Pulse-echo overlap technique of signal processing and ultrasonic velocity measurements of Cu(I) and some tetraalkylammonium salts in binary organic mixtures to study various structural effects

摘要

The study of ion-solvation has attarcted the attention of many workers during the last few years. In case of binary solvent mixtures, both the solvent components play an important role towards solvation of ions. The physical extreme of solvation is the transfer of an ion from vaccum to the solvent while the chemical extreme of solvation describes the stoichiometric chemical reaction with the solvent. The behavior of electrolytes in solution depends mainly on ion-ion and ion-solvent interactions. The ion-ion interaction in general, is stronger than the ion-solvent interactions. Ion-ion interaction in dilute electrolytic solutions is now theoratically well understood, but ion-solvent interaction(ion solvation)still remain partially explained. The term preferential solvation is used when the composition of the solvent components in mixed solvents in the neighbourhood of cation and anion furnished by an electrolyte is different from that in the bulk of solution. The solvation behavior of ions in mixed solvent has become an important subject of solution chemistry for last few years. Since in mixed solvent systems the dielectric constant and viscosity of the medium can be varied to a desired value, Binary mixture of water with organic solvents have been frequently used for the study of electrolytic solutions. In such solvent mixtures, the solvent structural effects are generally very strong. Consequently, ion solvation effects are overshadowed by the solvent structural effects. In order to minimize solvent structural effects attempts had been made for the study of ion-solvent interactions in binary mixtures of non-aqueous solvents with a non-polar component. The non-polar component of the solvent mixture played no significant role in ion solvation except to change the solvent properties such as dielectric constant and viscosity of the medium. Therefore, in such solvent systems the solvation effects considered to be only due to the polar component. Binary solvent mixtures comprising of two highly polar non-aqueous solvents were recently employed for the study of preferential solvation of ions.