Ultrasonic Waves and Electrochemistry. II. Colloidal and Ionic Vibration Potentials

Abstract

When ultrasonic waves are introduced into an ionic solution or a suspension of charged colloidal particles, alternating potential differences are generated between points separated by a finite distance in the direction of propagation (other than an integral multiple of the wavelength). Pulse-modulated ultrasonic waves have been used to study these effects at a carrier frequency of 200 kc/sec. The colloidal vibration potentials have been measured in a number of colloidal silica suspensions of various concentrations, particle sizes, and conductivities. The experimental results are in general agreement with the mathematical treatment of Enderby. Measurements of ionic vibration potentials in potassium chloride solutions indicate a value of 6μv per cm/sec for a 10−3-molar solution. This value corresponds to a difference of 80 in the apparent gram-ionic-masses of the hydrated potassium and chloride ions.