Chapter 16 - Metal Extraction

• Metals can be extracted from their ores
• Electrolysis


  1. Expensive

  2. Too much energy needed
• Reducing with cabon


  1. Removal of Oxygen from metal

  2. Less expensive

  3. Not pure
• Metals extracted by electrolysis

  • K
  • Na
  • Ca
  • Mg
  • Al
• Hall- Héroult process


  Al extraction
• ore=bauxite (Al2o3)
• Metals extracted by reduction with carbon


  • In
  • Fe
  • Sn
  • Pb
  • Cu
  • Ag
  • Au
  • Pt
• Electrolysis/Reduction with carbon


  1. Impurities are removed by roasting + (NaOH) base

  2. Filtering
• Bauxite (mp) 2000°C
• Reducing with carbon


  1. Add molten cryolite

  2. To reduce melting point

  3. To increase electrical conductivity

  4. As a solvent
• In iron extraction, Gases produced during the extraction: CO, CO2, N2
• Anode has to be replaced regularly
• In Al extraction, O2 is produced at the anode, reacts with carbon anode, CO2 is produced
• Iron extraction


  1. Limestone, coke, hematite

  2. Waste gas: CO, CO2, N2

  3. Molten slag

  4. Molten iron
• Major impurities: SiO2 (acidic oxide)
• pH = -log [H+]
• Stainless steel: Fe, Ni, Cr
• Metals with different reactivities

  Produce electricity due to chemical reaction
• The longer the reactivity difference between metals, the higher the voltage
• Hydrogen-Oxygen fuel cell


  1. H2 at anode, O2 at cathode

  2. PEM (Proton exchange membrane)

  3. 2H2 + O2 -> 2H2O
• Advantages of hydrogen fuel


  • More efficient
  • No need to recharge
  • Produce a large amount of energy
  • Water is the only product, no CO2 emission, no pollution
• Disadvantages of H2 fuel

  • Difficult to produce, store, transport
  • Explosive
  • Expensive