Abstract
Ultrasonic speed in fluids is one of the most important physical properties, which is closely related to the thermodynamic quantities. This article reviews the experimental technique for measuring the ultrasonic speed μ, its behavior in liquids at high pressures, and the estimation of the liquid density from the μ data. The temperature and pressure dependencies of the ultrasonic speed in halogenated benzenes are discussed. As a new attempt of the density estimation from the μ data, the liquid molar volume for these substances has been derived by means of the Peng-Robinson equation of state with a reasonable accuracy.
