| K Na Li Ca Mg Al | K₂O Na₂O Li₂O CaO MgO Al₂O₃ (bauxite) (dissolved in cryolite) | electrolysis • decomposition by electricity • molten oxide → molten metal + O₂ | expensive: huge amount of electricity
✓ reduction ✓decomposition | | --- | --- | --- | --- | | Zn Fe Pb Cu | ZnO Fe₂O₃ (haematite) PbO CuO | heating with carbon • carbon: reducing agent ◦ carbon monoxide formed
• oxide + C → molten metal + CO → oxide + CO → molten metal + CO₂ | combustion of carbon • exothermic → high temp.
✓ reduction ✗decomposition | | Hg Ag | HgO Ag₂O | thermal decomposition • oxide → metal + O₂ | ✓ reduction ✓decomposition |