Structural absorption of ultrasonic waves in aqueous solutions of alkali halides

Abstract

The absorption of sound in aqueous solutions of alkali halides decreases with increasing concentration irrespective of the frequency. The mechanism for this sound absorption is explained by a kinetic model describing the behaviour of the nearest-neighbour water molecules around the ions.

Isentropic Compressibility of Aqueous and Methanolic Sodium Thiocyanate Solutions

“…From Figure 2 it is apparent that the κ s isotherms possess a critical κ s value at 3.0 mol kg -1 which is independent of temperature and is related to the primary solvation of the solute (Endo and Nomoto, 1981). Beyond this concentration, overlap of cospheres of cation and anion occurs leading to the solvent shared, separated, and contact ion pairs (Marcus, 1985) due to the strong and predominant ion-ion interactions.…”

“…Considering the primary solvation number of Na + is 6 as a reference in aqueous medium (Caminiti et al, 1980;Ohtaki and Radnai, 1993) and the solvation number can be divided between the constituent ions (Endo and Nomoto, 1981), the primary solvation number of SCNis estimated to be 12.8. which is much higher than the reported coordination number (1.8 ( 0.2) obtained by Kameda et al (1994). The large difference in the primary solvation number may be due to the concentration difference.…”

“…Hinton and Amis (1971) and Ohtaki and Radnai (1993) reviewed the different approaches for studying the solvent structure around ions vis-a `-vis wide differences in solvation number for the same cation and anion. Among the many approaches the acoustic method (Bockris and Saluja, 1972;Endo and Nomoto, 1981) seems to be an alternative proposition for studying the solvent structure around the ions. Recently, we reported that the speed of sound and isentropic compressibility isotherms in aqueous sodium nitrate and sodium thiosulfate solutions converge at a particular concentration which has been correlated with the primary hydration shell of the solute (Rohman and Mahiuddin, 1997).…”

Thermodynamic properties in chemical reaction processes of seawater

“…There are many models to describe the kinetics between the ion and the hydrated water molecules, such as the models of Bockris [1949], Frank and Wen [1957], Samoilov [1965], Horne [1969], Bockris and Saluja [1972], and so forth. Endo and Nomoto [1981] have used the Bockris-Samoilov model to elucidate the sound absorption mechanism of alkali halide aqueous solutions. According to this model, the ionic hydration may be conventionally divided into two regions, a primary hydration (w•) associated with the interaction between the ion and the nearest-neighbour water molecules and a secondary hydration (w2) associated with the interaction between the ion and W l water molecules with other water molecules in the immediate vicinity.…”

“…quantitie s of seawater are determined from our water model on the [Endo, 1980a[Endo, , c, 1982 basis of X ray diffraction [Narten et al, 1967] and an electrolyte solution model [Bockris, 1949;Endo and Nomoto, 1981] of hydrated water around ions.…”