AP Chemistry / Unit 8: Acids and Bases
8.6 Molecular Structure of Acids and Bases
Notes
Acid strength increases when the conjugate base is more stable:
- More electronegative atoms near the O–H pull electron density (e.g., $\mathrm{CCl_3COOH}$ is stronger than $\mathrm{CH_3COOH}$).
- More oxygens: $HClO_4>HClO_3>HClO_2>HClO$.
- Resonance stabilizes conjugate bases.
Practice
Which is the strongest acid?
Most oxygens spread the charge.
$\mathrm{CF_3COOH}$ is stronger than $\mathrm{CH_3COOH}$ because:
Electron-withdrawing groups.
Carboxylic acids are more acidic than alcohols because:
Negative charge spreads over two oxygens.
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