Online Chemistry Notes: Chloroform vs. Bromoform

Below are the two molecules Chloroform ( CHCl3) and Bromoform( CHBr3). They are both polar molecules, but Bromoform will have a higher boiling point because Bromine is a larger molecule than Chlorine.
                               o                                     o                         B.P = 61.7  C          B.P. = 147-151 C

 Even though Chlorine is more electronegative, and it's bonds are a little more polar, the electronegativity of Bromine is close enough to Chlorine to negate this factor. 

So since the polarity of the two molecules cancel each other out, The London-dispersion forces determine which will have a higher boiling point.For this same reason, HBr has a higher boiling point than HCl.

Here is a link from Wayne Breslyn on how to draw the Lewis Structure of Bromoform:

Source:
Tro, Nivaldo J., Robert S. Boikess, Joseph H. Bularzik, and William M. Cleaver. "Liquids, Solids, and Intermolecular Forces." Chemistry A Molecular Approach. Upper Saddle River: Prentice Hall, 2008. 466. Print.

Updated by Z. on Jan. 17, 2015