned's Rule ◽  
Electromotive Force Measurements

This paper reports electromotive force measurements of the cells[Formula: see text]and[Formula: see text]in mixed solvents of urea, mole fraction x = 0.05, at five temperatures from 278.15 to 318.15 K. The standard potentials of Ag–AgCl electrode in mixed solvents were obtained from the emf of cell (A) for HCl of molality mA from 0.02 to 0.11 mol kg−1, both by extrapolation on the basis of an extended Debye–Hückel equation and by a polynomial approach proposed in this paper on the basis of Pitzer's electrolytic solution theory. The standard free energies of transfer for HCl are discussed. The activity coefficients of HClγA in HCl + NaCl + urea + water have also been obtained from the emf of cell (B) at constant total ionic strength I = 0.5, 1.0, 1.5, and 2.0 mol kg−1. The experimental results show that HCl obeys Harned's rule and log γA is a linear function of absolute temperature T. They also indicate that the relative partial molar enthalpy of HCl obeys a similar Harned's rule.

scholarly journals Machine Learning Guided Approach for Studying Solvation Environments

2019 ◽  
Author(s):  
Yasemin Basdogan ◽  
Mitchell C. Groenenboom ◽  
Ethan Henderson ◽  
Sandip De ◽  
Susan Rempe ◽  
...  
Keyword(s):  
A Priori ◽  
Optimization Procedure ◽  
Low Energy ◽  
Free Energies ◽  
Continuum Approach ◽  
Explicit Solvent ◽  
Linear Dimensionality Reduction ◽  
Solvent Molecules ◽  
Dynamics Simulations ◽  
Solvation Free Energies

<div><div><div><p>Toward practical modeling of local solvation effects of any solute in any solvent, we report a static and all-quantum mechanics based cluster-continuum approach for calculating single ion solvation free energies. This approach uses a global optimization procedure to identify low energy molecular clusters with different numbers of explicit solvent molecules and then employs the Smooth Overlap for Atomic Positions (SOAP) kernel to quantify the similarity between different low energy solute environments. From these data, we use sketch-map, a non-linear dimensionality reduction algorithm, to obtain a two-dimensional visual representation of the similarity between solute environments in differently sized microsolvated clusters. Without needing either dynamics simulations or an a priori knowledge of local solvation structure of the ions, this approach can be used to calculate solvation free energies with errors within five percent of experimental measurements for most cases.</p></div></div></div>

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