ULTRASONIC VELOCITIES IN PURE HYDROCARBONS AND MIXTURES

Ultrasonic velocities were measured in hydrocarbons of n-alkanes, 1-alkenes, and naphthenes as a function of temperature, using the ultrasonic pulse transmission method. The velocities of all the hydrocarbons measured decrease with increasing temperature approximately linearly, although the rate of decrease is different for different hydrocarbons. The data also show that hydrocarbons of the same homologous series with higher carbon content have higher bulk moduli (or lower compressibilities) and the measured velocities V in mixtures of these pure hydrocarbons obey a simple physical mixing law V = SIGMA-i(n) = 1 X(i)V(i), where X(i) is the volume fraction and V(i) is the velocity, respectively, of the ith component.