Question

Given acids, alkanes, alkyl halides, amines, and alcohols, of comparable molecular mass, what is the probably order of volatility?

Answer 1

We assess the degree of intermolecular force; the degree of interaction between individual molecules.

Explanation:

And thus in order of INCREASING boiling point, DECREASING volatility:

`"(i) alkanes; (ii) alkyl halides; (iii) amines; (iv) alcohols; (v) acid."`

Alcohols have a greater propensity to hydrogen bond than the amine, and are thus ranked higher: cf. `"ethyl alcohol", 78` `""^@C`, `"ethyl amine", 18` `""^@C`. Hydrogen bonding, the most potent intermolecular force, is decisive for carboxylic acids; cf. `"acetic acid", 118` `""^@C`.

As the alkyl chain grows, hydrophobic interactions become strong, and thus long chain alkanes, even without functionality, can have high boiling points.