Careful consideration of the structure of citric acid can allow us to predict that it is the middle acid group that has the lowest pK a . This is because the hydroxyl group also bonded to the middle c...Careful consideration of the structure of citric acid can allow us to predict that it is the middle acid group that has the lowest pK a . This is because the hydroxyl group also bonded to the middle carbon is electron-withdrawing by induction, and a negative charge associated with a conjugate base will be stabilized to the greatest extent on the middle carboxylate. (Notice that in this case, the oxygen, due to its position in the molecule, is not able to exert an electron-donating resonance eff…
