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At low temperatures, the energy that a molecule gains in collisions with its neigh- bors is generally not large enough to raise it to the first excited state of either rotation As the temperature is raised, the average energy of the molecules increases. In some collisions, a molecule may have enough energy transferred to it from another molecule There is no contribution at room temperature from vibration, because the molecules are still in the ground vibrational state. The temperature must be raised even further The predictions of this model are supportive of the theorem of equipartition of en- ergy. In addition, the inclusion in the model of energy quantization from quantum SECTION 21.4 • The Equipartition of Energy 653 Figure 21.8 An energy-level diagram for vibrational and rotational states of a diatomic molecule. Note that the rotational states lie closer together in energy than the vibrational states. Rotational states Rotational states Vibrational states ENERGY Quick Quiz 21.6 The molar specific heat of a diatomic gas is measured at constant volume and found to be 29.1 J/mol & K. The types of energy that are contribut- Quick Quiz 21.7 The molar specific heat of a gas is measured at constant volume and found to be 11R/2. The gas is most likely to be (a) monatomic The Molar Specific Heat of Solids The molar specific heats of solids also demonstrate a marked temperature depen- |