Question pertaining to Boiling points

Hi could someone please sort this doubt out for me. I got the answer but still can’t really understand why the BP of CO2>BP of C3H8


I think the B.P of CO2 is less than that of C3H8 cuz the intermolecular forces between CO2 molecules are weak, which means CO2 has a very low boiling point.
Also, carbon dioxide is a gas at room temperature so clearly it has the lowest boiling point.
Ethanol has a polar carbon-oxygen double bond, meaning it can form stronger intermolecular forces than alkanes, and propane is an alkane.
Hope it helps:)


hi tho could you pleases elaborate what diff intermolecular forces operate in the cases of CO2 and Alkanes. Thank you!

Both the CO2 and C3H8 have L.D.F present but the reason for difference in B.P is same as i mentioned above in the explanation:)


Ujjwal is right! I would only add that London dispersion forces (intermolecular forces) between molecules increase as we increase the number of electrons in a molecule. This is because larger molecules which have more electrons can become a “stronger” spontaneous dipole due to greater fluctuations in electron density, thus they can induce a stronger dipole in the adjacent molecules as well. Eventually, this leads to stronger intermolecular forces between the molecules, so an increase in melting/boiling points.

Imagine it as a civil revolution:D The more people (electrons) you have, the greater the “change” they can cause.

Hope this helps:)


ah I got it. Thanks Darius!