Lecture Question

[605379296]

Why is trichloroacetic acid a stronger acid than acetic acid again?

[MMckinney_4H]

If you picture a flow chart for electrons based on electronegativity for trichloroacetic acid, you'd see that Chlorine would be pulling the electrons from Carbon resulting in Carbon needing the electron from the covalent bond with the other Carbon even more. From here, the Oxygens would be far less electronegative than the Carbon they're attached and would pull on the Hydrogen more than usual. This results in the covalent bond between Oxygen and Hydrogen being more polar than usual (Oxygen pulls on the electron more), making the Hydrogen more partially positive so the bond is more likely to be broken. Acetic Acid doesn't have this same polarity strength as the are no Chlorine atoms. So, Trichloroacetic acid dissociates more in water making it a stronger acid.

[LReedy_3C]

Cl is better at delocalizing the charge of the molecule. The high electronegativity of Cl stabilizes the negative charge.