Question

What intermolecular interactions occur for `"(i) dihydrogen"`, `"(ii) acetone"`, `"(iii) propane"`, and `"(iv) ammonia"`, `"(v) water"`, and `"(vi) hydrogen fluoride"`?

Can you rank these in order of volatility?

Answer 1

Well, van der Waals interactions occur for each set of molecules.....

Explanation:

But van der Waals interactions are weak, and thus dihydrogen, for which ONLY dipersion forces operate, is the MOST VOLATILE of the given substances, with a normal boiling point of `-253.9` `""^@C`. Propane, which also possesses minimal intermolecular interaction, is next cab off the volatility rank.

For acetone, there is some degree of dipole-dipole interaction, in that there is some polarity in the carbonyl bond, i.e. `stackrel(delta+)C=stackrel(delta-)O`; compare the boiling point of acetone, `56` `""^@C`, with that of propane, `-42` `""^@C`, the which only has dispersion forces operating.

For ammonia, hydrogen chloride, and water a special type of dipole-dipole interaction operates, `"hydrogen bonding"`, and this occurs where hydrogen binds to a strongly electronegative element such as oxygen, or fluorine, or nitrogen. You should look up the normal boiling points of `HF` and `NH_3`, and `H_2O`, and compare them to their lower group hydrides.