| Popis: |
The heat capacities of the fluorinated fullerenes C 60 F 48 , C 60 F 46 , and C 60 F 36 have been measured in an adiabatic vacuum calorimeter over the temperature range from 8 K to 356 K. The heat capacity curve of C 60 F 48 reveals a gradual “order–disorder" transition between the temperatures 315 K and 345 K. Thermodynamic properties of C 60 F 48 in the transition region are as follows: T trs = (329.6 ± 0.4) K, Δ trs H = (7.0 ± 0.7) kJ · mol − 1 and Δ trs S = (21 ± 2) J · K − 1 mol − 1 . The C p curve of C 60 F 46 exhibits a glassy crystal transition in the temperature interval from 210 K to 245 K. The temperature dependence of the heat capacity of C 60 F 36 does not indicate any anomaly. The molar thermodynamic functions H m o ( T ) − H m o (0), S m o ( T ) − S m o (0), and G m o ( T ) − H m o (0) over the temperature range studied and entropies of formation Δ f T S m o at T = 298.15 K have been calculated for C 60 F 48 , C 60 F 46 , and C 60 F 36 . |
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