THERMODYNAMIC PROPERTIES OF CARBON TETRAFLUORIDE FROM 12 DEGREES K TO ITS BOILING POINT . SIGNIFICANCE OF PARAMETER

Low-temperature heat capacity data for carbon tetrafluoride of 99.985 mol % purity in the temperature range from 12 to 145.12°K are presented. Values were also derived experimentally for the entropies and temperatures of the solid transition, fusion, and vaporization (1 atm) as follows: ΔStr = 5.387 cal/(mol°K), Ttr = 76.23°K; ΔSf = 1.901 cal/(mol°K), Tf = 89.56°K; ΔSv= 19.457 cal/(mol°K), Tv = 145.12°K. The calorimetric entropy for carbon tetrafluoride is found to be 54.04 ± 0.13 cal/(mol°K), a value in excellent agreement with the statistical value of 54.037 cal/ (mol°K). The results are discussed in terms of the theory of Pople and Karasz. The parameter v is calculated for carbon tetrafluoride and used to account for the temperatures, entropies, and volume increments for the fusion and transition anomalies.