Heat Capacity, Equipartition, and Thermal Energy Transfer

All flashcards

Molar heat capacity at constant volume

The heat required per mole for a one-kelvin temperature increase while volume remains fixed.

Equipartition theorem

In classical thermal equilibrium, each active quadratic degree of freedom contributes average energy of $\frac{1}{2}k_BT$ per molecule.

Dulong–Petit law

A classical estimate that a solid element has molar heat capacity near $3R$.

Latent heat of fusion

Energy absorbed or released per unit mass during melting or freezing at the phase-change temperature.

Molar heat capacity at constant pressure

Heat required per mole for a one-kelvin temperature increase while pressure remains fixed; for a gas, it exceeds $C_V$.

Quiz questions

1. What does molar heat capacity at constant volume describe?Answer: Heat needed per mole for a one-kelvin temperature rise at fixed volume.
2. In the rigid-container ideal-gas heating model, why does supplied heat equal the gas's internal-energy change?Answer: The fixed volume prevents expansion work by the gas.
3. What is the classical molar heat capacity at constant volume of an ideal monatomic gas?Answer: $C_V=\frac{3}{2}R$
4. A monatomic ideal gas sample with $0.952\ \text{mol}$ receives $180\ \text{J}$ in a rigid container. Approximately how much does its temperature rise?Answer: $15.2\ \text{K}$
5. What expression gives the heat absorbed when a mass $m$ melts at its melting point, given latent heat of fusion $L_f$?Answer: $Q=mL_f$