Ultrasonics in chemistry

Measurements on the velocity and the attenuation of elastic waves in solutions can reveal changes internal to the solution, such as changes in the concentrations of the constituents. Any such change is characterized by a relaxation time, and the effect on velocity and attenuation is most apparent when the wave has angular frequency equal to the relaxation time; for many situations, such frequency lies in the range accessible to ultrasonic measurement. After developing the necessary background, this article describes the progress that has been made in applying ultrasonics to the chemistry of electrolytes.