Sept., 1982 ,
DYN$MIC ~ ~ E C H A N I C A PROPERTIES L OF POLYVINYL CHLORIDE
GELS
1639
energy. We may attribute this difference to the “reorganization energy” of the NO2 radical,6.21 that is, the NO2 radical in BNO2 is less stable than is the free NOz molecule. Qualitatively speaking, the odd electron “used up” in the H-F bond forms 51 resonating three-electron bond in free NOz, thus stabilizing the molecule with a gain of 18 kcal. The energy values given for FKOz in Tables I11 and I V are, of course, approximate values with an inherent uncertainty of A 2 kcal. This uncertainty resides in the reported value for the standard heat le2 = 1.85 X lo1$exp(-l8,43O/RT) of formation of nitryl fluoride, Le., -19 It 2 kcal. Turning our attention to Table I11 we observe The same uncertainty is carried over to the equithat the nitrogen-halogen bond energy in FNOs is librium constants in Table V. Thus the equiabout 15 kcal. higher than in C1K02, whereas the librium constant could be off, in the worst case, nitrogen-oxygen bond energy is larger in the case by as much as about two orders of magnitude. The conclusions reached earlier, however, would remain of nitryl chloride by about 3 kcal. It is interesting to note that the dissociation essentially the same. I n conclusion we may note that all reactions 2 to energy of 46.0 kcal. of the N-F bond in nitryl fluoride is about 9 kcal. less than the dissociation 8 show a strong temperature dependence and the energy of the N-F bond i.1 rit-osyl fluoride, 55.4 reaction which is promising for kinetic studies is kcal.,6 which in turn is about 9 kcal. less than the reaction 6, i e . , nitryl fluoride phis nitric oxide. average single bond energv of 64.6 kcal. for the The study of the kinetics of this reaction is presently 5-F bond in nitroven trifluoride (one-third the being carried out at this Laboratory. Acknowledgm ent.-The helpful discussions of energy for the dissociation of KF3 into N and 3F). The W-F bond dissociation energy in FXOz is this work with Dr. Hadley Ford are acknowledged. thus 18 kaal. less than the normal S-F single bond (21) M . Szwaro and M. G. Evans, J. Chsm. Phvs., 18, 618 (1950).
2= where 2 is the ratio of partition functions, Q N O ~ Q F ~ / Q F N O ~ Q F . At 300°K., assuming ideal gas behavior and pressures of 1 atm. for all species parlicipating in the reaction, Z is found to be ll.Gl2. Using this value, together with the correfiponding I
