Ultrasonic Spectra and Relaxation in Sodium Chloride Dioxane-Water Solutions

Abstract

Ultrasonic absorption spectra in sodium chloride dioxane-water solutions were measured by the ulrasonic pulse method. from 10 to 110 MHz, and ultrasonic velocities were measured by interference of pulse wave and continuous wave at 5 MHz.
Sodium chloride dissociates completely in aqueous solution, and ultrasonic absorption due to relaxation was not found in the solution. If dioxane added to the solution to reduce the dielectric constant, dissociation equilibrium was held between sodium ion, chloride ion and undissociated sodium chloride, and the ultrasonic absorption due to the relaxtion of the reaction was observed.
The volume change due to dissociation of sodium chloride was calculated from the ultrasonic absorption spectra, and compared with the values estimated from pressure change of dissociation equilibrium of sodium chloride in dioxane-water solutions, and the agreement between them was fairly good.
Therefore, the ultrasonic absorption found in sodium chloride dioxane-water solutions is attributed to the relaxation of dissociation equilibrium of sodium chloride in the solutions.