An Experimental Device for Measuring the Ultrasonic Absorption by Means of a Differential Method

Ultrasonic methods have proved to be a valuable instrument for relaxation studies of fast chemical reactions in solutions. This paper presents a new ultrasonic method based on a differential measurement using a reference liquid. The essential advantage of this method is its applicability over a wide range of frequencies. With ΔV ≈ 20 to 25 cm³/mole measurements in aqueous solutions are still possible at concentrations of 10⁻³ M of the reagent. An experimental equipment for the frequency range 5.5 MHz to 82.5 MHz is described, and first results are reported concerning the protolytic reaction of the amino group of the amino acid lysine.