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AS Level IMF question

Not able to upload the image but the question was to state the strongest type of intermolecular force in HI (hydrogen iodide). The marking scheme says vdW forces - why is it not permanent dipole-dipole?
In general, although dipole-dipole is usually more significant than the vdW, for some molecules (& because I is quite large and so has a large electron cloud), the vdW will actually be stronger than the permanent dipole-dipole. That is what this sheet says https://web.chem.ucsb.edu/~genchem/Chem1CS03/moreinfo/trends_in_boiling_points_.pdf

To be honest, I think I would have chosen the wrong answer as well if I saw that question - it might be worth just going over it with you teacher.
Reply 2
Original post by booklover1313
In general, although dipole-dipole is usually more significant than the vdW, for some molecules (& because I is quite large and so has a large electron cloud), the vdW will actually be stronger than the permanent dipole-dipole. That is what this sheet says https://web.chem.ucsb.edu/~genchem/Chem1CS03/moreinfo/trends_in_boiling_points_.pdf

To be honest, I think I would have chosen the wrong answer as well if I saw that question - it might be worth just going over it with you teacher.

thank you so much!
Original post by swyjk
thank you so much!

No problem!

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