Thermodynamics of Ion Association and Solvation in 2-Methoxyethanol:  Behavior of Tetraphenylarsonium, Picrate, and Tetraphenylborate Ions from Conductivity and Ultrasonic Data

Abstract

Precise measurements on electrical conductances and ultrasonic velocities of solutions of potassium picrate (KPic), potassium tetraphenylborate (KBPh 4 ), tetrabutylammonium tetraphenylborate (Bu 4 NBPh 4 ), and tetraphenylarsonium picrate (Ph 4 AsPic) in 2-methoxyethanol (ME) at temperatures 288.15 e T/K e 308.15 have been reported. The conductance data have been analyzed by the 1978 Fuoss conductance-concentration equation. Thermodynamics of the association processes have also been studied and the Coulombic forces are found to play a major role in the association processes. The limiting ionic conductances have been estimated from the appropriate division of the limiting molar conductivity values of the "reference electrolyte" Bu 4 -NBPh 4 . Strong association was found for all these salts in this solvent medium. The results strongly suggest the electrostriction of the solvent molecules around the potassium and picrate ions, while for the larger tetrabutylammonium and tetraphenylarsonium ions they are accommodated inside the space between the alkyl or aryl chains attached to the nitrogen or arsenic atom; for tetraphenylborate ion, however, neither electrostriction nor penetration of the solvent molecules is found to be important.

Thermodynamic and Acoustic Study on Molecular Interactions in Certain Binary Liquid Systems Involving Ethyl Benzoate

“…The compressibility behavior of solutes, which is the second derivative of the Gibbs energy, is a very sensitive indicator of molecular interactions and can provide useful information about this phenomenon [26][27][28]. The structural change of molecules takes place due to the existence of electrostatic field between interacting molecules.…”

Thermodynamic Studies on Silver and Thallium Nitrate

“…The obtained equilibrium constants (K A ) for the ion-association reaction served to investigate the thermodynamics of this process. Consequently, the standard Gibbs energy ( G A ), the enthalpy ( H A ), and the entropy ( S A ) of the ion-association process were calculated according to the following equations [21][22][23]: …”

The effect of temperature on association constants and conductivities of ferrous chloride and ferric chloride in DMF-water mixtures

“…From Table 4, it was observed that, while the values of ΔS o for FeCl3 decreased with a increase in the temperature, for FeCl2, they indicated some disorder. The main factors which govern the standard entropy of ion association of electrolytes are (i) the size and shape of the ions, (ii) charge density on ions, (iii) electrostriction of the solvent molecules around the ions, and (iv) the penetration of the solvent molecules inside the space of the ions [34]. For both FeCl2 and FeCl3, ΔS o values indicated a decrease, as the composition of DMF in DMF-water mixed solvents increased.…”