Comparison of the free energy of transfer of electrolytes, measured with cells without transference, with the sum of the free energies of the corresponding cations and anions with the Owen-cell on standard conditions

1983 ◽  
Vol 36 (10) ◽  
pp. 1997 ◽  
Author(s):  
K Schwabe ◽  
W Hoffmann ◽  
C Queck
Keyword(s):  
Free Energy ◽  
Free Energies ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Ph Values ◽  
Liquid Junction Potentials ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer ◽  
Very High ◽  
Junction Potential

The comparison of S2ΔS1G°tr(E1) with the sum of the values for the corresponding cation and anion S2ΔS1G°tr(Ct+)~S2ΔS1G°tr(X-) (measured) with Owen cells, gained by double extrapolation and by the assumption that the liquid junction potential at 1→0 may be neglected) gives values which differ by not more than ±5%. Most of the investigated acids allow the conclusion that the pH values, measured in cells with transference, and having the same electrodes, give good information on the acidity of the organic solvent and its water mixtures, referred to the standard state in water. That means that the pH, changed to the same H+ concentration in the solvent compared with that in water, is essentially an effect of the free energy of transfer of the hydrogen ion and not of very high liquid junction potentials.

Thermodynamics of transfer of Ph4C; scaled-particle theory and the Ph4As+/Ph4B− assumption for single ions

1979 ◽  
Vol 57 (15) ◽  
pp. 2004-2009 ◽  
Author(s):  
Michael H. Abraham ◽  
Asadollah Nasehzadeh
Keyword(s):  
Free Energy ◽  
Total Free Energy ◽  
Scaled Particle Theory ◽  
Free Energies ◽  
Particle Theory ◽  
Free Energy Of Transfer ◽  
Enthalpy And Entropy ◽  
Interaction Term ◽  
Energy Of Transfer ◽  
Entropy Of Transfer

Free energies of transfer of Ph4C from acetonitrile to 20 other solvents have been calculated from literature data. The contribution of the cavity term to the total free energy has been obtained from scaled-particle theory and Sinanoglu–Reisse–Moura Ramos theory. It is shown that there is little connection between the cavity term and the total free energy of transfer, and that there must be, in general, a large interaction term. If the latter is important for transfer of Ph4C, we argue that it must also be important for transfer of the ions Ph4As+ and Ph4B−. Previous suggestions that the interaction term is zero for transfer of these two ions are thus seen to be unreasonable. We also show, for six solvents, that the interaction term for Ph4C is very large in terms of enthalpy and entropy, and that scaled-particle theory seems not to apply to transfers of Ph4C between pure organic solvents.The free energy, enthalpy, and entropy of transfer of Ph4As+ = Ph4B− have been calculated by dividing the total transfer values into neutral and electrostatic contributions; reasonable agreement is obtained between calculated and observed values.

Solvation of ions. XXII. Solvation of cations by hard N,N-dimethylformamide and soft N,N-dimethylthioformamide

1974 ◽  
Vol 27 (5) ◽  
pp. 933 ◽  
Author(s):  
R Alexander ◽  
DA Owensby ◽  
AJ Parker ◽  
WE Waghorne
Keyword(s):  
Electrochemical Cell ◽  
Linear Free Energy Relationship ◽  
Free Energies ◽  
Univalent Cations ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Linear Free Energy ◽  
Solvation Of Ions ◽  
Solvation Mechanisms ◽  
Junction Potential

The free energies of transfer of some univalent cations from N,N-dimethylformamide to N,N- dimethylthioformamide at 25� are Li+, 64.0; Na+, 50.2; K+, 37.2; Cs+, 23.4; TI+, -4.2 and Ag+, - 87.0 kJ g-ion-1. The values are based on the assumption of negligible liquid junction potential in an electrochemical cell. Certain ones of these values can be interpreted in terms of general interactions of hard and soft cations with hard and soft basic solvents. A linear free energy relationship, ΔGtr(M+) = mΔGtr(K+), is roughly obeyed by many cations for transfer to a variety of solvents. Deviations from this relationship, for example ΔGtr(Ag2+) to acetonitrile, ΔGtr (Ph4As+) to water and ΔGtr (Ag+) to N,N-dimethylthioformamide, allow specific solvation mechanisms to be detected.

