ULTRASONIC SPEEDS AND THERMODYNAMIC PROPERTIES FOR PENTAFLUOROPROPYL ALCOHOL, TETRAFLUOROPROPYL ALCOHOL AND TRIFLUOROETHYL ALCOHOL UNDER HIGH-PRESSURES

The ultrasonic speeds u in pentafluoropropyl alcohol 5FP, tetrafluoropropyl alcohol 4FP and trifluoroethyl alcohol 3FE were measured by a sing-around technique operated at a frequency of 2 MHz. The measurements were carried out in the ranges of temperature from 283-348 K and pressure up to about 70 MPa with an uncertainty within +/- 0.2%. The results for these compounds show lower absolute u values and smaller pressure dependence than those for primary alcohols. Among the compounds studied, the u values for 4FP differ greatly in their pressure effect from those for 5FP and 3FE. The relationship between 1/u(partial derivative u/partial derivative p)T and isothermal compressibility K(T) for these alcohols is fitted well by a straight line having a slope of 5 +/- 0.2, as well as those for other alcohols; this slope is distinguishable from that of 4 +/- 0.15 for other hydrogen compounds reported elsewhere.