Sound Dispersion in Binary Mixtures of Halomethane Gases

Sound dispersion has been experimentally examined in all binary combinations of the halomethane gases, CH2F2, CHF3, CF4, CCl2F2, and CHCl2F. Concentrations of 25%, 50%, and 75% were examined in each combination. The experimentally determined vibrational relaxation time of each mixture was related to the equation τ−1=X2τAA−1+(1—X )2τBB−1+X(1—X) (τAB−1+τBA−1). A single relaxation time was observed in all the mixtures, and the above equation was found to be valid when the relaxation times of the individual gases in the mixture were similar and when their vibrational specific heats were similar. Values of (τAB−1+τBA−1) were deduced from the data and compared with values calculated from an extended version of the Schwartz, Slawsky, and Herzfeld theory. A Lennard‐Jones 7–28 interaction potential was used for the calculations and appears to be an appropriate potential for these molecules.