Effect of pH on volatility (odor) of organic acid Based on two assumptions:


Ionic solutes can generally be considered nonvolatile
As the pH of a solution of organic acid is increased, an increasing percentage of it is deprotonated, or ionized (Henderson-Hasselbach eqn).


I think I should be able to decrease the volatility of an organic acid solution by increasing pH. However, in several rough experiments with acetic acid, I don't observe a very strong reduction in odor with increasing pH. Even a theoretically neutralized solution retains a significant vinegar odor.

Any ideas why this might be?
Acetic acid is a weak acid (pKa 4.8). Even if you neutralize it, some acetate ions will react with water to form acetic acid and hydroxide ion (hydrolysis). Since acetic acid has a quite strong smell, we are able to detect its presence in neutral acetate solutions. If you will increase pH to a high value with a strong base, the concentration of acetic acid will drop (Le Châtelier's principle).