Final answer:
The a-carboxy group in carboxylic acids is more acidic compared to protons in alkanes due to resonance stabilization. Carboxylic acids have a lower pKa and therefore a stronger acid character when compared to alcohols, which is due to the ability of the carboxylate anion to delocalize negative charge.
Step-by-step explanation:
The a-carboxy group in carboxylic acids is indeed acidic, though when comparing it to other types of acids, the context can shift. Carboxylic acids are characterized by the presence of both a carbonyl group (C=O) and a hydroxyl group (-OH) on the same carbon, forming the -COOH group. This structure allows carboxylic acids to readily ionize, releasing H+ into solution and making the molecule acidic.
When compared to alkanes (pKa ~60), protons that are alpha to a carbonyl group (C=O), as in aldehydes, ketones, and carboxylic acid derivatives, are indeed more acidic (pKa ~20) due to resonance stabilization. This means that the a-carboxy group in carboxylic acids is more stable when it loses a proton, this stability being provided by the possible delocalization of negative charge through resonance.
For instance, while both carboxylic acids and alcohols contain an acid proton on an -OH group, carboxylic acids are significantly stronger acids (pKa ~5) than alcohols (pKa ~16), mainly due to the said resonance stabilization of the carboxylate anion formed upon deprotonation. Basically, carboxylic acids form a more stable conjugate base, the carboxylate, upon losing a proton.