Question

IMF's questions
1. List the IMF's in order of increasing strengths
2. What is the relationship between boiling point and IMF's?
3. What is the relationship between surface tension and IMF's?
4. What is the relationship between vapor pressure and IMF's?

Answer 1

IMFs - intermolecular forces!
At the weak end of the scale, you have your dispersion forces, which result from temporary dipoles. This is the force causing condensation of nonpolar molecules (like N2).

Then, you have your dipole-dipole and ion-dipole forces. In the former, you have two polar molecules attracted to one another, in the latter, one polar molecule and one ion.

Finally, you have the strongest: hydrogen bonds, which are somewhat like a very strong dipole-dipole bond but not as strong as a covalent one. They occur when hydrogen forms a bond with an electronegative O, N or F atom.

As for questions two through four, consider those phenomena in terms of a "battle": on one hand, you have thermal energy causing the molecules to bounce apart; on the other, you have the IMFs trying to keep everything together. Let's look at 2, for example: if you have stronger IMFs, the molecules resist being pushed away from one another. Thus, you need a LOT of heat to seperate them, and that results in a higher BP. See if you can do the rest.