Lecture Notes: Separation of Metals from Oxides

Key Concepts

Oxidation and Reduction

• Oxidation: Gaining of oxygen by a substance.
  • Example: Magnesium (Mg) reacts with oxygen (O2) to form magnesium oxide (MgO); magnesium is oxidized.
• Reduction: Loss of oxygen by a substance.
  • Example: Magnesium oxide (MgO) can be broken back into magnesium (Mg) and oxygen (O2); magnesium is reduced.

Metal Oxides

• Most metals oxidize when exposed to oxygen, forming metal oxides.
  • Example: Iron oxidizes to form iron oxide (rust) in the presence of oxygen.
• Unreactive Metals: Some metals, like gold, do not easily oxidize and can often be found in pure form.

Reduction of Metal Oxides

• The goal is to remove oxygen from metal oxides to obtain pure metals.
• Reduction with Carbon:
  • Carbon is used to take oxygen from metal oxides, forming carbon dioxide and leaving behind pure metal.
  • Example: Copper oxide (CuO) + Carbon (C) → Copper (Cu) + Carbon dioxide (CO2).
  • Copper is reduced (loses oxygen), and carbon is oxidized (gains oxygen).

Reactivity Series and Reduction Method

• Only metals less reactive than carbon can be reduced using carbon.
  • Applicable Metals: Zinc, iron, copper.
  • For more reactive metals, electrolysis is necessary.
• Reactivity Series: Positions carbon among metals to identify which metals can be reduced with carbon.

Example of Reduction: Extracting Iron

• Iron Ore (Fe2O3): Common iron oxide ore.
• Reduction Process:
  • Fe2O3 is combined with carbon and heated to extract pure iron (Fe) and form carbon dioxide.
  • Reaction: Fe2O3 + Carbon → Fe + CO2 (balanced equation needed).

Conclusion

• Direct reduction with carbon is a cost-effective method for extracting less reactive metals.
• Electrolysis is required for metals more reactive than carbon but is energy-intensive and expensive.

Closing

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