Trichloroacetic acid vs acetic acid

[Aren_Kasparian_1G]

Can someone explain again why trichloroacetic acid is a stronger acid compared to acetic acid?

[Devika Nair 2D]

The chlorines attached to the central carbon in trichloroacetic acid have a much higher electronegativity than the hydrogens attached to the central carbon in acetic acid. When the hydrogen is lost from the carboxyl group in both the acids, the oxygen suddenly has a negative charge (three lone pairs and one bond, formal charge of -1). This charge is unstable. What the highly electronegative chlorines do in the trichloroacetic acid is attract the negative charge, reducing the charge on the oxygen, and stabilizing the anion. The hydrogens can't do this. So the trichloroacetic acid is more stable and thus stronger.

[sgarza]

Chlorine, which has a high electronegativity or electron withdrawing ability, is able to counteract the dipole of the oxygen in the COOH group and the two dipoles essentially cancel each other out. The resulting structure is more stable in trichloroacetic acid versus acetic acid, so it's more likely that trichloroacetic acid will give off a proton to form its negatively charged anion.