Question

Write the expression for the internal energy (U) of n moles of a diatomic gas at temperature T​

Answer 1

Answer:

The internal energy (U) for a diatomic gas at temperature T is 5/2 NkT. A diatomic gas such as H₂, O₂, etc. have their internal energies as the sum of translational kinetic energies and rotational kinetic energies.

Answer 2

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The diatomic molecules have 2 degrees of freedom for rotational motion hence the internal energy for rotational kinetic energy is 2/2 NkT. Therefore U = 3/2NkT + 2/2NkT = 5/2 NkT.