Chloroacetic acid is stronger than acetic acid
Answers
Both contain COO- group which is resonance stabilize but chloroacetic acid contains one Cl group which group Negative inductive effect so it stabilizes the negative charge
Chlorine being a strong electron withdrawing group, pulls the negative charge towards itself by inductive effect so that the negative charge density on the oxygen atom is reduced, hence stabilizing the conjugate base of chloroacetic acid. While the negative charge on the oxygen atom in acetic acid is localized and the conjugate base is less stable.
This can also be viewed in the sense that chlorine increasing the overall polarity of the molecule by exerting a strong electron withdrawing effect on the bonded carbon atom. This decreases the electron density around it and it tries to compensate by pulling the C—O bond electron towards itself. In turn Oxygen atoms pulls the O—H bond electrons increasing bond polarity and decreasing bond strength. Hence chloroacetic acid finds it a lot easier to donate a proton than acetic acid.