[yonglu1989]

 From what i currently understand, Chlorine is more electronegative than iodine. So the force of the dipole dipole forces should be higher and therefore the boiling point should be much higher. I also understand that London dispersion forces increase with increasing molar mass (due to the number of electrons within the element). However, i was also informed that the dipole dipole forces are much stronger than that of London dispersion forces. So to sum it up, shouldn't HCl have a higher boiling point than HI? Clearly something is wrong with my logic because the order boiling points is: HI>HBr>HCl. Can someone please explain this? Thank you very much!!

[Vidya]

Boiling point  is  controlled by two factors ...dipole -dipole  and dispersion forces .Along the period it is the polarity or dipole dipole forces which are major dominating forces because there is an increase in the electronegativity  so boiling point increases along the period like H2S < HCl .

The order of boiling point down the group increases because of the increase in London dispersion forces and  it becomes the major factor because as go down the group there is big jump in the molar mass .

[mikasaur]

HF is actually the only hydrogen halide that forms Hydrogen bonds. After that, inter-molecular bonding occurs through Van der Waals forces which -- as you correctly stated -- increase as the number of electrons increase within an atom.

So the order of boiling points is actually HF>HI>HBr>HCl.

https://en.wikipedia.org/wiki/Hydrogen_halide#Physical_properties

[Vidya]

Yes you are right only in case of Vth group ,VI th group and VII th group where we have N,O and F ....their hydrides have higher boiling points because of special diople -diople attraction ....Hydrogen bonding ...
like NH3>PH3
H2O>H2S
and HF >HCl