| Abstract |
In this review, attention is initially focused upon the evolution of the Newton - Laplace Equation, that links the measured speed of sound iii a fluid in conjunction with its density, to a reliable estimate of its isentropic compressibility kappa (s). Definitions of ideal and excess isentropic quantities are formulated on the premise that the thermodynamic properties of an ideal mixture are mutually related in the same manner as ate those of a real mixture or a pure substance. It is shown that both intensive and extensive properties can he derived from the ideal Gibbs energy. Different approaches previously used to calculate ideal isentropic quantities are examined and some subtle errors are identified. The consequences of using conflicting definitions are pointed out Isentropic pressure derivatives obtained under different conditions and empirical models for estimating the differences between ultrasonic speeds in real and ideal liquid mixtures are discussed. |
