Extraction of metals and reduction

• Interactive metals such as gold are found in the earth‘s crust as the metal itself but most metals are found as compounds that require chemical reactions to extract the metal
• • Useful metals are often chemically combined with other substances forming ores
  • 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
• • In many cases, the ore is an oxide of the metal
  • Therefore, the extraction of these metals is a reduction process since oxygen is being removed
• Common examples of oxide ores are iron and aluminium ores 
• • Unreactive metals do not have to be extracted chemically as they are often found as the uncombinedelement
  • This occurs as they do not easily react with other substances due to their chemical stability
  • They are known as native metals and examples include gold and platinum which can both be mined directly from the Earth’s crust
• A metal can reduce another metal (remove oxygen) only if it is more reactive than the metal that is bonded to the oxygen.
• • The tendency to become oxidised is thus linked to how reactive a metal is and therefore its position on the reactivity series
  • Metals higher up are therefore less resistant to oxidation than the metals placed lower down which are more resistant to oxidation
• • The position of the metal on the reactivity series determines the method of extraction
  • Higher placed metals (above carbon) have to be extracted from their compounds using electrolysisas they are too reactive and cannot be reduced by carbon
• • The oxides of metals which are below carbon can be reduced by heating them with carbon 
  • The carbon removes the oxygen from the metal oxide
  • Carbon dioxide is formed as well as the metal element:

  metal oxide + carbon   →   metal   +   carbon dioxide
• Make sure you can explain why aluminium is extracted by electrolysis while iron is extracted by reduction as it is a question that often comes up.
• Extraction method table