Molar Specific Heat at Constant Volume from DOF (Cv = (f/2)R)
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Cv = (f/2)R
What each symbol means
| Symbol | What it stands for |
|---|---|
| R | Universal gas constant = 8.314 J mol⁻¹ K⁻¹ |
| f | Degrees of freedom per molecule (translational + rotational + vibrational) |
| Cv | Molar specific heat at constant volume (J mol⁻¹ K⁻¹) |
When to use this
Valid for ideal gases obeying equipartition theorem. Monatomic f=3: Cv=3R/2≈12.47. Diatomic rigid f=5: Cv=5R/2≈20.79. Diatomic with vibration f=7: Cv=7R/2≈29.10. Triatomic nonlinear rigid f=6: Cv=3R. Equipartition valid when kBT >> energy level spacing of the mode.