Explain how the method of extracting a metal depends on its place in the reactivity series. Give one example, with equations, for a metal of low, medium and high reactivity.

1. 1 · Open. Metals are obtained from ores. The method depends on the metal's place in the reactivity series.
2. 2 · Low reactivity: mercury.
   • Roast cinnabar: 2HgS + 3O₂ → 2HgO + 2SO₂
   • Heat further: 2HgO → 2Hg + O₂
3. 3 · Medium reactivity: zinc.
   • Roasting: 2ZnS + 3O₂ → 2ZnO + 2SO₂, or calcination: ZnCO₃ → ZnO + CO₂
   • Reduction with carbon: ZnO + C → Zn + CO
4. 4 · High reactivity: sodium.
   • Electrolysis of molten NaCl
   • Cathode: Na⁺ + e⁻ → Na; anode: 2Cl⁻ → Cl₂ + 2e⁻
5. 5 · Draw the flow chart. Draw: ore → concentration → roasting or calcination → reduction → refining → pure metal.
6. 6 · Real life. Iron for welding rail tracks is made by reducing iron oxide with aluminium, the thermite process.
7. 7 · Close in one line. So the more reactive a metal, the harder it is to extract.

Scoring tip: Name the process (roasting, calcination, reduction, electrolysis) next to each equation. The name of the process is a separate mark.