Liquid-junction potentials in ethylenediamine: Attempted calculations and evaluations using concentration cells

1977 ◽  
Vol 55 (16) ◽  
pp. 2962-2965 ◽  
Author(s):  
Suraj P. Makhija
Keyword(s):  
Sodium Iodide ◽  
Calculated Data ◽  
Potassium Bromide ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Sodium Amalgam ◽  
Liquid Junction Potentials ◽  
Ionic Mobilities ◽  
Concentration Cells ◽  
Junction Potential

Concentration cells of the type M(Hg)|MX(1)||MX(2)|M(Hg), where M(Hg) is potassium amalgam or sodium amalgam, were investigated with three electrolytes, potassium bromide, potassium iodide, and sodium iodide. An attempt was made to determine the necessity and magnitude of liquid-junction potential corrections. Only in the case of sodium iodide are the ionic mobilities of cation and anion quite different in ethylenediamine, and liquid-junction potential corrections are necessary to obtain agreement between observed and calculated data. The limiting equations of Nernst and of Lewis and Sargent were found to be appropriate for calculating liquid-junction potentials in ethylenediamine, provided that calculated activities were used in these equations.

Concerning the distant polar interaction in free energies of transfer. An explanation and an estimation procedure

1991 ◽  
Vol 69 (12) ◽  
pp. 1893-1903 ◽  
Author(s):  
J. Peter Guthrie
Keyword(s):  
Free Energy ◽  
Hydrogen Bonding ◽  
Estimation Procedure ◽  
Free Energies ◽  
Polar Interaction ◽  
Free Energies Of Transfer ◽  
Polar Groups ◽  
Polyfunctional Compounds ◽  
Free Energy Of Transfer ◽  
Energy Of Transfer

For polyfunctional compounds, free energies of transfer from gas to aqueous solution require corrections for the interactions of polar groups (Distant Polar Interactions). These corrections can be made with very few adjustable parameters by using a model of the solvation process assuming hydrogen bonding is the major source of the effect on free energy of transfer for polar groups, and that hydrogen bonding is perturbed by polar effects, measured by Taft σ*. Parameters evaluated for polyfluoro, polychloro, and polybromo compounds successfully predicted the free energies of transfer for mixed polyhalogen compounds. Preliminary parameters have been evaluated for ethers, amines, phenyl groups, nitriles, and esters. Key words: free energy of transfer, distant polar interaction, hydrogen bonding, solvation.

Thermodynamics of the dissociation of trans-cinnamic acid

1976 ◽  
Vol 54 (12) ◽  
pp. 1916-1917 ◽  
Author(s):  
Rebati Charan Das ◽  
Upendra Nath Dash ◽  
Kshama Nidhi Panda
Keyword(s):  
Free Energy ◽  
Dissociation Constant ◽  
Temperature Coefficient ◽  
Cinnamic Acid ◽  
Standard Enthalpy ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Dissociation Process ◽  
A Cell ◽  
Junction Potential

The dissociation constant of trans-cinnamic acid in water has been determined at 15, 20, 25, 30, 35, 40, and 45 °C using a cell without liquid junction potential. From the temperature coefficient of the dissociation constant, the standard enthalpy, entropy, and free energy changes of the dissociation process have been calculated.

Liquid junction potentials in electrochemical cells involving a dissimilar solvent junction

1974 ◽  
Vol 27 (8) ◽  
pp. 1617 ◽  
Author(s):  
JW Diggle ◽  
AJ Parker
Keyword(s):  
Propylene Carbonate ◽  
Electrochemical Cells ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Solvent Interactions ◽  
Liquid Junction Potentials ◽  
Junction Potential ◽  
Solvent Solvent

The liquid junction potential at a number of dissimilar solvent junctions has been determined within the framework of the tetraphenylarsonium tetraphenylborate extrathermodynamic assumption. The junctions investigated were H2O/solvent S, MeCN/solvent S and propylene carbonate (pcar)/solvent S. The liquid junction potentials obtained have primarily been related to solvent-solvent interactions at the junction, being, for water, lowest for an alcohol /H2O junction (10 mV) and the greatest for a dipolar aprotic/H20 junction (100-200 mV).

scholarly journals Electrodiffusion Phenomena in Neuroscience and the Nernst–Planck–Poisson Equations

Electrochem ◽  
2021 ◽  
Vol 2 (2) ◽  
pp. 197-215
Author(s):  
Jerzy J. Jasielec
Keyword(s):  
Electrical Potential ◽  
Signal Propagation ◽  
Liquid Junction Potential ◽  
Liquid Junction ◽  
Patch Clamp Technique ◽  
Poisson Equations ◽  
Cellular Environment ◽  
Electrochemical Transport ◽  
Insight Into ◽  
Junction Potential

This work is aimed to give an electrochemical insight into the ionic transport phenomena in the cellular environment of organized brain tissue. The Nernst–Planck–Poisson (NPP) model is presented, and its applications in the description of electrodiffusion phenomena relevant in nanoscale neurophysiology are reviewed. These phenomena include: the signal propagation in neurons, the liquid junction potential in extracellular space, electrochemical transport in ion channels, the electrical potential distortions invisible to patch-clamp technique, and calcium transport through mitochondrial membrane. The limitations, as well as the extensions of the NPP model that allow us to overcome these limitations, are also discussed.

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