01Why some acids are stronger
An acid is stronger when its conjugate base is more stable. Electronegative atoms nearby pull electron density and stabilize the negative charge (inductive effect). Resonance spreads it out.
For oxyacids, more O atoms → stronger: HClO₄ > HClO₃ > HClO₂ > HClO. For binary acids down a group, bond length rules: HI > HBr > HCl > HF.
02Notebook box
Stable conjugate base = strong acid.
Worked example: CCl₃COOH is stronger than CH₃COOH — Cl atoms withdraw electron density, stabilizing the carboxylate.