Reactivity Series

• Reactivity series — K, Na, Ca, Mg, Al, Zn, Fe, Pb, (H), Cu, Hg, Ag, Au (mnemonic: Please Stop Calling Me A Cute Zebra...).
• More reactive metal displaces less reactive from salt solution.
• Corrosion — oxidation of metals; prevention: painting, galvanising, alloying.
• Galvanisation — zinc coating on iron prevents rusting.
• Thermit reaction (Fe₂O₃ + Al) — highly exothermic.

1. Top metals — K, Na react violently with cold water.
2. Mg, Al, Zn, Fe — react with dilute acids to give H₂ (Fe needs catalyst sometimes).
3. Below hydrogen — Cu, Ag, Au do not displace H from dilute acids.
4. Displacement — Zn + CuSO₄ → ZnSO₄ + Cu (Zn above Cu).
5. No reaction — Cu + ZnSO₄ (Cu below Zn).
6. Rusting — Fe + O₂ + H₂O → hydrated Fe₂O₃; needs oxygen and water.
7. Prevention — oil/paint (barrier), galvanisation (sacrificial Zn), chromium plating.
8. Sacrificial protection — Mg blocks on ships protect iron hull.
9. Thermit — 2Al + Fe₂O₃ → 2Fe + Al₂O₃ + heat; welding rails.
10. Anodising — thick oxide on aluminium resists corrosion.

Will iron displace copper from CuSO₄ solution?

Step 1 — Activity series: Fe above Cu.
Step 2 — Fe + CuSO₄ → FeSO₄ + Cu (displacement occurs).
Step 3 — Blue solution fades; brown Cu deposits on iron.
Step 4 — Reverse (Cu + FeSO₄) — no reaction.
Conclusion: more reactive Fe displaces Cu.

• Memorising series but not applying to predict reactions.
• Misconception: all metals rust (rust specific to iron).
• Thinking galvanised iron rusts same as bare iron (Zn protects first).
• Placing hydrogen incorrectly in series.
• Forgetting both O₂ and H₂O needed for rusting.

• Write reactivity order for Na, Fe, Cu, Zn (most to least reactive).
• Why does zinc coating prevent rusting?
• Will Ag react with ZnSO₄? Why?
• Name two methods to prevent corrosion.

Open the Practice tab for graded questions on Reactivity Series.