Health & Environmental Research Online (HERO)


Print Feedback Export to File
8214183 
Journal Article 
Thermodynamic Properties of Carbonyl Fluoride from 12°K to Its Boiling Point. the Entropy from Molecular and Spectroscopic Data 
Pace, EL; Reno, MA 
1968 
Yes 
Journal of Chemical Physics
ISSN: 0021-9606
EISSN: 1089-7690 
48 
3 
1231-1235 
English 
The saturated molar heat capacity of carbonyl fluoride has been measured from 12°K to its normal boiling point, 188.58°K, for a sample of 99.85 mole % purity. The molar heat of fusion was found to be 1603.2 cal/mole at the solid-liquid-vapor equilibrium temperature of 161.89°K. The molar heat of vaporization at the normal boiling point was found to be 4368 cal/mole. The vapor pressure of the soh'd in the range from 130°K to the triple point of 161.89°K is represented by the equation log10P(mm) =80.946550-3017.1338/T-27.311382 log10T. The vapor pressure of liquid from the triple point to the normal boiling point is represented by the equation log10P(mm) =31.086907-1682.1748/T-8.4754322 log 10T. The standard entropy of carbonyl fluoride gas at the normal boiling point was found to be 57.09±0.14 cal/mole· °K) from the experimental data. A spectroscopic entropy of 57.23 cal/(mole·°K) was calculated by statistical procedures using the moments of inertia: I a=42.7928 amu·Å2; Ib=43.0130 amu·Å2; and Ic=85.9614 amu·Å 2 and the frequency assignment (in cm-1): v 1(A1) = 965; v2(A1) = 1928; v 3(A1)=584; v4(B1)=1249; v 5(B1) = 626; and v6(B2) =774. The agreement between the calorimetric and spectroscopic entropy establishes the fact that there is no residual entropy of randomness in the solid. It is suggested that the high-dipole moment (0.951 D) of the carbonyl fluoride is a factor which influences the ordering of the molecules in the solid.