The acidity of carboxylic acids increased by electron-withdrawing groups (EWG).

• Acetic Acid ($C{H}_{3}COOH$): The methyl group has a $+I$ effect, which slightly destabilizes the acetate ion.
• Chloroacetic Acid ($Cl-C{H}_{2}COOH$): Chlorine is highly electronegative and exerts a strong Inductive Effect ($-I$).
• Stability: The $-I$ effect pulls electron density away from the carboxylate group ($CO{O}^{-}$), dispersing the negative charge and stabilizing the conjugate base.
• Result: Chloroacetic acid releases a proton more readily, making it more acidic.