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

Mar 13, 2017

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:

$\text{(i) alkanes; (ii) alkyl halides; (iii) amines; (iv) alcohols; (v) acid.}$

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

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