Liberté. Egalité. Acidité.

Ever been confused about the line in the spec...


"...appreciate that carboxylic acids liberate CO2 from carbonates and hydrogen carbonates but phenol does not..."

Appreciate?
Liberate?

In plain English, know that carboxylic acids give off carbon dioxide with carbonates and hydrogen carbonates but phenol doesn't.

That's better,

Lets first establish the reason that carboxylic acids give off CO2 with carbonates and phenols don't is because carboxylic acids are more acidic.

Want to know why?

It comes down to the stability of the thing (anion) formed when the proton has gone. If the anion formed is stable then the proton will happily leave. 

The more stable it is, the more likely the proton is to leave, the more acidic the molecule.

Lets look at the contenders

When carboxylic acids give off a proton they form the carboxylate ion which is stable because the negative charge (lone pairs) forms a miniature delocalised system across the two oxygens, like this...

When phenols give off a proton they form the phenoxide ion which is stable because the negative charge (lone pairs) becomes part of the benzene delocalised system, like this...

The delocalisation is more effective in carboxylic acids then phenol so carboxylic acids are more acidic.

C'est très simple.

Liberté
Egalité
Acidité