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Chemistry Forums for Students => Undergraduate General Chemistry Forum => Topic started by: Bob Sacamano on September 18, 2010, 10:51:56 PM

Title: Why does propane have a lower boiling point than cyclopropane?
Post by: Bob Sacamano on September 18, 2010, 10:51:56 PM

I get why cyclopropane has a higher mp because it can xtalize better but I don't see why it has a higher boiling point as well.

Title: Re: Why does propane have a lower boiling point than cyclopropane?
Post by: Jorriss on September 18, 2010, 11:02:05 PM

Have you thought about the intermolecular forces and energies present in both molecules are compared them?

Title: Re: Why does propane have a lower boiling point than cyclopropane?
Post by: Bob Sacamano on September 18, 2010, 11:29:10 PM

The predominant intermolecular force must be van der waals forces. Propane has more bonds / molecule than cyclopropene but how does that effect the strength of the intermolecular forces?

Title: Re: Why does propane have a lower boiling point than cyclopropane?
Post by: Jorriss on September 18, 2010, 11:54:05 PM

Yeah, all there is van der waals. So that means for some reason, cyclopropane must have more significant intermolecular forces than n-propane.

Can you put forth a rationale for why cyclopropanes van der waal forces would be more significant?

Title: Re: Why does propane have a lower boiling point than cyclopropane?
Post by: Bob Sacamano on September 25, 2010, 04:45:58 PM

No, I can't. That's why I'm asking.