Key facts & rules

• Reactivity series (most to least): K, Na, Ca, Mg, Al, (C), Zn, Fe, (H), Cu, Ag, Au, Pt.
• Displacement: more reactive metal displaces less reactive metal from solution.
• Iron extracted by blast furnace: iron ore + coke + limestone → iron + CO₂ (reduction of Fe₂O₃ by CO).
• Aluminium extracted by electrolysis (too reactive for carbon reduction) — very high energy cost.
• Rusting: iron + oxygen + water → iron(III) oxide (hydrated). Prevented by: painting, galvanising, electroplating, sacrificial protection.
• Galvanising: coating iron with zinc (zinc is higher in reactivity series — acts as sacrificial anode).
• Alloys: steel (Fe + C — harder), stainless steel (Fe + C + Cr + Ni), brass (Cu + Zn), bronze (Cu + Sn).