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We know that the degree of freedom of oxygen is 5. For this the total kinetic energy of oxygen must be (5/2)nRT. But maximum books say that it should be (3/2) nRT where as our college teacher said it will be (5/2)nRT Which is the correct one? Please help me on this one.

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I'm taking this out of wikipedia: the molar specific heat at constant pressure, $C_p$ of oxygen is 29.4 J/(mol K). Other values from standard tables say 0.92J/gK at 298K, and we can check that this is the same thing. Dividing by the gas constant R=8.314 J/(mol K), we get $\frac{C_p}{nR}=3.5$, which tells us that $\frac{C_V}{nR}=2.5$, so we indeed have five degrees of freedom (three translational, two rotational).

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    $\begingroup$ Does it mean it will be (5/2)nRT? $\endgroup$
    – DJS
    Commented Mar 18, 2020 at 4:36
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    $\begingroup$ Yes, it does. Do you have a reputable source that says differently? Standard tables seem to agree that it is 5/2. $\endgroup$
    – NewUser
    Commented Mar 18, 2020 at 4:37

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