Energy Transfer by Collisions in Vapors of Chlorinated Methanes

Abstract

Ultrasonic velocity has been measured at 30°C in the four chlorinated methanes: methyl chloride, methylene chloride, chloroform, and carbon tetrachloride, at pressures from 1.5 cm Hg to more than one atmos in the case of methyl chloride, and with the others to the vapor pressures available up to 28°C and at frequencies from 0.2 to 2 Mc sec—1. Dispersion of the velocity has been found in each case, the relaxation frequency/pressure ratios, correcting for departure from the ideal gas law, at 30° being in CH3Cl, CHCl3, and CCl4 respectively 1.13, 27.3, and 23.3 Mc sec—1 atmos—1. In CH2Cl2 two relaxations have been found with respective frequency/pressure ratios after similar corrections of 2.27 and 105 Mc sec—1 atmos—1.