Expressions of acoustic parameters in organic liquid derived from Schaaff’s theory

Based on Schaaffs’ theory of ultrasonic speed in an organic liquid, new expressions of acoustic parameters, including those of the temperature coefficient of ultrasonic speed (∂C/∂T)P, the pressure coefficient (∂C/∂P)T, and the nonlinearity parameter B/A were derived and analyzed. It was found that the expressions could generally describe and expound acoustic properties of the liquid, and could even determine the parameters quantitatively. The expressions have two features: (i) they connect the acoustic parameters with the molecular radius of the medium; (ii) they indicate that under atmospheric pressure and at room temperature, the temperature coefficient (∂C/∂T)P is negative while the pressure coefficient (∂C/∂P)T is positive, and under the same conditions the B/A value in an organic liquid always exceeds 8. These results are confirmed by the experimental data from the literature.