Chapter 19:Extraction of Metals

Extraction of metals

  • The Earth’s crust contains metals and metal compound
    • [ ] such as gold, copper, iron oxide and aluminium oxide
  • A metal ore is a rock that contains enough of the metal to make it worthwhile extracting
  • They have to be extracted from their ores through processes
    • [ ] such as electrolysis, using a blast furnace or by reacting with more reactive material
  • Obtaining from ores is a reduction process
  • Middle order metals like iron are extracted by reducing with carbon in the blast furnace.
    • [ ] Blast furnace uses three raw materials (coke ,limestone and iron) .
    • [ ] Coke burns to produce carbon monoxide and heat producing Pig Iron-
  • Iron ore+ carbon monoxide ➡️iron + carbon dioxide
  • Limestone ➡️lime + carbon dioxide
  • Lime + sand ➡️calcium silicate
  • Aluminium ore is called bauxite .
    • [ ] The bauxite is purified to produce aluminium oxide.
    • [ ] The extraction is done by electrolysis.
    • [ ] The ions in the aluminium oxide must be free to move so that electricity can pass through it

Rusting

  • Reaction of iron with air /oxygen and water to form rust.
  • Rusting is a redox process.
  • You can prevent it by panting or coating with oil or grease, metal or electroplating.

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