01Three AP categories
Acid–base (proton transfer), redox (electron transfer), precipitation (insoluble product). Combustion and single replacement are redox.
Classify by what moves: protons, electrons, or ions forming a solid.
02Notebook box
Oxidation numbers change → redox.
Worked example: Zn + CuSO₄ → ZnSO₄ + Cu is redox (Zn 0 → +2).