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Physical significance of temperature

  1. Dec 10, 2014 #1

    kelvin490

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    Some books say when heat flows into a monatomic gas at constant volume, all of the added
    energy goes into an increase in random translational molecular kinetic energy. But when the temperature is increased by the same amount in a diatomic or polyatomic gas, additional heat is needed to supply the increased rotational and vibrational energies. Thus polyatomic gases have larger molar heat capacities
    than monatomic gases.

    Does the absolute temperature reflect translation kinetic energy of gases only? If all types of kinetic energy of gas particles are related to temperature, why polyatomic gases have larger molar heat capacities than monatomic gases?
     
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  3. Dec 10, 2014 #2

    CWatters

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  4. Dec 10, 2014 #3

    kelvin490

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    What confuses me, however, is that the principle of equipartition of energy says every degree of freedom contributes to 1/2 kT so total kinetic energy of diatomic molecule including rotational kinetic energy is 5/2 kT. How can we say absolute temperature relates only to translational degrees of freedom?
     
  5. Dec 10, 2014 #4

    Bystander

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    Monatomic.

    Diatomic.
    Because that statement is referring only to a monatomic molecule.
     
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