THERMODYNAMIC PROPERTIES OF 2 GASEOUS HALOGENATED ETHERS FROM SPEED-OF-SOUND MEASUREMENTS - DIFLUOROMETHOXY-DIFLUOROMETHANE AND 2-DIFLUOROMETHOXY-1,1,1-TRIFLUOROETHANE

We present measurements of the speed of sound in gaseous difluorometho xydifluoromethane (CHF2-O-CHF2) and 2-difluoromethoxy-1,1,1-trifluoroe thane (CF3-CH2-O-CHF2). These measurements were performed in an all-me tal apparatus between 255 and 384 K. We have obtained ideal-gas heat c apacities and second acoustic virial coefficients from analysis of the se measurements. Two methods of correlating the second acoustic virial coefficients, a square well model of the intermolecular interaction a nd a function due to Fitter and Curl, are presented.