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Chemistry Forums for Students => High School Chemistry Forum => Topic started by: LHM on December 12, 2010, 02:36:28 PM

Title: Largest Standard Molar Entropy
Post by: LHM on December 12, 2010, 02:36:28 PM

Of the gases He, H₂, and CH₄, which has the largest standard molar entropy at 25°C?

Since they're all gases, doesn't the one with the largest molar mass also have the largest standard molar entropy? So should the answer be CH₄?

But then I started to think about how a larger molar mass also implies greater London forces, which would seem to contradict the fact that the largest molar mass = largest standard molar entropy when they're in the same state, so is it assumed here that because the gas molecules are too far away to let London forces have any impact on them? What about in solids or liquids?

Title: Re: Largest Standard Molar Entropy
Post by: rabolisk on December 13, 2010, 11:11:57 AM

CH₄ is the answer, as it is a polyatomic molecule, capable of more movements or microstates.