Extraction of Metals

• The Earth’s crust contains metals and metal compounds such as gold, copper, iron oxide and aluminium oxide
• 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 which are called hematite and bauxite respectively
• Unreactive metals do not have to be extracted chemically as they are often found as the uncombined element

  • 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
• The position of the metal on the reactivity series influences the method of extraction

  • Those metals placed higher up on the series (above carbon) have to be extracted using electrolysis
  • Metals lower down on the series can be extracted by heating with carbon
• The Extraction Method Depends on the Position of a Metal in the Reactivity Series

  A) electrolysis

  B) molten chloride

  C) molten oxide

  D) electricity

  E) expensive

  F) heating

  G) reducing

  H) carbon

  I) carbon monoxide

  J) pure elements

  K) heating

  L) carbon

  M) hydrogen

  
• Types of chemical changes

  • oxidation and reduction aka redox
  • thermal decomposition - using heat to break down compounds
  • exothermic and endothermic - heat given off and heat being absorbed
  • displacement reaction for metals - based on reactivity series
  • displacement reaction for non-metals - halogens
  • reversible reactions
  • precipitation
  • neutralisation
• Effect of heat on carbonate

  A) stable

  B) decompose

  C) oxide

  D) carbon dioxide

  E) heat

  F) MgO

  G) CO2

  H) heat

  I) Na2CO3

  J) heat

  K) CaO + CO2

  
• The way a metal is extracted from its ore depends on the position of the metal in the reactivity series

  A) reactive

  B) carbon

  C) electrolysis

  D) reactive

  E) carbon

  F) reduction

  G) unreactive

  H) native