[ideaessence]

Hi.

I'm working on a lab report and these questions arose:

What are the dominant intermolecular forces in cyclohexanone? What are the dominant intermolecular forces in benzophenone?

It seems that both of them have dipole-dipole forces where that double-bond connected to the Oxygen is. And, benzophenone looks like it has a larger nonpolar part per molecule. Nonetheless, it seems to me that both have dipole-dipole forces and London/dispersion forces. Is this correct? How do I know what the dominant forces are? From what I understand, London/dispersion forces are weaker in nearly all cases, but not all cases, so I don't know how to tell for sure on this one.

The next question reads:

Why is benzophenone a solid at room temperature?

I assume this relates to intermolecular forces being stronger in benzophenone, but I don't see how to arrive at that conclusion. The benzophenone looks like it has a larger nonpolar region than the cyclohexanone. Does a delocalized part of a molecule have polarity or something?

Thanks for any help.

[Smrt guy]

Benzophenone has pi-pi interactions.  This and the significantly larger mass result in it being a solid with cyclohexanone being a liquid.