Pre-exam Intermolecular Forces Confusion
December 13, 2011 12:05 AM Subscribe
Intermolecular forces questions: Why do H-S-S-H molecules have dipole-dipole attractions to eachother? Why does ion-dipole attraction make for a stronger solute-solvent interaction than hydrogen bonding?
posted by sunnychef88 to Science & Nature (8 answers total)
My chemistry program keeps spitting out the answer that H-S-S-H molecules have dipole-dipole attractions. I'm struggling a little with determining whether molecules are polar here... are we supposed to be able to figure out that the H-S-S-H molecular geometry creates some sort of weakly polar attraction due to its symmetry? I drew the Lewis structure, and I guess I'm confused as to how you would get H-S-S-H being bent (if it is bent... best guess) when there are those two Sulfurs next to eachother as opposed to just one Sulfur, which would definitely be bent with the two lone pairs pushing it down. Can someone explain the Lewis structure and how the symmetry of it relates to polarity of the H-S-S-H molecule? A drawing of H-S-S-H would be appreciated. Google yielded nothing.
Also, I thought less than 0.4 debye electronegativity difference meant that the dipole wasn't significant, but I guess it's different in cases of intermolecular attraction. Could you clarify how EM difference plays into the polarity of a molecule?
Finally, why does ion-dipole attraction make for a stronger solute-solvent interaction than hydrogen bonding? I thought hydrogen bonding was the strongest IMF. Are IMF significantly different in solutions?